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Created February 17, 2018 02:01
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Respec schema.org transformations
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json-ld.html
<!DOCTYPE html><html lang="en" typeof="schema:TechArticle w3p:WD" prefix="w3p: http://www.w3.org/2001/02pd/rec54#"><head><meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"><meta http-equiv="content-type" content="text/html; charset=UTF-8"><meta name="generator" content="ReSpec Developer Edition"><meta lang="" property="schema:inLanguage" content="en"><style>/* --- EXAMPLES --- */
div.example-title {
min-width: 7.5em;
color: #b9ab2d;
}
div.example-title span {
text-transform: uppercase;
}
aside.example, div.example, div.illegal-example {
padding: 0.5em;
margin: 1em 0;
position: relative;
clear: both;
}
div.illegal-example { color: red }
div.illegal-example p { color: black }
aside.example, div.example {
padding: .5em;
border-left-width: .5em;
border-left-style: solid;
border-color: #e0cb52;
background: #fcfaee;
}
aside.example div.example {
border-left-width: .1em;
border-color: #999;
background: #fff;
}
aside.example div.example div.example-title {
color: #999;
}
</style><style>/* --- ISSUES/NOTES --- */
div.issue-title, div.note-title , div.ednote-title, div.warning-title {
padding-right: 1em;
min-width: 7.5em;
color: #b9ab2d;
}
div.issue-title { color: #e05252; }
div.note-title, div.ednote-title { color: #2b2; }
div.warning-title { color: #f22; }
div.issue-title span, div.note-title span, div.ednote-title span, div.warning-title span {
text-transform: uppercase;
}
div.note, div.issue, div.ednote, div.warning {
margin-top: 1em;
margin-bottom: 1em;
}
.note > p:first-child, .ednote > p:first-child, .issue > p:first-child, .warning > p:first-child { margin-top: 0 }
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span.note, span.ednote, span.issue, span.warning { padding: .1em .5em .15em; }
.issue {
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background: #fbe9e9;
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margin: 0 0.35em 0.25em -1.6em;
vertical-align: middle;
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font-style: normal;
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.permalink a, .permalink a:link, .permalink a:visited, .permalink a:hover, .permalink a:focus, .permalink a:active {
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text-decoration:none;
font-weight: bold;
color:#666 !important;
}
.permalink abbr {
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</style>
<title>JSON-LD 1.1</title>
<style type="text/css">
.hl-bold { font-weight: bold; color: #0a3; }
.comment { color: #999; }
table, thead, tr, td { padding: 5px; border-width: 1px; border-spacing: 0px; border-style: solid; border-collapse: collapse; }
table.example {width: 100%;}
.hl-bold {
font-weight: bold;
color: #0a3;
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.comment {
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.changed {
background-color: rgb(215, 238, 197);
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</style>
<style id="respec-mainstyle">/*****************************************************************
* ReSpec 3 CSS
* Robin Berjon - http://berjon.com/
*****************************************************************/
/* Override code highlighter background */
.hljs {
background: transparent !important;
}
/* --- INLINES --- */
h1 abbr,
h2 abbr,
h3 abbr,
h4 abbr,
h5 abbr,
h6 abbr,
a abbr {
border: none;
}
dfn {
font-weight: bold;
}
a.internalDFN {
color: inherit;
border-bottom: 1px solid #99c;
text-decoration: none;
}
a.externalDFN {
color: inherit;
border-bottom: 1px dotted #ccc;
text-decoration: none;
}
a.bibref {
text-decoration: none;
}
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font-style: normal;
}
code {
color: #c83500;
}
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color: inherit;
}
/* --- TOC --- */
.toc a,
.tof a {
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}
a .secno,
a .figno {
color: #000;
}
ul.tof,
ol.tof {
list-style: none outside none;
}
.caption {
margin-top: 0.5em;
font-style: italic;
}
/* --- TABLE --- */
table.simple {
border-spacing: 0;
border-collapse: collapse;
border-bottom: 3px solid #005a9c;
}
.simple th {
background: #005a9c;
color: #fff;
padding: 3px 5px;
text-align: left;
}
.simple th[scope="row"] {
background: inherit;
color: inherit;
border-top: 1px solid #ddd;
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.simple td {
padding: 3px 10px;
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background: #f0f6ff;
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/* --- DL --- */
.section dd > p:first-child {
margin-top: 0;
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.section dd > p:last-child {
margin-bottom: 0;
}
.section dd {
margin-bottom: 1em;
}
.section dl.attrs dd,
.section dl.eldef dd {
margin-bottom: 0;
}
#issue-summary > ul,
.respec-dfn-list {
column-count: 2;
}
#issue-summary li,
.respec-dfn-list li {
list-style: none;
}
details.respec-tests-details {
margin-left: 1em;
display: inline-block;
vertical-align: top;
}
details.respec-tests-details > * {
padding-right: 2em;
}
details.respec-tests-details[open] {
z-index: 999999;
position: absolute;
border: thin solid #cad3e2;
border-radius: .3em;
background-color: white;
padding-bottom: .5em;
}
details.respec-tests-details[open] > summary {
border-bottom: thin solid #cad3e2;
padding-left: 1em;
margin-bottom: 1em;
line-height: 2em;
}
details.respec-tests-details > ul {
width: 100%;
margin-top: -0.3em;
}
details.respec-tests-details > li {
padding-left: 1em;
}
@media print {
.removeOnSave {
display: none;
}
}
</style><style>/*
github.com style (c) Vasily Polovnyov <vast@whiteants.net>
*/
.hljs {
display: block;
overflow-x: auto;
padding: 0.5em;
color: #333;
background: #f8f8f8;
}
.hljs-comment,
.hljs-quote {
color: #998;
font-style: italic;
}
.hljs-keyword,
.hljs-selector-tag,
.hljs-subst {
color: #333;
font-weight: bold;
}
.hljs-number,
.hljs-literal,
.hljs-variable,
.hljs-template-variable,
.hljs-tag .hljs-attr {
color: #008080;
}
.hljs-string,
.hljs-doctag {
color: #d14;
}
.hljs-title,
.hljs-section,
.hljs-selector-id {
color: #900;
font-weight: bold;
}
.hljs-subst {
font-weight: normal;
}
.hljs-type,
.hljs-class .hljs-title {
color: #458;
font-weight: bold;
}
.hljs-tag,
.hljs-name,
.hljs-attribute {
color: #000080;
font-weight: normal;
}
.hljs-regexp,
.hljs-link {
color: #009926;
}
.hljs-symbol,
.hljs-bullet {
color: #990073;
}
.hljs-built_in,
.hljs-builtin-name {
color: #0086b3;
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font-weight: bold;
}
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background: #dfd;
}
.hljs-emphasis {
font-style: italic;
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font-weight: bold;
}
</style><link rel="stylesheet" href="https://www.w3.org/StyleSheets/TR/2016/W3C-WD"><link rel="canonical" href="https://www.w3.org/TR/json-ld11cg/"><script id="initialUserConfig" type="application/json">{
"localBiblio": {
"JSON-LD11CG": {
"title": "JSON-LD 1.1",
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}</script><meta name="description" content="JSON is a useful data serialization and messaging format.
This specification defines JSON-LD, a JSON-based format to serialize
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JSON to JSON-LD.
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<body aria-busy="false" class="h-entry"><div class="head">
<p><a href="https://www.w3.org/" class="logo">
<img alt="W3C" width="72" height="48" src="https://www.w3.org/StyleSheets/TR/2016/logos/W3C">
</a><!--_hyper: 1044231688;--></p>
<h1 class="title p-name" id="title" property="schema:name">JSON-LD 1.1</h1>
<h2 property="schema:alternativeHeadline" id="subtitle">A JSON-based Serialization for Linked Data</h2>
<h2 id="w3c-working-draft-17-february-2018"><abbr title="World Wide Web Consortium">W3C</abbr> Working Draft <time property="schema:datePublished" class="dt-published" datetime="2018-02-17">17 February 2018</time></h2>
<dl>
<dt>This version:</dt>
<dd><a class="u-url" href="https://www.w3.org/TR/2018/WD-json-ld11cg-20180217/">https://www.w3.org/TR/2018/WD-json-ld11cg-20180217/</a></dd>
<dt>Latest published version:</dt>
<dd><a href="https://www.w3.org/TR/json-ld11cg/">https://www.w3.org/TR/json-ld11cg/</a></dd>
<dt>Latest editor's draft:</dt>
<dd><a href="https://json-ld.org/spec/latest/json-ld/">https://json-ld.org/spec/latest/json-ld/</a></dd>
<dt>Previous version:</dt>
<dd><a rel="schema:isBasedOn" href="https://www.w3.org/TR/2014/REC-json-ld11cg-20140116/">https://www.w3.org/TR/2014/REC-json-ld11cg-20140116/</a></dd>
<dt>Editor:</dt>
<dd class="p-author h-card vcard" property="schema:editor" typeof="schema:Person" data-editor-id="44770"><meta property="schema:name" content="Gregg Kellogg"><a class="u-url url p-name fn" property="schema:url" href="http://greggkellogg.net/">Gregg Kellogg</a>, <span property="schema:worksFor" typeof="schema:Organization"><meta property="schema:name" content="Spec-Ops"><a property="schema:url" class="p-org org h-org h-card" href="https://spec-ops.io/">Spec-Ops</a></span> (v1.0 and v1.1)
</dd>
<dt>Authors:</dt>
<dd class="p-author h-card vcard" property="schema:contributor" typeof="schema:Person"><meta property="schema:name" content="Manu Sporny"><a class="u-url url p-name fn" property="schema:url" href="http://manu.sporny.org/">Manu Sporny</a>, <span property="schema:worksFor" typeof="schema:Organization"><meta property="schema:name" content="Digital Bazaar"><a property="schema:url" class="p-org org h-org h-card" href="https://digitalbazaar.com/">Digital Bazaar</a></span> (v1.0)
</dd>
<dd class="p-author h-card vcard" property="schema:contributor" typeof="schema:Person"><meta property="schema:name" content="Dave Longley"><a class="u-url url p-name fn" property="schema:url" href="https://digitalbazaar.com/">Dave Longley</a>, <span property="schema:worksFor" typeof="schema:Organization"><meta property="schema:name" content="Digital Bazaar"><a property="schema:url" class="p-org org h-org h-card" href="https://digitalbazaar.com/">Digital Bazaar</a></span> (v1.0)
</dd>
<dd class="p-author h-card vcard" property="schema:contributor" typeof="schema:Person" data-editor-id="44770"><meta property="schema:name" content="Gregg Kellogg"><a class="u-url url p-name fn" property="schema:url" href="http://greggkellogg.net/">Gregg Kellogg</a>, <span property="schema:worksFor" typeof="schema:Organization"><meta property="schema:name" content="Spec-Ops"><a property="schema:url" class="p-org org h-org h-card" href="https://spec-ops.io/">Spec-Ops</a></span> (v1.0 and v1.1)
</dd>
<dd class="p-author h-card vcard" property="schema:contributor" typeof="schema:Person" data-editor-id="44770"><meta property="schema:name" content="Markus Lanthaler"><a class="u-url url p-name fn" property="schema:url" href="http://www.markus-lanthaler.com/">Markus Lanthaler</a>, <span property="schema:worksFor" typeof="schema:Organization"><meta property="schema:name" content="Graz University of Technology"><a property="schema:url" class="p-org org h-org h-card" href="http://www.tugraz.at/">Graz University of Technology</a></span> (v1.0)
</dd>
<dd class="p-author h-card vcard" property="schema:contributor" typeof="schema:Person" data-editor-id="44770"><meta property="schema:name" content="Niklas Lindström"><a class="u-url url p-name fn" property="schema:url" href="http://neverspace.net/">Niklas Lindström</a> (v1.0)
</dd>
<dt>Participate:</dt>
<dd>
<a href="https://github.com/json-ld/json-ld.org">
GitHub json-ld/json-ld.org
</a>
</dd>
<dd>
<a href="https://github.com/json-ld/json-ld.org/issues/">
File a bug
</a>
</dd>
<dd>
<a href="https://github.com/json-ld/json-ld.org/commits/gh-pages">
Commit history
</a>
</dd>
<dd>
<a href="https://github.com/json-ld/json-ld.org/pulls/">
Pull requests
</a>
</dd>
</dl>
<p class="copyright">
<a href="https://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> ©
2010-2018
<a href="https://www.w3.org/"><abbr property="schema:publisher" content="World Wide Web Consortium" title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup>
(<a href="https://www.csail.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>,
<a href="https://www.ercim.eu/"><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>,
<a href="https://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</a>).
<abbr title="World Wide Web Consortium">W3C</abbr> <a href="https://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a href="https://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and
<a rel="license" href="https://www.w3.org/Consortium/Legal/2015/copyright-software-and-document">permissive document license</a>
rules apply.
</p>
<hr title="Separator for header">
</div>
<section id="abstract" class="introductory" property="schema:description"><h2 id="abstract-0">Abstract</h2>
<p>JSON is a useful data serialization and messaging format.
This specification defines JSON-LD, a JSON-based format to serialize
Linked Data. The syntax is designed to easily integrate into deployed
systems that already use JSON, and provides a smooth upgrade path from
JSON to JSON-LD.
It is primarily intended to be a way to use Linked Data in Web-based
programming environments, to build interoperable Web services, and to
store Linked Data in JSON-based storage engines.</p>
</section>
<section id="sotd" class="introductory"><h2 id="status-of-this-document">Status of This Document</h2>
<p>
<em>This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current <abbr title="World Wide Web Consortium">W3C</abbr> publications and the latest revision of this technical report can be found in the <a href="https://www.w3.org/TR/"><abbr title="World Wide Web Consortium">W3C</abbr> technical reports index</a> at https://www.w3.org/TR/.</em>
</p>
<p>This document has been developed by the
<a href="https://www.w3.org/community/json-ld/">JSON for Linking Data <abbr title="World Wide Web Consortium">W3C</abbr> Community Group</a>
as an update to the 1.0 recommendation [<cite><a class="bibref" href="#bib-JSON-LD">JSON-LD</a></cite>] developed
by the <a href="https://www.w3.org/2011/rdf-wg/wiki/Main_Page">RDF Working Group</a>.
The specification has undergone
significant development, review, and changes during the course of several years.</p>
<p>There are several independent
<a href="https://json-ld.org/test-suite/reports/">interoperable implementations</a> of
this specification, a test suite [<cite><a class="bibref" href="#bib-JSON-LD-TESTS">JSON-LD-TESTS</a></cite>] and a
<a href="https://json-ld.org/playground/">live JSON-LD playground</a> that is capable
of demonstrating the features described in this document.</p>
<p>
This document was published by the <a href="https://www.w3.org/community/json-ld/">JSON for Linking Data <abbr title="World Wide Web Consortium">W3C</abbr> Community Group</a> as a Working Draft.
This document is intended to become a <abbr title="World Wide Web Consortium">W3C</abbr> Recommendation.
Comments regarding this document are welcome. Please send them to
<a href="mailto:public-linked-json@w3.org">public-linked-json@w3.org</a>
(<a href="mailto:public-linked-json-request@w3.org?subject=subscribe">subscribe</a>,
<a href="https://lists.w3.org/Archives/Public/public-linked-json/">archives</a>).
</p>
<p>
Publication as a Working Draft does not imply endorsement by the <abbr title="World Wide Web Consortium">W3C</abbr>
Membership. This is a draft document and may be updated, replaced or obsoleted by other
documents at any time. It is inappropriate to cite this document as other than work in
progress.
</p>
<p>
This document was produced by
a group
operating under the
<a id="sotd_patent" property="w3p:patentRules" href="https://www.w3.org/Consortium/Patent-Policy/"><abbr title="World Wide Web Consortium">W3C</abbr> Patent Policy</a>.
<abbr title="World Wide Web Consortium">W3C</abbr> maintains a <a href="" rel="disclosure">public list of any patent
disclosures</a>
made in connection with the deliverables of
the group; that page also includes
instructions for disclosing a patent. An individual who has actual knowledge of a patent
which the individual believes contains
<a href="https://www.w3.org/Consortium/Patent-Policy/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with
<a href="https://www.w3.org/Consortium/Patent-Policy/#sec-Disclosure">section
6 of the <abbr title="World Wide Web Consortium">W3C</abbr> Patent Policy</a>.
</p>
<p>This document is governed by the <a id="w3c_process_revision" href="https://www.w3.org/2018/Process-20180201/">1 February 2018 <abbr title="World Wide Web Consortium">W3C</abbr> Process Document</a>.
</p>
<section typeof="schema:Chapter" resource="#set-of-documents" property="schema:hasPart">
<h3 id="set-of-documents">Set of Documents</h3>
<p>This document is one of three JSON-LD 1.1 Recommendations produced by the
<a href="https://www.w3.org/community/json-ld/">JSON for Linking Data <abbr title="World Wide Web Consortium">W3C</abbr> Community Group</a>:</p>
<ul>
<li><a href="https://json-ld.org/spec/latest/json-ld/">JSON-LD 1.1</a></li>
<li><a href="https://json-ld.org/spec/latest/json-ld-api/">JSON-LD 1.1 Processing Algorithms and API</a></li>
<li><a href="https://json-ld.org/spec/latest/json-ld-api/">JSON-LD 1.1 Framing</a></li>
</ul>
</section>
</section><nav id="toc"><h2 class="introductory" id="table-of-contents">Table of Contents</h2><ol class="toc"><li class="tocline"><a href="#introduction" class="tocxref"><span class="secno">1. </span>Introduction</a><ol class="toc"><li class="tocline"><a href="#how-to-read-this-document" class="tocxref"><span class="secno">1.1 </span>How to Read this Document</a></li><li class="tocline"><a href="#contributing" class="tocxref"><span class="secno">1.2 </span>Contributing</a></li><li class="tocline"><a href="#terminology" class="tocxref"><span class="secno">1.3 </span>Terminology</a></li><li class="tocline"><a href="#typographical-conventions" class="tocxref"><span class="secno">1.4 </span>Typographical conventions</a></li><li class="tocline"><a href="#design-goals-and-rationale" class="tocxref"><span class="secno">1.5 </span>Design Goals and Rationale</a></li><li class="tocline"><a href="#data-model-overview" class="tocxref"><span class="secno">1.6 </span>Data Model Overview</a></li><li class="tocline"><a href="#syntax-tokens-and-keywords" class="tocxref"><span class="secno">1.7 </span>Syntax Tokens and Keywords</a></li></ol></li><li class="tocline"><a href="#conformance" class="tocxref"><span class="secno">2. </span>Conformance</a></li><li class="tocline"><a href="#basic-concepts" class="tocxref"><span class="secno">3. </span>Basic Concepts</a><ol class="toc"><li class="tocline"><a href="#the-context" class="tocxref"><span class="secno">3.1 </span>The Context</a></li><li class="tocline"><a href="#iris" class="tocxref"><span class="secno">3.2 </span>IRIs</a></li><li class="tocline"><a href="#node-identifiers" class="tocxref"><span class="secno">3.3 </span>Node Identifiers</a></li><li class="tocline"><a href="#specifying-the-type" class="tocxref"><span class="secno">3.4 </span>Specifying the Type</a></li></ol></li><li class="tocline"><a href="#advanced-concepts" class="tocxref"><span class="secno">4. </span>Advanced Concepts</a><ol class="toc"><li class="tocline"><a href="#json-ld-1-1-processing-mode" class="tocxref"><span class="secno">4.1 </span>JSON-LD 1.1 Processing Mode</a></li><li class="tocline"><a href="#base-iri" class="tocxref"><span class="secno">4.2 </span>Base <abbr title="Internationalized Resource Identifier">IRI</abbr></a></li><li class="tocline"><a href="#default-vocabulary" class="tocxref"><span class="secno">4.3 </span>Default Vocabulary</a></li><li class="tocline"><a href="#compact-iris" class="tocxref"><span class="secno">4.4 </span>Compact IRIs</a></li><li class="tocline"><a href="#typed-values" class="tocxref"><span class="secno">4.5 </span>Typed Values</a></li><li class="tocline"><a href="#type-coercion" class="tocxref"><span class="secno">4.6 </span>Type Coercion</a></li><li class="tocline"><a href="#embedding" class="tocxref"><span class="secno">4.7 </span>Embedding</a></li><li class="tocline"><a href="#advanced-context-usage" class="tocxref"><span class="secno">4.8 </span>Advanced Context Usage</a></li><li class="tocline"><a href="#interpreting-json-as-json-ld" class="tocxref"><span class="secno">4.9 </span>Interpreting JSON as JSON-LD</a></li><li class="tocline"><a href="#string-internationalization" class="tocxref"><span class="secno">4.10 </span>String Internationalization</a></li><li class="tocline"><a href="#iri-expansion-within-a-context" class="tocxref"><span class="secno">4.11 </span><abbr title="Internationalized Resource Identifier">IRI</abbr> Expansion within a Context</a></li><li class="tocline"><a href="#sets-and-lists" class="tocxref"><span class="secno">4.12 </span>Sets and Lists</a></li><li class="tocline"><a href="#reverse-properties" class="tocxref"><span class="secno">4.13 </span>Reverse Properties</a></li><li class="tocline"><a href="#scoped-contexts" class="tocxref"><span class="secno">4.14 </span>Scoped Contexts</a></li><li class="tocline"><a href="#named-graphs" class="tocxref"><span class="secno">4.15 </span>Named Graphs</a><ol class="toc"></ol></li><li class="tocline"><a href="#identifying-blank-nodes" class="tocxref"><span class="secno">4.16 </span>Identifying Blank Nodes</a></li><li class="tocline"><a href="#aliasing-keywords" class="tocxref"><span class="secno">4.17 </span>Aliasing Keywords</a></li><li class="tocline"><a href="#data-indexing" class="tocxref"><span class="secno">4.18 </span>Data Indexing</a></li><li class="tocline"><a href="#named-graph-indexing" class="tocxref"><span class="secno">4.19 </span>Named Graph Indexing</a></li><li class="tocline"><a href="#language-indexing" class="tocxref"><span class="secno">4.20 </span>Language Indexing</a></li><li class="tocline"><a href="#node-identifier-indexing" class="tocxref"><span class="secno">4.21 </span>Node Identifier Indexing</a></li><li class="tocline"><a href="#named-graph-indexing-by-identifier" class="tocxref"><span class="secno">4.22 </span>Named Graph Indexing by Identifier</a></li><li class="tocline"><a href="#node-type-indexing" class="tocxref"><span class="secno">4.23 </span>Node Type Indexing</a></li><li class="tocline"><a href="#nested-properties" class="tocxref"><span class="secno">4.24 </span>Nested Properties</a></li><li class="tocline"><a href="#expanded-document-form" class="tocxref"><span class="secno">4.25 </span>Expanded Document Form</a></li><li class="tocline"><a href="#compacted-document-form" class="tocxref"><span class="secno">4.26 </span>Compacted Document Form</a></li><li class="tocline"><a href="#flattened-document-form" class="tocxref"><span class="secno">4.27 </span>Flattened Document Form</a></li><li class="tocline"><a href="#embedding-json-ld-in-html-documents" class="tocxref"><span class="secno">4.28 </span>Embedding JSON-LD in HTML Documents</a></li></ol></li><li class="tocline"><a href="#data-model" class="tocxref"><span class="secno">5. </span>Data Model</a></li><li class="tocline"><a href="#json-ld-grammar" class="tocxref"><span class="secno">6. </span>JSON-LD Grammar</a><ol class="toc"><li class="tocline"><a href="#terms-0" class="tocxref"><span class="secno">6.1 </span>Terms</a></li><li class="tocline"><a href="#node-objects" class="tocxref"><span class="secno">6.2 </span>Node Objects</a></li><li class="tocline"><a href="#graph-objects" class="tocxref"><span class="secno">6.3 </span>Graph Objects</a></li><li class="tocline"><a href="#value-objects" class="tocxref"><span class="secno">6.4 </span>Value Objects</a></li><li class="tocline"><a href="#lists-and-sets" class="tocxref"><span class="secno">6.5 </span>Lists and Sets</a></li><li class="tocline"><a href="#language-maps" class="tocxref"><span class="secno">6.6 </span>Language Maps</a></li><li class="tocline"><a href="#index-maps" class="tocxref"><span class="secno">6.7 </span>Index Maps</a></li><li class="tocline"><a href="#id-maps" class="tocxref"><span class="secno">6.8 </span>Id Maps</a></li><li class="tocline"><a href="#type-maps" class="tocxref"><span class="secno">6.9 </span>Type Maps</a></li><li class="tocline"><a href="#property-nesting" class="tocxref"><span class="secno">6.10 </span>Property Nesting</a></li><li class="tocline"><a href="#context-definitions" class="tocxref"><span class="secno">6.11 </span>Context Definitions</a></li></ol></li><li class="tocline"><a href="#relationship-to-rdf" class="tocxref"><span class="secno">7. </span>Relationship to RDF</a><ol class="toc"><li class="tocline"><a href="#serializing-deserializing-rdf" class="tocxref"><span class="secno">7.1 </span>Serializing/Deserializing RDF</a></li></ol></li><li class="tocline"><a href="#changes-since-1-0-recommendation-of-16-january-2014" class="tocxref"><span class="secno">A. </span>Changes since 1.0 Recommendation of 16 January 2014</a></li><li class="tocline"><a href="#open-issues" class="tocxref"><span class="secno">B. </span>Open Issues</a></li><li class="tocline"><a href="#relationship-to-other-linked-data-formats" class="tocxref"><span class="secno">C. </span>Relationship to Other Linked Data Formats</a><ol class="toc"><li class="tocline"><a href="#turtle" class="tocxref"><span class="secno">C.1 </span>Turtle</a><ol class="toc"></ol></li><li class="tocline"><a href="#rdfa" class="tocxref"><span class="secno">C.2 </span>RDFa</a></li><li class="tocline"><a href="#microformats" class="tocxref"><span class="secno">C.3 </span>Microformats</a></li><li class="tocline"><a href="#microdata" class="tocxref"><span class="secno">C.4 </span>Microdata</a></li></ol></li><li class="tocline"><a href="#iana-considerations" class="tocxref"><span class="secno">D. </span>IANA Considerations</a></li><li class="tocline"><a href="#security" class="tocxref"><span class="secno">E. </span>Security Considerations</a></li><li class="tocline"><a href="#acknowledgements" class="tocxref"><span class="secno">F. </span>Acknowledgements</a></li><li class="tocline"><a href="#references" class="tocxref"><span class="secno">G. </span>References</a><ol class="toc"><li class="tocline"><a href="#normative-references" class="tocxref"><span class="secno">G.1 </span>Normative references</a></li><li class="tocline"><a href="#informative-references" class="tocxref"><span class="secno">G.2 </span>Informative references</a></li></ol></li></ol></nav>
<section class="informative" id="introduction" typeof="schema:Chapter" resource="#introduction" property="schema:hasPart">
<!--OddPage--><h2 id="x1-introduction"><span class="secno">1. </span>Introduction&nbsp;<span class="permalink"><a href="#introduction" aria-label="Permalink for 1. Introduction" title="Permalink for 1. Introduction"><span property="schema:name" content="1. Introduction">§</span></a></span></h2><p><em>This section is non-normative.</em></p>
<p>Linked Data [<cite><a class="bibref" href="#bib-LINKED-DATA">LINKED-DATA</a></cite>] is a way to create a network of
standards-based machine interpretable data across different documents and
Web sites. It allows an application to start at one piece of Linked Data,
and follow embedded links to other pieces of Linked Data that are hosted on
different sites across the Web.</p>
<p>JSON-LD is a lightweight syntax to serialize Linked Data in
JSON [<cite><a class="bibref" href="#bib-RFC7159">RFC7159</a></cite>]. Its design allows existing JSON to be interpreted as
Linked Data with minimal changes. JSON-LD is primarily intended to be a
way to use Linked Data in Web-based programming environments, to build
interoperable Web services, and to store Linked Data in JSON-based storage engines. Since
JSON-LD is 100% compatible with JSON, the large number of JSON parsers and libraries
available today can be reused. In addition to all the features JSON provides,
JSON-LD introduces:</p>
<ul>
<li>a universal identifier mechanism for <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON objects</a>
via the use of <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>,</li>
<li>a way to disambiguate keys shared among different JSON documents by mapping
them to <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> via a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>,</li>
<li>a mechanism in which a value in a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> may refer
to a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> on a different site on the Web,</li>
<li>the ability to annotate <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a> with their language,</li>
<li>a way to associate datatypes with values such as dates and times,</li>
<li>and a facility to express one or more directed graphs, such as a social
network, in a single document.</li>
</ul>
<p>
JSON-LD is designed to be usable directly as JSON, with no knowledge of RDF
[<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>]. It is also designed to be usable as RDF, if desired, for
use with other Linked Data technologies like SPARQL. Developers who
require any of the facilities listed above or need to serialize an RDF Graph
or <a href="#dfn-dataset" class="internalDFN" data-link-type="dfn">RDF Dataset</a> in a JSON-based syntax will find JSON-LD of interest. People
intending to use JSON-LD with RDF tools will find it can be used as another
RDF syntax, like Turtle [<cite><a class="bibref" href="#bib-TURTLE">TURTLE</a></cite>]. Complete details of how JSON-LD relates
to RDF are in section <a href="#relationship-to-rdf" class="sec-ref"><span class="secno">7.</span> <span class="sec-title">Relationship to RDF</span></a>.
</p>
<p>
The syntax is designed to not disturb already
deployed systems running on JSON, but provide a smooth upgrade path from
JSON to JSON-LD. Since the shape of such data varies wildly, JSON-LD
features mechanisms to reshape documents into a deterministic structure
which simplifies their processing.</p>
<section class="informative" id="how-to-read-this-document" typeof="schema:Chapter" resource="#how-to-read-this-document" property="schema:hasPart">
<h3 id="x1-1-how-to-read-this-document"><span class="secno">1.1 </span>How to Read this Document&nbsp;<span class="permalink"><a href="#how-to-read-this-document" aria-label="Permalink for 1.1 How to Read this Document" title="Permalink for 1.1 How to Read this Document"><span property="schema:name" content="1.1 How to Read this Document">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>This document is a detailed specification for a serialization of Linked
Data in JSON. The document is primarily intended for the following audiences:</p>
<ul>
<li>Software developers who want to encode Linked Data in a variety of
programming languages that can use JSON</li>
<li>Software developers who want to convert existing JSON to JSON-LD</li>
<li>Software developers who want to understand the design decisions and
language syntax for JSON-LD</li>
<li>Software developers who want to implement processors and APIs for
JSON-LD</li>
<li>Software developers who want to generate or consume Linked Data,
an RDF graph, or an <a href="#dfn-dataset" class="internalDFN" data-link-type="dfn">RDF Dataset</a> in a JSON syntax</li>
</ul>
<p>A companion document, the JSON-LD 1.1 Processing Algorithms and API specification
[<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>], specifies how to work with JSON-LD at a higher level by
providing a standard library interface for common JSON-LD operations.</p>
<p>To understand the basics in this specification you must first be familiar with
<a href="https://tools.ietf.org/html/rfc7159">JSON</a>, which is detailed in [<cite><a class="bibref" href="#bib-RFC7159">RFC7159</a></cite>].</p>
<p>This document almost exclusively uses the term <abbr title="Internationalized Resource Identifier">IRI</abbr>
(<a href="https://www.w3.org/TR/ld-glossary/#internationalized-resource-identifier">Internationalized Resource Indicator</a>)
when discussing hyperlinks. Many Web developers are more familiar with the
URL (<a href="https://www.w3.org/TR/ld-glossary/#uniform-resource-locator">Uniform Resource Locator</a>)
terminology. The document also uses, albeit rarely, the URI
(<a href="https://www.w3.org/TR/ld-glossary/#uniform-resource-identifier">Uniform Resource Indicator</a>)
terminology. While these terms are often used interchangeably among
technical communities, they do have important distinctions from one
another and the specification goes to great lengths to try and use the
proper terminology at all times.
</p>
</section>
<section id="contributing" typeof="schema:Chapter" resource="#contributing" property="schema:hasPart">
<h3 id="x1-2-contributing"><span class="secno">1.2 </span>Contributing&nbsp;<span class="permalink"><a href="#contributing" aria-label="Permalink for 1.2 Contributing" title="Permalink for 1.2 Contributing"><span property="schema:name" content="1.2 Contributing">§</span></a></span></h3>
<p>There are a number of ways that one may participate in the development of
this specification:</p>
<ul>
<li>Technical discussion typically occurs on the public mailing list:
<a href="https://lists.w3.org/Archives/Public/public-linked-json/">public-linked-json@w3.org</a></li>
<!--<li><a href="https://json-ld.org/minutes/">Public teleconferences</a> are held
on Tuesdays at 1500UTC on the second and fourth week of each month.</li> -->
<li>The <a href="https://webchat.freenode.net/?channels=json-ld">#json-ld</a>
IRC channel is available for real-time discussion on irc.freenode.net.</li>
</ul>
</section>
<section class="normative" id="terminology" typeof="schema:Chapter" resource="#terminology" property="schema:hasPart">
<h3 id="x1-3-terminology"><span class="secno">1.3 </span>Terminology&nbsp;<span class="permalink"><a href="#terminology" aria-label="Permalink for 1.3 Terminology" title="Permalink for 1.3 Terminology"><span property="schema:name" content="1.3 Terminology">§</span></a></span></h3>
<p>This document uses the following terms as defined in JSON [<cite><a class="bibref" href="#bib-RFC7159">RFC7159</a></cite>]. Refer
to the <a href="https://tools.ietf.org/html/rfc7159#section-2">JSON Grammar section</a> in [<cite><a class="bibref" href="#bib-RFC7159">RFC7159</a></cite>] for formal definitions.</p>
<div data-oninclude="restrictReferences"><dl class="termlist" data-sort="" id="terms"><dt><dfn data-lt="arrays|array" id="dfn-arrays" data-dfn-type="dfn">array</dfn></dt><dd>
In the JSON serialization, an array structure is represented as square brackets surrounding zero
or more values. Values are separated by commas.
In the <a href="#dfn-internal-representation" class="internalDFN" data-link-type="dfn">internal representation</a>, an array is an <em>ordered</em> collection of zero or more values.
While JSON-LD uses the same array representation as JSON,
the collection is <em>unordered</em> by default. While order is
preserved in regular JSON arrays, it is not in regular JSON-LD arrays
unless specifically defined (see
<a class="externalDFN" href="https://json-ld.org/spec/latest/json-ld/#sets-and-lists">Sets and Lists</a> in
the JSON-LD Syntax specification [<cite><a class="bibref" href="#bib-JSON-LD11CG">JSON-LD11CG</a></cite>]).</dd>
<dt><dfn data-lt="json objects|json object" id="dfn-json-objects" data-dfn-type="dfn">JSON object</dfn></dt><dd>
In the JSON serialization, an <a class="externalDFN" href="https://tools.ietf.org/html/rfc7159#section-4">object</a> structure is represented as a pair of curly brackets surrounding zero or
more key-value pairs. A key is a <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>. A single colon comes after
each key, separating the key from the value. A single comma separates a value
from a following key. In JSON-LD the keys in an object <em class="rfc2119" title="MUST">MUST</em> be unique.
In the <a href="#dfn-internal-representation" class="internalDFN" data-link-type="dfn">internal representation</a> a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> is equivalent to a
<dfn data-lt="dictionaries|dictionary" class="preserve" data-dfn-type="dfn" id="dfn-dictionaries"><a href="https://heycam.github.io/webidl/#dfn-dictionary">dictionary</a></dfn> (see [<cite><a class="bibref" href="#bib-WEBIDL">WEBIDL</a></cite>]).</dd>
<dt class="changed"><dfn data-lt="internal representation|json-ld internal representation" id="dfn-internal-representation" data-dfn-type="dfn">JSON-LD internal representation</dfn></dt><dd class="changed">The JSON-LD
internal representation is the result of transforming a JSON syntactic structure
into the core data structures suitable for direct processing:
<a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">arrays</a>, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-dictionary">dictionaries</a>,
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a>, <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">numbers</a>, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#idl-boolean">booleans</a>, and <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>.</dd>
<dt><dfn id="dfn-null" data-dfn-type="dfn">null</dfn></dt><dd>
The use of the <a class="externalDFN" href="https://tools.ietf.org/html/rfc7159#section-3">null</a> value within JSON-LD is used to
ignore or reset values. A key-value pair in the <code>@context</code> where
the value, or the <code>@id</code> of the value, is <code>null</code>
explicitly decouples a term's association with an <abbr title="Internationalized Resource Identifier">IRI</abbr>. A key-value pair in
the body of a <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> whose value is <code>null</code> has the
same meaning as if the key-value pair was not defined. If
<code>@value</code>, <code>@list</code>, or <code>@set</code> is set to
<code>null</code> in expanded form, then the entire <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON
object</a> is ignored.</dd>
<dt><dfn data-lt="numbers|json number|json numbers|number" id="dfn-numbers" data-dfn-type="dfn">number</dfn></dt><dd>
In the JSON serialization, a <a class="externalDFN" href="https://tools.ietf.org/html/rfc7159#section-6">number</a> is similar to that used in most programming languages, except
that the octal and hexadecimal formats are not used and that leading
zeros are not allowed.
In the <a href="#dfn-internal-representation" class="internalDFN" data-link-type="dfn">internal representation</a>, a <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a> is equivalent to either
a <dfn class="preserve" data-dfn-type="dfn" id="dfn-long"><a href="https://heycam.github.io/webidl/#idl-long">long</a></dfn>
or <dfn class="preserve" data-dfn-type="dfn" id="dfn-double"><a href="https://heycam.github.io/webidl/#idl-double">double</a></dfn>, depending
on if the number has a non-zero fractional part (see [<cite><a class="bibref" href="#bib-WEBIDL">WEBIDL</a></cite>]).</dd>
<dt></dt>
<dt><dfn data-lt="strings|string" id="dfn-strings" data-dfn-type="dfn">string</dfn></dt><dd>
A <a class="externalDFN" href="https://tools.ietf.org/html/rfc7159#section-7">string</a> is a sequence of zero or more Unicode (UTF-8) characters,
wrapped in double quotes, using backslash escapes (if necessary). A
character is represented as a single character string.</dd>
<dt><dfn id="dfn-true" data-dfn-type="dfn">true</dfn> and <dfn id="dfn-false" data-dfn-type="dfn">false</dfn></dt><dd>
<a class="externalDFN" href="https://tools.ietf.org/html/rfc7159#section-3">Values</a> that are used to express one of two possible
<dfn data-lt="booleans|boolean" class="preserve" data-dfn-type="dfn" id="dfn-booleans"><a href="https://heycam.github.io/webidl/#idl-boolean">boolean</a></dfn> states.</dd></dl>
<p>Furthermore, the following terminology is used throughout this document:</p>
<dl class="termlist" data-sort=""><dt><dfn data-lt="absolute iris|absolute iri" id="dfn-absolute-iris" data-dfn-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></dfn></dt><dd>
An <a class="externalDFN" href="https://tools.ietf.org/html/rfc3987#section-1.3">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> is defined in [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>] containing a <em>scheme</em> along with a <em>path</em> and
optional <em>query</em> and fragment segments.</dd>
<dt><dfn id="dfn-active-context" data-dfn-type="dfn">active context</dfn></dt><dd>
A <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> that is used to resolve <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> while the processing
algorithm is running.</dd>
<dt><dfn data-lt="base iris|base iri" id="dfn-base-iris" data-dfn-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></dfn></dt><dd>
The <a href="#dfn-base-iris" class="internalDFN" data-link-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></a> is an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> established in the <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>,
or is based on the <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> location. The <a href="#dfn-base-iris" class="internalDFN" data-link-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></a> is used to turn
<a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative IRIs</a> into <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute IRIs</a>.</dd>
<dt><dfn data-lt="blank nodes|blank node" id="dfn-blank-nodes" data-dfn-type="dfn">blank node</dfn></dt><dd>
A <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> in a <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a> that is neither an
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>, nor a <a href="#dfn-json-ld-values" class="internalDFN" data-link-type="dfn">JSON-LD value</a>, nor a <a href="#dfn-lists" class="internalDFN" data-link-type="dfn">list</a>.
A <a class="externalDFN" href="https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node">blank node</a> does not contain a de-referenceable
identifier because it is either ephemeral in nature or does not contain information that needs to be
linked to from outside of the linked data graph. A blank node is assigned an identifier starting with
the prefix <code>_:</code>.</dd>
<dt><dfn data-lt="blank node identifiers|blank node identifier" id="dfn-blank-node-identifiers" data-dfn-type="dfn">blank node identifier</dfn></dt><dd>
A <a class="externalDFN" href="https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node-identifier">blank node identifier</a> is a string that can be used as an identifier for a
<a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a> within the scope of a JSON-LD document. Blank node identifiers
begin with <code>_:</code>.</dd>
<dt><dfn data-lt="compact iris|compact iri" id="dfn-compact-iris" data-dfn-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></dfn></dt><dd>
A compact <abbr title="Internationalized Resource Identifier">IRI</abbr> is has the form of <a href="#dfn-prefixes" class="internalDFN" data-link-type="dfn">prefix</a>:<em>suffix</em> and is used as a way
of expressing an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> without needing to define separate <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> definitions for
each <abbr title="Internationalized Resource Identifier">IRI</abbr> contained within a common vocabulary identified by <a href="#dfn-prefixes" class="internalDFN" data-link-type="dfn">prefix</a>.</dd>
<dt><dfn data-lt="contexts|context" id="dfn-contexts" data-dfn-type="dfn">context</dfn></dt><dd>
A a set of rules for interpreting a <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> as specified in
<a href="https://json-ld.org/spec/latest/json-ld/#the-context">The Context</a> of the JSON-LD Syntax specification [<cite><a class="bibref" href="#bib-JSON-LD11CG">JSON-LD11CG</a></cite>].</dd>
<dt></dt>
<dt><dfn id="dfn-default-graph" data-dfn-type="dfn">default graph</dfn></dt><dd>
The <a class="externalDFN" href="https://www.w3.org/TR/rdf11-concepts/#dfn-default-graph">default graph</a> is the only graph in a JSON-LD document which has no <a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph name</a>.
When executing an algorithm, the graph where data should be placed
if a <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a> is not specified.</dd>
<dt><dfn id="dfn-default-language" data-dfn-type="dfn">default language</dfn></dt><dd>
The default language is set in the <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> using the <code>@language</code> key whose
value <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a> representing a [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>] language code or <code>null</code>.</dd>
<dt></dt>
<dt><dfn data-lt="edges|edge" id="dfn-edges" data-dfn-type="dfn">edge</dfn></dt><dd>
Every <a href="#dfn-edges" class="internalDFN" data-link-type="dfn">edge</a> has a direction associated with it and is labeled with
an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>. Within the JSON-LD syntax
these edge labels are called <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a>. Whenever possible, an
<a href="#dfn-edges" class="internalDFN" data-link-type="dfn">edge</a> should be labeled with an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</dd>
<dt><dfn data-lt="expanded term definitions|expanded term definition" id="dfn-expanded-term-definitions" data-dfn-type="dfn">expanded term definition</dfn></dt><dd>
An expanded term definition, is a <a href="#dfn-term-definitions" class="internalDFN" data-link-type="dfn">term definition</a> where the value is a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a>
containing one or more <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> to define the associated <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
if this is a reverse property, the type associated with string values, and a container mapping.</dd>
<dt></dt>
<dt></dt>
<dt><dfn data-lt="graph names|graph name" id="dfn-graph-names" data-dfn-type="dfn">graph name</dfn></dt><dd>
The <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> identifying a <a class="externalDFN" href="https://www.w3.org/TR/rdf11-concepts/#dfn-graph-name">named graph</a>.</dd>
<dt class="changed"><dfn data-lt="graph objects|graph object" id="dfn-graph-objects" data-dfn-type="dfn">graph object</dfn></dt><dd class="changed">
A <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph object</a> represents a <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a> represented as the
value of a <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a> within a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>. When expanded, a
graph object <em class="rfc2119" title="MUST">MUST</em> have an <code>@graph</code> member, and may also have
<code>@context</code>, <code>@id</code>, and <code>@index</code> members.
A <dfn class="preserve" data-lt="simple graph objects|simple graph object" data-dfn-type="dfn" id="dfn-simple-graph-objects">simple graph object</dfn> is a
<a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph object</a> which does not have an <code>@id</code> member. Note
that <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> may have a <code>@graph</code> member, but are
not considered <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph objects</a> if they include any other properties.
A top-level object consisting of <code>@graph</code> is also not a <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph object</a>.</dd>
<dt class="changed"><dfn data-lt="id maps|id map" id="dfn-id-maps" data-dfn-type="dfn">id map</dfn></dt><dd class="changed">
An <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id map</a> is a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> value of a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> defined with
<code>@container</code> set to <code>@id</code>, who's keys are
interpreted as <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> representing the <code>@id</code>
of the associated <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>; value <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>.
If the value contains a property expanding to <code>@id</code>, it's value <em class="rfc2119" title="MUST">MUST</em>
be equivalent to the referencing key.</dd>
<dt><dfn data-lt="implicitly named graphs|implicitly named graph" id="dfn-implicitly-named-graphs" data-dfn-type="dfn">implicitly named graph</dfn></dt><dd>
A <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a> created from the value of a property having an
<a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> where <code>@container</code> is set to <code>@graph</code>.</dd>
<dt><dfn data-lt="index maps|index map" id="dfn-index-maps" data-dfn-type="dfn">index map</dfn></dt><dd>
An <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index map</a> is a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> value of a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> defined with
<code>@container</code> set to <code>@index</code>, whose values <em class="rfc2119" title="MUST">MUST</em> be any of the following types:
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>,
<a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>,
<a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a>,
<a href="#dfn-false" class="internalDFN" data-link-type="dfn">false</a>,
<a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>,
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>,
<a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a>,
<a href="#dfn-list-objects" class="internalDFN" data-link-type="dfn">list object</a>,
<a href="#dfn-set-object" class="internalDFN" data-link-type="dfn">set object</a>, or
an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of zero or more of the above possibilities.
</dd>
<dt><dfn data-lt="iris|internationalized resource identifier|iri" id="dfn-iris" data-dfn-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></dfn></dt><dd>
An <a class="externalDFN" href="https://tools.ietf.org/html/rfc3987#section-1.3">Internationalized Resource Identifier</a> as described in [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>].</dd>
<dt><dfn data-lt="json-ld documents|json-ld document" id="dfn-json-ld-documents" data-dfn-type="dfn">JSON-LD document</dfn></dt><dd>
A <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> is a serialization of a collection of
<a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graphs</a> and comprises exactly one
<a href="#dfn-default-graph" class="internalDFN" data-link-type="dfn">default graph</a> and zero or more <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graphs</a>.</dd>
<dt><dfn data-lt="json-ld processors|processors|json-ld processor" id="dfn-json-ld-processors" data-dfn-type="dfn">JSON-LD Processor</dfn></dt><dd>
A <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD Processor</a> is a system which can perform the algorithms defined in [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>].</dd>
<dt><dfn data-lt="json-ld values|json-ld value" id="dfn-json-ld-values" data-dfn-type="dfn">JSON-LD value</dfn></dt><dd>
A <a data-lt="JSON-LD values" href="#dfn-json-ld-values" class="internalDFN" data-link-type="dfn">JSON-LD value</a> is a <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>, a <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>,
<a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a> or <a href="#dfn-false" class="internalDFN" data-link-type="dfn">false</a>, a <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed value</a>, or a
<a href="#dfn-language-tagged-strings" class="internalDFN" data-link-type="dfn">language-tagged string</a>.</dd>
<dt><dfn data-lt="keywords|keyword" id="dfn-keywords" data-dfn-type="dfn">keyword</dfn></dt><dd>
A JSON key that is specific to JSON-LD, specified in the JSON-LD Syntax specification [<cite><a class="bibref" href="#bib-JSON-LD11CG">JSON-LD11CG</a></cite>]
in the section titled <a href="https://json-ld.org/spec/latest/json-ld/#syntax-tokens-and-keywords">Syntax Tokens and Keywords</a>.</dd>
<dt><dfn data-lt="language maps|language map" id="dfn-language-maps" data-dfn-type="dfn">language map</dfn></dt><dd>
An <a href="#dfn-language-maps" class="internalDFN" data-link-type="dfn">language map</a> is a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> value of a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> defined with
<code>@container</code> set to <code>@language</code>, whose keys <em class="rfc2119" title="MUST">MUST</em> be <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a> representing
[<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>] language codes and the values <em class="rfc2119" title="MUST">MUST</em> be any of the following types:
<a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>,
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>, or
an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of zero or more of the above possibilities.
</dd>
<dt><dfn data-lt="language-tagged strings|language-tagged string" id="dfn-language-tagged-strings" data-dfn-type="dfn">language-tagged string</dfn></dt><dd>
A <a class="externalDFN" href="https://www.w3.org/TR/rdf11-concepts/#dfn-language-tagged-string">language-tagged string</a> consists of a string and a non-empty language
tag as defined by [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>]. The <dfn id="dfn-language-tag" data-dfn-type="dfn">language tag</dfn> <em class="rfc2119" title="MUST">MUST</em> be well-formed according to
<a href="https://tools.ietf.org/html/bcp47#section-2.2.9">section 2.2.9 Classes of Conformance</a>
of [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>], and is normalized to lowercase.</dd>
<dt></dt>
<dt><dfn data-lt="graph|graphs|linked data graph" id="dfn-graph" data-dfn-type="dfn">linked data graph</dfn></dt><dd>
A labeled directed <a class="externalDFN" href="https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-graph">graph</a>, i.e., a set of <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a>
connected by <a href="#dfn-edges" class="internalDFN" data-link-type="dfn">edges</a>,
as specified in the <a href="https://json-ld.org/spec/latest/json-ld/#data-model">Data Model</a>
section of the JSON-LD specification [<cite><a class="bibref" href="#bib-JSON-LD11CG">JSON-LD11CG</a></cite>].
A <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">linked data graph</a> is a generalized representation of a
<a href="https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-graph">RDF graph</a>
as defined in [<cite><a class="bibref" href="#bib-RDF-CONCEPTS">RDF-CONCEPTS</a></cite>].</dd>
<dt><dfn data-lt="lists|list" id="dfn-lists" data-dfn-type="dfn">list</dfn></dt><dd>
A <a href="#dfn-lists" class="internalDFN" data-link-type="dfn">list</a> is an ordered sequence of <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>,
<a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank nodes</a>, and <a href="#dfn-json-ld-values" class="internalDFN" data-link-type="dfn">JSON-LD values</a>.
See <dfn data-lt="collection|rdf collection" class="preserve" data-dfn-type="dfn" id="dfn-collection"><a href="https://www.w3.org/TR/rdf-schema/#ch_collectionvocab">RDF collection</a></dfn>
in [<cite><a class="bibref" href="#bib-RDF-SCHEMA">RDF-SCHEMA</a></cite>].</dd>
<dt><dfn data-lt="list objects|list object" id="dfn-list-objects" data-dfn-type="dfn">list object</dfn></dt><dd>
A <a href="#dfn-list-objects" class="internalDFN" data-link-type="dfn">list object</a> is a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> that has an <code>@list</code>
member.</dd>
<dt></dt>
<dt><dfn data-lt="local contexts|local context" id="dfn-local-contexts" data-dfn-type="dfn">local context</dfn></dt><dd>
A <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> that is specified within a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a>,
specified via the <code>@context</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>.</dd>
<dt><dfn data-lt="named graphs|named graph" id="dfn-named-graphs" data-dfn-type="dfn">named graph</dfn></dt><dd>
A <a class="externalDFN" href="https://www.w3.org/TR/rdf11-concepts/#dfn-named-graph">named graph</a> is a <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">linked data graph</a> that is identified by an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a>.</dd>
<dt><dfn data-lt="nested properties|nested property" id="dfn-nested-properties" data-dfn-type="dfn">nested property</dfn></dt><dd>
A <a href="#dfn-nested-properties" class="internalDFN" data-link-type="dfn">nested property</a> is a <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a> which is contained within an object referenced by
a semantically meaningless <em>nesting property</em>.
</dd>
<dt><dfn data-lt="nodes|node" id="dfn-nodes" data-dfn-type="dfn">node</dfn></dt><dd>
Every <a class="externalDFN" href="https://www.w3.org/TR/rdf11-concepts/#dfn-node">node</a> is an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a>,
a <a href="#dfn-json-ld-values" class="internalDFN" data-link-type="dfn">JSON-LD value</a>, or a <a href="#dfn-lists" class="internalDFN" data-link-type="dfn">list</a>.
A piece of information that is represented in a <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">linked data graph</a>.</dd>
<dt><dfn data-lt="node objects|node object" id="dfn-node-objects" data-dfn-type="dfn">node object</dfn></dt><dd>
A <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> represents zero or more <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> of a
<a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> in the <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a> serialized by the
<a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a>. A <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> is a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>
if it exists outside of the JSON-LD <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> and:
<ul>
<li>it does not contain the <code>@value</code>, <code>@list</code>,
or <code>@set</code> keywords, or</li>
<li>it is not the top-most <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> in the JSON-LD document consisting
of no other members than <code>@graph</code> and <code>@context</code>.</li>
</ul>
</dd>
<dt></dt>
<dt></dt>
<dt><dfn data-lt="prefixes|prefix" id="dfn-prefixes" data-dfn-type="dfn">prefix</dfn></dt><dd>
A <a href="#dfn-prefixes" class="internalDFN" data-link-type="dfn">prefix</a> is the first component of a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> which comes from a
<a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> that maps to a string that, when prepended to the suffix of the <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
results in an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</dd>
<dt><dfn id="dfn-processing-mode" data-dfn-type="dfn">processing mode</dfn></dt><dd>
The processing mode defines how a JSON-LD document is processed.
By default, all documents are assumed to be conformant with
<a href="https://www.w3.org/TR/json-ld/">JSON-LD 1.0</a> [<cite><a class="bibref" href="#bib-JSON-LD">JSON-LD</a></cite>]. By defining
a different version using the <code>@version</code> member in a
<a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>, or via explicit API option, other processing modes
can be accessed. This specification defines extensions for the
<code>json-ld-1.1</code> <a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a>.</dd>
<dt><dfn data-lt="properties|property" id="dfn-properties" data-dfn-type="dfn">property</dfn></dt><dd>
The <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> label of an edge in a <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">linked data graph</a>.
See <dfn data-lt="predicate|predicates|rdf predicates|rdf predicate" class="preserve" data-dfn-type="dfn" id="dfn-predicate"><a href="https://www.w3.org/TR/rdf11-concepts/#dfn-predicate">RDF predicate</a></dfn> in [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>].</dd>
<dt></dt>
<dt><dfn data-lt="dataset|rdf dataset" id="dfn-dataset" data-dfn-type="dfn">RDF dataset</dfn></dt><dd>
A <a class="externalDFN" href="https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-dataset">dataset</a> as specified by [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>] representing a collection of
<a href="https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-graph">RDF graphs</a>.</dd>
<dt></dt>
<dt><dfn data-lt="triple|triples|rdf triples|rdf triple" id="dfn-triple" data-dfn-type="dfn">RDF triple</dfn></dt><dd>
A <a class="externalDFN" href="https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-triple">triple</a> as specified by [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>].</dd>
<dt><dfn data-lt="relative iris|relative iri" id="dfn-relative-iris" data-dfn-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></dfn></dt><dd>
A relative <abbr title="Internationalized Resource Identifier">IRI</abbr> is an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> that is relative to some other <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
typically the <a href="#dfn-base-iris" class="internalDFN" data-link-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></a> of the document. Note that
<a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a>, values of <code>@type</code>, and values of <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> defined to be <em>vocabulary relative</em>
are resolved relative to the <a href="#dfn-vocabulary-mapping" class="internalDFN" data-link-type="dfn">vocabulary mapping</a>, not the <a href="#dfn-base-iris" class="internalDFN" data-link-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</dd>
<dt><dfn id="dfn-set-object" data-dfn-type="dfn">set object</dfn></dt><dd>
A <a href="#dfn-set-object" class="internalDFN" data-link-type="dfn">set object</a> is a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> that has an <code>@set</code>
member.</dd>
<dt></dt>
<dt><dfn data-lt="terms|term" id="dfn-terms" data-dfn-type="dfn">term</dfn></dt><dd>
A <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is a short word defined in a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> that <em class="rfc2119" title="MAY">MAY</em> be expanded to an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
</dd>
<dt><dfn data-lt="term definitions|term definition" id="dfn-term-definitions" data-dfn-type="dfn">term definition</dfn></dt><dd>
A term definition is an entry in a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>, where the key defines a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> which may be used within
a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> as a <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a>, type, or elsewhere that a string is interpreted as a vocabulary item.
Its value is either a string (<dfn data-lt="simple terms|simple term|simple term definitions|simple term definition" id="dfn-simple-terms" data-dfn-type="dfn">simple term definition</dfn>), expanding to an absolute <abbr title="Internationalized Resource Identifier">IRI</abbr>, or an <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a>.
</dd>
<dt class="changed"><dfn data-lt="type maps|type map" id="dfn-type-maps" data-dfn-type="dfn">type map</dfn></dt><dd class="changed">
An <a href="#dfn-type-maps" class="internalDFN" data-link-type="dfn">type map</a> is a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> value of a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> defined with
<code>@container</code> set to <code>@type</code>, who's keys are
interpreted as <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> representing the <code>@type</code>
of the associated <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>;
value <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>, or <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of node objects.
If the value contains a property expanding to <code>@type</code>, it's values
are merged with the map value when expanding.</dd>
<dt></dt>
<dt><dfn data-lt="typed values|typed value" id="dfn-typed-values" data-dfn-type="dfn">typed value</dfn></dt><dd>
A <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed value</a> consists of a value, which is a <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>, and a type,
which is an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</dd>
<dt><dfn data-lt="value objects|value object" id="dfn-value-objects" data-dfn-type="dfn">value object</dfn></dt><dd>
A <a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a> is a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> that has an <code>@value</code>
member.</dd>
<dt><dfn id="dfn-vocabulary-mapping" data-dfn-type="dfn">vocabulary mapping</dfn></dt><dd>
The vocabulary mapping is set in the <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> using the <code>@vocab</code> key whose
value <em class="rfc2119" title="MUST">MUST</em> be an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> <code>null</code>.</dd></dl>
</div>
</section>
<section id="typographical-conventions" typeof="schema:Chapter" resource="#typographical-conventions" property="schema:hasPart">
<h3 id="x1-4-typographical-conventions"><span class="secno">1.4 </span>Typographical conventions&nbsp;<span class="permalink"><a href="#typographical-conventions" aria-label="Permalink for 1.4 Typographical conventions" title="Permalink for 1.4 Typographical conventions"><span property="schema:name" content="1.4 Typographical conventions">§</span></a></span></h3>
<div> <p>The following typographic conventions are used in this specification:</p>
<dl class="typography">
<dt><code>markup</code></dt>
<dd>Markup (elements, attributes, properties), machine processable values (string, characters, media types), property name, or a file name is in red-orange monospace font.</dd>
<dt><var>variable</var></dt>
<dd>A variable in pseudo-code or in an algorithm description is in italics.</dd>
<dt><dfn data-dfn-type="dfn" id="dfn-definition">definition</dfn></dt>
<dd>A definition of a term, to be used elsewhere in this or other specifications, is in bold and italics.</dd>
<dt><a data-lt="definition" href="#dfn-definition" class="internalDFN" data-link-type="dfn">definition reference</a></dt>
<dd>A reference to a definition <em>in this document</em> is underlined and is also an active link to the definition itself. </dd>
<dt><a data-lt="definition" href="#dfn-definition" class="internalDFN" data-link-type="dfn"><code>markup definition reference</code></a></dt>
<dd>A references to a definition <em>in this document</em>, when the reference itself is also a markup, is underlined, red-orange monospace font, and is also an active link to the definition itself.</dd>
<dt><a class="externalDFN">external definition reference</a></dt>
<dd>A reference to a definition <em>in another document</em> is underlined, in italics, and is also an active link to the definition itself.</dd>
<dt><a class="externalDFN"><code> markup external definition reference</code></a></dt>
<dd>A reference to a definition <em>in another document</em>, when the reference itself is also a markup, is underlined, in italics red-orange monospace font, and is also an active link to the definition itself.</dd>
<dt><a href=".">hyperlink</a></dt>
<dd>A hyperlink is underlined and in blue.</dd>
<dt>[<a href=".">reference</a>]</dt>
<dd>A document reference (normative or informative) is enclosed in square brackets and links to the references section.</dd>
<dt class="changed">Changes from Recommendation</dt>
<dd>Sections or phrases changed from the previous Recommendation are <span class="changed">highlighted</span>.</dd>
</dl>
<div class="note"><div role="heading" class="note-title marker" id="h-note" aria-level="4"><span>Note</span></div><p class="">Notes are in light green boxes with a green left border and with a "Note" header in green. Notes are normative or informative depending on the whether they are in a normative or informative section, respectively.</p></div>
<div class="example"><div class="example-title marker"><span>Example 1</span></div><pre class="hljs javascript" aria-busy="false">Examples are <span class="hljs-keyword">in</span> light khaki boxes, <span class="hljs-keyword">with</span> khaki left border, and <span class="hljs-keyword">with</span> a
numbered <span class="hljs-string">"Example"</span> header <span class="hljs-keyword">in</span> khaki. Examples are always informative.
The content <span class="hljs-keyword">of</span> the example is <span class="hljs-keyword">in</span> monospace font and may be syntax colored.</pre></div>
</div>
</section>
<section class="informative" id="design-goals-and-rationale" typeof="schema:Chapter" resource="#design-goals-and-rationale" property="schema:hasPart">
<h3 id="x1-5-design-goals-and-rationale"><span class="secno">1.5 </span>Design Goals and Rationale&nbsp;<span class="permalink"><a href="#design-goals-and-rationale" aria-label="Permalink for 1.5 Design Goals and Rationale" title="Permalink for 1.5 Design Goals and Rationale"><span property="schema:name" content="1.5 Design Goals and Rationale">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>JSON-LD satisfies the following design goals:</p>
<dl>
<dt>Simplicity</dt>
<dd>No extra processors or software libraries are necessary to use JSON-LD
in its most basic form. The language provides developers with a very easy
learning curve. Developers only need to know JSON and two
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a> (<code>@context</code>
and <code>@id</code>) to use the basic functionality in JSON-LD.</dd>
<dt>Compatibility</dt>
<dd>A JSON-LD document is always a valid JSON document. This ensures that
all of the standard JSON libraries work seamlessly with JSON-LD documents.</dd>
<dt>Expressiveness</dt>
<dd>The syntax serializes directed graphs. This ensures that almost
every real world data model can be expressed.</dd>
<dt>Terseness</dt>
<dd>The JSON-LD syntax is very terse and human readable, requiring as
little effort as possible from the developer.</dd>
<dt>Zero Edits, most of the time</dt>
<dd>JSON-LD ensures a smooth and simple transition from existing
JSON-based systems. In many cases,
zero edits to the JSON document and the addition of one line to the HTTP response
should suffice (see <a class="sectionRef sec-ref" href="#interpreting-json-as-json-ld">section <span class="secno">4.9</span> <span class="sec-title">Interpreting JSON as JSON-LD</span></a>).
This allows organizations that have
already deployed large JSON-based infrastructure to use JSON-LD's features
in a way that is not disruptive to their day-to-day operations and is
transparent to their current customers. However, there are times where
mapping JSON to a graph representation is a complex undertaking.
In these instances, rather than extending JSON-LD to support
esoteric use cases, we chose not to support the use case. While Zero
Edits is a design goal, it is not always possible without adding
great complexity to the language. JSON-LD focuses on simplicity when
possible.</dd>
<dt>Usable as RDF</dt>
<dd>JSON-LD is usable by developers as
idiomatic JSON, with no need to understand RDF [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>].
JSON-LD is also usable as RDF, so people intending to use JSON-LD
with RDF tools will find it can be used like any other RDF syntax.
Complete details of how JSON-LD relates to RDF are in section
<a href="#relationship-to-rdf" class="sec-ref"><span class="secno">7.</span> <span class="sec-title">Relationship to RDF</span></a>.</dd>
</dl>
</section>
<section class="informative" id="data-model-overview" typeof="schema:Chapter" resource="#data-model-overview" property="schema:hasPart">
<h3 id="x1-6-data-model-overview"><span class="secno">1.6 </span>Data Model Overview&nbsp;<span class="permalink"><a href="#data-model-overview" aria-label="Permalink for 1.6 Data Model Overview" title="Permalink for 1.6 Data Model Overview"><span property="schema:name" content="1.6 Data Model Overview">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>Generally speaking, the data model described by a
<a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> is a labeled,
directed <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a>. The graph contains
<a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a>, which are connected by
<a href="#dfn-edges" class="internalDFN" data-link-type="dfn">edges</a>. A <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> is typically data
such as a <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>, <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>,
<a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed values</a> (like dates and times)
or an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
There is also a special class of <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> called a
<a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a>, which is typically used to express data that does
not have a global identifier like an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
<a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">Blank nodes</a> are identified using a
<a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>. This simple data model is incredibly
flexible and powerful, capable of modeling almost any kind of
data. For a deeper explanation of the data model, see
section <a href="#data-model" class="sec-ref"><span class="secno">5.</span> <span class="sec-title">Data Model</span></a>.
</p>
<p>Developers who are familiar with Linked Data technologies will
recognize the data model as the RDF Data Model. To dive deeper into how
JSON-LD and RDF are related, see
section <a href="#relationship-to-rdf" class="sec-ref"><span class="secno">7.</span> <span class="sec-title">Relationship to RDF</span></a>.</p>
<p>At the surface level, a <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> is simply
<a href="https://tools.ietf.org/html/rfc7159">JSON</a>, detailed in [<cite><a class="bibref" href="#bib-RFC7159">RFC7159</a></cite>].
For the purpose of describing the core data structures,
this is limited to <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">arrays</a>, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-dictionary">dictionaries</a> (the parsed version of a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON Object</a>),
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a>, <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">numbers</a>, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#idl-boolean">booleans</a>, and <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>,
<span class="changed">called the <a href="#dfn-internal-representation" class="internalDFN" data-link-type="dfn">JSON-LD internal representation</a>.
This allows surface syntaxes other than JSON
to be manipulated using the same algorithms, when the syntax maps
to equivalent core data structures</span>.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-0" aria-level="4"><span>Note</span></div><p class="changed">Although not discussed in this specification,
parallel work using <a href="http://yaml.org/spec/1.2/spec.html">YAML</a> [<cite><a class="bibref" href="#bib-YAML">YAML</a></cite>]
and binary representations such as <a href="https://tools.ietf.org/html/rfc7049">CBOR</a> [<cite><a class="bibref" href="#bib-RFC7049">RFC7049</a></cite>]
could be used to map into the <a href="#dfn-internal-representation" class="internalDFN" data-link-type="dfn">internal representation</a>, allowing
the JSON-LD 1.1 API [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>] to operate as if the source was a
JSON document.</p></div>
</section>
<section class="normative" id="syntax-tokens-and-keywords" typeof="schema:Chapter" resource="#syntax-tokens-and-keywords" property="schema:hasPart">
<h3 id="x1-7-syntax-tokens-and-keywords"><span class="secno">1.7 </span>Syntax Tokens and Keywords&nbsp;<span class="permalink"><a href="#syntax-tokens-and-keywords" aria-label="Permalink for 1.7 Syntax Tokens and Keywords" title="Permalink for 1.7 Syntax Tokens and Keywords"><span property="schema:name" content="1.7 Syntax Tokens and Keywords">§</span></a></span></h3>
<p>JSON-LD specifies a number of syntax tokens and <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a>
that are a core part of the language:</p>
<dl data-sort=""><dt><code>:</code></dt>
<dd>The separator for JSON keys and values that use
<a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact IRIs</a>.</dd><dt><code>@base</code></dt>
<dd>Used to set the <a href="#dfn-base-iris" class="internalDFN" data-link-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></a> against which to resolve those <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative IRIs</a>
interpreted relative to the document.
This keyword is described in <a class="sectionRef sec-ref" href="#base-iri">section <span class="secno">4.2</span> <span class="sec-title">Base IRI</span></a>.</dd>
<dt><code>@container</code></dt>
<dd>Used to set the default container type for a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>.
This keyword is described in the following sections:
<ul>
<li><a class="sectionRef sec-ref" href="#sets-and-lists">section <span class="secno">4.12</span> <span class="sec-title">Sets and Lists</span></a>,</li>
<li class="changed"><a class="sectionRef sec-ref" href="#named-graphs">section <span class="secno">4.15</span> <span class="sec-title">Named Graphs</span></a>,</li>
<li><a class="sectionRef sec-ref" href="#data-indexing">section <span class="secno">4.18</span> <span class="sec-title">Data Indexing</span></a>,</li>
<li class="changed"><a class="sectionRef sec-ref" href="#named-graph-indexing">section <span class="secno">4.19</span> <span class="sec-title">Named Graph Indexing</span></a>,</li>
<li class="changed"><a class="sectionRef sec-ref" href="#language-indexing">section <span class="secno">4.20</span> <span class="sec-title">Language Indexing</span></a>,</li>
<li class="changed"><a class="sectionRef sec-ref" href="#node-identifier-indexing">section <span class="secno">4.21</span> <span class="sec-title">Node Identifier Indexing</span></a>,</li>
<li class="changed"><a class="sectionRef sec-ref" href="#named-graph-indexing-by-identifier">section <span class="secno">4.22</span> <span class="sec-title">Named Graph Indexing by Identifier</span></a>, and</li>
<li class="changed"><a class="sectionRef sec-ref" href="#node-type-indexing">section <span class="secno">4.23</span> <span class="sec-title">Node Type Indexing</span></a>.</li>
</ul></dd>
<dt><code>@context</code></dt>
<dd>Used to define the short-hand names that are used throughout a JSON-LD
document. These short-hand names are called <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> and help
developers to express specific identifiers in a compact manner. The
<code>@context</code> keyword is described in detail in
<a class="sectionRef sec-ref" href="#the-context">section <span class="secno">3.1</span> <span class="sec-title">The Context</span></a>.</dd>
<dt><code>@graph</code></dt><dd>Used to express a <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a>.
This keyword is described in <a class="sectionRef sec-ref" href="#named-graphs">section <span class="secno">4.15</span> <span class="sec-title">Named Graphs</span></a>.</dd>
<dt><code>@id</code></dt>
<dd>Used to uniquely identify <em>things</em> that are being described in the document
with <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> or
<a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifiers</a>. This keyword
is described in <a class="sectionRef sec-ref" href="#node-identifiers">section <span class="secno">3.3</span> <span class="sec-title">Node Identifiers</span></a>.</dd>
<dt><code>@index</code></dt>
<dd>Used to specify that a container is used to index information and
that processing should continue deeper into a JSON data structure.
This keyword is described in <a class="sectionRef sec-ref" href="#data-indexing">section <span class="secno">4.18</span> <span class="sec-title">Data Indexing</span></a>.</dd>
<dt><code>@language</code></dt>
<dd>Used to specify the language for a particular string value or the default
language of a JSON-LD document. This keyword is described in
<a class="sectionRef sec-ref" href="#string-internationalization">section <span class="secno">4.10</span> <span class="sec-title">String Internationalization</span></a>.</dd>
<dt><code>@list</code></dt>
<dd>Used to express an ordered set of data.
This keyword is described in <a class="sectionRef sec-ref" href="#sets-and-lists">section <span class="secno">4.12</span> <span class="sec-title">Sets and Lists</span></a>.</dd>
<dt class="changed"><code>@nest</code></dt><dd class="changed">Collects a set of <a href="#dfn-nested-properties" class="internalDFN" data-link-type="dfn">nested properties</a> within
a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>.</dd>
<dt class="changed"><code>@none</code></dt><dd class="changed">Used as an index value
in an id map, language map, type map or elsewhere where a dictionary is
used to index into other values.</dd>
<dt class="changed"><code>@prefix</code></dt><dd class="changed">
With the value <a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a>, allows this <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> to be used to construct a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
when compacting.</dd>
<dt><code>@reverse</code></dt>
<dd>Used to express reverse properties. This keyword is described in
<a class="sectionRef sec-ref" href="#reverse-properties">section <span class="secno">4.13</span> <span class="sec-title">Reverse Properties</span></a>.</dd>
<dt><code>@set</code></dt>
<dd>Used to express an unordered set of data and to ensure that values are always
represented as arrays. This keyword is described in
<a class="sectionRef sec-ref" href="#sets-and-lists">section <span class="secno">4.12</span> <span class="sec-title">Sets and Lists</span></a>.</dd>
<dt><code>@type</code></dt>
<dd>Used to set the data type of a <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> or
<a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed value</a>. This keyword is described in
<a class="sectionRef sec-ref" href="#typed-values">section <span class="secno">4.5</span> <span class="sec-title">Typed Values</span></a>.</dd>
<dt><code>@value</code></dt>
<dd>Used to specify the data that is associated with a particular
<a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a> in the graph. This keyword is described in
<a class="sectionRef sec-ref" href="#string-internationalization">section <span class="secno">4.10</span> <span class="sec-title">String Internationalization</span></a> and
<a class="sectionRef sec-ref" href="#typed-values">section <span class="secno">4.5</span> <span class="sec-title">Typed Values</span></a>.</dd>
<dt class="changed"><code>@version</code></dt><dd class="changed">
Used in a <a href="#dfn-context-definition" class="internalDFN" data-link-type="dfn">context definition</a> to set the <a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a>.
New features since <a href="https://www.w3.org/TR/json-ld/">JSON-LD 1.0</a> [<cite><a class="bibref" href="#bib-JSON-LD">JSON-LD</a></cite>] described in this specification are
only available when <a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a> has been explicitly set to
<code>json-ld-1.1</code>.
</dd>
<dt><code>@vocab</code></dt>
<dd>Used to expand properties and values in <code>@type</code> with a common prefix
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>. This keyword is described in <a class="sectionRef sec-ref" href="#default-vocabulary">section <span class="secno">4.3</span> <span class="sec-title">Default Vocabulary</span></a>.</dd>
</dl>
<p>All keys, <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a>, and values in JSON-LD are case-sensitive.</p>
</section>
</section>
<section id="conformance" typeof="schema:Chapter" resource="#conformance" property="schema:hasPart"><!--OddPage--><h2 id="x2-conformance"><span class="secno">2. </span>Conformance&nbsp;<span class="permalink"><a href="#conformance" aria-label="Permalink for 2. Conformance" title="Permalink for 2. Conformance"><span property="schema:name" content="2. Conformance">§</span></a></span></h2>
<p>
As well as sections marked as non-normative, all authoring guidelines, diagrams, examples,
and notes in this specification are non-normative. Everything else in this specification is
normative.
</p>
<p id="respecRFC2119">The key words <em class="rfc2119">MAY</em>, <em class="rfc2119">MUST</em>, <em class="rfc2119">MUST NOT</em>, <em class="rfc2119">RECOMMENDED</em>, <em class="rfc2119">SHOULD</em>, and <em class="rfc2119">SHOULD NOT</em> are
to be interpreted as described in [<cite><a class="bibref" href="#bib-RFC2119">RFC2119</a></cite>].
</p>
<p>Conformance criteria are relevant to authors and authoring tool implementers. As well
as sections marked as non-normative, all authoring guidelines, diagrams, examples,
and notes in this specification are non-normative. Everything else in this
specification is normative.</p>
<p>A <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> complies with this specification if it follows
the normative statements in appendix <a href="#json-ld-grammar" class="sec-ref"><span class="secno">6.</span> <span class="sec-title">JSON-LD Grammar</span></a>. JSON documents
can be interpreted as JSON-LD by following the normative statements in
<a class="sectionRef sec-ref" href="#interpreting-json-as-json-ld">section <span class="secno">4.9</span> <span class="sec-title">Interpreting JSON as JSON-LD</span></a>. For convenience, normative
statements for documents are often phrased as statements on the properties of the document.</p>
<p>This specification makes use of the following namespaces:</p>
<dl>
<dt><code>dc</code>:</dt>
<dd><code>http://purl.org/dc/terms/</code></dd>
<dt><code>cred</code>:</dt>
<dd><code>https://w3id.org/credentials#</code></dd>
<dt><code>foaf</code>:</dt>
<dd><code>http://xmlns.com/foaf/0.1/</code></dd>
<dt><code>prov</code></dt>
<dd><code>http://www.w3.org/ns/prov#</code></dd>
<dt><code>rdf</code>:</dt>
<dd><code>http://www.w3.org/1999/02/22-rdf-syntax-ns#</code></dd>
<dt><code>schema</code>:</dt>
<dd><code>http://schema.org/</code></dd>
<dt><code>xsd</code>:</dt>
<dd><code>http://www.w3.org/2001/XMLSchema#</code></dd>
</dl>
</section>
<section class="informative" id="basic-concepts" typeof="schema:Chapter" resource="#basic-concepts" property="schema:hasPart">
<!--OddPage--><h2 id="x3-basic-concepts"><span class="secno">3. </span>Basic Concepts&nbsp;<span class="permalink"><a href="#basic-concepts" aria-label="Permalink for 3. Basic Concepts" title="Permalink for 3. Basic Concepts"><span property="schema:name" content="3. Basic Concepts">§</span></a></span></h2><p><em>This section is non-normative.</em></p>
<p>JSON [<cite><a class="bibref" href="#bib-RFC7159">RFC7159</a></cite>] is a lightweight, language-independent data interchange format.
It is easy to parse and easy to generate. However, it is difficult to integrate JSON
from different sources as the data may contain keys that conflict with other
data sources. Furthermore, JSON has no
built-in support for hyperlinks, which are a fundamental building block on
the Web. Let's start by looking at an example that we will be using for the
rest of this section:</p>
<div class="example"><div class="example-title marker"><span>Example 2</span><span style="text-transform: none">: Sample JSON document</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Manu Sporny"</span>,
<span class="hljs-attr">"homepage"</span>: <span class="hljs-string">"http://manu.sporny.org/"</span>,
<span class="hljs-attr">"image"</span>: <span class="hljs-string">"http://manu.sporny.org/images/manu.png"</span>
}</pre></div>
<p>It's obvious to humans that the data is about a person whose
<code>name</code> is "Manu Sporny"
and that the <code>homepage</code> property contains the URL of that person's homepage.
A machine doesn't have such an intuitive understanding and sometimes,
even for humans, it is difficult to resolve ambiguities in such representations. This problem
can be solved by using unambiguous identifiers to denote the different concepts instead of
tokens such as "name", "homepage", etc.</p>
<p>Linked Data, and the Web in general, uses <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>
(<a href="https://tools.ietf.org/html/rfc3987#section-2">Internationalized Resource Identifiers</a> as described in [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>]) for unambiguous
identification. The idea is to use <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>
to assign unambiguous identifiers to data that may be of use to other developers.
It is useful for <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a>,
like <code>name</code> and <code>homepage</code>, to expand to <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>
so that developers don't accidentally step on each other's terms. Furthermore, developers and
machines are able to use this <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> (by using a web browser, for instance) to go to
the term and get a definition of what the term means. This process is known as <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
dereferencing.</p>
<p>Leveraging the popular <a href="http://schema.org/">schema.org vocabulary</a>,
the example above could be unambiguously expressed as follows:</p>
<div class="example"><div class="example-title marker"><span>Example 3</span><span style="text-transform: none">: Sample JSON-LD document using full IRIs instead of terms</span></div><pre class="nohighlight">{
"<span class="hl-bold">http://schema.org/name</span>": "Manu Sporny",
"<span class="hl-bold">http://schema.org/url</span>": <span class="hl-bold">{ "@id": </span>"http://manu.sporny.org/" <span class="hl-bold">}</span>, <span class="comment">← The '@id' keyword means 'This value is an identifier that is an IRI'</span>
"<span class="hl-bold">http://schema.org/image</span>": <span class="hl-bold">{ "@id": </span>"http://manu.sporny.org/images/manu.png" <span class="hl-bold">}</span>
}</pre></div>
<p>In the example above, every property is unambiguously identified by an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> and all values
representing <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> are explicitly marked as such by the
<code>@id</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>. While this is a valid JSON-LD
document that is very specific about its data, the document is also overly verbose and difficult
to work with for human developers. To address this issue, JSON-LD introduces the notion
of a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> as described in the next section.</p>
<section class="informative" id="the-context" typeof="schema:Chapter" resource="#the-context" property="schema:hasPart">
<h3 id="x3-1-the-context"><span class="secno">3.1 </span>The Context&nbsp;<span class="permalink"><a href="#the-context" aria-label="Permalink for 3.1 The Context" title="Permalink for 3.1 The Context"><span property="schema:name" content="3.1 The Context">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>When two people communicate with one another, the conversation takes
place in a shared environment, typically called
"the context of the conversation". This shared context allows the
individuals to use shortcut terms, like the first name of a mutual friend,
to communicate more quickly but without losing accuracy. A context in
JSON-LD works in the same way. It allows two applications to use shortcut
terms to communicate with one another more efficiently, but without
losing accuracy.</p>
<p>Simply speaking, a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> is used to map <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> to
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>. <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">Terms</a> are case sensitive
and any valid <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a> that is not a reserved JSON-LD <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>
can be used as a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>.</p>
<p>For the sample document in the previous section, a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> would
look something like this:</p>
<div class="example"><div class="example-title marker"><span>Example 4</span><span style="text-transform: none">: Context for the sample document in the previous section</span></div><pre class="nohighlight">{
<span class="hl-bold">"@context": {
"name": "http://schema.org/name",</span> <span class="comment">← This means that 'name' is shorthand for 'http://schema.org/name'</span> <span class="hl-bold">
"image": {
"@id": "http://schema.org/image",</span> <span class="comment">← This means that 'image' is shorthand for 'http://schema.org/image'</span> <span class="hl-bold">
"@type": "@id"</span> <span class="comment">← This means that a string value associated with 'image' should be interpreted as an identifier that is an IRI</span> <span class="hl-bold">
},
"homepage": {
"@id": "http://schema.org/url",</span> <span class="comment">← This means that 'homepage' is shorthand for 'http://schema.org/url'</span> <span class="hl-bold">
"@type": "@id"</span> <span class="comment">← This means that a string value associated with 'homepage' should be interpreted as an identifier that is an IRI</span> <span class="hl-bold">
}
}</span>
}</pre></div>
<p>As the <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> above shows, the value of a <a href="#dfn-term-definitions" class="internalDFN" data-link-type="dfn">term definition</a> can
either be a simple string, mapping the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> to an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
or a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a>.</p>
<p>When a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> is associated with a term, it is called
an <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a>. The example above specifies that
the values of <code>image</code> and <code>homepage</code>, if they are
strings, are to be interpreted as
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>. <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">Expanded term definitions</a>
also allow terms to be used for <a href="#data-indexing">index maps</a>
and to specify whether <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> values are to be
interpreted as <a href="#sets-and-lists">sets or lists</a>.
<a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">Expanded term definitions</a> may
be defined using <a data-lt="absolute IRI" href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute</a> or
<a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact IRIs</a> as keys, which is
mainly used to associate type or language information with an
<a data-lt="absolute IRI" href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute</a> or <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
<p><a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">Contexts</a> can either be directly embedded
into the document or be referenced. Assuming the context document in the previous
example can be retrieved at <code>https://json-ld.org/contexts/person.jsonld</code>,
it can be referenced by adding a single line and allows a JSON-LD document to
be expressed much more concisely as shown in the example below:</p>
<div class="example"><div class="example-title marker"><span>Example 5</span><span style="text-transform: none">: Referencing a JSON-LD context</span></div><pre class="nohighlight">{
<span class="hl-bold">"@context": "https://json-ld.org/contexts/person.jsonld",</span>
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
"image": "http://manu.sporny.org/images/manu.png"
}</pre></div>
<p>The referenced context not only specifies how the terms map to
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> in the Schema.org vocabulary but also
specifies that string values associated with
the <code>homepage</code> and <code>image</code> property
can be interpreted as an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> (<code>"@type": "@id"</code>,
see <a class="sectionRef sec-ref" href="#iris">section <span class="secno">3.2</span> <span class="sec-title">IRIs</span></a> for more details). This information allows developers
to re-use each other's data without having to agree to how their data will interoperate
on a site-by-site basis. External JSON-LD context documents may contain extra
information located outside of the <code>@context</code> key, such as
documentation about the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> declared in the
document. Information contained outside of the <code>@context</code> value
is ignored when the document is used as an external JSON-LD context document.</p>
<p>JSON documents can be interpreted as JSON-LD without having to be modified by
referencing a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> via an <a href="https://tools.ietf.org/html/rfc5988#section-5">HTTP Link Header</a>
as described in <a class="sectionRef sec-ref" href="#interpreting-json-as-json-ld">section <span class="secno">4.9</span> <span class="sec-title">Interpreting JSON as JSON-LD</span></a>. It is also
possible to apply a custom context using the JSON-LD 1.1 API [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>].</p>
<p>In <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD documents</a>,
<a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">contexts</a> may also be specified inline.
This has the advantage that documents can be processed even in the
absence of a connection to the Web. Ultimately, this is a modeling decision
and different use cases may require different handling.</p>
<div class="example"><div class="example-title marker"><span>Example 6</span><span style="text-transform: none">: In-line context definition</span></div><pre class="nohighlight">{
<span class="hl-bold">"@context": {
"name": "http://schema.org/name",
"image": {
"@id": "http://schema.org/image",
"@type": "@id"
},
"homepage": {
"@id": "http://schema.org/url",
"@type": "@id"
}
},</span>
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
"image": "http://manu.sporny.org/images/manu.png"
}</pre></div>
<p>This section only covers the most basic features of the JSON-LD
Context. More advanced features related to the JSON-LD Context are covered
in section <a href="#advanced-concepts" class="sectionRef sec-ref">section <span class="secno">4.</span> <span class="sec-title">Advanced Concepts</span></a>.
</p>
</section>
<section class="informative" id="iris" typeof="schema:Chapter" resource="#iris" property="schema:hasPart">
<h3 id="x3-2-iris"><span class="secno">3.2 </span>IRIs&nbsp;<span class="permalink"><a href="#iris" aria-label="Permalink for 3.2 IRIs" title="Permalink for 3.2 IRIs"><span property="schema:name" content="3.2 IRIs">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p><a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> (<a href="https://tools.ietf.org/html/rfc3987#section-2">Internationalized Resource Identifiers</a>
[<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>]) are fundamental to Linked Data as that is how most
<a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a> and <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a>
are identified. In JSON-LD, IRIs may be represented as an
<a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>. An
<a href="https://tools.ietf.org/html/rfc3987#section-1.3">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> is defined in [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>] as containing a
<em>scheme</em> along with <em>path</em> and optional <em>query</em> and
<em>fragment</em> segments. A <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a> is an <abbr title="Internationalized Resource Identifier">IRI</abbr>
that is relative to some other <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
In JSON-LD, with exceptions are as described below, all <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative IRIs</a>
are resolved relative to the <a href="#dfn-base-iris" class="internalDFN" data-link-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-1" aria-level="4"><span>Note</span></div><p class=""><a href="#dfn-properties" class="internalDFN" data-link-type="dfn">Properties</a>, values of <code>@type</code>,
and values of <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> with a <a href="#dfn-term-definitions" class="internalDFN" data-link-type="dfn">term definition</a>
that defines them as being relative to the <a href="#dfn-vocabulary-mapping" class="internalDFN" data-link-type="dfn">vocabulary mapping</a>,
may have the form of a <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, but are resolved using the
<a href="#dfn-vocabulary-mapping" class="internalDFN" data-link-type="dfn">vocabulary mapping</a>, and not the <a href="#dfn-base-iris" class="internalDFN" data-link-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p></div>
<p>A <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a> is interpreted as an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> when it is the
value of an <code>@id</code> member:</p>
<div class="example"><div class="example-title marker"><span>Example 7</span><span style="text-transform: none">: Values of @id are interpreted as IRI</span></div><pre class="nohighlight">{
<span class="comment">...</span>
"homepage": { "<span class="hl-bold">@id</span>": "http://example.com/" }
<span class="comment">...</span>
}</pre></div>
<p>Values that are interpreted as <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>, can also be
expressed as <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative IRIs</a>. For example,
assuming that the following document is located at
<code>http://example.com/about/</code>, the <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
<code>../</code> would expand to <code>http://example.com/</code> (for more
information on where <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative IRIs</a> can be
used, please refer to section <a href="#json-ld-grammar" class="sec-ref"><span class="secno">6.</span> <span class="sec-title">JSON-LD Grammar</span></a>).</p>
<div class="example"><div class="example-title marker"><span>Example 8</span><span style="text-transform: none">: IRIs can be relative</span></div><pre class="nohighlight">{
<span class="comment">...</span>
"homepage": { "<span class="hl-bold">@id</span>": "../" }
<span class="comment">...</span>
}</pre></div>
<p><a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">Absolute IRIs</a> can be expressed directly
in the key position like so:</p>
<div class="example"><div class="example-title marker"><span>Example 9</span><span style="text-transform: none">: IRI as a key</span></div><pre class="nohighlight">{
<span class="comment">...</span>
"<span class="hl-bold">http://schema.org/name</span>": "Manu Sporny"<span class="comment">,
...</span>
}</pre></div>
<p>In the example above, the key <code>http://schema.org/name</code>
is interpreted as an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
<p>Term-to-<abbr title="Internationalized Resource Identifier">IRI</abbr> expansion occurs if the key matches a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> defined
within the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 10</span><span style="text-transform: none">: Term expansion from context definition</span></div><pre class="nohighlight">{
"<span class="hl-bold">@context</span>": {
"<span class="hl-bold">name</span>": "<span class="hl-bold">http://schema.org/name</span>"
},
"<span class="hl-bold">name</span>": "Manu Sporny",
"status": "trollin'"
}</pre></div>
<p>JSON keys that do not expand to an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>, such as <code>status</code>
in the example above, are not Linked Data and thus ignored when processed.</p>
<p>If type <a href="#dfn-coercion" class="internalDFN" data-link-type="dfn">coercion</a> rules are specified in the <code>@context</code> for
a particular <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> or property <abbr title="Internationalized Resource Identifier">IRI</abbr>, an <abbr title="Internationalized Resource Identifier">IRI</abbr> is generated:</p>
<div class="example"><div class="example-title marker"><span>Example 11</span><span style="text-transform: none">: Type coercion</span></div><pre class="nohighlight">{<span class="hl-bold">
"@context": {
<span class="comment">...</span>
"homepage": {
"@id": "http://schema.org/url",
"@type": "@id"
}
<span class="comment">...</span>
},</span>
<span class="comment">...</span>
"homepage": "http://manu.sporny.org/"
<span class="comment">...</span>
}</pre></div>
<p>In the example above, since the value <code>http://manu.sporny.org/</code>
is expressed as a JSON <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>, the type <a href="#dfn-coercion" class="internalDFN" data-link-type="dfn">coercion</a>
rules will transform the value into an <abbr title="Internationalized Resource Identifier">IRI</abbr> when processing the data.
See <a class="sectionRef sec-ref" href="#type-coercion">section <span class="secno">4.6</span> <span class="sec-title">Type Coercion</span></a> for more
details about this feature.</p>
<p>In summary, <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> can be expressed in a variety of
different ways in JSON-LD:</p>
<ol>
<li><a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> keys that have a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> mapping in
the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a> expand to an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
(only applies outside of the <a href="#dfn-context-definition" class="internalDFN" data-link-type="dfn">context definition</a>).</li>
<li>An <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> is generated for the <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a> value specified using
<code>@id</code> or <code>@type</code>.</li>
<li>An <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> is generated for the <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a> value of any key for which there
are <a href="#dfn-coercion" class="internalDFN" data-link-type="dfn">coercion</a> rules that contain an <code>@type</code> key that is
set to a value of <code>@id</code> or <code>@vocab</code>.</li>
</ol>
<p>This section only covers the most basic features associated with IRIs
in JSON-LD. More advanced features related to IRIs are covered in
section <a href="#advanced-concepts" class="sec-ref"><span class="secno">4.</span> <span class="sec-title">Advanced Concepts</span></a>.
</p>
</section>
<section class="informative" id="node-identifiers" typeof="schema:Chapter" resource="#node-identifiers" property="schema:hasPart">
<h3 id="x3-3-node-identifiers"><span class="secno">3.3 </span>Node Identifiers&nbsp;<span class="permalink"><a href="#node-identifiers" aria-label="Permalink for 3.3 Node Identifiers" title="Permalink for 3.3 Node Identifiers"><span property="schema:name" content="3.3 Node Identifiers">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>To be able to externally reference <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a>
in a <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a>, it is important that
<a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a> have an identifier. <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>
are a fundamental concept of Linked Data, for
<a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a> to be truly linked, dereferencing the
identifier should result in a representation of that <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a>.
This may allow an application to retrieve further information about a
<a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a>.</p>
<p>In JSON-LD, a <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> is identified using the <code>@id</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 12</span><span style="text-transform: none">: Identifying a node</span></div><pre class="nohighlight">{
"@context": {
<span class="comment">...</span>
"name": "http://schema.org/name"
},
<span class="hl-bold">"@id": "http://me.markus-lanthaler.com/"</span>,
"name": "Markus Lanthaler"<span class="comment">,
...</span>
}</pre></div>
<p>The example above contains a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> identified by the <abbr title="Internationalized Resource Identifier">IRI</abbr>
<code>http://me.markus-lanthaler.com/</code>.</p>
<p>This section only covers the most basic features associated with
node identifiers in JSON-LD. More advanced features related to
node identifiers are covered in section <a href="#advanced-concepts" class="sec-ref"><span class="secno">4.</span> <span class="sec-title">Advanced Concepts</span></a>.
</p>
</section>
<section class="informative" id="specifying-the-type" typeof="schema:Chapter" resource="#specifying-the-type" property="schema:hasPart">
<h3 id="x3-4-specifying-the-type"><span class="secno">3.4 </span>Specifying the Type&nbsp;<span class="permalink"><a href="#specifying-the-type" aria-label="Permalink for 3.4 Specifying the Type" title="Permalink for 3.4 Specifying the Type"><span property="schema:name" content="3.4 Specifying the Type">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>The type of a particular node can be specified using the <code>@type</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>. In Linked Data, types are uniquely
identified with an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
<div class="example"><div class="example-title marker"><span>Example 13</span><span style="text-transform: none">: Specifying the type for a node</span></div><pre class="nohighlight">{
<span class="comment">...</span>
"@id": "http://example.org/places#BrewEats",
"<span class="hl-bold">@type</span>": "<span class="hl-bold">http://schema.org/Restaurant</span>"<span class="comment">,
...</span>
}</pre></div>
<p>A node can be assigned more than one type by using an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 14</span><span style="text-transform: none">: Specifying multiple types for a node</span></div><pre class="nohighlight">{
<span class="comment">...</span>
"@id": "http://example.org/places#BrewEats",
"<span class="hl-bold">@type</span>": <span class="hl-bold">[ "http://schema.org/Restaurant", "http://schema.org/Brewery" ]</span><span class="comment">,
...</span>
}</pre></div>
<p>The value of an <code>@type</code> key may also be a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> defined in the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 15</span><span style="text-transform: none">: Using a term to specify the type</span></div><pre class="nohighlight">{
"@context": {
<span class="comment">...</span>
<span class="hl-bold">"Restaurant": "http://schema.org/Restaurant", </span>
<span class="hl-bold">"Brewery": "http://schema.org/Brewery"</span>
},
"@id": "http://example.org/places#BrewEats",
<span class="hl-bold">"@type": [ "Restaurant", "Brewery" ]</span><span class="comment">,
...</span>
}</pre></div>
<div class="note"><div role="heading" class="note-title marker" id="h-note-2" aria-level="4"><span>Note</span></div><p class="">This section only covers the most basic features associated with
types in JSON-LD. It is worth noting that the <code>@type</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> is not only used to specify the type of a
<a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> but also to express <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed values</a>
(as described in <a class="sectionRef sec-ref" href="#typed-values">section <span class="secno">4.5</span> <span class="sec-title">Typed Values</span></a>) and to
<a data-lt="coercion" href="#dfn-coercion" class="internalDFN" data-link-type="dfn">type coerce</a> values (as described in
<a class="sectionRef sec-ref" href="#type-coercion">section <span class="secno">4.6</span> <span class="sec-title">Type Coercion</span></a>). Specifically, <code>@type</code>
cannot be used in a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> to define a <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a>'s
type. For a detailed description of the differences, please refer to
<a class="sectionRef sec-ref" href="#typed-values">section <span class="secno">4.5</span> <span class="sec-title">Typed Values</span></a>.</p></div>
</section>
</section>
<section class="normative" id="advanced-concepts" typeof="schema:Chapter" resource="#advanced-concepts" property="schema:hasPart">
<!--OddPage--><h2 id="x4-advanced-concepts"><span class="secno">4. </span>Advanced Concepts&nbsp;<span class="permalink"><a href="#advanced-concepts" aria-label="Permalink for 4. Advanced Concepts" title="Permalink for 4. Advanced Concepts"><span property="schema:name" content="4. Advanced Concepts">§</span></a></span></h2>
<p>JSON-LD has a number of features that provide functionality above and beyond
the core functionality described above. The following section describes this
advanced functionality in more detail.</p>
<section class="changed informative" id="json-ld-1-1-processing-mode" typeof="schema:Chapter" resource="#json-ld-1-1-processing-mode" property="schema:hasPart">
<h3 id="x4-1-json-ld-1-1-processing-mode"><span class="secno">4.1 </span>JSON-LD 1.1 Processing Mode&nbsp;<span class="permalink"><a href="#json-ld-1-1-processing-mode" aria-label="Permalink for 4.1 JSON-LD 1.1 Processing Mode" title="Permalink for 4.1 JSON-LD 1.1 Processing Mode"><span property="schema:name" content="4.1 JSON-LD 1.1 Processing Mode">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>New features defined in JSON-LD 1.1 are available
when the <a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a> is set to <code>json-ld-1.1</code>.
This may be set using the <code>@version</code> member in a <code>context</code>
set to the value <code>1.1</code> as a <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>, or through an API option.</p>
<div class="example"><div class="example-title marker"><span>Example 16</span><span style="text-transform: none">: Setting @version in context</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span><span class="comment">,
...</span>
}<span class="comment">,
...</span>
}</pre></div>
<p>The first <code>context</code> encountered when processing a
document determines the <code>processing mode</code>,
unless it is defined explicitly through an API option.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-3" aria-level="4"><span>Note</span></div><p class="">Setting the <a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a> explicitly
for JSON-LD 1.1 is necessary so that a JSON-LD 1.0 processor
does not attempt to process a JSON-LD 1.1 document and silently
produce different results.</p></div>
</section>
<section class="informative" id="base-iri" typeof="schema:Chapter" resource="#base-iri" property="schema:hasPart">
<h3 id="x4-2-base-iri"><span class="secno">4.2 </span>Base <abbr title="Internationalized Resource Identifier">IRI</abbr>&nbsp;<span class="permalink"><a href="#base-iri" aria-label="Permalink for 4.2 Base IRI" title="Permalink for 4.2 Base IRI"><span property="schema:name" content="4.2 Base IRI">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>JSON-LD allows <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>
to be specified in a relative form which is
resolved against the document base according
<a href="https://tools.ietf.org/html/rfc3986#section-5.1">section 5.1 Establishing a Base URI</a>
of [<cite><a class="bibref" href="#bib-RFC3986">RFC3986</a></cite>]. The <a href="#dfn-base-iris" class="internalDFN" data-link-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></a> may be explicitly set with a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>
using the <code>@base</code> keyword.</p>
<p>For example, if a JSON-LD document was retrieved from <code>http://example.com/document.jsonld</code>,
relative IRIs would resolve against that <abbr title="Internationalized Resource Identifier">IRI</abbr>:</p>
<div class="example"><div class="example-title marker"><span>Example 17</span><span style="text-transform: none">: Use a relative IRI as node identifier</span></div><pre class="nohighlight">{
"@context": {
"label": "http://www.w3.org/2000/01/rdf-schema#label"
},
<span class="hl-bold">"@id": ""</span>,
"label": "Just a simple document"
}</pre></div>
<p>This document uses an empty <code>@id</code>, which resolves to the document base.
However, if the document is moved to a different location, the <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> would change.
To prevent this without having to use an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>
may define an <code>@base</code> mapping, to overwrite the <a href="#dfn-base-iris" class="internalDFN" data-link-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></a> for the document.</p>
<div class="example"><div class="example-title marker"><span>Example 18</span><span style="text-transform: none">: Setting the document base in a document</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@base": "http://example.com/document.jsonld",</span>
"label": "http://www.w3.org/2000/01/rdf-schema#label"
},
"@id": "",
"label": "Just a simple document"
}</pre></div>
<p>Setting <code>@base</code> to <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a> will prevent
<a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative IRIs</a> to be expanded to
<a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute IRIs</a>.</p>
<p>Please note that the <code>@base</code> will be ignored if used in
external contexts.</p>
</section>
<section class="informative" id="default-vocabulary" typeof="schema:Chapter" resource="#default-vocabulary" property="schema:hasPart">
<h3 id="x4-3-default-vocabulary"><span class="secno">4.3 </span>Default Vocabulary&nbsp;<span class="permalink"><a href="#default-vocabulary" aria-label="Permalink for 4.3 Default Vocabulary" title="Permalink for 4.3 Default Vocabulary"><span property="schema:name" content="4.3 Default Vocabulary">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>At times, all properties and types may come from the same vocabulary. JSON-LD's
<code>@vocab</code> keyword allows an author to set a common prefix which
is used as the <a href="#dfn-vocabulary-mapping" class="internalDFN" data-link-type="dfn">vocabulary mapping</a> and is used
for all properties and types that do not match a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> and are neither
a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> nor an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> (i.e., they do
not contain a colon).</p>
<div class="example"><div class="example-title marker"><span>Example 19</span><span style="text-transform: none">: Using a common vocabulary prefix</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@vocab": "http://schema.org/"</span>
},
"@id": "http://example.org/places#BrewEats",
"@type": <span class="hl-bold">"Restaurant"</span>,
<span class="hl-bold">"name"</span>: "Brew Eats"
<span class="comment">...</span>
}</pre></div>
<p>If <code>@vocab</code> is used but certain keys in an
<a data-lt="JSON object" href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">object</a> should not be expanded using
the vocabulary <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> can be explicitly set
to <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a> in the <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>. For instance, in the
example below the <code>databaseId</code> member would not expand to an
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
<div class="example"><div class="example-title marker"><span>Example 20</span><span style="text-transform: none">: Using the null keyword to ignore data</span></div><pre class="nohighlight">{
"@context": {
"@vocab": "http://schema.org/",
<span class="hl-bold">"databaseId": null</span>
},
"@id": "http://example.org/places#BrewEats",
"@type": "Restaurant",
"name": "Brew Eats",
<span class="hl-bold">"databaseId"</span>: "23987520"
}</pre></div>
</section>
<section class="informative" id="compact-iris" typeof="schema:Chapter" resource="#compact-iris" property="schema:hasPart">
<h3 id="x4-4-compact-iris"><span class="secno">4.4 </span>Compact IRIs&nbsp;<span class="permalink"><a href="#compact-iris" aria-label="Permalink for 4.4 Compact IRIs" title="Permalink for 4.4 Compact IRIs"><span property="schema:name" content="4.4 Compact IRIs">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>A <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> is a way of expressing an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
using a <em>prefix</em> and <em>suffix</em> separated by a colon (<code>:</code>).
The <a href="#dfn-prefixes" class="internalDFN" data-link-type="dfn">prefix</a> is a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> taken from the
<a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a> and is a short string identifying a
particular <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> in a JSON-LD document. For example, the
prefix <code>foaf</code> may be used as a short hand for the
Friend-of-a-Friend vocabulary, which is identified using the <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
<code>http://xmlns.com/foaf/0.1/</code>. A developer may append
any of the FOAF vocabulary terms to the end of the prefix to specify a short-hand
version of the <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> for the vocabulary term. For example,
<code>foaf:name</code> would be expanded to the <abbr title="Internationalized Resource Identifier">IRI</abbr>
<code>http://xmlns.com/foaf/0.1/name</code>.</p>
<div class="example"><div class="example-title marker"><span>Example 21</span><span style="text-transform: none">: Prefix expansion</span></div><pre class="nohighlight">{
"<span class="hl-bold">@context</span>": {
"<span class="hl-bold">foaf</span>": "<span class="hl-bold">http://xmlns.com/foaf/0.1/</span>"
<span class="comment">...</span>
},
"@type": "<span class="hl-bold">foaf:Person</span>",
"<span class="hl-bold">foaf:name</span>": "Dave Longley"<span class="comment">,
...</span>
}</pre></div>
<p>In the example above, <code>foaf:name</code> expands to the <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
<code>http://xmlns.com/foaf/0.1/name</code> and <code>foaf:Person</code> expands
to <code>http://xmlns.com/foaf/0.1/Person</code>.</p>
<p><a href="#dfn-prefixes" class="internalDFN" data-link-type="dfn">Prefixes</a> are expanded when the form of the value
is a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> represented as a <code>prefix:suffix</code>
combination, the <em>prefix</em> matches a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> defined within the
<a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a>, and the <em>suffix</em> does not begin with two
slashes&nbsp;(<code>//</code>). The <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> is expanded by
concatenating the <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> mapped to the <em>prefix</em> to the (possibly empty)
<em>suffix</em>. If the <em>prefix</em> is not defined in the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a>,
or the suffix begins with two slashes (such as in <code>http://example.com</code>),
the value is interpreted as <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> instead. If the prefix is an
underscore (<code>_</code>), the value is interpreted as <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>
instead.</p>
<p class="changed">In JSON-LD 1.0, terms will be used as <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> prefixes when
compacting only if they map to a value that ends with a URI <a href="https://tools.ietf.org/html/rfc3986#section-2.2">gen-delim</a> character (e.g, <code>/</code>,
<code>#</code> and others, see [<cite><a class="bibref" href="#bib-RFC3986">RFC3986</a></cite>]).</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-4" aria-level="4"><span>Note</span></div><p class="">This represents a small change to the 1.0 algorithm to prevent IRIs
that are not really intended to be used as prefixes from being used for creating
<a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact IRIs</a>.</p></div>
<p class="changed">When <a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a> is set to <code>json-ld-1.1</code>, terms will be used as <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> prefixes
when compacting only if their <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> contains
a <code>@prefix</code> member with the value <a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a>, or if it has a
a <a href="#dfn-simple-terms" class="internalDFN" data-link-type="dfn">simple term definition</a> where the value ends with a URI <a href="https://tools.ietf.org/html/rfc3986#section-2.2">gen-delim</a> character
(e.g, <code>/</code>, <code>#</code> and others, see [<cite><a class="bibref" href="#bib-RFC3986">RFC3986</a></cite>]).</p>
<p>It's also possible to use compact IRIs within the context as shown in the
following example:</p>
<div class="example"><div class="example-title marker"><span>Example 22</span><span style="text-transform: none">: Using vocabularies</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"xsd": "http://www.w3.org/2001/XMLSchema#",
<span class="hl-bold">"foaf": "http://xmlns.com/foaf/0.1/"</span>,
<span class="hl-bold">"foaf:homepage"</span>: { "@type": "@id" },
"picture": { "@id": <span class="hl-bold">"foaf:depiction"</span>, "@type": "@id" }
},
"@id": "http://me.markus-lanthaler.com/",
"@type": "foaf:Person",
"foaf:name": "Markus Lanthaler",
"foaf:homepage": "http://www.markus-lanthaler.com/",
"picture": "http://twitter.com/account/profile_image/markuslanthaler"
}</pre></div>
</section>
<section class="informative" id="typed-values" typeof="schema:Chapter" resource="#typed-values" property="schema:hasPart">
<h3 id="x4-5-typed-values"><span class="secno">4.5 </span>Typed Values&nbsp;<span class="permalink"><a href="#typed-values" aria-label="Permalink for 4.5 Typed Values" title="Permalink for 4.5 Typed Values"><span property="schema:name" content="4.5 Typed Values">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>
A value with an associated type, also known as a
<a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed value</a>, is indicated by associating a value with
an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> which indicates the value's type. Typed values may be
expressed in JSON-LD in three ways:
</p>
<ol>
<li>By utilizing the <code>@type</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> when defining
a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> within an <code>@context</code> section.</li>
<li>By utilizing a <a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a>.</li>
<li>By using a native JSON type such as <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>, <a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a>, or <a href="#dfn-false" class="internalDFN" data-link-type="dfn">false</a>.</li>
</ol>
<p>The first example uses the <code>@type</code> keyword to associate a
type with a particular <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> in the <code>@context</code>:</p>
<div class="example"><div class="example-title marker"><span>Example 23</span><span style="text-transform: none">: Expanded term definition with type coercion</span></div><pre class="nohighlight">{
<span class="hl-bold">"@context": {
"modified": {
"@id": "http://purl.org/dc/terms/modified",
"@type": "http://www.w3.org/2001/XMLSchema#dateTime"
}
},</span>
<span class="comment">...</span>
"@id": "http://example.com/docs/1",
"modified": "2010-05-29T14:17:39+02:00"<span class="comment">,
...</span>
}</pre></div>
<p>The <em>modified</em> key's value above is automatically type coerced to a
<em>dateTime</em> value because of the information specified in the
<code>@context</code>. A <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD processor</a> will interpret the example above
as follows:</p>
<table class="example">
<thead><tr>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
<th>Value Type</th>
</tr></thead>
<tbody>
<tr>
<td>http://example.com/docs/1</td>
<td>http://purl.org/dc/terms/modified</td>
<td>2010-05-29T14:17:39+02:00</td>
<td>xsd:dateTime</td>
</tr>
</tbody>
</table>
<p>The second example uses the expanded form of setting the type information
in the body of a JSON-LD document:</p>
<div class="example"><div class="example-title marker"><span>Example 24</span><span style="text-transform: none">: Expanded value with type</span></div><pre class="nohighlight">{
"@context": {
"modified": {
"@id": "http://purl.org/dc/terms/modified"
}
},
<span class="comment">...</span>
"modified": <span class="hl-bold">{
"@value": "2010-05-29T14:17:39+02:00",
"@type": "http://www.w3.org/2001/XMLSchema#dateTime"
}</span>
<span class="comment">...</span>
}</pre></div>
<p>Both examples above would generate the value
<code>2010-05-29T14:17:39+02:00</code> with the type
<code>http://www.w3.org/2001/XMLSchema#dateTime</code>. Note that it is
also possible to use a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> or a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> to
express the value of a type.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-5" aria-level="4"><span>Note</span></div><p class="">The <code>@type</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> is also used to associate a type
with a <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a>. The concept of a <a href="#dfn-node-type" class="internalDFN" data-link-type="dfn">node type</a> and
a <a href="#dfn-value-type" class="internalDFN" data-link-type="dfn">value type</a> are different.</p></div>
<p>A <dfn data-dfn-type="dfn" id="dfn-node-type">node type</dfn> specifies the type of thing
that is being described, like a person, place, event, or web page. A
<dfn data-dfn-type="dfn" id="dfn-value-type">value type</dfn> specifies the data type of a particular value, such
as an integer, a floating point number, or a date.</p>
<div class="example"><div class="example-title marker"><span>Example 25</span><span style="text-transform: none">: Example demonstrating the context-sensitivity for @type</span></div><pre class="nohighlight">{
<span class="comment">...</span>
"@id": "http://example.org/posts#TripToWestVirginia",
<span class="hl-bold">"@type": "http://schema.org/BlogPosting"</span>, <span class="comment">← This is a node type</span>
"modified": {
"@value": "2010-05-29T14:17:39+02:00",
<span class="hl-bold">"@type": "http://www.w3.org/2001/XMLSchema#dateTime"</span> <span class="comment">← This is a value type</span>
}
<span class="comment">...</span>
}</pre></div>
<p>The first use of <code>@type</code> associates a <a href="#dfn-node-type" class="internalDFN" data-link-type="dfn">node type</a>
(<code>http://schema.org/BlogPosting</code>) with the <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a>,
which is expressed using the <code>@id</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>.
The second use of <code>@type</code> associates a <a href="#dfn-value-type" class="internalDFN" data-link-type="dfn">value type</a>
(<code>http://www.w3.org/2001/XMLSchema#dateTime</code>) with the
value expressed using the <code>@value</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>. As a
general rule, when <code>@value</code> and <code>@type</code> are used in
the same <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a>, the <code>@type</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> is expressing a <a href="#dfn-value-type" class="internalDFN" data-link-type="dfn">value type</a>.
Otherwise, the <code>@type</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> is expressing a
<a href="#dfn-node-type" class="internalDFN" data-link-type="dfn">node type</a>. The example above expresses the following data:</p>
<table class="example">
<thead><tr>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
<th>Value Type</th>
</tr></thead>
<tbody>
<tr>
<td>http://example.org/posts#TripToWestVirginia</td>
<td>rdf:type</td>
<td>schema:BlogPosting</td>
<td style="text-align:center;">-</td>
</tr>
<tr>
<td>http://example.org/posts#TripToWestVirginia</td>
<td>dc:modified</td>
<td>2010-05-29T14:17:39+02:00</td>
<td>xsd:dateTime</td>
</tr>
</tbody>
</table>
</section>
<section class="informative" id="type-coercion" typeof="schema:Chapter" resource="#type-coercion" property="schema:hasPart">
<h3 id="x4-6-type-coercion"><span class="secno">4.6 </span>Type Coercion&nbsp;<span class="permalink"><a href="#type-coercion" aria-label="Permalink for 4.6 Type Coercion" title="Permalink for 4.6 Type Coercion"><span property="schema:name" content="4.6 Type Coercion">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>JSON-LD supports the coercion of values to particular data types.
Type <dfn data-dfn-type="dfn" id="dfn-coercion">coercion</dfn> allows someone deploying JSON-LD to coerce the incoming or
outgoing values to the proper data type based on a mapping of data type <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> to
<a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a>. Using type coercion, value representation is preserved without requiring
the data type to be specified with each piece of data.</p>
<p>Type coercion is specified within an <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a>
using the <code>@type</code> key. The value of this key expands to an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
Alternatively, the <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> <code>@id</code> or <code>@vocab</code> may be used
as value to indicate that within the body of a JSON-LD document, a <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a> value of a
<a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> coerced to <code>@id</code> or <code>@vocab</code> is to be interpreted as an
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>. The difference between <code>@id</code> and <code>@vocab</code> is how values are expanded
to <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute IRIs</a>. <code>@vocab</code> first tries to expand the value
by interpreting it as <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>. If no matching <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is found in the
<a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a>, it tries to expand it as <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
if there's a colon in the value; otherwise, it will expand the value using the
<a data-lt="active context" href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context's</a> <a href="#dfn-vocabulary-mapping" class="internalDFN" data-link-type="dfn">vocabulary mapping</a>, if present.
Values coerced to <code>@id</code> in contrast are expanded as
<a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> if a colon is present; otherwise, they are interpreted
as <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
<p><a href="#dfn-terms" class="internalDFN" data-link-type="dfn">Terms</a> or <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact IRIs</a> used as the value of a
<code>@type</code> key may be defined within the same context. This means that one may specify a
<a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> like <code>xsd</code> and then use <code>xsd:integer</code> within the same
context definition.</p>
<p>The example below demonstrates how a JSON-LD author can coerce values to
<a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed values</a> and <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>.</p>
<div class="example"><div class="example-title marker"><span>Example 26</span><span style="text-transform: none">: Expanded term definition with types</span></div><pre class="nohighlight">{
"@context": {
"xsd": "http://www.w3.org/2001/XMLSchema#",
"name": "http://xmlns.com/foaf/0.1/name",
"age": <span class="hl-bold">{
"@id": "http://xmlns.com/foaf/0.1/age",
"@type": "xsd:integer"
}</span>,
"homepage": <span class="hl-bold">{
"@id": "http://xmlns.com/foaf/0.1/homepage",
"@type": "@id"
}</span>
},
"@id": "http://example.com/people#john",
"name": "John Smith",
"age": <span class="hl-bold">"41"</span>,
"homepage": <span class="hl-bold">[
"http://personal.example.org/",
"http://work.example.com/jsmith/"
]</span>
}</pre></div>
<p>The example shown above would generate the following data.</p>
<table class="example">
<thead><tr>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
<th>Value Type</th>
</tr></thead>
<tbody>
<tr>
<td>http://example.com/people#john</td>
<td>foaf:name</td>
<td>John Smith</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>http://example.com/people#john</td>
<td>foaf:age</td>
<td>41</td>
<td>xsd:integer</td>
</tr>
<tr>
<td rowspan="2">http://example.com/people#john</td>
<td rowspan="2">foaf:homepage</td>
<td>http://personal.example.org/</td>
<td><a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a></td>
</tr>
<tr>
<td>http://work.example.com/jsmith/</td>
<td><a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a></td>
</tr>
</tbody>
</table>
<p>Terms may also be defined using <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute IRIs</a>
or <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact IRIs</a>. This allows coercion rules
to be applied to keys which are not represented as a simple <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>.
For example:</p>
<div class="example"><div class="example-title marker"><span>Example 27</span><span style="text-transform: none">: Term definitions using compact and absolute IRIs</span></div><pre class="nohighlight">{
"@context": {
"foaf": "http://xmlns.com/foaf/0.1/",
"<span class="hl-bold">foaf:age</span>": {
<span class="hl-bold">"@id": "http://xmlns.com/foaf/0.1/age"</span>,
"@type": "xsd:integer"
},
"<span class="hl-bold">http://xmlns.com/foaf/0.1/homepage</span>": {
"@type": "@id"
}
},
"foaf:name": "John Smith",
"<span class="hl-bold">foaf:age</span>": "41",
"<span class="hl-bold">http://xmlns.com/foaf/0.1/homepage</span>": [
"http://personal.example.org/",
"http://work.example.com/jsmith/"
]
}</pre></div>
<p>In this case the <code>@id</code> definition in the term definition is optional.
If it does exist, the <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> representing
the term will always be expanded to <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> defined by the <code>@id</code>
key—regardless of whether a prefix is defined or not.</p>
<p>Type coercion is always performed using the unexpanded value of the key. In the
example above, that means that type coercion is done looking for <code>foaf:age</code>
in the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a> and not for the corresponding, expanded
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> <code>http://xmlns.com/foaf/0.1/age</code>.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-6" aria-level="4"><span>Note</span></div><p class="">Keys in the context are treated as <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> for the purpose of
expansion and value coercion. At times, this may result in multiple representations for the same expanded <abbr title="Internationalized Resource Identifier">IRI</abbr>.
For example, one could specify that <code>dog</code> and <code>cat</code> both expanded to <code>http://example.com/vocab#animal</code>.
Doing this could be useful for establishing different type coercion or language specification rules. It also allows a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> (or even an
absolute <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>) to be defined as something else entirely. For example, one could specify that
the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> <code>http://example.org/zoo</code> should expand to
<code>http://example.org/river</code>, but this usage is discouraged because it would lead to a
great deal of confusion among developers attempting to understand the JSON-LD document.</p></div>
</section>
<section class="informative" id="embedding" typeof="schema:Chapter" resource="#embedding" property="schema:hasPart">
<h3 id="x4-7-embedding"><span class="secno">4.7 </span>Embedding&nbsp;<span class="permalink"><a href="#embedding" aria-label="Permalink for 4.7 Embedding" title="Permalink for 4.7 Embedding"><span property="schema:name" content="4.7 Embedding">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p><dfn data-dfn-type="dfn" id="dfn-embedding">Embedding</dfn> is a JSON-LD feature that allows an author to
use <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> as
<a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a> values. This is a commonly used mechanism for
creating a parent-child relationship between two <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a>.</p>
<p>Without embedding, <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> can be linked by referencing the
identifier of another <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>. For example:</p>
<div class="example"><div class="example-title marker"><span>Example 28</span><span style="text-transform: none">: Referencing node objects</span></div><pre class="nohighlight">[{
"@context": {
"@vocab": "http://schema.org/",
<span class="hl-bold">"knows": {"@type": "@id"}</span>
},
"name": "Manu Sporny",
"@type": "Person",
<span class="hl-bold">"knows": "http://foaf.me/gkellogg#me"</span>
}, {
"@id": "http://foaf.me/gkellogg#me",
"@type": "Person",
"name": "Gregg Kellogg"
}]</pre></div>
<p>The previous example describes two <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>, for Manu and Gregg, with
the <code>knows</code> property defined to treat string values as identifiers.
Embedding allows the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> for Gregg to be <em>embedded</em> as a value
of the <code>knows</code> property:</p>
<div class="example"><div class="example-title marker"><span>Example 29</span><span style="text-transform: none">: Embedding a node object as property value of another node object</span></div><pre class="nohighlight">{
"@context": {
"@vocab": "http://schema.org/"
},
"name": "Manu Sporny",
<span class="hl-bold">"knows": {</span>
"@id": "http://foaf.me/gkellogg#me",
"@type": "Person",
"name": "Gregg Kellogg"
<span class="hl-bold">}</span>
}</pre></div>
<p>A <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>, like the one used above, may be used in
any value position in the body of a JSON-LD document. Note that <a href="#type-coercion">type coercion</a> of the <code>knows</code> property
is not required, as the value is not a string.</p>
</section>
<section class="informative" id="advanced-context-usage" typeof="schema:Chapter" resource="#advanced-context-usage" property="schema:hasPart">
<h3 id="x4-8-advanced-context-usage"><span class="secno">4.8 </span>Advanced Context Usage&nbsp;<span class="permalink"><a href="#advanced-context-usage" aria-label="Permalink for 4.8 Advanced Context Usage" title="Permalink for 4.8 Advanced Context Usage"><span property="schema:name" content="4.8 Advanced Context Usage">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>Section <a href="#the-context" class="sec-ref"><span class="secno">3.1</span> <span class="sec-title">The Context</span></a> introduced the basics of what makes
JSON-LD work. This section expands on the basic principles of the
<a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> and demonstrates how more advanced use cases can
be achieved using JSON-LD. </p>
<p>In general, contexts may be used at any time a
<a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> is defined. The only time that one cannot
express a context is inside a context definition itself. For example, a
<a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> may use more than one context at different
points in a document:</p>
<div class="example"><div class="example-title marker"><span>Example 30</span><span style="text-transform: none">: Using multiple contexts</span></div><pre class="nohighlight">[
{
<span class="hl-bold">"@context": "http://example.org/contexts/person.jsonld",</span>
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
"depiction": "http://twitter.com/account/profile_image/manusporny"
},
{
<span class="hl-bold">"@context": "http://example.org/contexts/place.jsonld",</span>
"name": "The Empire State Building",
"description": "The Empire State Building is a 102-story landmark in New York City.",
"geo": {
"latitude": "40.75",
"longitude": "73.98"
}
}
]</pre></div>
<p>Duplicate context <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> are overridden using a
most-recently-defined-wins mechanism.</p>
<div class="example"><div class="example-title marker"><span>Example 31</span><span style="text-transform: none">: Scoped contexts within node objects</span></div><pre class="nohighlight">{
<span class="hl-bold">"@context": {
"name": "http://example.com/person#name",
"details": "http://example.com/person#details"
}</span>,
"<span class="hl-bold">name</span>": "Markus Lanthaler",
<span class="comment">...</span>
"details": {
<span class="hl-bold">"@context": {
"name": "http://example.com/organization#name"
}</span>,
"<span class="hl-bold">name</span>": "Graz University of Technology"
}
}</pre></div>
<p>In the example above, the <code>name</code> <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is overridden
in the more deeply nested <code>details</code> structure. Note that this is
rarely a good authoring practice and is typically used when working with
legacy applications that depend on a specific structure of the
<a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a>. If a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is redefined within a
context, all previous rules associated with the previous definition are
removed. If a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is redefined to <code>null</code>,
the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is effectively removed from the list of
<a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> defined in the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a>.</p>
<p>Multiple contexts may be combined using an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a>, which is processed
in order. The set of contexts defined within a specific <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> are
referred to as <a href="#dfn-local-contexts" class="internalDFN" data-link-type="dfn">local contexts</a>. The
<a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a> refers to the accumulation of
<a href="#dfn-local-contexts" class="internalDFN" data-link-type="dfn">local contexts</a> that are in scope at a
specific point within the document. Setting a <a href="#dfn-local-contexts" class="internalDFN" data-link-type="dfn">local context</a>
to <code>null</code> effectively resets the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a>
to an empty context. The following example specifies an external context
and then layers an embedded context on top of the external context:</p>
<div class="example"><div class="example-title marker"><span>Example 32</span><span style="text-transform: none">: Combining external and local contexts</span></div><pre class="nohighlight">{
<span class="hl-bold">"@context": [
"https://json-ld.org/contexts/person.jsonld",
{
"pic": "http://xmlns.com/foaf/0.1/depiction"
}
],</span>
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
<span class="hl-bold">"pic": "http://twitter.com/account/profile_image/manusporny"</span>
}</pre></div>
<div class="note"><div role="heading" class="note-title marker" id="h-note-7" aria-level="4"><span>Note</span></div><p class="">When possible, the <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> definition should be put
at the top of a JSON-LD document. This makes the document easier to read and
might make streaming parsers more efficient. Documents that do not have the
<a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> at the top are still conformant JSON-LD.</p></div>
<div class="note"><div role="heading" class="note-title marker" id="h-note-8" aria-level="4"><span>Note</span></div><p class="">To avoid forward-compatibility issues, <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a>
starting with an&nbsp;<code>@</code> character are to be avoided as they
might be used as <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> in future versions
of JSON-LD. Terms starting with an&nbsp;<code>@</code> character that are not
<a data-lt="keyword" href="#dfn-keywords" class="internalDFN" data-link-type="dfn">JSON-LD 1.1 keywords</a> are treated as any other term, i.e.,
they are ignored unless mapped to an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>. Furthermore, the use of
empty <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> (<code>""</code>) is not allowed as
not all programming languages are able to handle empty JSON keys.</p></div>
</section>
<section class="normative" id="interpreting-json-as-json-ld" typeof="schema:Chapter" resource="#interpreting-json-as-json-ld" property="schema:hasPart">
<h3 id="x4-9-interpreting-json-as-json-ld"><span class="secno">4.9 </span>Interpreting JSON as JSON-LD&nbsp;<span class="permalink"><a href="#interpreting-json-as-json-ld" aria-label="Permalink for 4.9 Interpreting JSON as JSON-LD" title="Permalink for 4.9 Interpreting JSON as JSON-LD"><span property="schema:name" content="4.9 Interpreting JSON as JSON-LD">§</span></a></span></h3>
<p>Ordinary JSON documents can be interpreted as JSON-LD by referencing a JSON-LD
<a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> document in an <a href="https://tools.ietf.org/html/rfc5988#section-5">HTTP Link Header</a>. Doing so allows JSON to
be unambiguously machine-readable without requiring developers to drastically
change their documents and provides an upgrade path for existing infrastructure
without breaking existing clients that rely on the <code>application/json</code>
media type or a media type with a <code>+json</code> suffix as defined in
[<cite><a class="bibref" href="#bib-RFC6839">RFC6839</a></cite>].</p>
<p>In order to use an external context with an ordinary JSON document, an author
<em class="rfc2119" title="MUST">MUST</em> specify an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> to a valid <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> in
an <a href="https://tools.ietf.org/html/rfc5988#section-5">HTTP Link Header</a> [<cite><a class="bibref" href="#bib-RFC5988">RFC5988</a></cite>] using the <code>http://www.w3.org/ns/json-ld#context</code>
link relation. The referenced document <em class="rfc2119" title="MUST">MUST</em> have a top-level <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a>.
The <code>@context</code> subtree within that object is added to the top-level
<a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> of the referencing document. If an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a>
is at the top-level of the referencing document and its items are
<a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON objects</a>, the <code>@context</code>
subtree is added to all <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> items. All extra information located outside
of the <code>@context</code> subtree in the referenced document <em class="rfc2119" title="MUST">MUST</em> be
discarded. Effectively this means that the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a> is
initialized with the referenced external <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>. A response <em class="rfc2119" title="MUST NOT">MUST NOT</em>
contain more than one <a href="https://tools.ietf.org/html/rfc5988#section-5">HTTP Link Header</a> [<cite><a class="bibref" href="#bib-RFC5988">RFC5988</a></cite>] using the
<code>http://www.w3.org/ns/json-ld#context</code> link relation.</p>
<p>The following example demonstrates the use of an external context with an
ordinary JSON document:</p>
<div class="example"><div class="example-title marker"><span>Example 33</span><span style="text-transform: none">: Referencing a JSON-LD context from a JSON document via an HTTP Link Header</span></div><pre class="nohighlight" data-content-type="http">GET /ordinary-json-document.json HTTP/1.1
Host: example.com
Accept: application/ld+json,application/json,*/*;q=0.1
====================================
HTTP/1.1 200 OK
<span class="comment">...</span>
Content-Type: <span class="hl-bold">application/json</span>
<span class="hl-bold">Link: &lt;https://json-ld.org/contexts/person.jsonld&gt;; rel="http://www.w3.org/ns/json-ld#context"; type="application/ld+json"</span>
{
"name": "Markus Lanthaler",
"homepage": "http://www.markus-lanthaler.com/",
"image": "http://twitter.com/account/profile_image/markuslanthaler"
}</pre></div>
<p>Please note that <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD documents</a>
served with the <code>application/ld+json</code>
media type <em class="rfc2119" title="MUST">MUST</em> have all context information, including references to external
contexts, within the body of the document. Contexts linked via a
<code>http://www.w3.org/ns/json-ld#context</code> <a href="https://tools.ietf.org/html/rfc5988#section-5">HTTP Link Header</a> <em class="rfc2119" title="MUST">MUST</em> be
ignored for such documents.</p>
</section>
<section class="informative" id="string-internationalization" typeof="schema:Chapter" resource="#string-internationalization" property="schema:hasPart">
<h3 id="x4-10-string-internationalization"><span class="secno">4.10 </span>String Internationalization&nbsp;<span class="permalink"><a href="#string-internationalization" aria-label="Permalink for 4.10 String Internationalization" title="Permalink for 4.10 String Internationalization"><span property="schema:name" content="4.10 String Internationalization">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>At times, it is important to annotate a <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>
with its language. In JSON-LD this is possible in a variety of ways.
First, it is possible to define a <a href="#dfn-default-language" class="internalDFN" data-link-type="dfn">default language</a> for a JSON-LD document
by setting the <code>@language</code> key in the <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 34</span><span style="text-transform: none">: Setting the default language of a JSON-LD document</span></div><pre class="nohighlight">{
<span class="hl-bold">"@context": {
<span class="comment">...</span>
"@language": "ja"
}</span>,
"name": <span class="hl-bold">"花澄"</span>,
"occupation": <span class="hl-bold">"科学者"</span>
}</pre></div>
<p>The example above would associate the <code>ja</code> language
code with the two <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a> <em>花澄</em> and <em>科学者</em>.
<a href="https://tools.ietf.org/html/bcp47#section-2">Languages codes</a> are defined in [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>]. The <a href="#dfn-default-language" class="internalDFN" data-link-type="dfn">default language</a> applies to all
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a> values that are not <a href="#type-coercion">type coerced</a>.</p>
<p>To clear the <a href="#dfn-default-language" class="internalDFN" data-link-type="dfn">default language</a> for a subtree, <code>@language</code> can
be set to <code>null</code> in a <a href="#dfn-local-contexts" class="internalDFN" data-link-type="dfn">local context</a> as follows:</p>
<div class="example"><div class="example-title marker"><span>Example 35</span><span style="text-transform: none">: Clearing default language</span></div><pre class="nohighlight">{
"@context": {
<span class="comment">...</span>
"@language": "ja"
},
"name": "花澄",
"details": {
<span class="hl-bold">"@context": {
"@language": null
}</span>,
"occupation": "Ninja"
}
}</pre></div>
<p>Second, it is possible to associate a language with a specific <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>
using an <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 36</span><span style="text-transform: none">: Expanded term definition with language</span></div><pre class="nohighlight">{
"@context": {
<span class="comment">...</span>
"ex": "http://example.com/vocab/",
"@language": "ja",
"name": { "@id": "ex:name", <span class="hl-bold">"@language": null</span> },
"occupation": { "@id": "ex:occupation" },
"occupation_en": { "@id": "ex:occupation", <span class="hl-bold">"@language": "en"</span> },
"occupation_cs": { "@id": "ex:occupation", <span class="hl-bold">"@language": "cs"</span> }
},
<span class="hl-bold">"name": "Yagyū Muneyoshi",
"occupation": "忍者",
"occupation_en": "Ninja",
"occupation_cs": "Nindža"</span><span class="comment">,
...</span>
}</pre></div>
<p>The example above would associate <em>忍者</em> with the specified default
language code <code>ja</code>, <em>Ninja</em> with the language code
<code>en</code>, and <em>Nindža</em> with the language code <code>cs</code>.
The value of <code>name</code>, <em>Yagyū Muneyoshi</em> wouldn't be
associated with any language code since <code>@language</code> was reset to
<a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a> in the <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a>.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-9" aria-level="4"><span>Note</span></div><p class="">Language associations are only applied to plain
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a>. <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">Typed values</a>
or values that are subject to <a href="#type-coercion">type coercion</a>
are not language tagged.</p></div>
<p>Just as in the example above, systems often need to express the value of a
property in multiple languages. Typically, such systems also try to ensure that
developers have a programmatically easy way to navigate the data structures for
the language-specific data. In this case, <a href="#dfn-language-maps" class="internalDFN" data-link-type="dfn">language maps</a>
may be utilized.</p>
<div class="example"><div class="example-title marker"><span>Example 37</span><span style="text-transform: none">: Language map expressing a property in three languages</span></div><pre class="nohighlight">{
"@context": {
<span class="comment">...</span>
"occupation": { "@id": "ex:occupation", <span class="hl-bold">"@container": "@language"</span> }
},
"name": "Yagyū Muneyoshi",
"occupation": <span class="hl-bold">{
"ja": "忍者",
"en": "Ninja",
"cs": "Nindža"
}</span>
<span class="comment">...</span>
}</pre></div>
<p>The example above expresses exactly the same information as the previous
example but consolidates all values in a single property. To access the
value in a specific language in a programming language supporting dot-notation
accessors for object properties, a developer may use the
<code>property.language</code> pattern. For example, to access the occupation
in English, a developer would use the following code snippet:
<code>obj.occupation.en</code>.</p>
<p>Third, it is possible to override the <a href="#dfn-default-language" class="internalDFN" data-link-type="dfn">default language</a> by using a
<a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 38</span><span style="text-transform: none">: Overriding default language using an expanded value</span></div><pre class="nohighlight">{
"@context": {
<span class="comment">...</span>
"@language": "ja"
},
"name": "花澄",
"occupation": <span class="hl-bold">{
"@value": "Scientist",
"@language": "en"
}</span>
}</pre></div>
<p>This makes it possible to specify a plain string by omitting the
<code>@language</code> tag or setting it to <code>null</code> when expressing
it using a <a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 39</span><span style="text-transform: none">: Removing language information using an expanded value</span></div><pre class="nohighlight">{
"@context": {
<span class="comment">...</span>
"@language": "ja"
},
"name": <span class="hl-bold">{
"@value": "Frank"
}</span>,
"occupation": {
"@value": "Ninja",
"@language": "en"
},
"speciality": "手裏剣"
}</pre></div>
</section>
<section class="informative" id="iri-expansion-within-a-context" typeof="schema:Chapter" resource="#iri-expansion-within-a-context" property="schema:hasPart">
<h3 id="x4-11-iri-expansion-within-a-context"><span class="secno">4.11 </span><abbr title="Internationalized Resource Identifier">IRI</abbr> Expansion within a Context&nbsp;<span class="permalink"><a href="#iri-expansion-within-a-context" aria-label="Permalink for 4.11 IRI Expansion within a Context" title="Permalink for 4.11 IRI Expansion within a Context"><span property="schema:name" content="4.11 IRI Expansion within a Context">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>In general, normal <abbr title="Internationalized Resource Identifier">IRI</abbr> expansion rules apply
anywhere an <abbr title="Internationalized Resource Identifier">IRI</abbr> is expected (see <a class="sectionRef sec-ref" href="#iris">section <span class="secno">3.2</span> <span class="sec-title">IRIs</span></a>). Within
a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> definition, this can mean that terms defined
within the context may also be used within that context as long as
there are no circular dependencies. For example, it is common to use
the <code>xsd</code> namespace when defining <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed values</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 40</span><span style="text-transform: none">: IRI expansion within a context</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"xsd": "http://www.w3.org/2001/XMLSchema#"</span>,
"name": "http://xmlns.com/foaf/0.1/name",
"age": {
"@id": "http://xmlns.com/foaf/0.1/age",
"@type": <span class="hl-bold">"xsd:integer"</span>
},
"homepage": {
"@id": "http://xmlns.com/foaf/0.1/homepage",
"@type": "@id"
}
}<span class="comment">,
...</span>
}</pre></div>
<p>In this example, the <code>xsd</code> <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is defined
and used as a <a href="#dfn-prefixes" class="internalDFN" data-link-type="dfn">prefix</a> for the <code>@type</code> coercion
of the <code>age</code> property.</p>
<p><a href="#dfn-terms" class="internalDFN" data-link-type="dfn">Terms</a> may also be used when defining the <abbr title="Internationalized Resource Identifier">IRI</abbr> of another
<a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 41</span><span style="text-transform: none">: Using a term to define the IRI of another term within a context</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"foaf": "http://xmlns.com/foaf/0.1/"</span>,
"xsd": "http://www.w3.org/2001/XMLSchema#",
"name": <span class="hl-bold">"foaf:name"</span>,
"age": {
"@id": <span class="hl-bold">"foaf:age"</span>,
"@type": "xsd:integer"
},
"homepage": {
"@id": <span class="hl-bold">"foaf:homepage"</span>,
"@type": "@id"
}
}<span class="comment">,
...</span>
}</pre></div>
<p><a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">Compact IRIs</a>
and <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> may be used on the left-hand side of a
<a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> definition.</p>
<div class="example"><div class="example-title marker"><span>Example 42</span><span style="text-transform: none">: Using a compact IRI as a term</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"foaf": "http://xmlns.com/foaf/0.1/"</span>,
"xsd": "http://www.w3.org/2001/XMLSchema#",
"name": "foaf:name",
"<span class="hl-bold">foaf:age</span>": {
"@type": "xsd:integer"
},
"<span class="hl-bold">foaf:homepage</span>": <span class="hl-bold">{
"@type": "@id"
}</span>
}<span class="comment">,
...</span>
}</pre></div>
<p>
In this example, the <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> form is used in two different
ways.
In the first approach, <code>foaf:age</code> declares both the
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> for the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> (using short-form) as well as the
<code>@type</code> associated with the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>. In the second
approach, only the <code>@type</code> associated with the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is
specified. The full <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> for
<code>foaf:homepage</code> is determined by looking up the <code>foaf</code>
<a href="#dfn-prefixes" class="internalDFN" data-link-type="dfn">prefix</a> in the
<a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>.
</p>
<p>
<a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">Absolute IRIs</a> may also be used in the key position in a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>:
</p>
<div class="example"><div class="example-title marker"><span>Example 43</span><span style="text-transform: none">: Associating context definitions with absolute IRIs</span></div><pre class="nohighlight">{
"@context": {
"foaf": "http://xmlns.com/foaf/0.1/",
"xsd": "http://www.w3.org/2001/XMLSchema#",
"name": "foaf:name",
"foaf:age": {
"@id": "foaf:age",
"@type": "xsd:integer"
},
"<span class="hl-bold">http://xmlns.com/foaf/0.1/homepage</span>": {
"@type": "@id"
}
}<span class="comment">,
...</span>
}</pre></div>
<p>In order for the <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> to match above, the <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
needs to be used in the <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a>. Also note that <code>foaf:homepage</code>
will not use the <code>{ "@type": "@id" }</code> declaration because
<code>foaf:homepage</code> is not the same as <code>http://xmlns.com/foaf/0.1/homepage</code>.
That is, <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> are looked up in a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> using
direct string comparison before the <a href="#dfn-prefixes" class="internalDFN" data-link-type="dfn">prefix</a> lookup mechanism is applied.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-10" aria-level="4"><span>Note</span></div><p class="">While it is possible to define a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, or
an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> to expand to some other unrelated <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>
(for example, <code>foaf:name</code> expanding to
<code>http://example.org/unrelated#species</code>), such usage is strongly
discouraged.</p></div>
<p>The only exception for using terms in the <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> is that
circular definitions are not allowed. That is,
a definition of <em>term1</em> cannot depend on the
definition of <em>term2</em> if <em>term2</em> also depends on
<em>term1</em>. For example, the following <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> definition
is illegal:</p>
<div class="example"><div class="example-title marker"><span>Example 44</span><span style="text-transform: none">: Illegal circular definition of terms within a context</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"term1": "term2:foo",
"term2": "term1:bar"</span>
}<span class="comment">,
...</span>
}</pre></div>
</section>
<section class="informative" id="sets-and-lists" typeof="schema:Chapter" resource="#sets-and-lists" property="schema:hasPart">
<h3 id="x4-12-sets-and-lists"><span class="secno">4.12 </span>Sets and Lists&nbsp;<span class="permalink"><a href="#sets-and-lists" aria-label="Permalink for 4.12 Sets and Lists" title="Permalink for 4.12 Sets and Lists"><span property="schema:name" content="4.12 Sets and Lists">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>A JSON-LD author can express multiple values in a compact way by using
<a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">arrays</a>. Since graphs do not describe ordering for links
between nodes, arrays in JSON-LD do not provide an ordering of the
contained elements by default. This is exactly the opposite from regular JSON
arrays, which are ordered by default. For example, consider the following
simple document:</p>
<div class="example"><div class="example-title marker"><span>Example 45</span><span style="text-transform: none">: Multiple values with no inherent order</span></div><pre class="nohighlight">{
<span class="comment">...</span>
"@id": "http://example.org/people#joebob",
"foaf:nick": <span class="hl-bold">[ "joe", "bob", "JB" ]</span><span class="comment">,
...</span>
}</pre></div>
<p>The example shown above would result in the following data being generated,
each relating the node to an individual value, with no inherent order:</p>
<table class="example">
<thead><tr>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
</tr></thead>
<tbody>
<tr>
<td>http://example.org/people#joebob</td>
<td>foaf:nick</td>
<td>joe</td>
</tr>
<tr>
<td>http://example.org/people#joebob</td>
<td>foaf:nick</td>
<td>bob</td>
</tr>
<tr>
<td>http://example.org/people#joebob</td>
<td>foaf:nick</td>
<td>JB</td>
</tr>
</tbody>
</table>
<p>Multiple values may also be expressed using the expanded form:</p>
<div class="example"><div class="example-title marker"><span>Example 46</span><span style="text-transform: none">: Using an expanded form to set multiple values</span></div><pre class="nohighlight">{
"@id": "http://example.org/articles/8",
"dc:title": <span class="hl-bold"> [
{
"@value": "Das Kapital",
"@language": "de"
},
{
"@value": "Capital",
"@language": "en"
}
]</span>
}</pre></div>
<p>The example shown above would generate the following data, again with
no inherent order:</p>
<table class="example">
<thead><tr>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
<th>Language</th>
</tr></thead>
<tbody>
<tr>
<td>http://example.org/articles/8</td>
<td>dc:title</td>
<td>Das Kapital</td>
<td>de</td>
</tr>
<tr>
<td>http://example.org/articles/8</td>
<td>dc:title</td>
<td>Capital</td>
<td>en</td>
</tr>
</tbody>
</table>
<p>Although multiple values of a property are typically of the same type,
JSON-LD places no restriction on this, and a property may have values
of different types:</p>
<div class="example"><div class="example-title marker"><span>Example 47</span><span style="text-transform: none">: Multiple array values of different types</span></div><pre class="nohighlight">{
"@id": "http://example.org/people#michael",
"dc:name": [
"Michael",
{"@value": "Mike"},
{"@value": "Miguel", "@language": "es"},
{ "@id": "https://www.wikidata.org/wiki/Q4927524" },
42
]
}</pre></div>
<p>The example shown above would generate the following data, also with
no inherent order:</p>
<table class="example">
<thead><tr>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
<th>Language</th>
<th>Value Type</th>
</tr></thead>
<tbody>
<tr>
<td>http://example.org/people#michael</td>
<td>dc:name</td>
<td>Michael</td>
<td></td>
<td></td>
</tr>
<tr>
<td>http://example.org/people#michael</td>
<td>dc:name</td>
<td>Mike</td>
<td></td>
<td></td>
</tr>
<tr>
<td>http://example.org/people#michael</td>
<td>dc:name</td>
<td>Miguel</td>
<td>es</td>
<td></td>
</tr>
<tr>
<td>http://example.org/people#michael</td>
<td>dc:name</td>
<td>https://www.wikidata.org/wiki/Q4927524</td>
<td></td>
<td></td>
</tr>
<tr>
<td>http://example.org/people#michael</td>
<td>dc:name</td>
<td>42</td>
<td></td>
<td>xsd:integer</td>
</tr>
</tbody>
</table>
<p>As the notion of ordered collections is rather important in data
modeling, it is useful to have specific language support. In JSON-LD,
a list may be represented using the <code>@list</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> as follows:</p>
<div class="example"><div class="example-title marker"><span>Example 48</span><span style="text-transform: none">: An ordered collection of values in JSON-LD</span></div><pre class="nohighlight">{
<span class="comment">...</span>
"@id": "http://example.org/people#joebob",
"foaf:nick": <span class="hl-bold">{
"@list": [ "joe", "bob", "jaybee" ]
}</span><span class="comment">,
...</span>
}</pre></div>
<p>This describes the use of this <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> as being ordered,
and order is maintained when processing a document. If every use of a given multi-valued
property is a list, this may be abbreviated by setting <code>@container</code>
to <code>@list</code> in the <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 49</span><span style="text-transform: none">: Specifying that a collection is ordered in the context</span></div><pre class="nohighlight">{
<span class="hl-bold">"@context": {
<span class="comment">...</span>
"nick": {
"@id": "http://xmlns.com/foaf/0.1/nick",
"@container": "@list"
}
}</span>,
<span class="comment">...</span>
"@id": "http://example.org/people#joebob",
"nick": <span class="hl-bold">[ "joe", "bob", "jaybee" ]</span><span class="comment">,
...</span>
}</pre></div>
<div class="note"><div role="heading" class="note-title marker" id="h-note-11" aria-level="4"><span>Note</span></div><p class="">List of lists in the form of <a href="#dfn-list-objects" class="internalDFN" data-link-type="dfn">list objects</a>
are not allowed in this version of JSON-LD. This decision was made due to the
extreme amount of added complexity when processing lists of lists.</p></div>
<p>While <code>@list</code> is used to describe <em>ordered lists</em>,
the <code>@set</code> keyword is used to describe <em>unordered sets</em>.
The use of <code>@set</code> in the body of a JSON-LD document
is optimized away when processing the document, as it is just syntactic
sugar. However, <code>@set</code> is helpful when used within the context
of a document.
Values of terms associated with an <code>@set</code> or <code>@list</code> container
are always represented in the form of an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a>,
even if there is just a single value that would otherwise be optimized to
a non-array form in compact form (see
<a class="sectionRef sec-ref" href="#compacted-document-form">section <span class="secno">4.26</span> <span class="sec-title">Compacted Document Form</span></a>). This makes post-processing of
JSON-LD documents easier as the data is always in array form, even if the
array only contains a single value.</p>
</section>
<section class="informative" id="reverse-properties" typeof="schema:Chapter" resource="#reverse-properties" property="schema:hasPart">
<h3 id="x4-13-reverse-properties"><span class="secno">4.13 </span>Reverse Properties&nbsp;<span class="permalink"><a href="#reverse-properties" aria-label="Permalink for 4.13 Reverse Properties" title="Permalink for 4.13 Reverse Properties"><span property="schema:name" content="4.13 Reverse Properties">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>JSON-LD serializes directed <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graphs</a>. That means that
every <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a> points from a <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> to another <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a>
or <a data-lt="JSON-LD value" href="#dfn-json-ld-values" class="internalDFN" data-link-type="dfn">value</a>. However, in some cases, it is desirable
to serialize in the reverse direction. Consider for example the case where a person
and its children should be described in a document. If the used vocabulary does not
provide a <em>children</em> <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a> but just a <em>parent</em>
<a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a>, every <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> representing a child would have to
be expressed with a <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a> pointing to the parent as in the following
example.</p>
<div class="example"><div class="example-title marker"><span>Example 50</span><span style="text-transform: none">: A document with children linking to their parent</span></div><pre class="nohighlight">[
{
<span class="hl-bold">"@id": "#homer"</span>,
"http://example.com/vocab#name": "Homer"
}, {
"@id": "#bart",
"http://example.com/vocab#name": "Bart",
<span class="hl-bold">"http://example.com/vocab#parent": { "@id": "#homer" }</span>
}, {
"@id": "#lisa",
"http://example.com/vocab#name": "Lisa",
<span class="hl-bold">"http://example.com/vocab#parent": { "@id": "#homer" }</span>
}
]</pre></div>
<p>Expressing such data is much simpler by using JSON-LD's <code>@reverse</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 51</span><span style="text-transform: none">: A person and its children using a reverse property</span></div><pre class="nohighlight">{
"@id": "#homer",
"http://example.com/vocab#name": "Homer",
<span class="hl-bold">"@reverse"</span>: {
<span class="hl-bold">"http://example.com/vocab#parent"</span>: [
{
"@id": "#bart",
"http://example.com/vocab#name": "Bart"
}, {
"@id": "#lisa",
"http://example.com/vocab#name": "Lisa"
}
]
}
}</pre></div>
<p>The <code>@reverse</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> can also be used in
<a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definitions</a>
to create reverse properties as shown in the following example:</p>
<div class="example"><div class="example-title marker"><span>Example 52</span><span style="text-transform: none">: Using @reverse to define reverse properties</span></div><pre class="nohighlight">{
"@context": { "name": "http://example.com/vocab#name",
<span class="hl-bold">"children": { "@reverse": "http://example.com/vocab#parent" }</span>
},
"@id": "#homer",
"name": "Homer",
<span class="hl-bold">"children"</span>: [
{
"@id": "#bart",
"name": "Bart"
}, {
"@id": "#lisa",
"name": "Lisa"
}
]
}</pre></div>
</section>
<section class="informative changed" id="scoped-contexts" typeof="schema:Chapter" resource="#scoped-contexts" property="schema:hasPart">
<h3 id="x4-14-scoped-contexts"><span class="secno">4.14 </span>Scoped Contexts&nbsp;<span class="permalink"><a href="#scoped-contexts" aria-label="Permalink for 4.14 Scoped Contexts" title="Permalink for 4.14 Scoped Contexts"><span property="schema:name" content="4.14 Scoped Contexts">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>An <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> can include a <code>@context</code>
property, which defines a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> for <a data-lt="JSON-LD
value" href="#dfn-json-ld-values" class="internalDFN" data-link-type="dfn">values</a> of properties defined using that <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>. This allows
values to use <a href="#dfn-term-definitions" class="internalDFN" data-link-type="dfn">term definitions</a>, <a href="#dfn-base-iris" class="internalDFN" data-link-type="dfn">base <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
<a href="#dfn-vocabulary-mapping" class="internalDFN" data-link-type="dfn">vocabulary mapping</a> or <a href="#dfn-default-language" class="internalDFN" data-link-type="dfn">default language</a> which is different from the
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> they are contained in, in exactly the same was as if the
<a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> were specified within the value itself.</p>
<div class="example"><div class="example-title marker"><span>Example 53</span><span style="text-transform: none">: Defining an @context within a term definition</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"name": "http://schema.org/name",
"interest": {
"@id": "http://xmlns.com/foaf/0.1/interest",
<span class="hl-bold">"@context": {"@vocab": "http://xmlns.com/foaf/0.1/"}</span>
}
},
"name": "Manu Sporny",
"interest": <span class="hl-bold">{
"@id": "https://www.w3.org/TR/json-ld/",
"name": "JSON-LD",
"topic": "Linking Data"
}</span>
}</pre></div>
<p>In this case, the social profile is defined using the schema.org vocabulary, but interest is imported from FOAF, and is used to define a node describing one of Manu's interests where those properties now come from the FOAF vocabulary.</p>
<p>Expanding this document, uses a combination of terms defined in the outer context, and those defined specifically for that term.</p>
<div class="example"><div class="example-title marker"><span>Example 54</span><span style="text-transform: none">: Expanded document using a scoped context</span></div><pre class="nohighlight">[{
"http://schema.org/name": [{"@value": "Manu Sporny"}],
"http://xmlns.com/foaf/0.1/interest": [{
"@id": "https://www.w3.org/TR/json-ld/",
"http://schema.org/name": [{"@value": "JSON-LD"}],
<span class="hl-bold">"http://xmlns.com/foaf/0.1/topic": [{"@value": "Linking Data"}]</span>
}]
}]</pre></div>
<p>Scoping can also be performed using a term used as a value of <code>@type</code>:</p>
<div class="example"><div class="example-title marker"><span>Example 55</span><span style="text-transform: none">: Defining an @context within a term definition used on @type</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"name": "http://schema.org/name",
"interest": "http://xmlns.com/foaf/0.1/interest",
<span class="hl-bold">"Document"</span>: {
"@id": "http://xmlns.com/foaf/0.1/Document",
<span class="hl-bold">"@context": {"@vocab": "http://xmlns.com/foaf/0.1/"}</span>
}
},
"@type": "Person",
"name": "Manu Sporny",
"interest": {
"@id": "https://www.w3.org/TR/json-ld/",
<span class="hl-bold">"@type": "Document"</span>,
"name": "JSON-LD",
"topic": "Linking Data"
}
}</pre></div>
<p>Scoping on <code>@type</code> is useful when common properties are used to relate things of different types, where the vocabularies in use within different entities calls for different context scoping. For example, `hasPart`/`partOf` may be common terms used in a document, but mean different things depending on the context.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-12" aria-level="4"><span>Note</span></div><p class="">Scoped Contexts are a new feature in JSON-LD 1.1, requiring
<a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a> set to <code>json-ld-1.1</code>.</p></div>
</section>
<section class="informative" id="named-graphs" typeof="schema:Chapter" resource="#named-graphs" property="schema:hasPart">
<h3 id="x4-15-named-graphs"><span class="secno">4.15 </span>Named Graphs&nbsp;<span class="permalink"><a href="#named-graphs" aria-label="Permalink for 4.15 Named Graphs" title="Permalink for 4.15 Named Graphs"><span property="schema:name" content="4.15 Named Graphs">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>At times, it is necessary to make statements about a <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a>
itself, rather than just a single <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a>. This can be done by
grouping a set of <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a> using the <code>@graph</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>. A developer may also name data expressed using the
<code>@graph</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> by pairing it with an
<code>@id</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> as shown in the following example:</p>
<div class="example"><div class="example-title marker"><span>Example 56</span><span style="text-transform: none">: Identifying and making statements about a graph</span></div><pre class="nohighlight">{
"@context": {
"generatedAt": {
"@id": "http://www.w3.org/ns/prov#generatedAtTime",
"@type": "http://www.w3.org/2001/XMLSchema#date"
},
"Person": "http://xmlns.com/foaf/0.1/Person",
"name": "http://xmlns.com/foaf/0.1/name",
"knows": "http://xmlns.com/foaf/0.1/knows"
},
<span class="hl-bold">"@id": "_:graph",
"generatedAt": "2012-04-09",
"@graph":</span> [
{
"@id": "http://manu.sporny.org/about#manu",
"@type": "Person",
"name": "Manu Sporny",
"knows": "http://greggkellogg.net/foaf#me"
}, {
"@id": "http://greggkellogg.net/foaf#me",
"@type": "Person",
"name": "Gregg Kellogg",
"knows": "http://manu.sporny.org/about#manu"
}
]
}</pre></div>
<p>The example above expresses a <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a> that is identified
by the <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">Blank Node identifier</a> <code>_:graph</code>. That
graph is composed of the statements about Manu and Gregg. Metadata about
the graph itself is expressed via the <code>generatedAt</code> property,
which specifies when the graph was generated. An alternative view of the
information above is represented in table form below:</p>
<table class="example">
<thead><tr>
<th>Graph</th>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
<th>Value Type</th>
</tr></thead>
<tbody>
<tr>
<td>&nbsp;</td>
<td>_:graph</td>
<td>prov:generatedAtTime</td>
<td>2012-04-09</td>
<td>xsd:date</td>
</tr>
<tr>
<td>_:graph</td>
<td>http://manu.sporny.org/about#manu</td>
<td>xsd:type</td>
<td>foaf:Person</td>
<td></td>
</tr>
<tr>
<td>_:graph</td>
<td>http://manu.sporny.org/about#manu</td>
<td>foaf:name</td>
<td>Manu Sporny</td>
<td></td>
</tr>
<tr>
<td>_:graph</td>
<td>http://manu.sporny.org/about#manu</td>
<td>foaf:knows</td>
<td>http://greggkellogg.net/foaf#me</td>
<td></td>
</tr>
<tr>
<td>_:graph</td>
<td>http://greggkellogg.net/foaf#me</td>
<td>xsd:type</td>
<td>foaf:Person</td>
<td></td>
</tr>
<tr>
<td>_:graph</td>
<td>http://greggkellogg.net/foaf#me</td>
<td>foaf:name</td>
<td>Gregg Kellogg</td>
<td></td>
</tr>
<tr>
<td>_:graph</td>
<td>http://greggkellogg.net/foaf#me</td>
<td>foaf:knows</td>
<td>http://manu.sporny.org/about#manu</td>
<td></td>
</tr>
</tbody>
</table>
<p>When a JSON-LD document's top-level structure is an
<a data-lt="JSON object" href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">object</a> that contains no other
<a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> than <code>@graph</code> and
optionally <code>@context</code> (properties that are not mapped to an
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> are ignored),
<code>@graph</code> is considered to express the otherwise implicit
<a href="#dfn-default-graph" class="internalDFN" data-link-type="dfn">default graph</a>. This mechanism can be useful when a number
of <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a> exist at the document's top level that
share the same <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>, which is, e.g., the case when a
document is <a href="#flattened-document-form">flattened</a>. The
<code>@graph</code> keyword collects such nodes in an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a>
and allows the use of a shared context.</p>
<div class="example"><div class="example-title marker"><span>Example 57</span><span style="text-transform: none">: Using @graph to explicitly express the default graph</span></div><pre class="nohighlight">{
"@context": {<span class="comment">...</span>},
"<span class="hl-bold">@graph</span>": [
{
"@id": "http://manu.sporny.org/about#manu",
"@type": "foaf:Person",
"name": "Manu Sporny",
"knows": "http://greggkellogg.net/foaf#me"
}, {
"@id": "http://greggkellogg.net/foaf#me",
"@type": "foaf:Person",
"name": "Gregg Kellogg",
"knows": "http://manu.sporny.org/about#manu"
}
]
}</pre></div>
<p>In this case, embedding doesn't work as each <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>
references the other. This is equivalent to using multiple
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> in array and defining
the <code>@context</code> within each <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>:</p>
<div class="example"><div class="example-title marker"><span>Example 58</span><span style="text-transform: none">: Context needs to be duplicated if @graph is not used</span></div><pre class="nohighlight">[
{
<span class="hl-bold">"@context": {<span class="comment">...</span>},</span>
"@id": "http://manu.sporny.org/about#manu",
"@type": "foaf:Person",
"name": "Manu Sporny",
"knows": "http://greggkellogg.net/foaf#me"
},
{
<span class="hl-bold">"@context": {<span class="comment">...</span>},</span>
"@id": "http://greggkellogg.net/foaf#me",
"@type": "foaf:Person",
"name": "Gregg Kellogg",
"knows": "http://manu.sporny.org/about#manu"
}
]</pre></div>
<section class="changed" id="graph-containers" typeof="schema:Chapter" resource="#graph-containers" property="schema:hasPart">
<h4 id="x4-15-1-graph-containers"><span class="secno">4.15.1 </span>Graph Containers&nbsp;<span class="permalink"><a href="#graph-containers" aria-label="Permalink for 4.15.1 Graph Containers" title="Permalink for 4.15.1 Graph Containers"><span property="schema:name" content="4.15.1 Graph Containers">§</span></a></span></h4>
<p>In some cases, it is useful to logically partition data into separate
graphs, without making this explicit within the JSON expression. For
example, a JSON document may contain data against which other metadata is
asserted and it is useful to separate this data in the data model using
the notion of <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graphs</a>, without the syntactic overhead
associated with the <code>@graph</code> keyword.</p>
<p>An <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> can use <code>@graph</code> as the
value of <code>@container</code>. This indicates that values of this
<a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> should be considered to be <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graphs</a>, where the
<a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph name</a> is an automatically assigned <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>
creating an <a href="#dfn-implicitly-named-graphs" class="internalDFN" data-link-type="dfn">implicitly named graph</a>. When expanded, these become
<a href="#dfn-simple-graph-objects" class="internalDFN" data-link-type="dfn">simple graph objects</a>.</p>
<p>An alternative to our example above could use an anonymously <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a>
as follows:</p>
<div class="example"><div class="example-title marker"><span>Example 59</span><span style="text-transform: none">: Implicitly named graph</span></div><pre class="nohighlight">{
"@context": {
"@version": 1.1,
"generatedAt": {
"@id": "http://www.w3.org/ns/prov#generatedAtTime",
"@type": "http://www.w3.org/2001/XMLSchema#date"
},
"Person": "http://xmlns.com/foaf/0.1/Person",
"name": "http://xmlns.com/foaf/0.1/name",
"knows": "http://xmlns.com/foaf/0.1/knows",
<span class="hl-bold">"claim": {
"@id": "https://w3id.org/credentials#claim",
"@container": "@graph"
}</span>
},
<span class="hl-bold">"generatedAt": "2012-04-09",
"claim": [</span>
{
"@id": "http://manu.sporny.org/about#manu",
"@type": "Person",
"name": "Manu Sporny",
"knows": "http://greggkellogg.net/foaf#me"
}, {
"@id": "http://greggkellogg.net/foaf#me",
"@type": "Person",
"name": "Gregg Kellogg",
"knows": "http://manu.sporny.org/about#manu"
}
<span class="hl-bold">]</span>
}</pre></div>
<p>The example above expresses a <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a> that is identified
by the <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a> <code>_:claim</code>. That
graph is composed of the statements about Manu and Gregg. Metadata about
the graph itself is expressed via the <code>generatedAt</code> property,
which specifies when the graph was generated. An alternative view of the
information above is represented in table form below:</p>
<table class="example">
<thead><tr>
<th>Graph</th>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
<th>Value Type</th>
</tr></thead>
<tbody>
<tr>
<td>&nbsp;</td>
<td>_:metadata</td>
<td>prov:generatedAtTime</td>
<td>2012-04-09</td>
<td>xsd:date</td>
</tr>
<tr>
<td>&nbsp;</td>
<td>_:metadata</td>
<td>cred:claim</td>
<td>_:claim</td>
<td></td>
</tr>
<tr>
<td>_:claim</td>
<td>http://manu.sporny.org/about#manu</td>
<td>xsd:type</td>
<td>foaf:Person</td>
<td></td>
</tr>
<tr>
<td>_:claim</td>
<td>http://manu.sporny.org/about#manu</td>
<td>foaf:name</td>
<td>Manu Sporny</td>
<td></td>
</tr>
<tr>
<td>_:claim</td>
<td>http://manu.sporny.org/about#manu</td>
<td>foaf:knows</td>
<td>http://greggkellogg.net/foaf#me</td>
<td></td>
</tr>
<tr>
<td>_:claim</td>
<td>http://greggkellogg.net/foaf#me</td>
<td>xsd:type</td>
<td>foaf:Person</td>
<td></td>
</tr>
<tr>
<td>_:claim</td>
<td>http://greggkellogg.net/foaf#me</td>
<td>foaf:name</td>
<td>Gregg Kellogg</td>
<td></td>
</tr>
<tr>
<td>_:claim</td>
<td>http://greggkellogg.net/foaf#me</td>
<td>foaf:knows</td>
<td>http://manu.sporny.org/about#manu</td>
<td></td>
</tr>
</tbody>
</table>
<p>Expanding this graph results in the following:</p>
<div class="example"><div class="example-title marker"><span>Example 60</span><span style="text-transform: none">: Implicitly named graph after expansion</span></div><pre class="nohighlight">[{
<span class="hl-bold">"http://www.w3.org/ns/prov#generatedAtTime": [{
"@value": "2012-04-09",
"@type": "http://www.w3.org/2001/XMLSchema#date"
}],
"https://w3id.org/credentials#claim": [{</span>
"@graph": [{
"@id": "http://manu.sporny.org/about#manu",
"@type": ["http://xmlns.com/foaf/0.1/Person"],
"http://xmlns.com/foaf/0.1/knows": [{
"@value": "http://greggkellogg.net/foaf#me"
}],
"http://xmlns.com/foaf/0.1/name": [{
"@value": "Manu Sporny"
}]
}, {
"@id": "http://greggkellogg.net/foaf#me",
"@type": ["http://xmlns.com/foaf/0.1/Person"],
"http://xmlns.com/foaf/0.1/knows": [{
"@value": "http://manu.sporny.org/about#manu"
}],
"http://xmlns.com/foaf/0.1/name": [{
"@value": "Gregg Kellogg"
}]
}]
<span class="hl-bold">}]</span>
}]</pre></div>
<div class="note"><div role="heading" class="note-title marker" id="h-note-13" aria-level="5"><span>Note</span></div><p class="">Strictly speaking, the value of such a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>
is not a <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a>, rather it is the <a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph name</a>
associated with the <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a>, which exists separately within
the <a href="#dfn-dataset" class="internalDFN" data-link-type="dfn">dataset</a>.</p></div>
<div class="note"><div role="heading" class="note-title marker" id="h-note-14" aria-level="5"><span>Note</span></div><p class="">Graph Containers are a new feature in JSON-LD 1.1, requiring
<a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a> set to <code>json-ld-1.1</code>.</p></div>
</section>
</section>
<section class="informative" id="identifying-blank-nodes" typeof="schema:Chapter" resource="#identifying-blank-nodes" property="schema:hasPart">
<h3 id="x4-16-identifying-blank-nodes"><span class="secno">4.16 </span>Identifying Blank Nodes&nbsp;<span class="permalink"><a href="#identifying-blank-nodes" aria-label="Permalink for 4.16 Identifying Blank Nodes" title="Permalink for 4.16 Identifying Blank Nodes"><span property="schema:name" content="4.16 Identifying Blank Nodes">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>At times, it becomes necessary to be able to express information without
being able to uniquely identify the <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> with an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.
This type of node is called a <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a>. JSON-LD does not require
all nodes to be identified using <code>@id</code>. However, some graph topologies
may require identifiers to be serializable. Graphs containing loops, e.g., cannot
be serialized using embedding alone, <code>@id</code> must be used to connect the nodes.
In these situations, one can use <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifiers</a>,
which look like <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> using an underscore (<code>_</code>)
as scheme. This allows one to reference the node locally within the document, but
makes it impossible to reference the node from an external document. The
<a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a> is scoped to the document in which it is used.</p>
<div class="example"><div class="example-title marker"><span>Example 61</span><span style="text-transform: none">: Specifying a local blank node identifier</span></div><pre class="nohighlight">{
<span class="comment">...</span>
"@id": "<span class="hl-bold">_:n1</span>",
"name": "Secret Agent 1",
"knows": {
"name": "Secret Agent 2",
"knows": { "@id": "<span class="hl-bold">_:n1</span>" }
}
}</pre></div>
<p>The example above contains information about two secret agents that cannot be identified
with an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>. While expressing that <em>agent&nbsp;1</em> knows <em>agent&nbsp;2</em>
is possible without using <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifiers</a>,
it is necessary to assign <em>agent&nbsp;1</em> an identifier so that it can be referenced
from <em>agent&nbsp;2</em>.</p>
<p>It is worth noting that blank node identifiers may be relabeled during processing.
If a developer finds that they refer to the <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a> more than once,
they should consider naming the node using a dereferenceable <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> so that
it can also be referenced from other documents.</p>
</section>
<section class="informative" id="aliasing-keywords" typeof="schema:Chapter" resource="#aliasing-keywords" property="schema:hasPart">
<h3 id="x4-17-aliasing-keywords"><span class="secno">4.17 </span>Aliasing Keywords&nbsp;<span class="permalink"><a href="#aliasing-keywords" aria-label="Permalink for 4.17 Aliasing Keywords" title="Permalink for 4.17 Aliasing Keywords"><span property="schema:name" content="4.17 Aliasing Keywords">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>Each of the JSON-LD <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a>,
except for <code>@context</code>, may be aliased to application-specific
keywords. This feature allows legacy JSON content to be utilized
by JSON-LD by re-using JSON keys that already exist in legacy documents.
This feature also allows developers to design domain-specific implementations
using only the JSON-LD <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>.</p>
<div class="example"><div class="example-title marker"><span>Example 62</span><span style="text-transform: none">: Aliasing keywords</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"url": "@id"</span>,
<span class="hl-bold">"a": "@type"</span>,
"name": "http://xmlns.com/foaf/0.1/name"
},
"<span class="hl-bold">url</span>": "http://example.com/about#gregg",
"<span class="hl-bold">a</span>": "http://xmlns.com/foaf/0.1/Person",
"name": "Gregg Kellogg"
}</pre></div>
<p>In the example above, the <code>@id</code> and <code>@type</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a> have been given the aliases
<strong>url</strong> and <strong>a</strong>, respectively.</p>
<p>Since keywords cannot be redefined, they can also not be aliased to
other keywords.</p>
</section>
<section class="informative" id="data-indexing" typeof="schema:Chapter" resource="#data-indexing" property="schema:hasPart">
<h3 id="x4-18-data-indexing"><span class="secno">4.18 </span>Data Indexing&nbsp;<span class="permalink"><a href="#data-indexing" aria-label="Permalink for 4.18 Data Indexing" title="Permalink for 4.18 Data Indexing"><span property="schema:name" content="4.18 Data Indexing">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>Databases are typically used to make access to
data more efficient. Developers often extend this sort of functionality into
their application data to deliver similar performance gains. Often this
data does not have any meaning from a Linked Data standpoint, but is
still useful for an application.</p>
<p>JSON-LD introduces the notion of <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index maps</a>
that can be used to structure data into a form that is
more efficient to access. The data indexing feature allows an author to
structure data using a simple key-value map where the keys do not map
to <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>. This enables direct access to data
instead of having to scan an array in search of a specific item.
In JSON-LD such data can be specified by associating the
<code>@index</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> with a
<code>@container</code> declaration in the context:</p>
<div class="example"><div class="example-title marker"><span>Example 63</span><span style="text-transform: none">: Indexing data in JSON-LD</span></div><pre class="nohighlight">{
"@context": {
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
<span class="hl-bold">"@container": "@index"</span>
}
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
<span class="hl-bold">"post": {
"en": {
"@id": "http://example.com/posts/1/en",
"body": "World commodities were up today with heavy trading of crude oil...",
"words": 1539
},
"de": {
"@id": "http://example.com/posts/1/de",
"body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
"words": 1204
}</span>
}
}</pre></div>
<p>In the example above, the <strong>post</strong> <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> has
been marked as an <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index map</a>. The <strong>en</strong> and
<strong>de</strong> keys will be ignored semantically, but preserved
syntactically, by the <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD Processor</a>. This allows a developer to
access the German version of the <strong>post</strong> using the
following code snippet: <code>obj.post.de</code>.</p>
<p>The interpretation of the data above is expressed in
the table below. Note how the index keys do not appear in the Linked Data
below, but would continue to exist if the document were compacted or
expanded (see <a class="sectionRef sec-ref" href="#compacted-document-form">section <span class="secno">4.26</span> <span class="sec-title">Compacted Document Form</span></a> and
<a class="sectionRef sec-ref" href="#expanded-document-form">section <span class="secno">4.25</span> <span class="sec-title">Expanded Document Form</span></a>) using a <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD processor</a>:</p>
<table class="example">
<thead><tr>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
</tr></thead>
<tbody>
<tr>
<td>http://example.com/</td>
<td>rdf:type</td>
<td>schema:Blog</td>
</tr>
<tr>
<td>http://example.com/</td>
<td>schema:name</td>
<td>World Financial News</td>
</tr>
<tr>
<td>http://example.com/</td>
<td>schema:blogPost</td>
<td>http://example.com/posts/1/en</td>
</tr>
<tr>
<td>http://example.com/</td>
<td>schema:blogPost</td>
<td>http://example.com/posts/1/de</td>
</tr>
<tr>
<td>http://example.com/posts/1/en</td>
<td>schema:articleBody</td>
<td>World commodities were up today with heavy trading of crude oil...</td>
</tr>
<tr>
<td>http://example.com/posts/1/en</td>
<td>schema:wordCount</td>
<td>1539</td>
</tr>
<tr>
<td>http://example.com/posts/1/de</td>
<td>schema:articleBody</td>
<td>Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...</td>
</tr>
<tr>
<td>http://example.com/posts/1/de</td>
<td>schema:wordCount</td>
<td>1204</td>
</tr>
</tbody>
</table>
<p class="changed">The value of <code>@container</code> can also
be an array containing both <code>@index</code> and <code>@set</code>.
When <em>compacting</em>, this ensures that a <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD Processor</a> will use
the <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> form for all values of indexes.</p>
<div class="example"><div class="example-title marker"><span>Example 64</span><span style="text-transform: none">: Indexing data in JSON-LD with @set representation</span></div><pre class="nohighlight changed">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
"@container": <span class="hl-bold">["@index", "@set"]</span>
}
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
"post": {
"en": <span class="hl-bold">[</span>{
"@id": "http://example.com/posts/1/en",
"body": "World commodities were up today with heavy trading of crude oil...",
"words": 1539
}<span class="hl-bold">]</span>,
"de": <span class="hl-bold">[</span>{
"@id": "http://example.com/posts/1/de",
"body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
"words": 1204
}<span class="hl-bold">]</span>
}
}</pre></div>
<p class="changed">The special index <code>@none</code> is used for indexing
data which does not have an associated index, which is useful to maintain
a normalized representation.</p>
<div class="example"><div class="example-title marker"><span>Example 65</span><span style="text-transform: none">: Indexing data using @none</span></div><pre class="nohighlight">{
"@context": {
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
<span class="hl-bold">"@container": "@index"</span>
}
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
"post": {
"en": {
"@id": "http://example.com/posts/1/en",
"body": "World commodities were up today with heavy trading of crude oil...",
"words": 1539
},
"de": {
"@id": "http://example.com/posts/1/de",
"body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
"words": 1204
},
<span class="hl-bold">"@none": {
"body": "Unindexed description",
"words": 20
}</span>
}
}</pre></div>
</section>
<section class="changed" id="named-graph-indexing" typeof="schema:Chapter" resource="#named-graph-indexing" property="schema:hasPart">
<h3 id="x4-19-named-graph-indexing"><span class="secno">4.19 </span>Named Graph Indexing&nbsp;<span class="permalink"><a href="#named-graph-indexing" aria-label="Permalink for 4.19 Named Graph Indexing" title="Permalink for 4.19 Named Graph Indexing"><span property="schema:name" content="4.19 Named Graph Indexing">§</span></a></span></h3>
<p>In addition to indexing <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> by index, <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph objects</a> may
also be indexed by an index. By using the <code>@graph</code>
container type, introduced in <a href="#graph-containers" class="sectionRef sec-ref">section <span class="secno">4.15.1</span> <span class="sec-title">Graph Containers</span></a>
in addition to <code>@index</code>, an object value of such a property is
treated as a key-value map where the keys do not map to <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>, but
are taken from an <code>@index</code> property associated with <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graphs</a>
which are their values. When expanded, these must be <a href="#dfn-simple-graph-objects" class="internalDFN" data-link-type="dfn">simple graph objects</a></p>
<p>The following example describes a default graph referencing multiple named
graphs using an <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index map</a>.</p>
<div class="example"><div class="example-title marker"><span>Example 66</span><span style="text-transform: none">: Indexing graph data in JSON-LD</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
"@container": <span class="hl-bold">["@graph"</span>, "@index"<span class="hl-bold">]</span>
}
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
<span class="hl-bold">"post": {
"en": {
"@id": "http://example.com/posts/1/en",
"body": "World commodities were up today with heavy trading of crude oil...",
"words": 1539
},
"de": {
"@id": "http://example.com/posts/1/de",
"body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
"words": 1204
}</span>
}
}</pre></div>
<p>This expands to the following:</p>
<div class="example"><div class="example-title marker"><span>Example 67</span><span style="text-transform: none">: Indexed graph data after expansion</span></div><pre class="nohighlight">[{
"@id": "http://example.com/",
"@type": ["http://schema.org/Blog"],
"http://schema.org/blogPost": [{
<span class="hl-bold">"@graph"</span>: [{
"@id": "http://example.com/posts/1/de",
"http://schema.org/articleBody": [{
"@value": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl..."
}],
"http://schema.org/wordCount": [{"@value": 1204}]
}],
"@index": "de"
}, {
<span class="hl-bold">"@graph"</span>: [{
"@id": "http://example.com/posts/1/en",
"http://schema.org/articleBody": [{
"@value": "World commodities were up today with heavy trading of crude oil..."
}],
"http://schema.org/wordCount": [{"@value": 1539}]
}],
"@index": "en"
}],
"http://schema.org/name": [{"@value": "World Financial News"}]
}]</pre></div>
<p>When expressed as Quads, this becomes the following:</p>
<table class="example">
<thead><tr>
<th>Graph</th>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
<th>Value Type</th>
</tr></thead>
<tbody>
<tr>
<td>&nbsp;</td>
<td>http://example.com/</td>
<td>rdf:type</td>
<td>schema:Blog</td>
<td></td>
</tr>
<tr>
<td>&nbsp;</td>
<td>http://example.com/</td>
<td>schema:name</td>
<td>World Financial News</td>
<td></td>
</tr>
<tr>
<td>&nbsp;</td>
<td>http://example.com/</td>
<td>schema:blogPost</td>
<td>_:b1</td>
<td></td>
</tr>
<tr>
<td>&nbsp;</td>
<td>http://example.com/</td>
<td>schema:blogPost</td>
<td>_:b2</td>
<td></td>
</tr>
<tr>
<td>_:b1</td>
<td>http://example.com/posts/1/de</td>
<td>schema:wordCount</td>
<td>1204</td>
<td>xsd:integer</td>
</tr>
<tr>
<td>_:b1</td>
<td>http://example.com/posts/1/de</td>
<td>schema:articleBody</td>
<td>Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...</td>
<td></td>
</tr>
<tr>
<td>_:b2</td>
<td>http://example.com/posts/1/en</td>
<td>schema:wordCount</td>
<td>1539</td>
<td>xsd:integer</td>
</tr>
<tr>
<td>_:b2</td>
<td>http://example.com/posts/1/en</td>
<td>schema:articleBody</td>
<td>World commodities were up today with heavy trading of crude oil...</td>
<td></td>
</tr>
</tbody>
</table>
<p>As with <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index maps</a>, when used with <code>@graph</code>, a container may also
include <code>@set</code> to ensure that key values are always contained in an array.</p>
<p class="changed">The special index <code>@none</code> is used for indexing
graphs which does not have an <code>@index</code> key, which is useful to maintain
a normalized representation. <span class="note">Note, however, that
compacting a document where multiple unidentified named graphs are
compacted using the <code>@none</code> index will result in the content
of those graphs being merged. To prevent this, give each graph a distinct
<code>@index</code> key.</span></p>
<div class="example"><div class="example-title marker"><span>Example 68</span><span style="text-transform: none">: Indexing graphs using @none for no index</span></div><pre class="nohighlight">{
"@context": {
"@version": 1.1,
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
"@container": ["@graph", "@index"]
}
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
"post": {
"en": {
"@id": "http://example.com/posts/1/en",
"body": "World commodities were up today with heavy trading of crude oil...",
"words": 1539
},
"@none": {
"@id": "http://example.com/posts/1/de",
"body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
"words": 1204
}
}
}</pre></div>
<p>This expands to the following:</p>
<div class="example"><div class="example-title marker"><span>Example 69</span><span style="text-transform: none">: Indexed languaged-tagged strings with @none after expansion</span></div><pre class="nohighlight">[{
"@id": "http://example.com/",
"@type": ["http://schema.org/Blog"],
"http://schema.org/blogPost": [{
"@graph": [{
"@id": "http://example.com/posts/1/de",
"http://schema.org/articleBody": [{
"@value": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl..."
}],
"http://schema.org/wordCount": [{"@value": 1204}]
}]
}, {
"@graph": [{
"@id": "http://example.com/posts/1/en",
"http://schema.org/articleBody": [{
"@value": "World commodities were up today with heavy trading of crude oil..."
}],
"http://schema.org/wordCount": [{"@value": 1539}]
}],
"@index": "en"
}],
"http://schema.org/name": [{"@value": "World Financial News"}]
}]</pre></div>
</section>
<section class="informative changed" id="language-indexing" typeof="schema:Chapter" resource="#language-indexing" property="schema:hasPart">
<h3 id="x4-20-language-indexing"><span class="secno">4.20 </span>Language Indexing&nbsp;<span class="permalink"><a href="#language-indexing" aria-label="Permalink for 4.20 Language Indexing" title="Permalink for 4.20 Language Indexing"><span property="schema:name" content="4.20 Language Indexing">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>JSON which includes string values in multiple languages may be
represented using a <a href="#dfn-language-maps" class="internalDFN" data-link-type="dfn">language map</a> to allow for easily
indexing property values by <a href="#dfn-language-tag" class="internalDFN" data-link-type="dfn">language tag</a>. This enables direct access to
language values instead of having to scan an array in search of a specific item.
In JSON-LD such data can be specified by associating the
<code>@language</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> with a
<code>@container</code> declaration in the context:</p>
<div class="example"><div class="example-title marker"><span>Example 70</span><span style="text-transform: none">: Indexing languaged-tagged strings in JSON-LD</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"vocab"</span>: <span class="hljs-string">"http://example.com/vocab/"</span>,
<span class="hljs-attr">"label"</span>: {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"vocab:label"</span>,
<span class="hljs-attr">"@container"</span>: <span class="hljs-string">"@language"</span>
}
},
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://example.com/queen"</span>,
<span class="hljs-attr">"label"</span>: {
<span class="hljs-attr">"en"</span>: <span class="hljs-string">"The Queen"</span>,
<span class="hljs-attr">"de"</span>: [ <span class="hljs-string">"Die Königin"</span>, <span class="hljs-string">"Ihre Majestät"</span> ]
}
}</pre></div>
<p>In the example above, the <strong>label</strong> <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> has
been marked as an <a href="#dfn-language-maps" class="internalDFN" data-link-type="dfn">language map</a>. The <strong>en</strong> and
<strong>de</strong> keys are implicitly associated with their respective
values by the <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD Processor</a>. This allows a developer to
access the German version of the <strong>label</strong> using the
following code snippet: <code>obj.label.de</code>.</p>
<p>The value of <code>@container</code> can also
be an array containing both <code>@language</code> and <code>@set</code>.
When <em>compacting</em>, this ensures that a <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD Processor</a> will use
the <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> form for all values of language tags.</p>
<div class="example"><div class="example-title marker"><span>Example 71</span><span style="text-transform: none">: Indexing languaged-tagged strings in JSON-LD with @set representation</span></div><pre class="nohighlight">{
"@context": {
"vocab": "http://example.com/vocab/",
"label": {
"@id": "vocab:label",
"@container": <span class="hl-bold">[</span>"@language", <span class="hl-bold">"@set"]</span>
}
},
"@id": "http://example.com/queen",
"label": {
"en": <span class="hl-bold">[</span>"The Queen"<span class="hl-bold">]</span>,
"de": [ "Die Königin", "Ihre Majestät" ]
}
}</pre></div>
<p class="changed">The special index <code>@none</code> is used for indexing
data which does not have a language, which is useful to maintain
a normalized representation.</p>
<div class="example"><div class="example-title marker"><span>Example 72</span><span style="text-transform: none">: Indexing languaged-tagged strings using @none for no language</span></div><pre class="nohighlight">{
"@context": {
"vocab": "http://example.com/vocab/",
"label": {
"@id": "vocab:label",
"@container": "@language"
}
},
"@id": "http://example.com/queen",
"label": {
"en": "The Queen",
"de": [ "Die Königin", "Ihre Majestät" ],
"@none": "The Queen"
}
}</pre></div>
</section>
<section class="informative changed" id="node-identifier-indexing" typeof="schema:Chapter" resource="#node-identifier-indexing" property="schema:hasPart">
<h3 id="x4-21-node-identifier-indexing"><span class="secno">4.21 </span>Node Identifier Indexing&nbsp;<span class="permalink"><a href="#node-identifier-indexing" aria-label="Permalink for 4.21 Node Identifier Indexing" title="Permalink for 4.21 Node Identifier Indexing"><span property="schema:name" content="4.21 Node Identifier Indexing">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>In addition to <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index maps</a>, JSON-LD introduces the notion of <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id maps</a>
for structuring data. The id indexing feature allows an author to
structure data using a simple key-value map where the keys map
to <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>. This enables direct access to associated <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>
instead of having to scan an array in search of a specific item.
In JSON-LD such data can be specified by associating the
<code>@id</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> with a
<code>@container</code> declaration in the context:</p>
<div class="example"><div class="example-title marker"><span>Example 73</span><span style="text-transform: none">: Indexing data in JSON-LD by node identifiers</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
<span class="hl-bold">"@container": "@id"</span>
}
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
<span class="hl-bold">"post": {
"http://example.com/posts/1/en": {
"body": "World commodities were up today with heavy trading of crude oil...",
"words": 1539
},
"http://example.com/posts/1/de": {
"body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
"words": 1204
}
}</span>
}</pre></div>
<p>In the example above, the <code>post</code> <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> has
been marked as an <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id map</a>. The <code>http://example.com/posts/1/en</code> and
<code>http://example.com/posts/1/de</code> keys will be interpreted
as the <code>@id</code> property of the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> value.</p>
<p>The interpretation of the data above is exactly the same
as that in <a class="sectionRef sec-ref" href="#data-indexing">section <span class="secno">4.18</span> <span class="sec-title">Data Indexing</span></a>
using a <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD processor</a>.</p>
<p>The value of <code>@container</code> can also
be an array containing both <code>@id</code> and <code>@set</code>.
When <em>compacting</em>, this ensures that a <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD processor</a> will use
the <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> form for all values of node identifiers.</p>
<div class="example"><div class="example-title marker"><span>Example 74</span><span style="text-transform: none">: Indexing data in JSON-LD by node identifiers with @set representation</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
"@container": <span class="hl-bold">[</span>"@id", <span class="hl-bold">"@set"]</span>
}
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
"post": {
"http://example.com/posts/1/en": <span class="hl-bold">[</span>{
"body": "World commodities were up today with heavy trading of crude oil...",
"words": 1539
}<span class="hl-bold">]</span>,
"http://example.com/posts/1/de": <span class="hl-bold">[</span>{
"body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
"words": 1204
}<span class="hl-bold">]</span>
}
}</pre></div>
<p class="changed">The special index <code>@none</code> is used for indexing
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> which do not have an <code>@id</code>, which is useful to maintain
a normalized representation. The <code>@none</code> index may also be
a term which expands to <code>@none</code>, such as the term <em>none</em>
used in the example below.</p>
<div class="example"><div class="example-title marker"><span>Example 75</span><span style="text-transform: none">: Indexing data in JSON-LD by node identifiers using @none</span></div><pre class="nohighlight">{
"@context": {
"@version": 1.1,
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
"@container": "@id"
},
<span class="hl-bold">"none": "@none"</span>
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
"post": {
"http://example.com/posts/1/en": {
"body": "World commodities were up today with heavy trading of crude oil...",
"words": 1539
},
"http://example.com/posts/1/de": {
"body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
"words": 1204
},
<span class="hl-bold">"none": {
"body": "Description for object within an @id",
"words": 20
}</span>
}
}</pre></div>
<div class="note"><div role="heading" class="note-title marker" id="h-note-15" aria-level="4"><span>Note</span></div><p class=""><a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">Id maps</a> are a new feature in JSON-LD 1.1, requiring
<a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a> set to <code>json-ld-1.1</code>.</p></div>
</section>
<section class="changed" id="named-graph-indexing-by-identifier" typeof="schema:Chapter" resource="#named-graph-indexing-by-identifier" property="schema:hasPart">
<h3 id="x4-22-named-graph-indexing-by-identifier"><span class="secno">4.22 </span>Named Graph Indexing by Identifier&nbsp;<span class="permalink"><a href="#named-graph-indexing-by-identifier" aria-label="Permalink for 4.22 Named Graph Indexing by Identifier" title="Permalink for 4.22 Named Graph Indexing by Identifier"><span property="schema:name" content="4.22 Named Graph Indexing by Identifier">§</span></a></span></h3>
<p>In addition to indexing <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> by identifier, <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph objects</a> may
also be indexed by their <a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph name</a>. By using the <code>@graph</code>
container type, introduced in <a href="#graph-containers" class="sectionRef sec-ref">section <span class="secno">4.15.1</span> <span class="sec-title">Graph Containers</span></a>
in addition to <code>@id</code>, an object value of such a property is
treated as a key-value map where the keys represent the identifiers of <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graphs</a>
which are their values.</p>
<p>The following example describes a default graph referencing multiple named
graphs using an <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id map</a>.</p>
<div class="example"><div class="example-title marker"><span>Example 76</span><span style="text-transform: none">: Referencing named graphs using an id map</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"generatedAt": {
"@id": "http://www.w3.org/ns/prov#generatedAtTime",
"@type": "http://www.w3.org/2001/XMLSchema#date"
},
"Person": "http://xmlns.com/foaf/0.1/Person",
"name": "http://xmlns.com/foaf/0.1/name",
"knows": "http://xmlns.com/foaf/0.1/knows",
<span class="hl-bold">"graphMap": {
"@id": "http://example.org/graphMap",
"@container": ["@graph", "@id"]
}</span>
},
"@id": "_:graph",
"generatedAt": "2012-04-09",
<span class="hl-bold">"graphMap": {
"_:manu":</span> {
"@id": "http://manu.sporny.org/about#manu",
"@type": "Person",
"name": "Manu Sporny",
"knows": "http://greggkellogg.net/foaf#me"
},
<span class="hl-bold">"_:gregg"</span>: {
"@id": "http://greggkellogg.net/foaf#me",
"@type": "Person",
"name": "Gregg Kellogg",
"knows": "http://manu.sporny.org/about#manu"
}
}
}</pre></div>
<p>This expands to the following:</p>
<div class="example"><div class="example-title marker"><span>Example 77</span><span style="text-transform: none">: Referencing named graphs after expansion</span></div><pre class="nohighlight">[{
"@id": "_:graph",
"http://example.org/graphMap": [{
"@id": "_:gregg",
"@graph": [{
"@id": "http://greggkellogg.net/foaf#me",
"@type": ["http://xmlns.com/foaf/0.1/Person"],
"http://xmlns.com/foaf/0.1/knows": [{"@value": "http://manu.sporny.org/about#manu"}],
"http://xmlns.com/foaf/0.1/name": [{"@value": "Gregg Kellogg"}]
}]
}, {
"@id": "_:manu",
"@graph": [{
"@id": "http://manu.sporny.org/about#manu",
"@type": [
"http://xmlns.com/foaf/0.1/Person"
],
"http://xmlns.com/foaf/0.1/knows": [
{
"@value": "http://greggkellogg.net/foaf#me"
}
],
"http://xmlns.com/foaf/0.1/name": [
{
"@value": "Manu Sporny"
}
]
}]
}],
"http://www.w3.org/ns/prov#generatedAtTime": [{
"@value": "2012-04-09",
"@type": "http://www.w3.org/2001/XMLSchema#date"
}]
}]</pre></div>
<p>When expressed as Quads, this becomes the following:</p>
<table class="example">
<thead><tr>
<th>Graph</th>
<th>Subject</th>
<th>Property</th>
<th>Value</th>
<th>Value Type</th>
</tr></thead>
<tbody>
<tr>
<td>&nbsp;</td>
<td>_:graph</td>
<td>prov:generatedAtTime</td>
<td>2012-04-09</td>
<td>xsd:date</td>
</tr>
<tr>
<td>&nbsp;</td>
<td>_:graph</td>
<td>http://example.org/graphMap</td>
<td>http://manu.sporny.org/about#manu</td>
<td></td>
</tr>
<tr>
<td>&nbsp;</td>
<td>_:graph</td>
<td>http://example.org/graphMap</td>
<td>http://greggkellogg.net/foaf#me</td>
<td></td>
</tr>
<tr>
<td>_:manu</td>
<td>http://manu.sporny.org/about#manu</td>
<td>xsd:type</td>
<td>foaf:Person</td>
<td></td>
</tr>
<tr>
<td>_:manu</td>
<td>http://manu.sporny.org/about#manu</td>
<td>foaf:name</td>
<td>Manu Sporny</td>
<td></td>
</tr>
<tr>
<td>_:manu</td>
<td>http://manu.sporny.org/about#manu</td>
<td>foaf:knows</td>
<td>http://greggkellogg.net/foaf#me</td>
<td></td>
</tr>
<tr>
<td>_:gregg</td>
<td>http://greggkellogg.net/foaf#me</td>
<td>xsd:type</td>
<td>foaf:Person</td>
<td></td>
</tr>
<tr>
<td>_:gregg</td>
<td>http://greggkellogg.net/foaf#me</td>
<td>foaf:name</td>
<td>Gregg Kellogg</td>
<td></td>
</tr>
<tr>
<td>_:gregg</td>
<td>http://greggkellogg.net/foaf#me</td>
<td>foaf:knows</td>
<td>http://manu.sporny.org/about#manu</td>
<td></td>
</tr>
</tbody>
</table>
<p>As with <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id maps</a>, when used with <code>@graph</code>, a container may also
include <code>@set</code> to ensure that key values are always contained in an array.</p>
<p>As with <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id maps</a>, the special index <code>@none</code> is used for indexing
<a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graphs</a> which do not have an <code>@id</code>, which is useful to maintain
a normalized representation. The <code>@none</code> index may also be
a term which expands to <code>@none</code>.
<span class="note">Note, however, that if multiple graphs are represented without
an <code>@id</code>, they will be merged on expansion. To prevent this,
use <code>@none</code> judiciously, and consider giving graphs
their own distinct identifier.</span></p>
<div class="example"><div class="example-title marker"><span>Example 78</span><span style="text-transform: none">: Referencing named graphs using an id map with @none</span></div><pre class="nohighlight">{
"@context": {
"@version": 1.1,
"generatedAt": {
"@id": "http://www.w3.org/ns/prov#generatedAtTime",
"@type": "http://www.w3.org/2001/XMLSchema#date"
},
"Person": "http://xmlns.com/foaf/0.1/Person",
"name": "http://xmlns.com/foaf/0.1/name",
"knows": "http://xmlns.com/foaf/0.1/knows",
"graphMap": {
"@id": "http://example.org/graphMap",
"@container": ["@graph", "@id"]
}
},
"@id": "_:graph",
"generatedAt": "2012-04-09",
"graphMap": {
<span class="hl-bold">"@none"</span>: [{
"@id": "http://manu.sporny.org/about#manu",
"@type": "Person",
"name": "Manu Sporny",
"knows": "http://greggkellogg.net/foaf#me"
}, {
"@id": "http://greggkellogg.net/foaf#me",
"@type": "Person",
"name": "Gregg Kellogg",
"knows": "http://manu.sporny.org/about#manu"
}]
}
}</pre></div>
<div class="note"><div role="heading" class="note-title marker" id="h-note-16" aria-level="4"><span>Note</span></div><p class="">Graph Containers are a new feature in JSON-LD 1.1, requiring
<a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a> set to <code>json-ld-1.1</code>.</p></div>
</section>
<section class="informative changed" id="node-type-indexing" typeof="schema:Chapter" resource="#node-type-indexing" property="schema:hasPart">
<h3 id="x4-23-node-type-indexing"><span class="secno">4.23 </span>Node Type Indexing&nbsp;<span class="permalink"><a href="#node-type-indexing" aria-label="Permalink for 4.23 Node Type Indexing" title="Permalink for 4.23 Node Type Indexing"><span property="schema:name" content="4.23 Node Type Indexing">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>In addition to <a data-lt="id map" href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id</a> and <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index maps</a>, JSON-LD introduces the notion of <a href="#dfn-type-maps" class="internalDFN" data-link-type="dfn">type maps</a>
for structuring data. The type indexing feature allows an author to
structure data using a simple key-value map where the keys map
to <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>. This enables data to be structured based on the <code>@type</code>
of specific <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>.
In JSON-LD such data can be specified by associating the
<code>@type</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> with a
<code>@container</code> declaration in the context:</p>
<div class="example"><div class="example-title marker"><span>Example 79</span><span style="text-transform: none">: Indexing data in JSON-LD by type</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"schema": "http://schema.org/",
"name": "schema:name",
"affiliation": {
"@id": "schema:affiliation",
<span class="hl-bold">"@container": "@type"</span>
}
},
"name": "Manu Sporny",
"affiliation": {
<span class="hl-bold">"schema:Corporation"</span>: {
"@id": "https://digitalbazaar.com/",
"name": "Digital Bazaar"
},
<span class="hl-bold">"schema:ProfessionalService"</span>: {
"@id": "https://spec-ops.io",
"name": "Spec-Ops"
}
}
}</pre></div>
<p>In the example above, the <code>affiliation</code> <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> has
been marked as an <a href="#dfn-type-maps" class="internalDFN" data-link-type="dfn">type map</a>. The <code>schema:Corporation</code> and
<code>schema:ProfessionalService</code> keys will be interpreted
as the <code>@type</code> property of the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> value.</p>
<p>The value of <code>@container</code> can also
be an array containing both <code>@type</code> and <code>@set</code>.
When <em>compacting</em>, this ensures that a <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD processor</a> will use
the <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> form for all values of types.</p>
<div class="example"><div class="example-title marker"><span>Example 80</span><span style="text-transform: none">: Indexing data in JSON-LD by type with @set representation</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"schema": "http://schema.org/",
"name": "schema:name",
"affiliation": {
"@id": "schema:affiliation",
"@container": <span class="hl-bold">[</span>"@type", <span class="hl-bold">"@set"]</span>
}
},
"name": "Manu Sporny",
"affiliation": {
"schema:Corporation": <span class="hl-bold">[</span>{
"@id": "https://digitalbazaar.com/",
"name": "Digital Bazaar"
}<span class="hl-bold">]</span>,
"schema:ProfessionalService": <span class="hl-bold">[</span>{
"@id": "https://spec-ops.io",
"name": "Spec-Ops"
}<span class="hl-bold">]</span>
}
}</pre></div>
<p class="changed">The special index <code>@none</code> is used for indexing
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> which do not have an <code>@type</code>, which is useful to maintain
a normalized representation. The <code>@none</code> index may also be
a term which expands to <code>@none</code>, such as the term <em>none</em>
used in the example below.</p>
<div class="example"><div class="example-title marker"><span>Example 81</span><span style="text-transform: none">: Indexing data in JSON-LD by type using @none</span></div><pre class="nohighlight">{
"@context": {
"@version": 1.1,
"schema": "http://schema.org/",
"name": "schema:name",
"affiliation": {
"@id": "schema:affiliation",
"@container": "@type"
},
<span class="hl-bold">"none": "@none"</span>
},
"name": "Manu Sporny",
"affiliation": {
"schema:Corporation": {
"@id": "https://digitalbazaar.com/",
"name": "Digital Bazaar"
},
"schema:ProfessionalService": {
"@id": "https://spec-ops.io",
"name": "Spec-Ops"
},
<span class="hl-bold">"none": {
"@id": "http://greggkellogg.net/",
"name": "Gregg Kellogg"
}</span>
}
}</pre></div>
<p>As with <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id maps</a>, when used with <code>@type</code>, a container may also
include <code>@set</code> to ensure that key values are always contained in an array.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-17" aria-level="4"><span>Note</span></div><p class=""><a href="#dfn-type-maps" class="internalDFN" data-link-type="dfn">Type maps</a> are a new feature in JSON-LD 1.1, requiring
<a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a> set to <code>json-ld-1.1</code>.</p></div>
</section>
<section class="informative changed" id="nested-properties" typeof="schema:Chapter" resource="#nested-properties" property="schema:hasPart">
<h3 id="x4-24-nested-properties"><span class="secno">4.24 </span>Nested Properties&nbsp;<span class="permalink"><a href="#nested-properties" aria-label="Permalink for 4.24 Nested Properties" title="Permalink for 4.24 Nested Properties"><span property="schema:name" content="4.24 Nested Properties">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>Many JSON APIs separate properties from their entities using an
intermediate object; in JSON-LD these are called <a href="#dfn-nested-properties" class="internalDFN" data-link-type="dfn">nested properties</a>.
For example, a set of possible labels may be grouped
under a common property:</p>
<div class="example"><div class="example-title marker"><span>Example 82</span><span style="text-transform: none">: Nested properties</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"skos": "http://www.w3.org/2004/02/skos/core#",
<span class="hl-bold">"labels": "@nest"</span>,
"main_label": {"@id": "skos:prefLabel"},
"other_label": {"@id": "skos:altLabel"},
"homepage": {"@id": "http://schema.org/description", "@type": "@id"}
},
"@id": "http://example.org/myresource",
"homepage": "http://example.org",
"labels": {
"main_label": "This is the main label for my resource",
"other_label": "This is the other label"
}
}</pre></div>
<p>By defining <em>labels</em> using the <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> <code>@nest</code>,
a <a href="#dfn-json-ld-processors" class="internalDFN" data-link-type="dfn">JSON-LD processor</a> will ignore the nesting created by using the
<em>labels</em> property and process the contents as if it were declared
directly within containing object. In this case, the <em>labels</em>
property is semantically meaningless. Defining it as equivalent to
<code>@nest</code> causes it to be ignored when expanding, making it
equivalent to the following:</p>
<div class="example"><div class="example-title marker"><span>Example 83</span><span style="text-transform: none">: Nested properties folded into containing object</span></div><pre class="nohighlight">{
"@context": {
"skos": "http://www.w3.org/2004/02/skos/core#",
"main_label": {"@id": "skos:prefLabel"},
"other_label": {"@id": "skos:altLabel"},
"homepage": {"@id": "http://schema.org/description", "@type": "@id"}
},
"@id": "http://example.org/myresource",
"homepage": "http://example.org",
<span class="hl-bold">"main_label": "This is the main label for my resource",
"other_label": "This is the other label"</span>
}</pre></div>
<p>Similarly, node definitions may contain a <code>@nest</code> property to
reference a term aliased to <code>@nest</code> which causes such
values to be nested under that aliased term.</p>
<div class="example"><div class="example-title marker"><span>Example 84</span><span style="text-transform: none">: Defining property nesting</span></div><pre class="nohighlight">{
"@context": {
<span class="hl-bold">"@version": 1.1</span>,
"skos": "http://www.w3.org/2004/02/skos/core#",
<span class="hl-bold">"labels": "@nest"</span>,
"main_label": {"@id": "skos:prefLabel", <span class="hl-bold">"@nest": "labels"</span>},
"other_label": {"@id": "skos:altLabel", <span class="hl-bold">"@nest": "labels"</span>},
"homepage": {"@id": "http://schema.org/description", "@type": "@id"}
},
"@id": "http://example.org/myresource",
"homepage": "http://example.org",
"labels": {
"main_label": "This is the main label for my resource",
"other_label": "This is the other label"
}
}</pre></div>
<div class="note"><div role="heading" class="note-title marker" id="h-note-18" aria-level="4"><span>Note</span></div><p class=""><a href="#dfn-nested-properties" class="internalDFN" data-link-type="dfn">Nested properties</a> are a new feature in JSON-LD 1.1, requiring
<a href="#dfn-processing-mode" class="internalDFN" data-link-type="dfn">processing mode</a> set to <code>json-ld-1.1</code>.</p></div>
</section>
<section class="informative" id="expanded-document-form" typeof="schema:Chapter" resource="#expanded-document-form" property="schema:hasPart">
<h3 id="x4-25-expanded-document-form"><span class="secno">4.25 </span>Expanded Document Form&nbsp;<span class="permalink"><a href="#expanded-document-form" aria-label="Permalink for 4.25 Expanded Document Form" title="Permalink for 4.25 Expanded Document Form"><span property="schema:name" content="4.25 Expanded Document Form">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>The JSON-LD 1.1 Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>]
defines a method for <em>expanding</em> a JSON-LD document.
<dfn data-dfn-type="dfn" id="dfn-expansion"><a href="https://json-ld.org/spec/latest/json-ld-api/#dfn-expansion">Expansion</a></dfn> is the process of taking a JSON-LD document and applying a
<code>@context</code> such that all IRIs, types, and values
are expanded so that the <code>@context</code> is no longer necessary.</p>
<p>For example, assume the following JSON-LD input document:</p>
<div class="example"><div class="example-title marker"><span>Example 85</span><span style="text-transform: none">: Sample JSON-LD document to be expanded</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/name"</span>,
<span class="hljs-attr">"homepage"</span>: {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/homepage"</span>,
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"@id"</span>
}
},
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Manu Sporny"</span>,
<span class="hljs-attr">"homepage"</span>: <span class="hljs-string">"http://manu.sporny.org/"</span>
}</pre></div>
<p>Running the JSON-LD <a href="https://json-ld.org/spec/latest/json-ld-api/#expansion-algorithm">Expansion algorithm</a> against the JSON-LD input document
provided above would result in the following output:</p>
<div class="example"><div class="example-title marker"><span>Example 86</span><span style="text-transform: none">: Expanded form for the previous example</span></div><pre class="hljs json" aria-busy="false">[
{
<span class="hljs-attr">"http://xmlns.com/foaf/0.1/name"</span>: [
{ <span class="hljs-attr">"@value"</span>: <span class="hljs-string">"Manu Sporny"</span> }
],
<span class="hljs-attr">"http://xmlns.com/foaf/0.1/homepage"</span>: [
{ <span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/"</span> }
]
}
]</pre></div>
<p><a href="#application-ld-json">JSON-LD's media type</a> defines a
<code>profile</code> parameter which can be used to signal or request
expanded document form. The profile URI identifying expanded document
form is <code>http://www.w3.org/ns/json-ld#expanded</code>.</p>
</section>
<section class="informative" id="compacted-document-form" typeof="schema:Chapter" resource="#compacted-document-form" property="schema:hasPart">
<h3 id="x4-26-compacted-document-form"><span class="secno">4.26 </span>Compacted Document Form&nbsp;<span class="permalink"><a href="#compacted-document-form" aria-label="Permalink for 4.26 Compacted Document Form" title="Permalink for 4.26 Compacted Document Form"><span property="schema:name" content="4.26 Compacted Document Form">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>The JSON-LD 1.1 Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>] defines
a method for <em>compacting</em> a JSON-LD document. <dfn data-dfn-type="dfn" id="dfn-compaction"><a href="https://json-ld.org/spec/latest/json-ld-api/#dfn-compaction">Compaction</a></dfn> is the process
of applying a developer-supplied context to shorten <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>
to <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> or <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact IRIs</a>
and JSON-LD values expressed in expanded form to simple values such as
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a> or <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">numbers</a>.
Often this makes it simpler to work with document as the data is expressed in
application-specific terms. Compacted documents are also typically easier to read
for humans.</p>
<p>For example, assume the following JSON-LD input document:</p>
<div class="example"><div class="example-title marker"><span>Example 87</span><span style="text-transform: none">: Sample expanded JSON-LD document</span></div><pre class="hljs json" aria-busy="false">[
{
<span class="hljs-attr">"http://xmlns.com/foaf/0.1/name"</span>: [ <span class="hljs-string">"Manu Sporny"</span> ],
<span class="hljs-attr">"http://xmlns.com/foaf/0.1/homepage"</span>: [
{
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/"</span>
}
]
}
]</pre></div>
<p>Additionally, assume the following developer-supplied JSON-LD context:</p>
<div class="example"><div class="example-title marker"><span>Example 88</span><span style="text-transform: none">: Sample context</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/name"</span>,
<span class="hljs-attr">"homepage"</span>: {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/homepage"</span>,
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"@id"</span>
}
}
}</pre></div>
<p>Running the JSON-LD <a href="https://json-ld.org/spec/latest/json-ld-api/#compaction-algorithm">Compaction algorithm</a> given the context supplied above
against the JSON-LD input document provided above would result in the following
output:</p>
<div class="example"><div class="example-title marker"><span>Example 89</span><span style="text-transform: none">: Compact form of the sample document once sample context has been applied</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/name"</span>,
<span class="hljs-attr">"homepage"</span>: {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/homepage"</span>,
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"@id"</span>
}
},
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Manu Sporny"</span>,
<span class="hljs-attr">"homepage"</span>: <span class="hljs-string">"http://manu.sporny.org/"</span>
}</pre></div>
<p><a href="#application-ld-json">JSON-LD's media type</a> defines a
<code>profile</code> parameter which can be used to signal or request
compacted document form. The profile URI identifying compacted document
form is <code>http://www.w3.org/ns/json-ld#compacted</code>.</p>
</section>
<section class="informative" id="flattened-document-form" typeof="schema:Chapter" resource="#flattened-document-form" property="schema:hasPart">
<h3 id="x4-27-flattened-document-form"><span class="secno">4.27 </span>Flattened Document Form&nbsp;<span class="permalink"><a href="#flattened-document-form" aria-label="Permalink for 4.27 Flattened Document Form" title="Permalink for 4.27 Flattened Document Form"><span property="schema:name" content="4.27 Flattened Document Form">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>The JSON-LD 1.1 Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>] defines
a method for <em>flattening</em> a JSON-LD document. <dfn data-dfn-type="dfn" id="dfn-flattening"><a href="https://json-ld.org/spec/latest/json-ld-api/#dfn-flattening">Flattening</a></dfn> collects all
properties of a <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> in a single <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> and labels
all <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank nodes</a> with
<a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifiers</a>.
This ensures a shape of the data and consequently may drastically simplify the code
required to process JSON-LD in certain applications.</p>
<p>For example, assume the following JSON-LD input document:</p>
<div class="example"><div class="example-title marker"><span>Example 90</span><span style="text-transform: none">: Sample JSON-LD document to be flattened</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/name"</span>,
<span class="hljs-attr">"knows"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/knows"</span>
},
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://me.markus-lanthaler.com/"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Markus Lanthaler"</span>,
<span class="hljs-attr">"knows"</span>: [
{
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/about#manu"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Manu Sporny"</span>
}, {
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Dave Longley"</span>
}
]
}</pre></div>
<p>Running the JSON-LD <a href="https://json-ld.org/spec/latest/json-ld-api/#flattening-algorithm">Flattening algorithm</a> against the JSON-LD input document in
the example above and using the same context would result in the following
output:</p>
<div class="example"><div class="example-title marker"><span>Example 91</span><span style="text-transform: none">: Flattened and compacted form for the previous example</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/name"</span>,
<span class="hljs-attr">"knows"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/knows"</span>
},
<span class="hljs-attr">"@graph"</span>: [
{
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"_:b0"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Dave Longley"</span>
}, {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/about#manu"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Manu Sporny"</span>
}, {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://me.markus-lanthaler.com/"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Markus Lanthaler"</span>,
<span class="hljs-attr">"knows"</span>: [
{ <span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/about#manu"</span> },
{ <span class="hljs-attr">"@id"</span>: <span class="hljs-string">"_:b0"</span> }
]
}
]
}</pre></div>
<p><a href="#application-ld-json">JSON-LD's media type</a> defines a
<code>profile</code> parameter which can be used to signal or request
flattened document form. The profile URI identifying flattened document
form is <code>http://www.w3.org/ns/json-ld#flattened</code>. It can be
combined with the profile URI identifying
<a href="#expanded-document-form">expanded document form</a> or
<a href="#compacted-document-form">compacted document from</a>.</p>
</section>
<section class="informative" id="embedding-json-ld-in-html-documents" typeof="schema:Chapter" resource="#embedding-json-ld-in-html-documents" property="schema:hasPart">
<h3 id="x4-28-embedding-json-ld-in-html-documents"><span class="secno">4.28 </span>Embedding JSON-LD in HTML Documents&nbsp;<span class="permalink"><a href="#embedding-json-ld-in-html-documents" aria-label="Permalink for 4.28 Embedding JSON-LD in HTML Documents" title="Permalink for 4.28 Embedding JSON-LD in HTML Documents"><span property="schema:name" content="4.28 Embedding JSON-LD in HTML Documents">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>HTML script tags can be used to embed blocks of data in documents.
This way, JSON-LD content can be easily embedded in HTML by placing
it in a script element with the <code>type</code> attribute set to
<code>application/ld+json</code>.</p>
<div class="example"><div class="example-title marker"><span>Example 92</span><span style="text-transform: none">: Embedding JSON-LD in HTML</span></div><pre class="nohighlight" data-content-type="text/html"><span class="hl-bold">&lt;script type="application/ld+json"&gt;</span>
{
"@context": "https://json-ld.org/contexts/person.jsonld",
"@id": "http://dbpedia.org/resource/John_Lennon",
"name": "John Lennon",
"born": "1940-10-09",
"spouse": "http://dbpedia.org/resource/Cynthia_Lennon"
}
<span class="hl-bold">&lt;/script&gt;</span></pre></div>
<p>Depending on how the HTML document is served, certain strings may need
to be escaped.</p>
<p>Defining how such data may be used is beyond the scope of this specification.
The embedded JSON-LD document might be extracted as is or, e.g., be
interpreted as RDF.</p>
<p>If JSON-LD content is extracted as RDF [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>], it should be expanded into an
<a href="#dfn-dataset" class="internalDFN" data-link-type="dfn">RDF Dataset</a> using the
<a href="https://json-ld.org/spec/latest/json-ld-api/#deserialize-json-ld-to-rdf-algorithm">Deserialize JSON-LD to RDF Algorithm</a>
[<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>].</p>
</section>
</section>
<section class="normative" id="data-model" typeof="schema:Chapter" resource="#data-model" property="schema:hasPart">
<!--OddPage--><h2 id="x5-data-model"><span class="secno">5. </span>Data Model&nbsp;<span class="permalink"><a href="#data-model" aria-label="Permalink for 5. Data Model" title="Permalink for 5. Data Model"><span property="schema:name" content="5. Data Model">§</span></a></span></h2>
<p>JSON-LD is a serialization format for Linked Data based on JSON.
It is therefore important to distinguish between the syntax, which is
defined by JSON in [<cite><a class="bibref" href="#bib-RFC7159">RFC7159</a></cite>], and the <dfn data-dfn-type="dfn" id="dfn-data-model">data model</dfn> which is
an extension of the <a href="https://www.w3.org/TR/rdf11-concepts/#data-model">RDF data model</a> [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>]. The precise
details of how JSON-LD relates to the RDF data model are given in
<a class="sectionRef sec-ref" href="#relationship-to-rdf">section <span class="secno">7.</span> <span class="sec-title">Relationship to RDF</span></a>.</p>
<p>To ease understanding for developers unfamiliar with the RDF model, the
following summary is provided:</p>
<ul>
<li>A <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> serializes a
<a data-link-type="dfn" href="https://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">generalized RDF Dataset</a>
[<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>], which is a collection of <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graphs</a>
that comprises exactly one <a href="#dfn-default-graph" class="internalDFN" data-link-type="dfn">default graph</a>
and zero or more <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graphs</a>.</li>
<li>The <a href="#dfn-default-graph" class="internalDFN" data-link-type="dfn">default graph</a> does not have a name and <em class="rfc2119" title="MAY">MAY</em> be empty.</li>
<li>Each <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a> is a pair consisting of an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or
<a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a> (the
<a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph name</a>)
and a <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a>. Whenever practical, the <a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph name</a> <em class="rfc2119" title="SHOULD">SHOULD</em> be an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</li>
<li>A <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a>
is a labeled directed graph, i.e., a set of <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a>
connected by <a href="#dfn-edges" class="internalDFN" data-link-type="dfn">edges</a>.</li>
<li>Every <a href="#dfn-edges" class="internalDFN" data-link-type="dfn">edge</a> has a direction associated with it and is labeled with
an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>. Within the JSON-LD syntax
these edge labels are called <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a>.
Whenever practical, an <a href="#dfn-edges" class="internalDFN" data-link-type="dfn">edge</a> <em class="rfc2119" title="SHOULD">SHOULD</em> be labeled with an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</li>
<li>Every <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a>
is an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a>, a <a href="#dfn-json-ld-values" class="internalDFN" data-link-type="dfn">JSON-LD value</a>,
or a <a href="#dfn-lists" class="internalDFN" data-link-type="dfn">list</a>.</li>
<li>A <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> having an outgoing edge <em class="rfc2119" title="MUST">MUST</em> be an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a
<a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a>.</li>
<li>A <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a> <em class="rfc2119" title="MUST NOT">MUST NOT</em> contain unconnected <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a>,
i.e., nodes which are not connected by an <a href="#dfn-edges" class="internalDFN" data-link-type="dfn">edge</a> to any other <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a>.
<div class="example"><div class="example-title marker"><span>Example 93</span><span style="text-transform: none">: Illegal Unconnected Node</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://example.org/1"</span>
}</pre></div>
<div class="note"><div role="heading" class="note-title marker" id="h-note-19" aria-level="3"><span>Note</span></div><div class="">
This effectively just prohibits unnested, empty <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>
and unnested <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> that contain only an <code>@id</code>.
A document may have <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">nodes</a> which are unrelated, as long as one or more
properties are defined, or the <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> is referenced from another <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>.
</div></div>
</li>
<li>An <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> (Internationalized Resource Identifier) is a string that conforms to the syntax
defined in [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>]. <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> used within a
<a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a> <em class="rfc2119" title="SHOULD">SHOULD</em> return a Linked Data document describing
the resource denoted by that <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> when being dereferenced.</li>
<li>A <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a> is a <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> which is neither an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
nor a <a href="#dfn-json-ld-values" class="internalDFN" data-link-type="dfn">JSON-LD value</a>, nor a <a href="#dfn-lists" class="internalDFN" data-link-type="dfn">list</a>. A blank node <em class="rfc2119" title="MAY">MAY</em> be identified
using a <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>.</li>
<li>A <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>
is a string that can be used as an identifier for a <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a> within
the scope of a <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a>. Blank node identifiers begin with
<code>_:</code>.</li>
<li>A <a href="#dfn-json-ld-values" class="internalDFN" data-link-type="dfn">JSON-LD value</a> is a <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed value</a>, a <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a> (which is interpreted
as <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed value</a> with type <code>xsd:string</code>), a <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>
(<a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">numbers</a> with a non-zero fractional part, i.e., the result of a modulo‑1 operation,
are interpreted as <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed values</a> with type <code>xsd:double</code>, all other
<a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">numbers</a> are interpreted as <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed values</a>
with type <code>xsd:integer</code>), <a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a> or <a href="#dfn-false" class="internalDFN" data-link-type="dfn">false</a> (which are interpreted as
<a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed values</a> with type <code>xsd:boolean</code>),
or a <a href="#dfn-language-tagged-strings" class="internalDFN" data-link-type="dfn">language-tagged string</a>.</li>
<li>A <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed value</a> consists of a value, which is a string, and a type, which is an
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</li>
<li>A <a href="#dfn-language-tagged-strings" class="internalDFN" data-link-type="dfn">language-tagged string</a>
consists of a string and a non-empty <a href="#dfn-language-tag" class="internalDFN" data-link-type="dfn">language tag</a> as defined by [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>].
The language tag <em class="rfc2119" title="MUST">MUST</em> be well-formed according to section
<a href="https://tools.ietf.org/html/bcp47#section-2.2.9">2.2.9 Classes of Conformance</a>
of [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>].</li>
<li>A <a href="#dfn-lists" class="internalDFN" data-link-type="dfn">list</a> is a sequence of zero or more <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>,
<a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank nodes</a>, and <a href="#dfn-json-ld-values" class="internalDFN" data-link-type="dfn">JSON-LD values</a>.
<a href="#dfn-lists" class="internalDFN" data-link-type="dfn">Lists</a> are interpreted as
<dfn data-dfn-type="dfn" id="dfn-rdf-list-structures"><a href="https://www.w3.org/TR/rdf11-mt/#rdf-collections">RDF list structures</a></dfn> [<cite><a class="bibref" href="#bib-RDF11-MT">RDF11-MT</a></cite>].</li>
</ul>
<p><a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD documents</a> <em class="rfc2119" title="MAY">MAY</em> contain data
that cannot be represented by the <a href="#dfn-data-model" class="internalDFN" data-link-type="dfn">data model</a>
defined above. Unless otherwise specified, such data is ignored when a
<a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> is being processed. One result of this rule
is that properties which are not mapped to an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
a <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank node</a>, or <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> will be ignored.</p>
<p class="changed">Additionally, the JSON serialization format is internally represented using
the <a href="#dfn-internal-representation" class="internalDFN" data-link-type="dfn">JSON-LD internal representation</a>, which uses the generic
concepts of <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">arrays</a>, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-dictionary">dictionaries</a>,
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a>, <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">numbers</a>, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#idl-boolean">booleans</a>, and <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a> to describe
the data represented by a JSON document.</p>
<p style="text-align: center"><img src="linked-data-graph.png" title="An illustration of the data model" alt="An illustration of the data model"></p>
<p style="text-align: center">Figure&nbsp;1: An illustration of the data model.</p>
</section>
<section class="normative" id="json-ld-grammar" typeof="schema:Chapter" resource="#json-ld-grammar" property="schema:hasPart">
<!--OddPage--><h2 id="x6-json-ld-grammar"><span class="secno">6. </span>JSON-LD Grammar&nbsp;<span class="permalink"><a href="#json-ld-grammar" aria-label="Permalink for 6. JSON-LD Grammar" title="Permalink for 6. JSON-LD Grammar"><span property="schema:name" content="6. JSON-LD Grammar">§</span></a></span></h2>
<p>This appendix restates the syntactic conventions described in the
previous sections more formally.</p>
<p>A <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> <em class="rfc2119" title="MUST">MUST</em> be valid <a href="https://tools.ietf.org/html/rfc7159#section-2">JSON text</a> as described
in [<cite><a class="bibref" href="#bib-RFC7159">RFC7159</a></cite>], <span class="changed">or some format that can be represented
in the <a href="#dfn-internal-representation" class="internalDFN" data-link-type="dfn">JSON-LD internal representation</a> that is equivalent to
valid <a href="https://tools.ietf.org/html/rfc7159#section-2">JSON text</a></span>.</p>
<p>A <a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a> <em class="rfc2119" title="MUST">MUST</em> be a single <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>
or an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> whose elements are each
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> at the top level.</p>
<p>In contrast to JSON, in JSON-LD the keys in <a data-lt="JSON object" href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">objects</a>
<em class="rfc2119" title="MUST">MUST</em> be unique.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-20" aria-level="3"><span>Note</span></div><p class="">JSON-LD allows <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a> to be aliased
(see <a class="sectionRef sec-ref" href="#aliasing-keywords">section <span class="secno">4.17</span> <span class="sec-title">Aliasing Keywords</span></a> for details). Whenever a <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> is
discussed in this grammar, the statements also apply to an alias for
that <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>. For example, if the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a>
defines the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> <code>id</code> as an alias for <code>@id</code>,
that alias may be legitimately used as a substitution for <code>@id</code>.
Note that <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> aliases are not expanded during context
processing.</p></div>
<section class="normative" id="terms-0" typeof="schema:Chapter" resource="#terms-0" property="schema:hasPart">
<h3 id="x6-1-terms"><span class="secno">6.1 </span>Terms&nbsp;<span class="permalink"><a href="#terms-0" aria-label="Permalink for 6.1 Terms" title="Permalink for 6.1 Terms"><span property="schema:name" content="6.1 Terms">§</span></a></span></h3>
<p>A <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is a short-hand <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a> that expands
to an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> or a <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>.</p>
<p>A <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> <em class="rfc2119" title="MUST NOT">MUST NOT</em> equal any of the JSON-LD
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a>.</p>
<p class="changed">When used as the <a href="#dfn-prefixes" class="internalDFN" data-link-type="dfn">prefix</a> in a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">Compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, to avoid
the potential ambiguity of a <a href="#dfn-prefixes" class="internalDFN" data-link-type="dfn">prefix</a> being confused with an <abbr title="Internationalized Resource Identifier">IRI</abbr>
scheme, <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> <em class="rfc2119" title="SHOULD NOT">SHOULD NOT</em> come from the list of URI schemes as defined in
[<cite><a class="bibref" href="#bib-IANA-URI-SCHEMES">IANA-URI-SCHEMES</a></cite>]. Similarly, to avoid confusion between a
<a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">Compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> and a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>, terms <em class="rfc2119" title="SHOULD NOT">SHOULD NOT</em> include a colon (<code>:</code>)
and <em class="rfc2119" title="SHOULD">SHOULD</em> be restricted to the form of
<code><a href="https://tools.ietf.org/html/rfc3987#section-2.2">isegment-nz-nc</a></code>
as defined in [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>].</p>
<p>To avoid forward-compatibility issues, a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> <em class="rfc2119" title="SHOULD NOT">SHOULD NOT</em> start
with an <code>@</code> character as future versions of JSON-LD may introduce
additional <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a>. Furthermore, the term <em class="rfc2119" title="MUST NOT">MUST NOT</em>
be an empty <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a> (<code>""</code>) as not all programming languages
are able to handle empty JSON keys.</p>
<p>See <a class="sectionRef sec-ref" href="#the-context">section <span class="secno">3.1</span> <span class="sec-title">The Context</span></a> and
<a class="sectionRef sec-ref" href="#iris">section <span class="secno">3.2</span> <span class="sec-title">IRIs</span></a> for further discussion
on mapping <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> to <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>.</p>
</section>
<section class="normative" id="node-objects" typeof="schema:Chapter" resource="#node-objects" property="schema:hasPart">
<h3 id="x6-2-node-objects"><span class="secno">6.2 </span>Node Objects&nbsp;<span class="permalink"><a href="#node-objects" aria-label="Permalink for 6.2 Node Objects" title="Permalink for 6.2 Node Objects"><span property="schema:name" content="6.2 Node Objects">§</span></a></span></h3>
<p>A <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> represents zero or more properties of a
<a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> in the <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a> serialized by the
<a href="#dfn-json-ld-documents" class="internalDFN" data-link-type="dfn">JSON-LD document</a>. A <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> is a
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> if it exists outside of a JSON-LD
<a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> and:</p>
<ul>
<li>it is the top-most <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> in the JSON-LD document,</li>
<li>it does not contain the <code>@value</code>, <code>@list</code>,
or <code>@set</code> keywords, and</li>
<li class="changed">it is not a <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph object</a>.</li>
</ul>
<p>The <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> of a <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a> in
a <a href="#dfn-graph" class="internalDFN" data-link-type="dfn">graph</a> may be spread among different
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> within a document. When
that happens, the keys of the different
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> need to be merged to create the
properties of the resulting <a href="#dfn-nodes" class="internalDFN" data-link-type="dfn">node</a>.</p>
<p>A <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a>. All keys
which are not <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>, <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact IRIs</a>, <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a> valid in the
<a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a>, or one of the following <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a>
<span class="changed">(or alias of such a keyword)</span>
<em class="rfc2119" title="MUST">MUST</em> be ignored when processed:</p>
<ul>
<li><code>@context</code>,</li>
<li><code>@id</code>,</li>
<li><code>@graph</code>,</li>
<li class="changed"><code>@nest</code>,</li>
<li><code>@type</code>,</li>
<li><code>@reverse</code>, or</li>
<li><code>@index</code></li>
</ul>
<p>If the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> contains the <code>@context</code>
key, its value <em class="rfc2119" title="MUST">MUST</em> be <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>, an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
a <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-context-definition" class="internalDFN" data-link-type="dfn">context definition</a>, or
an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> composed of any of these.</p>
<p>If the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> contains the <code>@id</code> key,
its value <em class="rfc2119" title="MUST">MUST</em> be an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
or a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> (including
<a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifiers</a>).
See <a class="sectionRef sec-ref" href="#node-identifiers">section <span class="secno">3.3</span> <span class="sec-title">Node Identifiers</span></a>,
<a class="sectionRef sec-ref" href="#compact-iris">section <span class="secno">4.4</span> <span class="sec-title">Compact IRIs</span></a>, and
<a class="sectionRef sec-ref" href="#identifying-blank-nodes">section <span class="secno">4.16</span> <span class="sec-title">Identifying Blank Nodes</span></a> for further discussion on
<code>@id</code> values.</p>
<p>If the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> contains the <code>@graph</code>
key, its value <em class="rfc2119" title="MUST">MUST</em> be
a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> or
an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of zero or more <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>.
If the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> contains an <code>@id</code> keyword,
its value is used as the <a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph name</a> of a <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a>.
See <a class="sectionRef sec-ref" href="#named-graphs">section <span class="secno">4.15</span> <span class="sec-title">Named Graphs</span></a> for further discussion on
<code>@graph</code> values. As a special case, if a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a>
contains no keys other than <code>@graph</code> and <code>@context</code>, and the
<a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> is the root of the JSON-LD document, the
<a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> is not treated as a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>; this
is used as a way of defining <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>
that may not form a connected graph. This allows a
<a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> to be defined which is shared by all of the constituent
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>.</p>
<p>If the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> contains the <code>@type</code>
key, its value <em class="rfc2119" title="MUST">MUST</em> be either an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a
<a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
(including <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifiers</a>),
a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> defined in the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a> expanding into an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, or
an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of any of these.
See <a class="sectionRef sec-ref" href="#specifying-the-type">section <span class="secno">3.4</span> <span class="sec-title">Specifying the Type</span></a> for further discussion on
<code>@type</code> values.</p>
<p>If the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> contains the <code>@reverse</code> key,
its value <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> containing members representing reverse
properties. Each value of such a reverse property <em class="rfc2119" title="MUST">MUST</em> be an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
a <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>,
a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> or an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> containing a combination of these.</p>
<p>If the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> contains the <code>@index</code> key,
its value <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>. See
<a class="sectionRef sec-ref" href="#data-indexing">section <span class="secno">4.18</span> <span class="sec-title">Data Indexing</span></a> for further discussion
on <code>@index</code> values.</p>
<p class="changed">If the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> contains the <code>@nest</code> key,
its value <em class="rfc2119" title="MUST">MUST</em> be an <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> or an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON objects</a>
which <em class="rfc2119" title="MUST NOT">MUST NOT</em> include a <a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a>. See
<a class="sectionRef sec-ref" href="#property-nesting">section <span class="secno">6.10</span> <span class="sec-title">Property Nesting</span></a> for further discussion
on <code>@nest</code> values.</p>
<p>Keys in a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> that are not
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a> <em class="rfc2119" title="MAY">MAY</em> expand to an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>
using the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a>. The values associated with keys that expand
to an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> <em class="rfc2119" title="MUST">MUST</em> be one of the following:</p>
<ul>
<li><a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>,</li>
<li><a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>,</li>
<li><a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a>,</li>
<li><a href="#dfn-false" class="internalDFN" data-link-type="dfn">false</a>,</li>
<li><a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>,</li>
<li><a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>,</li>
<li class="changed"><a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph object</a>,</li>
<li><a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a>,</li>
<li><a href="#dfn-list-objects" class="internalDFN" data-link-type="dfn">list object</a>,</li>
<li><a href="#dfn-set-object" class="internalDFN" data-link-type="dfn">set object</a>,</li>
<li>an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of zero or more of any of the possibilities above,</li>
<li>a <a href="#dfn-language-maps" class="internalDFN" data-link-type="dfn">language map</a>,</li>
<li>an <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index map</a>,</li>
<li class="changed">an <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id map</a>, or</li>
<li class="changed">an <a href="#dfn-type-maps" class="internalDFN" data-link-type="dfn">type map</a></li>
</ul>
</section>
<section class="normative" id="graph-objects" typeof="schema:Chapter" resource="#graph-objects" property="schema:hasPart">
<h3 id="x6-3-graph-objects"><span class="secno">6.3 </span>Graph Objects&nbsp;<span class="permalink"><a href="#graph-objects" aria-label="Permalink for 6.3 Graph Objects" title="Permalink for 6.3 Graph Objects"><span property="schema:name" content="6.3 Graph Objects">§</span></a></span></h3>
<p>A <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph object</a> represents a <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a>, which <em class="rfc2119" title="MAY">MAY</em> include
include an explicit <a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph name</a>.
A <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> is a <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph object</a> if
it exists outside of a JSON-LD <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a>,
it is not a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>,
it is not the top-most <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> in the JSON-LD document, and
it consists of no members other than <code>@graph</code>,
<code>@index</code>, <code>@id</code>
and <code>@context</code>, or an alias of one of these <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a>.</p>
<p>If the <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph object</a> contains the <code>@context</code>
key, its value <em class="rfc2119" title="MUST">MUST</em> be <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>, an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
a <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-context-definition" class="internalDFN" data-link-type="dfn">context definition</a>, or
an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> composed of any of these.</p>
<p>If the <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph object</a> contains the <code>@id</code> key,
its value is used as the identifier (<a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph name</a>) of a <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a>, and
<em class="rfc2119" title="MUST">MUST</em> be an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
or a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> (including
<a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifiers</a>).
See <a class="sectionRef sec-ref" href="#node-identifiers">section <span class="secno">3.3</span> <span class="sec-title">Node Identifiers</span></a>,
<a class="sectionRef sec-ref" href="#compact-iris">section <span class="secno">4.4</span> <span class="sec-title">Compact IRIs</span></a>, and
<a class="sectionRef sec-ref" href="#identifying-blank-nodes">section <span class="secno">4.16</span> <span class="sec-title">Identifying Blank Nodes</span></a> for further discussion on
<code>@id</code> values.</p>
<p>A <a href="#dfn-graph-objects" class="internalDFN" data-link-type="dfn">graph object</a> without an <code>@id</code> member is also a
<a href="#dfn-simple-graph-objects" class="internalDFN" data-link-type="dfn">simple graph object</a> and represents a <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a> without an
explicit identifier, although in the data model it still has a
<a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph name</a>, which is an implicitly allocated
<a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>.</p>
<p>The value of the <code>@graph</code> key <em class="rfc2119" title="MUST">MUST</em> be
a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> or
an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of zero or more <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>.
See <a class="sectionRef sec-ref" href="#named-graphs">section <span class="secno">4.15</span> <span class="sec-title">Named Graphs</span></a> for further discussion on
<code>@graph</code> values..</p>
</section>
<section class="normative" id="value-objects" typeof="schema:Chapter" resource="#value-objects" property="schema:hasPart">
<h3 id="x6-4-value-objects"><span class="secno">6.4 </span>Value Objects&nbsp;<span class="permalink"><a href="#value-objects" aria-label="Permalink for 6.4 Value Objects" title="Permalink for 6.4 Value Objects"><span property="schema:name" content="6.4 Value Objects">§</span></a></span></h3>
<p>A <a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a> is used to explicitly associate a type or a
language with a value to create a <a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed value</a> or a <a href="#dfn-language-tagged-strings" class="internalDFN" data-link-type="dfn">language-tagged
string</a>.</p>
<p>A <a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a> <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> containing the
<code>@value</code> key. It <em class="rfc2119" title="MAY">MAY</em> also contain an <code>@type</code>,
an <code>@language</code>, an <code>@index</code>, or an <code>@context</code> key but <em class="rfc2119" title="MUST NOT">MUST NOT</em> contain
both an <code>@type</code> and an <code>@language</code> key at the same time.
A <a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a> <em class="rfc2119" title="MUST NOT">MUST NOT</em> contain any other keys that expand to an
<a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>.</p>
<p>The value associated with the <code>@value</code> key <em class="rfc2119" title="MUST">MUST</em> be either a
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>, a <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>, <a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a>,
<a href="#dfn-false" class="internalDFN" data-link-type="dfn">false</a> or <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>.</p>
<p>The value associated with the <code>@type</code> key <em class="rfc2119" title="MUST">MUST</em> be a
<a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>, a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a string which can be turned
into an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> using the <a href="#dfn-vocabulary-mapping" class="internalDFN" data-link-type="dfn">vocabulary mapping</a>, or <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>.</p>
<p>The value associated with the <code>@language</code> key <em class="rfc2119" title="MUST">MUST</em> have the
<a href="https://tools.ietf.org/html/bcp47#section-2.1.1">lexical form</a> described in [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>], or be <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>.</p>
<p>The value associated with the <code>@index</code> key <em class="rfc2119" title="MUST">MUST</em> be a
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>.</p>
<p>See <a class="sectionRef sec-ref" href="#typed-values">section <span class="secno">4.5</span> <span class="sec-title">Typed Values</span></a> and
<a class="sectionRef sec-ref" href="#string-internationalization">section <span class="secno">4.10</span> <span class="sec-title">String Internationalization</span></a>
for more information on <a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value objects</a>.</p>
</section>
<section class="normative" id="lists-and-sets" typeof="schema:Chapter" resource="#lists-and-sets" property="schema:hasPart">
<h3 id="x6-5-lists-and-sets"><span class="secno">6.5 </span>Lists and Sets&nbsp;<span class="permalink"><a href="#lists-and-sets" aria-label="Permalink for 6.5 Lists and Sets" title="Permalink for 6.5 Lists and Sets"><span property="schema:name" content="6.5 Lists and Sets">§</span></a></span></h3>
<p>A <a href="#dfn-lists" class="internalDFN" data-link-type="dfn">list</a> represents an <em>ordered</em> set of values. A set
represents an <em>unordered</em> set of values. Unless otherwise specified,
<a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">arrays</a> are unordered in JSON-LD. As such, the
<code>@set</code> keyword, when used in the body of a JSON-LD document,
represents just syntactic sugar which is optimized away when processing the document.
However, it is very helpful when used within the context of a document. Values
of terms associated with an <code>@set</code> or <code>@list</code> container
will always be represented in the form of an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> when a document
is processed—even if there is just a single value that would otherwise be optimized to
a non-array form in <a href="#compacted-document-form">compact document form</a>.
This simplifies post-processing of the data as the data is always in a
deterministic form.</p>
<p>A <a href="#dfn-list-objects" class="internalDFN" data-link-type="dfn">list object</a> <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> that contains no
keys that expand to an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> other
than <code>@list</code>, <code>@context</code>, and <code>@index</code>.</p>
<p>A <a href="#dfn-set-object" class="internalDFN" data-link-type="dfn">set object</a> <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> that contains no
keys that expand to an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> other
than <code>@list</code>, <code>@context</code>, and <code>@index</code>.
Please note that the <code>@index</code> key will be ignored when being processed.</p>
<p>In both cases, the value associated with the keys <code>@list</code> and <code>@set</code>
<em class="rfc2119" title="MUST">MUST</em> be one of the following types:</p>
<ul>
<li><a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>,</li>
<li><a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>,</li>
<li><a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a>,</li>
<li><a href="#dfn-false" class="internalDFN" data-link-type="dfn">false</a>,</li>
<li><a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>,</li>
<li><a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>,</li>
<li><a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a>, or</li>
<li>an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of zero or more of the above possibilities</li>
</ul>
<p>See <a class="sectionRef sec-ref" href="#sets-and-lists">section <span class="secno">4.12</span> <span class="sec-title">Sets and Lists</span></a> for further discussion on sets and lists.</p>
</section>
<section class="normative" id="language-maps" typeof="schema:Chapter" resource="#language-maps" property="schema:hasPart">
<h3 id="x6-6-language-maps"><span class="secno">6.6 </span>Language Maps&nbsp;<span class="permalink"><a href="#language-maps" aria-label="Permalink for 6.6 Language Maps" title="Permalink for 6.6 Language Maps"><span property="schema:name" content="6.6 Language Maps">§</span></a></span></h3>
<p>A <a href="#dfn-language-maps" class="internalDFN" data-link-type="dfn">language map</a> is used to associate a language with a value in a
way that allows easy programmatic access. A <a href="#dfn-language-maps" class="internalDFN" data-link-type="dfn">language map</a> may be
used as a term value within a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> if the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is defined
with <code>@container</code> set to <code>@language</code>,
<span class="changed">
or an array containing both <code>@language</code> and <code>@set</code>
</span>. The keys of a
<a href="#dfn-language-maps" class="internalDFN" data-link-type="dfn">language map</a> <em class="rfc2119" title="MUST">MUST</em> be <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a> representing
[<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>] language codes, the <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> <code>@none</code>,
or a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> which expands to <code>@none</code>,
and the values <em class="rfc2119" title="MUST">MUST</em> be any of the following types:</p>
<ul>
<li><a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>,</li>
<li><a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>, or</li>
<li>an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of zero or more of the <a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a></li>
</ul>
<p>See <a class="sectionRef sec-ref" href="#string-internationalization">section <span class="secno">4.10</span> <span class="sec-title">String Internationalization</span></a> for further discussion
on language maps.</p>
</section>
<section class="normative" id="index-maps" typeof="schema:Chapter" resource="#index-maps" property="schema:hasPart">
<h3 id="x6-7-index-maps"><span class="secno">6.7 </span>Index Maps&nbsp;<span class="permalink"><a href="#index-maps" aria-label="Permalink for 6.7 Index Maps" title="Permalink for 6.7 Index Maps"><span property="schema:name" content="6.7 Index Maps">§</span></a></span></h3>
<p>An <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index map</a> allows keys that have no semantic meaning,
but should be preserved regardless, to be used in JSON-LD documents.
An <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index map</a> may
be used as a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> value within a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> if the
term is defined with <code>@container</code> set to <code>@index</code>,
<span class="changed">
or an array containing both <code>@index</code> and <code>@set</code>
</span>.
The values of the members of an <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index map</a> <em class="rfc2119" title="MUST">MUST</em> be one
of the following types:</p>
<ul>
<li><a href="#dfn-strings" class="internalDFN" data-link-type="dfn">string</a>,</li>
<li><a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>,</li>
<li><a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a>,</li>
<li><a href="#dfn-false" class="internalDFN" data-link-type="dfn">false</a>,</li>
<li><a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>,</li>
<li><a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>,</li>
<li><a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value object</a>,</li>
<li><a href="#dfn-list-objects" class="internalDFN" data-link-type="dfn">list object</a>,</li>
<li><a href="#dfn-set-object" class="internalDFN" data-link-type="dfn">set object</a>,</li>
<li>an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of zero or more of the above possibilities</li>
</ul>
<p>See <a class="sectionRef sec-ref" href="#data-indexing">section <span class="secno">4.18</span> <span class="sec-title">Data Indexing</span></a> for further information on this topic.</p>
<p class="changed"><a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">Index Maps</a> may also be used to map indexes to associated
<a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graphs</a>, if the term is defined with <code>@container</code>
set to an array containing both <code>@graph</code> and
<code>@index</code>, and optionally including <code>@set</code>. The
value consists of the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> contained within the <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named
graph</a> which is named using the referencing key, which can be
represented as a <a href="#dfn-simple-graph-objects" class="internalDFN" data-link-type="dfn">simple graph object</a>.</p>
</section>
<section class="changed" id="id-maps" typeof="schema:Chapter" resource="#id-maps" property="schema:hasPart">
<h3 id="x6-8-id-maps"><span class="secno">6.8 </span>Id Maps&nbsp;<span class="permalink"><a href="#id-maps" aria-label="Permalink for 6.8 Id Maps" title="Permalink for 6.8 Id Maps"><span property="schema:name" content="6.8 Id Maps">§</span></a></span></h3>
<p>An <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id map</a> is used to associate an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> with a value that allows easy
programmatic access. An <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id map</a> may be used as a term value within a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> if the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>
is defined with <code>@container</code> set to <code>@id</code>,
or an array containing both <code>@id</code> and <code>@set</code>.
The keys of an <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id map</a> <em class="rfc2119" title="MUST">MUST</em> be <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>
(<a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> (including <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifiers</a>), or <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>),
the <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> <code>@none</code>,
or a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> which expands to <code>@none</code>,
and the values <em class="rfc2119" title="MUST">MUST</em> be <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>.</p>
<p>If the value contains a property expanding to <code>@id</code>, it's value <em class="rfc2119" title="MUST">MUST</em>
be equivalent to the referencing key. Otherwise, the property from the value is used as
the <code>@id</code> of the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> value when expanding.</p>
<p><a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">Id Maps</a> may also be used to map <a href="#dfn-graph-names" class="internalDFN" data-link-type="dfn">graph names</a> to their
<a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graphs</a>, if the term is defined with <code>@container</code>
set to an array containing both <code>@graph</code> and <code>@id</code>,
and optionally including <code>@set</code>. The value consists of the
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a> contained within the <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graph</a>
which is named using the referencing key.</p>
</section>
<section class="changed" id="type-maps" typeof="schema:Chapter" resource="#type-maps" property="schema:hasPart">
<h3 id="x6-9-type-maps"><span class="secno">6.9 </span>Type Maps&nbsp;<span class="permalink"><a href="#type-maps" aria-label="Permalink for 6.9 Type Maps" title="Permalink for 6.9 Type Maps"><span property="schema:name" content="6.9 Type Maps">§</span></a></span></h3>
<p>A <a href="#dfn-type-maps" class="internalDFN" data-link-type="dfn">type map</a> is used to associate an <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a> with a value that allows easy
programmatic access. A <a href="#dfn-type-maps" class="internalDFN" data-link-type="dfn">type map</a> may be used as a term value within a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> if the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>
is defined with <code>@container</code> set to <code>@type</code>,
or an array containing both <code>@type</code> and <code>@set</code>.
The keys of a <a href="#dfn-type-maps" class="internalDFN" data-link-type="dfn">type map</a> <em class="rfc2119" title="MUST">MUST</em> be <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>
(<a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> (including <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifiers</a>), or <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>),
the <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a> <code>@none</code>,
or a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> which expands to <code>@none</code>,
and the values <em class="rfc2119" title="MUST">MUST</em> be <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>.</p>
<p>If the value contains a property expanding to <code>@type</code>, and it's value
is contains the referencing key after suitable expansion of both the referencing key
and the value, then the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> already contains the type. Otherwise, the property from the value is
added as a <code>@type</code> of the <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> value when expanding.</p>
</section>
<section class="changed" id="property-nesting" typeof="schema:Chapter" resource="#property-nesting" property="schema:hasPart">
<h3 id="x6-10-property-nesting"><span class="secno">6.10 </span>Property Nesting&nbsp;<span class="permalink"><a href="#property-nesting" aria-label="Permalink for 6.10 Property Nesting" title="Permalink for 6.10 Property Nesting"><span property="schema:name" content="6.10 Property Nesting">§</span></a></span></h3>
<p>A <a href="#dfn-nested-properties" class="internalDFN" data-link-type="dfn">nested property</a> is used to gather <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> of a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> in a separate
<a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a>, or <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> of <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON objects</a> which are not
<a href="#dfn-value-objects" class="internalDFN" data-link-type="dfn">value objects</a>. It is semantically transparent and is removed
during the process of <a data-link-type="dfn" href="https://json-ld.org/spec/latest/json-ld-api/#dfn-expansion">expansion</a>. Property nesting is recursive, and
collections of nested properties may contain further nesting.</p>
<p>Semantically, nesting is treated as if the properties and values were declared directly
within the containing <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>.</p>
</section>
<section class="normative" id="context-definitions" typeof="schema:Chapter" resource="#context-definitions" property="schema:hasPart">
<h3 id="x6-11-context-definitions"><span class="secno">6.11 </span>Context Definitions&nbsp;<span class="permalink"><a href="#context-definitions" aria-label="Permalink for 6.11 Context Definitions" title="Permalink for 6.11 Context Definitions"><span property="schema:name" content="6.11 Context Definitions">§</span></a></span></h3>
<p>A <dfn data-dfn-type="dfn" id="dfn-context-definition">context definition</dfn> defines a <a href="#dfn-local-contexts" class="internalDFN" data-link-type="dfn">local context</a> in a
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>.</p>
<p>A <a href="#dfn-context-definition" class="internalDFN" data-link-type="dfn">context definition</a> <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a> whose
keys <em class="rfc2119" title="MUST">MUST</em> be either <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">terms</a>, <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact IRIs</a>, <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute IRIs</a>,
or one of the <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a> <code>@language</code>, <code>@base</code>,
<code>@vocab</code>, or <code class="changed">@version</code>.</p>
<p>If the <a href="#dfn-context-definition" class="internalDFN" data-link-type="dfn">context definition</a> has an <code>@language</code> key,
its value <em class="rfc2119" title="MUST">MUST</em> have the <a href="https://tools.ietf.org/html/bcp47#section-2.1.1">lexical form</a> described in [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>] or be <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>.</p>
<p>If the <a href="#dfn-context-definition" class="internalDFN" data-link-type="dfn">context definition</a> has an <code>@base</code> key,
its value <em class="rfc2119" title="MUST">MUST</em> be an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-relative-iris" class="internalDFN" data-link-type="dfn">relative <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
or <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>.</p>
<p>If the <a href="#dfn-context-definition" class="internalDFN" data-link-type="dfn">context definition</a> has an <code>@vocab</code> key,
its value <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
a <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>, a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>, or <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>.</p>
<p class="changed">If the <a href="#dfn-context-definition" class="internalDFN" data-link-type="dfn">context definition</a> has an <code>@version</code> key,
its value <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a> with the value <code>1.1</code>.</p>
<p>The value of keys that are not <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a> <em class="rfc2119" title="MUST">MUST</em> be either an
<a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>,
a <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>, a <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>, <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>,
or an <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a>.</p>
<p>An <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> is used to describe the mapping
between a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> and its expanded identifier, as well as other
properties of the value associated with the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> when it is
used as key in a <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>.</p>
<p>An <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-json-objects" class="internalDFN" data-link-type="dfn">JSON object</a>
composed of zero or more keys from
<code>@id</code>,
<code>@reverse</code>,
<code>@type</code>,
<code>@language</code>,
<code class="changed">@context</code>,
<code class="changed">@prefix</code>, or
<code>@container</code>. An
<a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> <em class="rfc2119" title="SHOULD NOT">SHOULD NOT</em> contain any other keys.</p>
<p>If an <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> has an <code>@reverse</code> member,
it <em class="rfc2119" title="MUST NOT">MUST NOT</em> have <code>@id</code> or <code>@nest</code> members at the same time. If an
<code>@container</code> member exists, its value <em class="rfc2119" title="MUST">MUST</em> be <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>,
<code>@set</code>, or <code>@index</code>.</p>
<p>If the term being defined is not a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> or
<a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a> and the <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a> does not have an
<code>@vocab</code> mapping, the <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> <em class="rfc2119" title="MUST">MUST</em>
include the <code>@id</code> key.</p>
<p>If the <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> contains the <code>@id</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>, its value <em class="rfc2119" title="MUST">MUST</em> be <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>, an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>,
a <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>, a <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>,
or a <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>.</p>
<p>If the <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> contains the <code>@type</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>, its value <em class="rfc2119" title="MUST">MUST</em> be an <a href="#dfn-absolute-iris" class="internalDFN" data-link-type="dfn">absolute <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a
<a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a>, a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>, <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>, or one of the
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keywords</a> <code>@id</code> or <code>@vocab</code>.</p>
<p>If the <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> contains the <code>@language</code> <a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>,
its value <em class="rfc2119" title="MUST">MUST</em> have the <a href="https://tools.ietf.org/html/bcp47#section-2.1.1">lexical form</a> described in [<cite><a class="bibref" href="#bib-BCP47">BCP47</a></cite>] or be <a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>.</p>
<p>If the <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> contains the <code>@container</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>, its value <em class="rfc2119" title="MUST">MUST</em> be either
<code>@list</code>,
<code>@set</code>,
<code>@language</code>,
<code>@index</code>,
<span class="changed"><code>@id</code></span>,
<span class="changed"><code>@graph</code></span>,
<span class="changed"><code>@type</code></span>, or be
<a href="#dfn-null" class="internalDFN" data-link-type="dfn">null</a>
<span class="changed">
or an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> containing exactly any one of those keywords, or a
combination of <code>@set</code> and any of <code>@index</code>,
<code>@id</code>, <code>@graph</code>, <code>@type</code>,
<code>@language</code> in any order
</span>.
<span class="changed"><code>@container</code> may also be an array
containing <code>@graph</code> along with either <code>@id</code> or
<code>@index</code> and also optionally including <code>@set</code>.</span>
If the value
is <code>@language</code>, when the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is used outside of the
<code>@context</code>, the associated value <em class="rfc2119" title="MUST">MUST</em> be a <a href="#dfn-language-maps" class="internalDFN" data-link-type="dfn">language map</a>.
If the value is <code>@index</code>, when the <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a> is used outside of
the <code>@context</code>, the associated value <em class="rfc2119" title="MUST">MUST</em> be an
<a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index map</a>.</p>
<p class="changed">If an <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> has an <code>@context</code> member,
it <em class="rfc2119" title="MUST">MUST</em> be a valid <code>context definition</code>.</p>
<p class="changed">If the <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> contains the <code>@nest</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>, its value <em class="rfc2119" title="MUST">MUST</em> be either <code>@nest</code>, or a term
which expands to <code>@nest</code>.</p>
<p class="changed">If the <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> contains the <code>@prefix</code>
<a href="#dfn-keywords" class="internalDFN" data-link-type="dfn">keyword</a>, its value <em class="rfc2119" title="MUST">MUST</em> be <code>true</code> or <code>false</code>.</p>
<p><a href="#dfn-terms" class="internalDFN" data-link-type="dfn">Terms</a> <em class="rfc2119" title="MUST NOT">MUST NOT</em> be used in a circular manner. That is,
the definition of a term cannot depend on the definition of another term if that other
term also depends on the first term.</p>
<p>See <a class="sectionRef sec-ref" href="#the-context">section <span class="secno">3.1</span> <span class="sec-title">The Context</span></a> for further discussion on contexts.</p>
</section>
</section>
<section class="normative" id="relationship-to-rdf" typeof="schema:Chapter" resource="#relationship-to-rdf" property="schema:hasPart">
<!--OddPage--><h2 id="x7-relationship-to-rdf"><span class="secno">7. </span>Relationship to RDF&nbsp;<span class="permalink"><a href="#relationship-to-rdf" aria-label="Permalink for 7. Relationship to RDF" title="Permalink for 7. Relationship to RDF"><span property="schema:name" content="7. Relationship to RDF">§</span></a></span></h2>
<p>JSON-LD is a
<dfn data-dfn-type="dfn" id="dfn-concrete-rdf-syntax"><a href="https://www.w3.org/TR/rdf11-concepts/#dfn-concrete-rdf-syntax">concrete RDF syntax</a></dfn>
as described in [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>]. Hence, a JSON-LD document is both an
RDF document <em>and</em> a JSON document and correspondingly represents an
instance of an RDF data model. However, JSON-LD also extends the RDF data
model to optionally allow JSON-LD to serialize
<dfn data-lt="generalized rdf dataset|generalized rdf datasets" data-dfn-type="dfn" id="dfn-generalized-rdf-dataset"><a href="https://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">generalized RDF Datasets</a></dfn>.
The JSON-LD extensions to the RDF data model are:</p>
<ul>
<li>In JSON-LD <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> can be
<a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> or <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank nodes</a>
whereas in RDF properties (predicates) have to be <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>. This
means that JSON-LD serializes
<a data-link-type="dfn" href="https://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">generalized RDF Datasets</a>.</li>
<li>In JSON-LD <a href="#dfn-lists" class="internalDFN" data-link-type="dfn">lists</a> are part of the data model
whereas in RDF they are part of a vocabulary, namely [<cite><a class="bibref" href="#bib-RDF-SCHEMA">RDF-SCHEMA</a></cite>].</li>
<li>RDF values are either typed <em>literals</em>
(<a href="#dfn-typed-values" class="internalDFN" data-link-type="dfn">typed values</a>) or
<a href="#dfn-language-tagged-strings" class="internalDFN" data-link-type="dfn">language-tagged strings</a> whereas
JSON-LD also supports JSON's native data types, i.e., <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">number</a>,
<a href="#dfn-strings" class="internalDFN" data-link-type="dfn">strings</a>, and the boolean values <a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a>
and <a href="#dfn-false" class="internalDFN" data-link-type="dfn">false</a>. The JSON-LD 1.1 Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>]
defines the <a href="https://json-ld.org/spec/latest/json-ld-api/#data-round-tripping">conversion rules</a>
between JSON's native data types and RDF's counterparts to allow round-tripping.</li>
</ul>
<p>Summarized, these differences mean that JSON-LD is capable of serializing any RDF
graph or dataset and most, but not all, JSON-LD documents can be directly
interpreted as RDF as described in RDF 1.1 Concepts [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>].</p>
<p>For authors and developers working with <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank nodes</a>
as <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> when deserializing to RDF,
three potential approaches are suggested:</p>
<ul>
<li>If the author is not yet ready to commit to a stable <abbr title="Internationalized Resource Identifier">IRI</abbr>, the
property should be mapped to an <abbr title="Internationalized Resource Identifier">IRI</abbr> that is documented as unstable.</li>
<li>If the developer wishes to use <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank nodes</a>
as <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> and also wishes to interpret the
data as a
<a data-link-type="dfn" href="https://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">generalized RDF Dataset</a>,
there is an option, <a href="https://json-ld.org/spec/latest/json-ld-api/#dom-jsonldoptions-producegeneralizedrdf"><em>produce generalized RDF</em></a>, in the
<a href="https://json-ld.org/spec/latest/json-ld-api/#deserialize-json-ld-to-rdf-algorithm">Deserialize JSON-LD to RDF algorithm</a> [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>] to do so. Note that a
<a data-link-type="dfn" href="https://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">generalized RDF Dataset</a>
is an extension of RDF; it does not conform to the RDF standard.</li>
<li>If the author or developer wishes to use <a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank nodes</a>
as <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> and wishes to interpret the data
as a standard (non-generalized)
<a href="#dfn-dataset" class="internalDFN" data-link-type="dfn">RDF Dataset</a>,
it is possible to losslessly interpret JSON-LD as RDF by transforming
<a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank nodes</a> used as
<a href="#dfn-properties" class="internalDFN" data-link-type="dfn">properties</a> to <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a>,
by minting new "Skolem IRIs" as per
<a href="https://www.w3.org/TR/rdf11-concepts/#section-skolemization">Replacing Blank Nodes with IRIs</a>
of [<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>].</li>
</ul>
<p>The normative algorithms for interpreting JSON-LD as RDF and serializing
RDF as JSON-LD are specified in the JSON-LD 1.1 Processing Algorithms and API
specification [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>].</p>
<p>Even though JSON-LD serializes
<a data-link-type="dfn" href="https://www.w3.org/TR/rdf11-concepts/#dfn-generalized-rdf-dataset">generalized RDF Datasets</a>, it can
also be used as a <dfn data-dfn-type="dfn" id="dfn-rdf-graph-source"><a href="https://www.w3.org/TR/rdf11-concepts/#dfn-rdf-source">RDF graph source</a></dfn>.
In that case, a consumer <em class="rfc2119" title="MUST">MUST</em> only use the default graph and ignore all <a href="#dfn-named-graphs" class="internalDFN" data-link-type="dfn">named graphs</a>.
This allows servers to expose data in languages such as Turtle and JSON-LD
using content negotiation.</p>
<div class="note"><div role="heading" class="note-title marker" id="h-note-21" aria-level="3"><span>Note</span></div><p class="">Publishers supporting both dataset and graph syntaxes have to ensure that
the primary data is stored in the default graph to enable consumers that do not support
datasets to process the information.</p></div>
<section class="informative" id="serializing-deserializing-rdf" typeof="schema:Chapter" resource="#serializing-deserializing-rdf" property="schema:hasPart">
<h3 id="x7-1-serializing-deserializing-rdf"><span class="secno">7.1 </span>Serializing/Deserializing RDF&nbsp;<span class="permalink"><a href="#serializing-deserializing-rdf" aria-label="Permalink for 7.1 Serializing/Deserializing RDF" title="Permalink for 7.1 Serializing/Deserializing RDF"><span property="schema:name" content="7.1 Serializing/Deserializing RDF">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>The process of serializing RDF as JSON-LD and deserializing JSON-LD to RDF
depends on executing the algorithms defined in
<a href="https://json-ld.org/spec/latest/json-ld-api/#rdf-serialization-deserialization-algorithms">RDF Serialization-Deserialization Algorithms</a>
in the JSON-LD 1.1 Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>].
It is beyond the scope of this document to detail these algorithms any further,
but a summary of the necessary operations is provided to illustrate the process.</p>
<p>The procedure to deserialize a JSON-LD document to RDF involves the
following steps:</p>
<ol>
<li>Expand the JSON-LD document, removing any context; this ensures
that properties, types, and values are given their full representation
as <a href="#dfn-iris" class="internalDFN" data-link-type="dfn">IRIs</a> and expanded values. <a data-link-type="dfn" href="https://json-ld.org/spec/latest/json-ld-api/#dfn-expansion">Expansion</a>
is discussed further in <a class="sectionRef sec-ref" href="#expanded-document-form">section <span class="secno">4.25</span> <span class="sec-title">Expanded Document Form</span></a>.</li>
<li>Flatten the document, which turns the document into an array of
<a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node objects</a>. Flattening is discussed
further in <a class="sectionRef sec-ref" href="#flattened-document-form">section <span class="secno">4.27</span> <span class="sec-title">Flattened Document Form</span></a>.</li>
<li>Turn each <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> into a series of <a href="#dfn-triple" class="internalDFN" data-link-type="dfn">RDF triples</a>.</li>
</ol>
<p>For example, consider the following JSON-LD document in compact form:</p>
<div class="example"><div class="example-title marker"><span>Example 94</span><span style="text-transform: none">: Sample JSON-LD document</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/name"</span>,
<span class="hljs-attr">"knows"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/knows"</span>
},
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://me.markus-lanthaler.com/"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Markus Lanthaler"</span>,
<span class="hljs-attr">"knows"</span>: [
{
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/about#manu"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Manu Sporny"</span>
}, {
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"Dave Longley"</span>
}
]
}</pre></div>
<p>Running the JSON-LD <a href="https://json-ld.org/spec/latest/json-ld-api/#expansion-algorithm">Expansion</a> and <a href="https://json-ld.org/spec/latest/json-ld-api/#flattening-algorithm">Flattening</a> algorithms against the
JSON-LD input document in the example above would result in the
following output:</p>
<div class="example"><div class="example-title marker"><span>Example 95</span><span style="text-transform: none">: Flattened and expanded form for the previous example</span></div><pre class="hljs json" aria-busy="false">[
{
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"_:b0"</span>,
<span class="hljs-attr">"http://xmlns.com/foaf/0.1/name"</span>: <span class="hljs-string">"Dave Longley"</span>
}, {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/about#manu"</span>,
<span class="hljs-attr">"http://xmlns.com/foaf/0.1/name"</span>: <span class="hljs-string">"Manu Sporny"</span>
}, {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://me.markus-lanthaler.com/"</span>,
<span class="hljs-attr">"http://xmlns.com/foaf/0.1/name"</span>: <span class="hljs-string">"Markus Lanthaler"</span>,
<span class="hljs-attr">"http://xmlns.com/foaf/0.1/knows"</span>: [
{ <span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/about#manu"</span> },
{ <span class="hljs-attr">"@id"</span>: <span class="hljs-string">"_:b0"</span> }
]
}
]</pre></div>
<p>Deserializing this to RDF now is a straightforward process of turning
each <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> into one or more RDF triples. This can be
expressed in Turtle as follows:</p>
<div class="example"><div class="example-title marker"><span>Example 96</span><span style="text-transform: none">: Turtle representation of expanded/flattened document</span></div><pre class="hljs javascript" data-content-type="text/turtle" aria-busy="false">@prefix foaf: <span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">http:</span>//<span class="hljs-attr">xmlns.com</span>/<span class="hljs-attr">foaf</span>/<span class="hljs-attr">0.1</span>/&gt;</span></span> .
_:b0 foaf:name <span class="hljs-string">"Dave Longley"</span> .
&lt;http:<span class="hljs-comment">//manu.sporny.org/about#manu&gt; foaf:name "Manu Sporny" .</span>
&lt;http:<span class="hljs-comment">//me.markus-lanthaler.com/&gt; foaf:name "Markus Lanthaler" ;</span>
foaf:knows &lt;http:<span class="hljs-comment">//manu.sporny.org/about#manu&gt;, _:b0 .</span></pre></div>
<p>The process of serializing RDF as JSON-LD can be thought of as the
inverse of this last step, creating an expanded JSON-LD document closely
matching the triples from RDF, using a single <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a>
for all triples having a common subject, and a single <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a>
for those triples also having a common predicate.</p>
</section>
</section>
<section class="appendix informative" id="changes-since-1-0-recommendation-of-16-january-2014" typeof="schema:Chapter" resource="#changes-since-1-0-recommendation-of-16-january-2014" property="schema:hasPart">
<!--OddPage--><h2 id="a-changes-since-1-0-recommendation-of-16-january-2014"><span class="secno">A. </span>Changes since 1.0 Recommendation of 16 January 2014&nbsp;<span class="permalink"><a href="#changes-since-1-0-recommendation-of-16-january-2014" aria-label="Permalink for A. Changes since 1.0 Recommendation of 16 January 2014" title="Permalink for A. Changes since 1.0 Recommendation of 16 January 2014"><span property="schema:name" content="A. Changes since 1.0 Recommendation of 16 January 2014">§</span></a></span></h2><p><em>This section is non-normative.</em></p>
<ul>
<li>An <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> can now have an
<code>@context</code> property, which defines a <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> used for values of
a <a href="#dfn-properties" class="internalDFN" data-link-type="dfn">property</a> identified with such a <a href="#dfn-terms" class="internalDFN" data-link-type="dfn">term</a>.</li>
<li><code>@container</code> values within an <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> may now
include <code>@id</code>, <code>@graph</code> and <code>@type</code>, corresponding to <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id maps</a> and <a href="#dfn-type-maps" class="internalDFN" data-link-type="dfn">type maps</a>.</li>
<li>An <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> can now have an
<code>@nest</code> property, which identifies a term expanding to
<code>@nest</code> which is used for containing properties using the same
<code>@nest</code> mapping. When expanding, the values of a property
expanding to <code>@nest</code> are treated as if they were contained
within the enclosing <a href="#dfn-node-objects" class="internalDFN" data-link-type="dfn">node object</a> directly.</li>
<li>The JSON syntax has been abstracted into an <a href="#dfn-internal-representation" class="internalDFN" data-link-type="dfn">internal representation</a>
to allow for other serializations that are functionally equivalent
to JSON.</li>
<li>Added <a href="#language-indexing" class="sectionRef sec-ref">section <span class="secno">4.20</span> <span class="sec-title">Language Indexing</span></a>.</li>
<li>The value for <code>@container</code> in an <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a>
can also be an <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> containing any appropriate container
keyword along with <code>@set</code> (other than <code>@list</code>).
This allows a way to ensure that such property values will always
be expressed in <a href="#dfn-arrays" class="internalDFN" data-link-type="dfn">array</a> form.</li>
<li>In JSON-LD 1.1, terms will be used as <a href="#dfn-compact-iris" class="internalDFN" data-link-type="dfn">compact <abbr title="Internationalized Resource Identifier">IRI</abbr></a> prefixes
when compacting only if
a <a href="#dfn-simple-terms" class="internalDFN" data-link-type="dfn">simple term definition</a> is used where the value ends with a URI <a href="https://tools.ietf.org/html/rfc3986#section-2.2">gen-delim</a> character,
or if their <a href="#dfn-expanded-term-definitions" class="internalDFN" data-link-type="dfn">expanded term definition</a> contains
a <code>@prefix</code> member with the value <a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a>. The 1.0 algorithm has
been updated to only consider terms that map to a value that ends with a URI
<a href="https://tools.ietf.org/html/rfc3986#section-2.2">gen-delim</a> character.</li>
<li>Values of properties where the associated <a href="#dfn-term-definitions" class="internalDFN" data-link-type="dfn">term definition</a>
has <code>@container</code> set to <code>@graph</code> are interpreted as
<a href="#dfn-implicitly-named-graphs" class="internalDFN" data-link-type="dfn">implicitly named graphs</a>, where the associated graph name is
assigned from a new <a href="#dfn-blank-node-identifiers" class="internalDFN" data-link-type="dfn">blank node identifier</a>. Other combinations
include <code>["@container", "@id"]</code>, <code>["@container", "@index"]</code> each also
may include <code>"@set"</code>, which create maps from the
graph identifier or index value similar to <a href="#dfn-index-maps" class="internalDFN" data-link-type="dfn">index maps</a>
and <a href="#dfn-id-maps" class="internalDFN" data-link-type="dfn">id maps</a>.</li>
</ul>
</section>
<section class="appendix informative" id="open-issues" typeof="schema:Chapter" resource="#open-issues" property="schema:hasPart">
<!--OddPage--><h2 id="b-open-issues"><span class="secno">B. </span>Open Issues&nbsp;<span class="permalink"><a href="#open-issues" aria-label="Permalink for B. Open Issues" title="Permalink for B. Open Issues"><span property="schema:name" content="B. Open Issues">§</span></a></span></h2><p><em>This section is non-normative.</em></p>
<p>The following is a list of open issues being worked on for the next release.</p>
<div class="issue" id="issue-333"><div role="heading" class="issue-title marker" id="h-issue" aria-level="3"><a href="https://github.com/json-ld/json-ld.org/issues/333"><span>Issue 333</span></a><span style="text-transform: none">: Support JSON values that aren't mapped</span></div></div>
<div class="issue" id="issue-538"><div role="heading" class="issue-title marker" id="h-issue-0" aria-level="3"><a href="https://github.com/json-ld/json-ld.org/issues/538"><span>Issue 538</span></a></div><p class=""></p></div>
<div class="issue" id="issue-547"><div role="heading" class="issue-title marker" id="h-issue-1" aria-level="3"><a href="https://github.com/json-ld/json-ld.org/issues/547"><span>Issue 547</span></a><span style="text-transform: none">: Content addressable contexts</span></div></div>
<div class="issue" id="issue-548"><div role="heading" class="issue-title marker" id="h-issue-2" aria-level="3"><a href="https://github.com/json-ld/json-ld.org/issues/548"><span>Issue 548</span></a><span style="text-transform: none">: Use version 2.0 instead of 1.1</span></div></div>
</section>
<section class="appendix informative" id="relationship-to-other-linked-data-formats" typeof="schema:Chapter" resource="#relationship-to-other-linked-data-formats" property="schema:hasPart">
<!--OddPage--><h2 id="c-relationship-to-other-linked-data-formats"><span class="secno">C. </span>Relationship to Other Linked Data Formats&nbsp;<span class="permalink"><a href="#relationship-to-other-linked-data-formats" aria-label="Permalink for C. Relationship to Other Linked Data Formats" title="Permalink for C. Relationship to Other Linked Data Formats"><span property="schema:name" content="C. Relationship to Other Linked Data Formats">§</span></a></span></h2><p><em>This section is non-normative.</em></p>
<p>The JSON-LD examples below demonstrate how JSON-LD can be used to
express semantic data marked up in other linked data formats such as Turtle,
RDFa, Microformats, and Microdata. These sections are merely provided as
evidence that JSON-LD is very flexible in what it can express across different
Linked Data approaches.</p>
<section class="informative" id="turtle" typeof="schema:Chapter" resource="#turtle" property="schema:hasPart">
<h3 id="c-1-turtle"><span class="secno">C.1 </span>Turtle&nbsp;<span class="permalink"><a href="#turtle" aria-label="Permalink for C.1 Turtle" title="Permalink for C.1 Turtle"><span property="schema:name" content="C.1 Turtle">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>The following are examples of transforming RDF expressed in Turtle [<cite><a class="bibref" href="#bib-TURTLE">TURTLE</a></cite>]
into JSON-LD.</p>
<section id="prefix-definitions" typeof="schema:Chapter" resource="#prefix-definitions" property="schema:hasPart">
<h4 id="c-1-1-prefix-definitions"><span class="secno">C.1.1 </span>Prefix definitions&nbsp;<span class="permalink"><a href="#prefix-definitions" aria-label="Permalink for C.1.1 Prefix definitions" title="Permalink for C.1.1 Prefix definitions"><span property="schema:name" content="C.1.1 Prefix definitions">§</span></a></span></h4>
<p>The JSON-LD context has direct equivalents for the Turtle
<code>@prefix</code> declaration:</p>
<div class="example"><div class="example-title marker"><span>Example 97</span><span style="text-transform: none">: A set of statements serialized in Turtle</span></div><pre class="hljs javascript" data-content-type="text/turtle" aria-busy="false">@prefix foaf: <span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">http:</span>//<span class="hljs-attr">xmlns.com</span>/<span class="hljs-attr">foaf</span>/<span class="hljs-attr">0.1</span>/&gt;</span></span> .
&lt;http:<span class="hljs-comment">//manu.sporny.org/about#manu&gt; a foaf:Person;</span>
foaf:name <span class="hljs-string">"Manu Sporny"</span>;
foaf:homepage &lt;http:<span class="hljs-comment">//manu.sporny.org/&gt; .</span></pre></div>
<div class="example"><div class="example-title marker"><span>Example 98</span><span style="text-transform: none">: The same set of statements serialized in JSON-LD</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"foaf"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/"</span>
},
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/about#manu"</span>,
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"foaf:Person"</span>,
<span class="hljs-attr">"foaf:name"</span>: <span class="hljs-string">"Manu Sporny"</span>,
<span class="hljs-attr">"foaf:homepage"</span>: { <span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/"</span> }
}</pre></div>
</section>
<section id="embedding-0" typeof="schema:Chapter" resource="#embedding-0" property="schema:hasPart">
<h4 id="c-1-2-embedding"><span class="secno">C.1.2 </span>Embedding&nbsp;<span class="permalink"><a href="#embedding-0" aria-label="Permalink for C.1.2 Embedding" title="Permalink for C.1.2 Embedding"><span property="schema:name" content="C.1.2 Embedding">§</span></a></span></h4>
<p>Both Turtle and JSON-LD allow embedding, although Turtle only allows embedding of
<a href="#dfn-blank-nodes" class="internalDFN" data-link-type="dfn">blank nodes</a>.</p>
<div class="example"><div class="example-title marker"><span>Example 99</span><span style="text-transform: none">: Embedding in Turtle</span></div><pre class="hljs css" data-content-type="text/turtle" aria-busy="false">@<span class="hljs-keyword">prefix</span> foaf: &lt;http://xmlns.com/foaf/<span class="hljs-number">0.1</span>/&gt; .
&lt;http://manu.sporny.org/about#manu&gt;
a foaf:Person;
<span class="hljs-selector-tag">foaf</span><span class="hljs-selector-pseudo">:name</span> "<span class="hljs-selector-tag">Manu</span> <span class="hljs-selector-tag">Sporny</span>";
<span class="hljs-selector-tag">foaf</span><span class="hljs-selector-pseudo">:knows</span> <span class="hljs-selector-attr">[ a foaf:Person; foaf:name "Gregg Kellogg" ]</span> .</pre></div>
<div class="example"><div class="example-title marker"><span>Example 100</span><span style="text-transform: none">: Same embedding example in JSON-LD</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"foaf"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/"</span>
},
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://manu.sporny.org/about#manu"</span>,
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"foaf:Person"</span>,
<span class="hljs-attr">"foaf:name"</span>: <span class="hljs-string">"Manu Sporny"</span>,
<span class="hljs-attr">"foaf:knows"</span>: {
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"foaf:Person"</span>,
<span class="hljs-attr">"foaf:name"</span>: <span class="hljs-string">"Gregg Kellogg"</span>
}
}</pre></div>
</section>
<section id="conversion-of-native-data-types" typeof="schema:Chapter" resource="#conversion-of-native-data-types" property="schema:hasPart">
<h4 id="c-1-3-conversion-of-native-data-types"><span class="secno">C.1.3 </span>Conversion of native data types&nbsp;<span class="permalink"><a href="#conversion-of-native-data-types" aria-label="Permalink for C.1.3 Conversion of native data types" title="Permalink for C.1.3 Conversion of native data types"><span property="schema:name" content="C.1.3 Conversion of native data types">§</span></a></span></h4>
<p>In JSON-LD numbers and boolean values are native data types. While Turtle
has a shorthand syntax to express such values, RDF's abstract syntax requires
that numbers and boolean values are represented as typed literals. Thus,
to allow full round-tripping, the JSON-LD 1.1 Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>]
defines conversion rules between JSON-LD's native data types and RDF's
counterparts. <a href="#dfn-numbers" class="internalDFN" data-link-type="dfn">Numbers</a> without fractions are
converted to <code>xsd:integer</code>-typed literals, numbers with fractions
to <code>xsd:double</code>-typed literals and the two boolean values
<a href="#dfn-true" class="internalDFN" data-link-type="dfn">true</a> and <a href="#dfn-false" class="internalDFN" data-link-type="dfn">false</a> to a <code>xsd:boolean</code>-typed
literal. All typed literals are in canonical lexical form.</p>
<div class="example"><div class="example-title marker"><span>Example 101</span><span style="text-transform: none">: JSON-LD using native data types for numbers and boolean values</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"ex"</span>: <span class="hljs-string">"http://example.com/vocab#"</span>
},
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://example.com/"</span>,
<span class="hljs-attr">"ex:numbers"</span>: [ <span class="hljs-number">14</span>, <span class="hljs-number">2.78</span> ],
<span class="hljs-attr">"ex:booleans"</span>: [ <span class="hljs-literal">true</span>, <span class="hljs-literal">false</span> ]
}</pre></div>
<div class="example"><div class="example-title marker"><span>Example 102</span><span style="text-transform: none">: Same example in Turtle using typed literals</span></div><pre class="hljs css" data-content-type="text/turtle" aria-busy="false">@<span class="hljs-keyword">prefix</span> ex: &lt;http://example.com/vocab#&gt; .
@prefix xsd: &lt;http://www.w3.org/<span class="hljs-number">2001</span>/XMLSchema#&gt; .
&lt;http://example.com/&gt;
ex:numbers <span class="hljs-string">"14"</span>^^xsd:integer, <span class="hljs-string">"2.78E0"</span>^^xsd:double ;
<span class="hljs-selector-tag">ex</span><span class="hljs-selector-pseudo">:booleans</span> "<span class="hljs-selector-tag">true</span>"^^<span class="hljs-selector-tag">xsd</span><span class="hljs-selector-pseudo">:boolean</span>, "<span class="hljs-selector-tag">false</span>"^^<span class="hljs-selector-tag">xsd</span><span class="hljs-selector-pseudo">:boolean</span> .</pre></div>
</section>
<section id="lists" typeof="schema:Chapter" resource="#lists" property="schema:hasPart">
<h4 id="c-1-4-lists"><span class="secno">C.1.4 </span>Lists&nbsp;<span class="permalink"><a href="#lists" aria-label="Permalink for C.1.4 Lists" title="Permalink for C.1.4 Lists"><span property="schema:name" content="C.1.4 Lists">§</span></a></span></h4>
<p>Both JSON-LD and Turtle can represent sequential lists of values.</p>
<div class="example"><div class="example-title marker"><span>Example 103</span><span style="text-transform: none">: A list of values in Turtle</span></div><pre class="hljs javascript" data-content-type="text/turtle" aria-busy="false">@prefix foaf: <span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">http:</span>//<span class="hljs-attr">xmlns.com</span>/<span class="hljs-attr">foaf</span>/<span class="hljs-attr">0.1</span>/&gt;</span></span> .
&lt;http:<span class="hljs-comment">//example.org/people#joebob&gt; a foaf:Person;</span>
foaf:name <span class="hljs-string">"Joe Bob"</span>;
foaf:nick ( <span class="hljs-string">"joe"</span> <span class="hljs-string">"bob"</span> <span class="hljs-string">"jaybee"</span> ) .</pre></div>
<div class="example"><div class="example-title marker"><span>Example 104</span><span style="text-transform: none">: Same example with a list of values in JSON-LD</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"foaf"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/"</span>
},
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://example.org/people#joebob"</span>,
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"foaf:Person"</span>,
<span class="hljs-attr">"foaf:name"</span>: <span class="hljs-string">"Joe Bob"</span>,
<span class="hljs-attr">"foaf:nick"</span>: {
<span class="hljs-attr">"@list"</span>: [ <span class="hljs-string">"joe"</span>, <span class="hljs-string">"bob"</span>, <span class="hljs-string">"jaybee"</span> ]
}
}</pre></div>
</section>
</section>
<section class="informative" id="rdfa" typeof="schema:Chapter" resource="#rdfa" property="schema:hasPart">
<h3 id="c-2-rdfa"><span class="secno">C.2 </span>RDFa&nbsp;<span class="permalink"><a href="#rdfa" aria-label="Permalink for C.2 RDFa" title="Permalink for C.2 RDFa"><span property="schema:name" content="C.2 RDFa">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>The following example describes three people with their respective names and
homepages in RDFa [<cite><a class="bibref" href="#bib-RDFA-CORE">RDFA-CORE</a></cite>].</p>
<div class="example"><div class="example-title marker"><span>Example 105</span><span style="text-transform: none">: RDFa fragment that describes three people</span></div><pre class="nohighlight" data-content-type="text/html">&lt;div <span class="hl-bold">prefix="foaf: http://xmlns.com/foaf/0.1/"</span>&gt;
&lt;ul&gt;
&lt;li <span class="hl-bold">typeof="foaf:Person"</span>&gt;
&lt;a <span class="hl-bold">property="foaf:homepage" href="http://example.com/bob/"&gt;
&lt;span property="foaf:name"</span>&gt;Bob&lt;/span&gt;
&lt;/a&gt;
&lt;/li&gt;
&lt;li <span class="hl-bold">typeof="foaf:Person"</span>&gt;
&lt;a <span class="hl-bold">property="foaf:homepage" href="http://example.com/eve/"&gt;
&lt;span property="foaf:name"</span>&gt;Eve&lt;/span&gt;
&lt;/a&gt;
&lt;/li&gt;
&lt;li <span class="hl-bold">typeof="foaf:Person"</span>&gt;
&lt;a <span class="hl-bold">property="foaf:homepage" href="http://example.com/manu/"&gt;
&lt;span property="foaf:name"</span>&gt;Manu&lt;/span&gt;
&lt;/a&gt;
&lt;/li&gt;
&lt;/ul&gt;
&lt;/div&gt;</pre></div>
<p>An example JSON-LD implementation using a single <a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> is
described below.</p>
<div class="example"><div class="example-title marker"><span>Example 106</span><span style="text-transform: none">: Same description in JSON-LD (context shared among node objects)</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"foaf"</span>: <span class="hljs-string">"http://xmlns.com/foaf/0.1/"</span>
},
<span class="hljs-attr">"@graph"</span>: [
{
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"foaf:Person"</span>,
<span class="hljs-attr">"foaf:homepage"</span>: <span class="hljs-string">"http://example.com/bob/"</span>,
<span class="hljs-attr">"foaf:name"</span>: <span class="hljs-string">"Bob"</span>
}, {
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"foaf:Person"</span>,
<span class="hljs-attr">"foaf:homepage"</span>: <span class="hljs-string">"http://example.com/eve/"</span>,
<span class="hljs-attr">"foaf:name"</span>: <span class="hljs-string">"Eve"</span>
}, {
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"foaf:Person"</span>,
<span class="hljs-attr">"foaf:homepage"</span>: <span class="hljs-string">"http://example.com/manu/"</span>,
<span class="hljs-attr">"foaf:name"</span>: <span class="hljs-string">"Manu"</span>
}
]
}</pre></div>
</section>
<section class="informative" id="microformats" typeof="schema:Chapter" resource="#microformats" property="schema:hasPart">
<h3 id="c-3-microformats"><span class="secno">C.3 </span>Microformats&nbsp;<span class="permalink"><a href="#microformats" aria-label="Permalink for C.3 Microformats" title="Permalink for C.3 Microformats"><span property="schema:name" content="C.3 Microformats">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>The following example uses a simple Microformats hCard example to express
how Microformats [<cite><a class="bibref" href="#bib-MICROFORMATS">MICROFORMATS</a></cite>] are represented in JSON-LD.</p>
<div class="example"><div class="example-title marker"><span>Example 107</span><span style="text-transform: none">: HTML fragment with a simple Microformats hCard</span></div><pre class="hljs javascript" data-content-type="text/html" aria-busy="false">&lt;div <span class="hljs-class"><span class="hljs-keyword">class</span></span>=<span class="hljs-string">"vcard"</span>&gt;
<span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">a</span> <span class="hljs-attr">class</span>=<span class="hljs-string">"url fn"</span> <span class="hljs-attr">href</span>=<span class="hljs-string">"http://tantek.com/"</span>&gt;</span>Tantek Çelik<span class="hljs-tag">&lt;/<span class="hljs-name">a</span>&gt;</span></span>
&lt;<span class="hljs-regexp">/div&gt;</span></pre></div>
<p>The representation of the hCard expresses the Microformat terms in the
<a href="#dfn-contexts" class="internalDFN" data-link-type="dfn">context</a> and uses them directly for the <code>url</code> and <code>fn</code>
properties. Also note that the Microformat to JSON-LD processor has
generated the proper URL type for <code>http://tantek.com/</code>.</p>
<div class="example"><div class="example-title marker"><span>Example 108</span><span style="text-transform: none">: Same hCard representation in JSON-LD</span></div><pre class="hljs json" aria-busy="false">{
<span class="hljs-attr">"@context"</span>: {
<span class="hljs-attr">"vcard"</span>: <span class="hljs-string">"http://microformats.org/profile/hcard#vcard"</span>,
<span class="hljs-attr">"url"</span>: {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://microformats.org/profile/hcard#url"</span>,
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"@id"</span>
},
<span class="hljs-attr">"fn"</span>: <span class="hljs-string">"http://microformats.org/profile/hcard#fn"</span>
},
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"vcard"</span>,
<span class="hljs-attr">"url"</span>: <span class="hljs-string">"http://tantek.com/"</span>,
<span class="hljs-attr">"fn"</span>: <span class="hljs-string">"Tantek Çelik"</span>
}</pre></div>
</section>
<section class="informative" id="microdata" typeof="schema:Chapter" resource="#microdata" property="schema:hasPart">
<h3 id="c-4-microdata"><span class="secno">C.4 </span>Microdata&nbsp;<span class="permalink"><a href="#microdata" aria-label="Permalink for C.4 Microdata" title="Permalink for C.4 Microdata"><span property="schema:name" content="C.4 Microdata">§</span></a></span></h3><p><em>This section is non-normative.</em></p>
<p>The HTML Microdata [<cite><a class="bibref" href="#bib-MICRODATA">MICRODATA</a></cite>] example below expresses book information as
a Microdata Work item.</p>
<div class="example"><div class="example-title marker"><span>Example 109</span><span style="text-transform: none">: HTML fragments that describes a book using microdata</span></div><pre class="hljs xml" data-content-type="text/html" aria-busy="false"><span class="hljs-tag">&lt;<span class="hljs-name">dl</span> <span class="hljs-attr">itemscope</span>
<span class="hljs-attr">itemtype</span>=<span class="hljs-string">"http://purl.org/vocab/frbr/core#Work"</span>
<span class="hljs-attr">itemid</span>=<span class="hljs-string">"http://purl.oreilly.com/works/45U8QJGZSQKDH8N"</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">dt</span>&gt;</span>Title<span class="hljs-tag">&lt;/<span class="hljs-name">dt</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">dd</span>&gt;</span><span class="hljs-tag">&lt;<span class="hljs-name">cite</span> <span class="hljs-attr">itemprop</span>=<span class="hljs-string">"http://purl.org/dc/terms/title"</span>&gt;</span>Just a Geek<span class="hljs-tag">&lt;/<span class="hljs-name">cite</span>&gt;</span><span class="hljs-tag">&lt;/<span class="hljs-name">dd</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">dt</span>&gt;</span>By<span class="hljs-tag">&lt;/<span class="hljs-name">dt</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">dd</span>&gt;</span><span class="hljs-tag">&lt;<span class="hljs-name">span</span> <span class="hljs-attr">itemprop</span>=<span class="hljs-string">"http://purl.org/dc/terms/creator"</span>&gt;</span>Wil Wheaton<span class="hljs-tag">&lt;/<span class="hljs-name">span</span>&gt;</span><span class="hljs-tag">&lt;/<span class="hljs-name">dd</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">dt</span>&gt;</span>Format<span class="hljs-tag">&lt;/<span class="hljs-name">dt</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">dd</span> <span class="hljs-attr">itemprop</span>=<span class="hljs-string">"http://purl.org/vocab/frbr/core#realization"</span>
<span class="hljs-attr">itemscope</span>
<span class="hljs-attr">itemtype</span>=<span class="hljs-string">"http://purl.org/vocab/frbr/core#Expression"</span>
<span class="hljs-attr">itemid</span>=<span class="hljs-string">"http://purl.oreilly.com/products/9780596007683.BOOK"</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">link</span> <span class="hljs-attr">itemprop</span>=<span class="hljs-string">"http://purl.org/dc/terms/type"</span> <span class="hljs-attr">href</span>=<span class="hljs-string">"http://purl.oreilly.com/product-types/BOOK"</span>&gt;</span>
Print
<span class="hljs-tag">&lt;/<span class="hljs-name">dd</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">dd</span> <span class="hljs-attr">itemprop</span>=<span class="hljs-string">"http://purl.org/vocab/frbr/core#realization"</span>
<span class="hljs-attr">itemscope</span>
<span class="hljs-attr">itemtype</span>=<span class="hljs-string">"http://purl.org/vocab/frbr/core#Expression"</span>
<span class="hljs-attr">itemid</span>=<span class="hljs-string">"http://purl.oreilly.com/products/9780596802189.EBOOK"</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">link</span> <span class="hljs-attr">itemprop</span>=<span class="hljs-string">"http://purl.org/dc/terms/type"</span> <span class="hljs-attr">href</span>=<span class="hljs-string">"http://purl.oreilly.com/product-types/EBOOK"</span>&gt;</span>
Ebook
<span class="hljs-tag">&lt;/<span class="hljs-name">dd</span>&gt;</span>
<span class="hljs-tag">&lt;/<span class="hljs-name">dl</span>&gt;</span></pre></div>
<p>Note that the JSON-LD representation of the Microdata information stays
true to the desires of the Microdata community to avoid contexts and
instead refer to items by their full <a href="#dfn-iris" class="internalDFN" data-link-type="dfn"><abbr title="Internationalized Resource Identifier">IRI</abbr></a>.</p>
<div class="example"><div class="example-title marker"><span>Example 110</span><span style="text-transform: none">: Same book description in JSON-LD (avoiding contexts)</span></div><pre class="hljs json" aria-busy="false">[
{
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://purl.oreilly.com/works/45U8QJGZSQKDH8N"</span>,
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"http://purl.org/vocab/frbr/core#Work"</span>,
<span class="hljs-attr">"http://purl.org/dc/terms/title"</span>: <span class="hljs-string">"Just a Geek"</span>,
<span class="hljs-attr">"http://purl.org/dc/terms/creator"</span>: <span class="hljs-string">"Whil Wheaton"</span>,
<span class="hljs-attr">"http://purl.org/vocab/frbr/core#realization"</span>:
[
<span class="hljs-string">"http://purl.oreilly.com/products/9780596007683.BOOK"</span>,
<span class="hljs-string">"http://purl.oreilly.com/products/9780596802189.EBOOK"</span>
]
}, {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://purl.oreilly.com/products/9780596007683.BOOK"</span>,
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"http://purl.org/vocab/frbr/core#Expression"</span>,
<span class="hljs-attr">"http://purl.org/dc/terms/type"</span>: <span class="hljs-string">"http://purl.oreilly.com/product-types/BOOK"</span>
}, {
<span class="hljs-attr">"@id"</span>: <span class="hljs-string">"http://purl.oreilly.com/products/9780596802189.EBOOK"</span>,
<span class="hljs-attr">"@type"</span>: <span class="hljs-string">"http://purl.org/vocab/frbr/core#Expression"</span>,
<span class="hljs-attr">"http://purl.org/dc/terms/type"</span>: <span class="hljs-string">"http://purl.oreilly.com/product-types/EBOOK"</span>
}
]</pre></div>
</section>
</section>
<section class="appendix normative" id="iana-considerations" typeof="schema:Chapter" resource="#iana-considerations" property="schema:hasPart">
<!--OddPage--><h2 id="d-iana-considerations"><span class="secno">D. </span>IANA Considerations&nbsp;<span class="permalink"><a href="#iana-considerations" aria-label="Permalink for D. IANA Considerations" title="Permalink for D. IANA Considerations"><span property="schema:name" content="D. IANA Considerations">§</span></a></span></h2>
<p>This section has been submitted to the Internet Engineering Steering
Group (IESG) for review, approval, and registration with IANA.</p>
<h2 id="application-ld-json">application/ld+json&nbsp;<span class="permalink"><a href="#iana-considerations" aria-label="Permalink for application/ld+json" title="Permalink for application/ld+json"><span property="schema:name" content="application/ld+json">§</span></a></span></h2>
<dl>
<dt>Type name:</dt>
<dd>application</dd>
<dt>Subtype name:</dt>
<dd>ld+json</dd>
<dt>Required parameters:</dt>
<dd>None</dd>
<dt>Optional parameters:</dt>
<dd>
<dl>
<dt><code>profile</code></dt>
<dd>
<p>A non-empty list of space-separated URIs identifying specific
constraints or conventions that apply to a JSON-LD document according to [<cite><a class="bibref" href="#bib-RFC6906">RFC6906</a></cite>].
A profile does not change the semantics of the resource representation
when processed without profile knowledge, so that clients both with
and without knowledge of a profiled resource can safely use the same
representation. The <code>profile</code> parameter <em class="rfc2119" title="MAY">MAY</em> be used by
clients to express their preferences in the content negotiation process.
If the profile parameter is given, a server <em class="rfc2119" title="SHOULD">SHOULD</em> return a document that
honors the profiles in the list which are recognized by the server.
It is <em class="rfc2119" title="RECOMMENDED">RECOMMENDED</em> that profile URIs are dereferenceable and provide
useful documentation at that URI. For more information and background
please refer to [<cite><a class="bibref" href="#bib-RFC6906">RFC6906</a></cite>].</p>
<p>This specification defines three values for the <code>profile</code> parameter.
To request or specify <a href="#expanded-document-form">expanded JSON-LD document form</a>,
the URI <code>http://www.w3.org/ns/json-ld#expanded</code> <em class="rfc2119" title="SHOULD">SHOULD</em> be used.
To request or specify <a href="#compacted-document-form">compacted JSON-LD document form</a>,
the URI <code>http://www.w3.org/ns/json-ld#compacted</code> <em class="rfc2119" title="SHOULD">SHOULD</em> be used.
To request or specify <a href="#flattened-document-form">flattened JSON-LD document form</a>,
the URI <code>http://www.w3.org/ns/json-ld#flattened</code> <em class="rfc2119" title="SHOULD">SHOULD</em> be used.
Please note that, according [<cite><a class="bibref" href="#bib-HTTP11">HTTP11</a></cite>], the value of the <code>profile</code>
parameter has to be enclosed in quotes (<code>"</code>) because it contains
special characters and, if multiple profiles are combined, whitespace.</p>
<p>When processing the "profile" media type parameter, it is important to
note that its value contains one or more URIs and not IRIs. In some cases
it might therefore be necessary to convert between IRIs and URIs as specified in
<a href="https://tools.ietf.org/html/rfc3986#section-5.1">section 3 Relationship between IRIs and URIs</a>
of [<cite><a class="bibref" href="#bib-RFC3987">RFC3987</a></cite>].</p>
</dd>
</dl>
</dd>
<dt>Encoding considerations:</dt>
<dd>See <a href="https://tools.ietf.org/html/rfc6839#section-3.1">RFC&nbsp;6839, section 3.1</a>.</dd>
<dt>Security considerations:</dt>
<dd>See [<cite><a class="bibref" href="#bib-RFC7159">RFC7159</a></cite>]
<p>Since JSON-LD is intended to be a pure data exchange format for
directed graphs, the serialization <em class="rfc2119" title="SHOULD NOT">SHOULD NOT</em> be passed through a
code execution mechanism such as JavaScript's <code>eval()</code>
function to be parsed. An (invalid) document may contain code that,
when executed, could lead to unexpected side effects compromising
the security of a system.</p>
<p>When processing JSON-LD documents, links to remote contexts are
typically followed automatically, resulting in the transfer of files
without the explicit request of the user for each one. If remote
contexts are served by third parties, it may allow them to gather
usage patterns or similar information leading to privacy concerns.
Specific implementations, such as the API defined in the
JSON-LD 1.1 Processing Algorithms and API specification [<cite><a class="bibref" href="#bib-JSON-LD11CG-API">JSON-LD11CG-API</a></cite>],
may provide fine-grained mechanisms to control this behavior.</p>
<p>JSON-LD contexts that are loaded from the Web over non-secure connections,
such as HTTP, run the risk of being altered by an attacker such that
they may modify the JSON-LD <a href="#dfn-active-context" class="internalDFN" data-link-type="dfn">active context</a> in a way that
could compromise security. It is advised that any application that
depends on a remote context for mission critical purposes vet and
cache the remote context before allowing the system to use it.</p>
<p>Given that JSON-LD allows the substitution of long IRIs with short terms,
JSON-LD documents may expand considerably when processed and, in the worst case,
the resulting data might consume all of the recipient's resources. Applications
should treat any data with due skepticism.</p>
</dd>
<dt>Interoperability considerations:</dt>
<dd>Not Applicable</dd>
<dt>Published specification:</dt>
<dd>http://www.w3.org/TR/json-ld</dd>
<dt>Applications that use this media type:</dt>
<dd>Any programming environment that requires the exchange of
directed graphs. Implementations of JSON-LD have been created for
JavaScript, Python, Ruby, PHP, and C++.
</dd>
<dt>Additional information:</dt>
<dd>
<dl>
<dt>Magic number(s):</dt>
<dd>Not Applicable</dd>
<dt>File extension(s):</dt>
<dd>.jsonld</dd>
<dt>Macintosh file type code(s):</dt>
<dd>TEXT</dd>
</dl>
</dd>
<dt>Person &amp; email address to contact for further information:</dt>
<dd>Manu Sporny &lt;msporny@digitalbazaar.com&gt;</dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>None</dd>
<dt>Author(s):</dt>
<dd>Manu Sporny, Dave Longley, Gregg Kellogg, Markus Lanthaler, Niklas Lindström</dd>
<dt>Change controller:</dt>
<dd><abbr title="World Wide Web Consortium">W3C</abbr></dd>
</dl>
<p>Fragment identifiers used with <a href="#application-ld-json">application/ld+json</a>
are treated as in RDF syntaxes, as per
<a href="https://www.w3.org/TR/rdf11-concepts/#section-fragID">RDF 1.1 Concepts and Abstract Syntax</a>
[<cite><a class="bibref" href="#bib-RDF11-CONCEPTS">RDF11-CONCEPTS</a></cite>].</p>
</section>
<section id="security" class="appendix" typeof="schema:Chapter" resource="#security" property="schema:hasPart">
<!--OddPage--><h2 id="e-security-considerations"><span class="secno">E. </span>Security Considerations&nbsp;<span class="permalink"><a href="#security" aria-label="Permalink for E. Security Considerations" title="Permalink for E. Security Considerations"><span property="schema:name" content="E. Security Considerations">§</span></a></span></h2>
<div class="ednote"><div role="heading" class="ednote-title marker" id="h-ednote" aria-level="3"><span>Editor's note</span></div><p class="">Consider requirements from <a href="https://w3ctag.github.io/security-questionnaire/">Self-Review Questionnaire: Security and Privacy</a>.</p></div>
<p>See, <a href="#iana-considerations" class="sectionRef sec-ref">section <span class="secno">D.</span> <span class="sec-title">IANA Considerations</span></a></p>
</section>
<section class="appendix informative" id="acknowledgements" typeof="schema:Chapter" resource="#acknowledgements" property="schema:hasPart">
<!--OddPage--><h2 id="f-acknowledgements"><span class="secno">F. </span>Acknowledgements&nbsp;<span class="permalink"><a href="#acknowledgements" aria-label="Permalink for F. Acknowledgements" title="Permalink for F. Acknowledgements"><span property="schema:name" content="F. Acknowledgements">§</span></a></span></h2><p><em>This section is non-normative.</em></p>
<p>The authors would like to extend a deep appreciation and the most sincere
thanks to Mark Birbeck, who contributed foundational concepts
to JSON-LD via his work on RDFj. JSON-LD uses a number of core concepts
introduced in RDFj, such as the context as a mechanism to provide an
environment for interpreting JSON data. Mark had also been very involved in
the work on RDFa as well. RDFj built upon that work. JSON-LD exists
because of the work and ideas he started nearly a decade ago in 2004.</p>
<p>A large amount of thanks goes out to the JSON-LD Community Group
participants who worked through many of the technical issues on the mailing
list and the weekly telecons - of special mention are François Daoust,
Stéphane Corlosquet, Lin Clark, and Zdenko 'Denny' Vrandečić.</p>
<p>The work of David I. Lehn and Mike Johnson are appreciated for
reviewing, and performing several early implementations
of the specification. Thanks also to Ian Davis for this work on RDF/JSON.</p>
<p>Thanks to the following individuals, in order of their first name, for
their input on the specification: Adrian Walker, Alexandre Passant,
Andy Seaborne, Ben Adida, Blaine Cook, Bradley Allen, Brian Peterson,
Bryan Thompson, Conal Tuohy, Dan Brickley, Danny Ayers, Daniel Leja,
Dave Reynolds, David Booth, David I. Lehn, David Wood, Dean Landolt,
Ed Summers, elf Pavlik,
Eric Prud'hommeaux, Erik Wilde, Fabian Christ, Jon A. Frost, Gavin Carothers,
Glenn McDonald, Guus Schreiber, Henri Bergius, Jose María Alvarez Rodríguez,
Ivan Herman, Jack Moffitt, Josh Mandel, KANZAKI Masahide, Kingsley Idehen,
Kuno Woudt, Larry Garfield, Mark Baker, Mark MacGillivray, Marko Rodriguez,
Marios Meimaris, Matt Wuerstl,
Melvin Carvalho, Nathan Rixham, Olivier Grisel, Paolo Ciccarese, Pat Hayes,
Patrick Logan, Paul Kuykendall, Pelle Braendgaard,
Peter Patel-Schneider, Peter Williams, Pierre-Antoine Champin,
Richard Cyganiak, Roy T. Fielding, Sandro Hawke, Simon Grant, Srecko Joksimovic,
Stephane Fellah, Steve Harris, Ted Thibodeau Jr., Thomas Steiner, Tim Bray,
Tom Morris, Tristan King, Sergio Fernández, Werner Wilms, and William Waites.</p>
</section>
<section id="references" class="appendix" typeof="schema:Chapter" resource="#references" property="schema:hasPart"><!--OddPage--><h2 id="g-references"><span class="secno">G. </span>References&nbsp;<span class="permalink"><a href="#references" aria-label="Permalink for G. References" title="Permalink for G. References"><span property="schema:name" content="G. References">§</span></a></span></h2><section id="normative-references" typeof="schema:Chapter" resource="#normative-references" property="schema:hasPart"><h3 id="g-1-normative-references"><span class="secno">G.1 </span>Normative references&nbsp;<span class="permalink"><a href="#normative-references" aria-label="Permalink for G.1 Normative references" title="Permalink for G.1 Normative references"><span property="schema:name" content="G.1 Normative references">§</span></a></span></h3><dl class="bibliography" resource=""><dt id="bib-BCP47">[BCP47]</dt><dd><a href="https://tools.ietf.org/html/bcp47" property="schema:dependencies"><cite>Tags for Identifying Languages</cite></a>. A. Phillips; M. Davis. IETF. September 2009. IETF Best Current Practice. URL: <a href="https://tools.ietf.org/html/bcp47" property="schema:dependencies">https://tools.ietf.org/html/bcp47</a>
</dd><dt id="bib-IANA-URI-SCHEMES">[IANA-URI-SCHEMES]</dt><dd><a href="https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml" property="schema:dependencies"><cite>Uniform Resource Identifier (URI) Schemes</cite></a>. IANA. URL: <a href="https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml" property="schema:dependencies">https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml</a>
</dd><dt id="bib-JSON-LD">[JSON-LD]</dt><dd><a href="https://www.w3.org/TR/json-ld/" property="schema:dependencies"><cite>JSON-LD 1.0</cite></a>. Manu Sporny; Gregg Kellogg; Markus Lanthaler. W3C. 16 January 2014. W3C Recommendation. URL: <a href="https://www.w3.org/TR/json-ld/" property="schema:dependencies">https://www.w3.org/TR/json-ld/</a>
</dd><dt id="bib-JSON-LD11CG-API">[JSON-LD11CG-API]</dt><dd><a href="https://json-ld.org/spec/latest/json-ld-api/" property="schema:dependencies"><cite>JSON-LD 1.1 Processing Algorithms and API</cite></a>. Gregg Kellogg. W3C. CG Draft. URL: <a href="https://json-ld.org/spec/latest/json-ld-api/" property="schema:dependencies">https://json-ld.org/spec/latest/json-ld-api/</a>
</dd><dt id="bib-RDF-CONCEPTS">[RDF-CONCEPTS]</dt><dd><a href="https://www.w3.org/TR/rdf-concepts/" property="schema:dependencies"><cite>Resource Description Framework (RDF): Concepts and Abstract Syntax</cite></a>. Graham Klyne; Jeremy Carroll. W3C. 10 February 2004. W3C Recommendation. URL: <a href="https://www.w3.org/TR/rdf-concepts/" property="schema:dependencies">https://www.w3.org/TR/rdf-concepts/</a>
</dd><dt id="bib-RDF11-CONCEPTS">[RDF11-CONCEPTS]</dt><dd><a href="https://www.w3.org/TR/rdf11-concepts/" property="schema:dependencies"><cite>RDF 1.1 Concepts and Abstract Syntax</cite></a>. Richard Cyganiak; David Wood; Markus Lanthaler. W3C. 25 February 2014. W3C Recommendation. URL: <a href="https://www.w3.org/TR/rdf11-concepts/" property="schema:dependencies">https://www.w3.org/TR/rdf11-concepts/</a>
</dd><dt id="bib-RFC2119">[RFC2119]</dt><dd><a href="https://tools.ietf.org/html/rfc2119" property="schema:dependencies"><cite>Key words for use in RFCs to Indicate Requirement Levels</cite></a>. S. Bradner. IETF. March 1997. Best Current Practice. URL: <a href="https://tools.ietf.org/html/rfc2119" property="schema:dependencies">https://tools.ietf.org/html/rfc2119</a>
</dd><dt id="bib-RFC3986">[RFC3986]</dt><dd><a href="https://tools.ietf.org/html/rfc3986" property="schema:dependencies"><cite>Uniform Resource Identifier (URI): Generic Syntax</cite></a>. T. Berners-Lee; R. Fielding; L. Masinter. IETF. January 2005. Internet Standard. URL: <a href="https://tools.ietf.org/html/rfc3986" property="schema:dependencies">https://tools.ietf.org/html/rfc3986</a>
</dd><dt id="bib-RFC3987">[RFC3987]</dt><dd><a href="https://tools.ietf.org/html/rfc3987" property="schema:dependencies"><cite>Internationalized Resource Identifiers (IRIs)</cite></a>. M. Duerst; M. Suignard. IETF. January 2005. Proposed Standard. URL: <a href="https://tools.ietf.org/html/rfc3987" property="schema:dependencies">https://tools.ietf.org/html/rfc3987</a>
</dd><dt id="bib-RFC5988">[RFC5988]</dt><dd><a href="https://tools.ietf.org/html/rfc5988" property="schema:dependencies"><cite>Web Linking</cite></a>. M. Nottingham. IETF. October 2010. Proposed Standard. URL: <a href="https://tools.ietf.org/html/rfc5988" property="schema:dependencies">https://tools.ietf.org/html/rfc5988</a>
</dd><dt id="bib-RFC7159">[RFC7159]</dt><dd><a href="https://tools.ietf.org/html/rfc7159" property="schema:dependencies"><cite>The JavaScript Object Notation (JSON) Data Interchange Format</cite></a>. T. Bray, Ed.. IETF. March 2014. Proposed Standard. URL: <a href="https://tools.ietf.org/html/rfc7159" property="schema:dependencies">https://tools.ietf.org/html/rfc7159</a>
</dd></dl></section><section id="informative-references" typeof="schema:Chapter" resource="#informative-references" property="schema:hasPart"><h3 id="g-2-informative-references"><span class="secno">G.2 </span>Informative references&nbsp;<span class="permalink"><a href="#informative-references" aria-label="Permalink for G.2 Informative references" title="Permalink for G.2 Informative references"><span property="schema:name" content="G.2 Informative references">§</span></a></span></h3><dl class="bibliography" resource=""><dt id="bib-HTTP11">[HTTP11]</dt><dd><a href="https://tools.ietf.org/html/rfc7230" property="schema:citation"><cite>Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing</cite></a>. R. Fielding, Ed.; J. Reschke, Ed.. IETF. June 2014. Proposed Standard. URL: <a href="https://tools.ietf.org/html/rfc7230" property="schema:citation">https://tools.ietf.org/html/rfc7230</a>
</dd><dt id="bib-JSON-LD-TESTS">[JSON-LD-TESTS]</dt><dd><a href="https://json-ld.org/test-suite/" property="schema:citation"><cite>JSON-LD 1.1 Test Suite</cite></a>. Gregg Kellogg. Linking Data in JSON Community Group. URL: <a href="https://json-ld.org/test-suite/" property="schema:citation">https://json-ld.org/test-suite/</a>
</dd><dt id="bib-JSON-LD11CG">[JSON-LD11CG]</dt><dd><a href="https://json-ld.org/spec/latest/json-ld/" property="schema:citation"><cite>JSON-LD 1.1</cite></a>. Gregg Kellogg. W3C. CG Draft. URL: <a href="https://json-ld.org/spec/latest/json-ld/" property="schema:citation">https://json-ld.org/spec/latest/json-ld/</a>
</dd><dt id="bib-JSON-LD11CG-FRAMING">[JSON-LD11CG-FRAMING]</dt><dd><a href="https://json-ld.org/spec/latest/json-ld-api/" property="schema:citation"><cite>JSON-LD 1.1 Framing</cite></a>. Gregg Kellogg. W3C. CG Draft. URL: <a href="https://json-ld.org/spec/latest/json-ld-api/" property="schema:citation">https://json-ld.org/spec/latest/json-ld-api/</a>
</dd><dt id="bib-ld-glossary">[ld-glossary]</dt><dd><a href="https://www.w3.org/TR/ld-glossary/" property="schema:citation"><cite>Linked Data Glossary</cite></a>. Bernadette Hyland; Ghislain Auguste Atemezing; Michael Pendleton; Biplav Srivastava. W3C. 27 June 2013. W3C Note. URL: <a href="https://www.w3.org/TR/ld-glossary/" property="schema:citation">https://www.w3.org/TR/ld-glossary/</a>
</dd><dt id="bib-LINKED-DATA">[LINKED-DATA]</dt><dd><a href="https://www.w3.org/DesignIssues/LinkedData.html" property="schema:citation"><cite>Linked Data Design Issues</cite></a>. Tim Berners-Lee. W3C. 27 July 2006. W3C-Internal Document. URL: <a href="https://www.w3.org/DesignIssues/LinkedData.html" property="schema:citation">https://www.w3.org/DesignIssues/LinkedData.html</a>
</dd><dt id="bib-MICRODATA">[MICRODATA]</dt><dd><a href="https://www.w3.org/TR/microdata/" property="schema:citation"><cite>HTML Microdata</cite></a>. Charles McCathie Nevile; Dan Brickley. W3C. 10 October 2017. W3C Working Draft. URL: <a href="https://www.w3.org/TR/microdata/" property="schema:citation">https://www.w3.org/TR/microdata/</a>
</dd><dt id="bib-MICROFORMATS">[MICROFORMATS]</dt><dd><a href="http://microformats.org" property="schema:citation"><cite>Microformats</cite></a>. URL: <a href="http://microformats.org" property="schema:citation">http://microformats.org</a>
</dd><dt id="bib-RDF-SCHEMA">[RDF-SCHEMA]</dt><dd><a href="https://www.w3.org/TR/rdf-schema/" property="schema:citation"><cite>RDF Schema 1.1</cite></a>. Dan Brickley; Ramanathan Guha. W3C. 25 February 2014. W3C Recommendation. URL: <a href="https://www.w3.org/TR/rdf-schema/" property="schema:citation">https://www.w3.org/TR/rdf-schema/</a>
</dd><dt id="bib-RDF11-MT">[RDF11-MT]</dt><dd><a href="https://www.w3.org/TR/rdf11-mt/" property="schema:citation"><cite>RDF 1.1 Semantics</cite></a>. Patrick Hayes; Peter Patel-Schneider. W3C. 25 February 2014. W3C Recommendation. URL: <a href="https://www.w3.org/TR/rdf11-mt/" property="schema:citation">https://www.w3.org/TR/rdf11-mt/</a>
</dd><dt id="bib-RDFA-CORE">[RDFA-CORE]</dt><dd><a href="https://www.w3.org/TR/rdfa-core/" property="schema:citation"><cite>RDFa Core 1.1 - Third Edition</cite></a>. Ben Adida; Mark Birbeck; Shane McCarron; Ivan Herman et al. W3C. 17 March 2015. W3C Recommendation. URL: <a href="https://www.w3.org/TR/rdfa-core/" property="schema:citation">https://www.w3.org/TR/rdfa-core/</a>
</dd><dt id="bib-RFC6839">[RFC6839]</dt><dd><a href="https://tools.ietf.org/html/rfc6839" property="schema:citation"><cite>Additional Media Type Structured Syntax Suffixes</cite></a>. T. Hansen; A. Melnikov. IETF. January 2013. Informational. URL: <a href="https://tools.ietf.org/html/rfc6839" property="schema:citation">https://tools.ietf.org/html/rfc6839</a>
</dd><dt id="bib-RFC6906">[RFC6906]</dt><dd><a href="https://tools.ietf.org/html/rfc6906" property="schema:citation"><cite>The 'profile' Link Relation Type</cite></a>. E. Wilde. IETF. March 2013. Informational. URL: <a href="https://tools.ietf.org/html/rfc6906" property="schema:citation">https://tools.ietf.org/html/rfc6906</a>
</dd><dt id="bib-RFC7049">[RFC7049]</dt><dd><a href="https://tools.ietf.org/html/rfc7049" property="schema:citation"><cite>Concise Binary Object Representation (CBOR)</cite></a>. C. Bormann; P. Hoffman. IETF. October 2013. Proposed Standard. URL: <a href="https://tools.ietf.org/html/rfc7049" property="schema:citation">https://tools.ietf.org/html/rfc7049</a>
</dd><dt id="bib-TURTLE">[TURTLE]</dt><dd><a href="https://www.w3.org/TR/turtle/" property="schema:citation"><cite>RDF 1.1 Turtle</cite></a>. Eric Prud'hommeaux; Gavin Carothers. W3C. 25 February 2014. W3C Recommendation. URL: <a href="https://www.w3.org/TR/turtle/" property="schema:citation">https://www.w3.org/TR/turtle/</a>
</dd><dt id="bib-WEBIDL">[WEBIDL]</dt><dd><a href="https://heycam.github.io/webidl/" property="schema:citation"><cite>Web IDL</cite></a>. Cameron McCormack; Boris Zbarsky; Tobie Langel. W3C. 15 December 2016. W3C Editor's Draft. URL: <a href="https://heycam.github.io/webidl/" property="schema:citation">https://heycam.github.io/webidl/</a>
</dd><dt id="bib-YAML">[YAML]</dt><dd><a href="http://yaml.org/spec/1.2/spec.html" property="schema:citation"><cite>YAML Ain’t Markup Language (YAML™) Version 1.2</cite></a>. Oren Ben-Kiki; Clark Evans; Ingy döt Net.1 October 2009. URL: <a href="http://yaml.org/spec/1.2/spec.html" property="schema:citation">http://yaml.org/spec/1.2/spec.html</a>
</dd></dl></section></section><p role="navigation" id="back-to-top"><a href="#toc"><abbr title="Back to Top">↑</abbr></a></p><script src="https://www.w3.org/scripts/TR/2016/fixup.js"></script></body></html>
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{
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{
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{
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{
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{
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{
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"id": "#value-objects",
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{
"id": "https://www.w3.org/",
"publisher": "World Wide Web Consortium"
}
]
}
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