IGSN is theInternational Geo Sample Number https://igsn.github.io/

igsn-1-0-schema.xsd

<!-- saved here as a gist, for reference in case it gets changed or is taken offline -->
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schema.igsn.org/description/1.0" targetNamespace="http://schema.igsn.org/description/1.0" elementFormDefault="qualified" xml:lang="EN" version="1.0">

  <xs:include schemaLocation="include/accessType.xsd"/>
  <xs:include schemaLocation="include/collectionType.xsd"/>
  <xs:include schemaLocation="include/contributorType.xsd"/>
  <xs:include schemaLocation="include/featureType.xsd"/>
  <xs:include schemaLocation="include/geometryType.xsd"/>
  <xs:include schemaLocation="include/identifierType.xsd"/>
  <xs:include schemaLocation="include/materialType.xsd"/>
  <xs:include schemaLocation="include/methodType.xsd"/>
  <xs:include schemaLocation="include/relationType.xsd"/>
  <xs:include schemaLocation="include/resourceType.xsd"/>
  <xs:include schemaLocation="include/sampleType.xsd"/>
  <xs:include schemaLocation="include/sridType.xsd"/>

  <xs:annotation>
    <xs:documentation>
	International Geo Sample Number (IGSN) Metadata Kernel
	Description Schema
	Version 1.0
        November 15, 2015
	W3C XML Schema validated by oXygen XML Editor v17.1
	(c)2011-2016, IGSN e.V.
        info@igsn.org
    </xs:documentation>
  </xs:annotation>

  <xs:element name="resource">
    <xs:annotation>
      <xs:appinfo>IGSN "birth certificate" for a physical sample, associated feature, or collection</xs:appinfo>
    </xs:annotation>
    <xs:complexType>

      <xs:sequence>

        <xs:element name="identifier" minOccurs="1" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(1.) identifier - currently only type=IGSN is supported</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:simpleContent>
              <xs:extension base="xs:string">
                <xs:attribute name="type" type="identifierType" use="required" fixed="IGSN"/>
              </xs:extension>
            </xs:simpleContent>
          </xs:complexType>
        </xs:element> <!-- identifier -->

        <xs:element name="name" minOccurs="1" maxOccurs="1" type="xs:string">
          <xs:annotation>
            <xs:documentation>(2.) name - the collector or contributor's local/field name; not globally unique but typically unique within a submitted set</xs:documentation>
          </xs:annotation>
        </xs:element> <!-- name -->

        <xs:element name="alternateIdentifiers" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(3.) alternateIdentifiers - other formal identifiers for this resource, in addition to the IGSN</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:element name="alternateIdentifier" minOccurs="1" maxOccurs="unbounded">
                <xs:complexType>
                  <xs:simpleContent>
                    <xs:extension base="xs:string">
                      <xs:attribute name="type" type="identifierType" use="optional"/>
                    </xs:extension>
                  </xs:simpleContent>
                </xs:complexType>
              </xs:element> <!-- alternateIdentifiers.alternateIdentifier -->
            </xs:sequence>
          </xs:complexType>
        </xs:element> <!-- alternateIdentifiers -->

        <xs:element name="parentIdentifier" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(4.) parentIdentifier - IGSN of a resource from which this resource derives; note that a sample may have multiple parents</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:simpleContent>
              <xs:extension base="xs:string">
                <xs:attribute name="type" type="identifierType" use="required" fixed="IGSN"/>
              </xs:extension>
            </xs:simpleContent>
          </xs:complexType>
        </xs:element> <!-- parentIdentifier -->

        <xs:element name="collectionIdentifier" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(5.) collectionIdentifier - IGSN of a set of related resources to which this resource belongs</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:simpleContent>
              <xs:extension base="xs:string">
                <xs:attribute name="type" type="identifierType" use="required" fixed="IGSN"/>
              </xs:extension>
            </xs:simpleContent>
          </xs:complexType>
        </xs:element> <!-- collectionIdentifier -->

        <xs:element name="relatedIdentifiers" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(6.) relatedIdentifiers - formal identifiers of resources related to this resource, including the scheme and relationtype for each; here we link to a field expedition, journal article, etc.</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:element name="relatedIdentifier" minOccurs="1" maxOccurs="unbounded">
                <xs:complexType>
                  <xs:simpleContent>
                    <xs:extension base="xs:string">
                      <xs:attribute name="type" type="identifierType" use="required"/>
                      <xs:attribute name="relationType" type="relationType" use="required"/>
                    </xs:extension>
                  </xs:simpleContent>
                </xs:complexType>
              </xs:element> <!-- relatedIdentifiers.relatedIdentifier -->
            </xs:sequence>
          </xs:complexType>
        </xs:element> <!-- relatedIdentifiers -->

        <xs:element name="description" minOccurs="0" maxOccurs="1" type="xs:string">
          <xs:annotation>
            <xs:documentation>(7.) description - free-text description of this resource</xs:documentation>
          </xs:annotation>
        </xs:element> <!-- description -->

        <xs:element name="registrant" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(8.) registrant (cf. datacite:publisher) - agent (person or organization) that registered the IGSN for this resource</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:element name="identifier" minOccurs="0" maxOccurs="1">
                <xs:complexType>
                  <xs:simpleContent>
                    <xs:extension base="xs:string">
                      <xs:attribute name="type" type="identifierType" use="required"/>
                    </xs:extension>
                  </xs:simpleContent>
                </xs:complexType>
              </xs:element> <!-- identifier -->
              <xs:element name="name" type="xs:string" minOccurs="1" maxOccurs="1"/>
              <xs:element name="affiliation" minOccurs="0" maxOccurs="1">
                <xs:complexType>
                  <xs:sequence>
                    <xs:element name="identifier" minOccurs="0" maxOccurs="1">
                      <xs:complexType>
                        <xs:simpleContent>
                          <xs:extension base="xs:string">
                            <xs:attribute name="type" type="identifierType" use="required"/>
                          </xs:extension>
                        </xs:simpleContent>
                      </xs:complexType>
                    </xs:element> <!-- registrant.affiliation.identifier -->
                    <xs:element name="name">
                      <xs:simpleType>
                        <xs:restriction base="xs:string"/>
                      </xs:simpleType>
                    </xs:element> <!-- registrant.affiliation.name -->
                  </xs:sequence>
                </xs:complexType>
              </xs:element> <!-- registrant.affiliation -->
            </xs:sequence>
          </xs:complexType>
        </xs:element> <!-- registrant -->

        <xs:element name="collector" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(9.) collector (cf. datacite:creator) - agent (person or organization) that created or extracted this physical specimen; typically only used for samples</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:element name="identifier" minOccurs="0" maxOccurs="1">
                <xs:complexType>
                  <xs:simpleContent>
                    <xs:extension base="xs:string">
                      <xs:attribute name="type" type="identifierType" use="required"/>
                    </xs:extension>
                  </xs:simpleContent>
                </xs:complexType>
              </xs:element> <!-- collector.identifier -->
              <xs:element name="name" type="xs:string" minOccurs="1" maxOccurs="1"/>
              <xs:element name="affiliation" minOccurs="0" maxOccurs="1">
                <xs:complexType>
                  <xs:sequence>
                    <xs:element name="identifier" minOccurs="0">
                      <xs:complexType>
                        <xs:simpleContent>
                          <xs:extension base="xs:string">
                            <xs:attribute name="type" type="identifierType" use="required"/>
                          </xs:extension>
                        </xs:simpleContent>
                      </xs:complexType>
                    </xs:element> <!-- collector.affiliation.identifier -->
                    <xs:element name="name">
                      <xs:simpleType>
                        <xs:restriction base="xs:string"/>
                      </xs:simpleType>
                    </xs:element> <!-- collector.affiliation.name -->
                  </xs:sequence>
                </xs:complexType>
              </xs:element> <!-- collector.affiliation -->
            </xs:sequence>
          </xs:complexType>
        </xs:element> <!-- collector -->

        <xs:element name="contributors" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(10.) contributors - agents (persons or organizations) that contributed to this resource; investigator, funder, technician, etc.</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:element name="contributor" minOccurs="1" maxOccurs="unbounded">
                <xs:complexType>
                  <xs:sequence>
                    <xs:element name="identifier" minOccurs="0" maxOccurs="1">
                      <xs:complexType>
                        <xs:simpleContent>
                          <xs:extension base="xs:string">
                            <xs:attribute name="type" type="identifierType" use="required"/>
                          </xs:extension>
                        </xs:simpleContent>
                      </xs:complexType>
                    </xs:element> <!-- contributors.contributor.identifier -->
                    <xs:element name="name">
                      <xs:simpleType>
                        <xs:restriction base="xs:string"/>
                      </xs:simpleType>
                    </xs:element> <!-- contributors.contributor.name -->
                  </xs:sequence>
                  <xs:attribute name="type" type="contributorType" use="required"/>
                </xs:complexType>
              </xs:element> <!-- contributors.contributor -->
            </xs:sequence>
          </xs:complexType>
        </xs:element> <!-- contributors -->

        <xs:element name="geoLocations" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(11.) geoLocations (geometry cf. odm2:samplingfeaturegeotype|toponym) - location of the resource, expressed as 2-D geometry and/or place name(s)</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:element name="geoLocation" minOccurs="1" maxOccurs="unbounded">
                <xs:complexType>
                  <xs:choice>
                    <xs:element name="geometry" minOccurs="1" maxOccurs="1">
                      <xs:complexType>
                        <xs:simpleContent>
                          <xs:extension base="xs:string">
                            <xs:attribute name="type" type="geometryType" use="required"/>
                            <xs:attribute name="sridType" type="sridType" use="optional"/>
                          </xs:extension>
                        </xs:simpleContent>
                      </xs:complexType>
                    </xs:element> <!-- geometry -->
                    <xs:element name="toponym" minOccurs="1" maxOccurs="1">
                      <xs:complexType>
                        <xs:sequence>
                          <xs:element name="identifier" minOccurs="0" maxOccurs="1">
                            <xs:complexType>
                              <xs:simpleContent>
                                <xs:extension base="xs:string">
                                  <xs:attribute name="type" type="identifierType" use="required"/>
                                </xs:extension>
                              </xs:simpleContent>
                            </xs:complexType>
                          </xs:element> <!-- toponym.identifier -->
                          <xs:element name="name" minOccurs="0" maxOccurs="1" type="xs:string">
                          </xs:element> <!-- toponym.name -->
                        </xs:sequence>
                      </xs:complexType>
                    </xs:element> <!-- toponym -->
                  </xs:choice>
                </xs:complexType>
              </xs:element> <!-- geoLocation -->
            </xs:sequence>
          </xs:complexType>
        </xs:element> <!-- geoLocations -->

        <xs:element name="resourceTypes" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(12.) resourceTypes - broad classification of this resource; must provide 1 term from ODM2 vocabulary (specimentype or samplingfeaturetype) plus 0-N additional terms from any vocabulary</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:element name="resourceType" minOccurs="1" maxOccurs="1">
                <xs:simpleType>
                  <xs:union memberTypes="featureType sampleType collectionType"/>
                </xs:simpleType>
              </xs:element> <!-- resourceTypes.resourceType -->
              <xs:element name="alternateResourceTypes" minOccurs="0" maxOccurs="1">
                <xs:complexType>
                  <xs:sequence>
                    <xs:element name="alternateResourceType" minOccurs="1" maxOccurs="unbounded">
                      <xs:simpleType>
                        <xs:union memberTypes="xs:string xs:anyURI"/>
                      </xs:simpleType>
                    </xs:element> <!-- resourceTypes.alternateResourceTypes.alternateResourceType -->
                  </xs:sequence>
                </xs:complexType>
              </xs:element> <!-- resourceTypes.alternateResourceTypes -->
            </xs:sequence>
          </xs:complexType>
        </xs:element> <!-- resourceTypes -->

        <xs:element name="materials" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(13.) materials - physical medium of this resource; must provide 1 term from ODM2 vocabulary (medium) plus 0-N additional terms from any vocabulary; typically only used for samples</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:element name="material" minOccurs="1" maxOccurs="unbounded" type="materialType"/>

              <xs:element name="alternateMaterials" minOccurs="0" maxOccurs="1">
                <xs:complexType>
                  <xs:sequence>
                    <xs:element name="alternateMaterial" minOccurs="1" maxOccurs="unbounded">
                      <xs:simpleType>
                        <xs:union memberTypes="xs:string xs:anyURI"/>
                      </xs:simpleType>
                    </xs:element> <!-- materials.alternateMaterials.alternateMaterial -->
                  </xs:sequence>
                </xs:complexType>
              </xs:element> <!-- materials.alternateMaterials -->
            </xs:sequence>
          </xs:complexType>
        </xs:element> <!-- materials -->

        <xs:element name="collectionMethods" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(14.) collectionMethods - broad classification of instrument/technique used to create or extract this resource - must provide 1 term from SESAR (collectionMethod) vocabulary plus 0-N additional terms from any vocabulary; typically only used for samples</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:element name="collectionMethod" minOccurs="1" maxOccurs="1" type="methodType"/>
              <xs:element name="alternateCollectionMethods" minOccurs="0" maxOccurs="1">
                <xs:complexType>
                  <xs:sequence>
                    <xs:element name="alternateCollectionMethod" minOccurs="1" maxOccurs="unbounded">
                      <xs:simpleType>
                        <xs:union memberTypes="xs:string xs:anyURI"/>
                      </xs:simpleType>
                    </xs:element> <!-- collectionMethods.alternateCollectionMethods.alternateCollectionMethod -->
                  </xs:sequence>
                </xs:complexType>
              </xs:element> <!-- collectionMethod.alternateCollectionMethods -->
            </xs:sequence>
          </xs:complexType>
        </xs:element> <!-- collectionMethod -->

        <xs:element name="collectionTime" minOccurs="0" maxOccurs="1" type="xs:dateTime">
          <xs:annotation>
            <xs:documentation>(15.) collectionTime - time at which this resource was created or extracted; typically only used for samples</xs:documentation>
          </xs:annotation>
        </xs:element> <!-- collectionTime -->

        <xs:element name="sampleAccess" minOccurs="1" maxOccurs="1" type="accessType">
          <xs:annotation>
            <xs:documentation>(16.) sampleAccess - indicates whether this resource is available for reuse beyond the original contributor; typically only used for samples</xs:documentation>
          </xs:annotation>
        </xs:element> <!-- sampleAccess -->

        <xs:element name="supplementalMetadata" minOccurs="0" maxOccurs="1">
          <xs:annotation>
            <xs:documentation>(17.) supplementalMetadata - link to any additional documentation, as structured metadata or free text</xs:documentation>
          </xs:annotation>
          <xs:complexType>
            <xs:sequence>
              <xs:element name="record" minOccurs="1" maxOccurs="unbounded" type="xs:anyURI"/>
            </xs:sequence>
          </xs:complexType>
        </xs:element> <!-- supplementalMetadata -->

      </xs:sequence>

      <xs:attribute name="type" type="resourceType" use="required"/>

    </xs:complexType>
  </xs:element> <!-- resource -->

</xs:schema>