Extracts URLs from HTML attributes with type of URI.

XPath selector - All URLs from HTML attributes

-- When fed to XPath selects all URLs from HTML document
-- from within HTML attributes designated to hold URL
-- One-line version
"//a/@href | //applet/@codebase | //area/@href | //base/@href | //blockquote/@cite | //body/@background | //del/@cite | //form/@action | //frame/@src | //frame/@longdesc | //head/@profile | //iframe/@longdesc | //iframe/@url | //img/@longdesc | //img/@usemap | //input/@src | //input/@usemap | //ins/@cite | //object/@classid | //object/@codebase | //object/@data | //object/@usemap | //q/@cite | //img/@src | //link/@href | //source/@src | //embed/@src | //script/@src | //audio/@src | //button/@formaction | //command/@icon | //html/@manifest | //input/@formaction | //video/@poster | //video/@src"

-- Multi-line version (readable)
"//a/@href 
| //applet/@codebase 
| //area/@href 
| //base/@href 
| //blockquote/@cite 
| //body/@background 
| //del/@cite 
| //form/@action 
| //frame/@src 
| //frame/@longdesc 
| //head/@profile 
| //iframe/@longdesc 
| //iframe/@url 
| //img/@longdesc 
| //img/@usemap 
| //input/@src
| //input/@usemap 
| //ins/@cite 
| //object/@classid 
| //object/@codebase 
| //object/@data 
| //object/@usemap 
| //q/@cite 
| //img/@src
| //link/@href 
| //source/@src 
| //embed/@src
| //script/@src
| //audio/@src 
| //button/@formaction 
| //command/@icon 
| //html/@manifest 
| //input/@formaction 
| //video/@poster 
| //video/@src"