Cleaned merge conflicts
authorcharles
Wed, 19 Jun 2013 10:32:41 +0200
changeset 48 572b8e4323a4
parent 47 de8bb5a09666 (current diff)
parent 44 8b419617ca70 (diff)
child 49 bf09b34876a3
Cleaned merge conflicts
Changed text for user agent non-normative guidance - https://www.w3.org/Bugs/Public/show_bug.cgi?id=22188
Update status for Last Call
longdesc1/longdesc.html
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/longdesc1/longdesc-diff-fpwd-wd0606.html	Wed Jun 19 10:32:41 2013 +0200
@@ -0,0 +1,3762 @@
+
+<html dir="ltr" lang="en" xmlns="http://www.w3.org/1999/xhtml">
+<head>
+<meta content="text/html; charset=utf-8" http-equiv="content-type" />
+<title>HTML Image Description Extension</title>
+
+<style type="text/css">
+/*<![CDATA[*/
+      .issue {border: dashed red 2px; background-color: #ffd}
+      .example, .example code {color: #404; background-color:#eee}
+      .example::before {float:left;
+        margin-top: -.2em;
+        background-color: white;
+            display: block;
+            border: 1px solid black;
+            color: #404;
+            padding: 2px;
+        content: "Example: (non-normative)"}
+      
+      .example:first-child {padding-top:1em}
+      
+        /* Make these stand-out more... */
+        .externalDFN {
+            font-style: italic;
+            background-color: #fff9d6;
+        }
+        /* Switch statement */
+        dl.switch dt::before {
+            content: "↪ ";
+            margin-left: 1em;
+        }
+        /* Better spacing around various lists (implied paragraph children) */
+        ol > li, section:not(#toc) ul > li, section dl > dt {
+            margin: 1em 0;
+        }
+        /* domintro styling */
+        dl.domintro {
+            background-color: rgb(221, 255, 221);
+            padding: 1em 0.5em 1em 2em;
+            clear: both;
+        }
+        dl.domintro dt {
+            color: black;
+        }
+        dl.domintro > dd {
+            color: green;
+        }
+        dl.domintro::before {
+            float: right;
+            background-color: white;
+            display: block;
+            border: 2px solid black;
+            color: green;
+            margin-top: -20px;
+            padding: 2px;
+            content: "This box is non-normative.";
+        }
+        /* Fancy table stuff */
+        table {
+            border-collapse: collapse;
+        }
+        thead tr {
+            border-bottom: 2px solid black;
+        }
+        tbody tr:not(:last-child) {
+            border-bottom: 1px solid black;
+        }
+        td {
+            border-left: 1px solid black;
+            padding: 4px;
+        }
+/*****************************************************************
+ * ReSpec 3 CSS
+ * Robin Berjon - http://berjon.com/
+ *****************************************************************/
+/* --- INLINES --- */
+em.rfc2119 { 
+    text-transform:     lowercase;
+    font-variant:       small-caps;
+    font-style:         normal;
+    color:              #900;
+}
+h1 acronym, h2 acronym, h3 acronym, h4 acronym, h5 acronym, h6 acronym, a acronym,
+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;
+}
+cite .bibref {
+    font-style: normal;
+}
+code {
+    color:  #ff4500;
+}
+/* --- TOC --- */
+.toc a, .tof a {
+    text-decoration:    none;
+}
+a .secno, a .figno {
+    color:  #000;
+}
+ul.tof, ol.tof {
+    list-style: none outside none;
+}
+.caption {
+    margin-top: 0.5em;
+    font-style:   italic;
+}
+
+/* --- DL --- */
+.section dd > p:first-child {
+    margin-top: 0;
+}
+.section dd > p:last-child {
+    margin-bottom: 0;
+}
+.section dd {
+    margin-bottom:  1em;
+}
+.section dl.attrs dd, .section dl.eldef dd {
+    margin-bottom:  0;
+}
+/* --- ISSUES/NOTES --- */
+div.note-title {
+    padding-right:  1em;
+    min-width: 7.5em;
+    color: #b9ab2d;
+}
+div.note-title { color: #52e052; }
+div.note-title span {
+    text-transform: uppercase;
+}
+div.note {
+    margin-top: 1em;
+    margin-bottom: 1em;
+}
+.note > p:first-child { margin-top: 0 }
+.note {
+    padding: .5em;
+    border-left-width: .5em;
+    border-left-style: solid;
+}
+div.note {
+    padding: 0.5em;
+    margin: 1em 0;
+    position: relative;
+    clear: both;
+}
+span.note { padding: .1em .5em .15em; }
+.note {
+    border-color: #52e052;
+    background: #e9fbe9;
+}
+
+pre.idl {
+    border-top: 1px solid #90b8de;
+    border-bottom: 1px solid #90b8de;
+    padding:    1em;
+    line-height:    120%;
+}
+pre.idl::before {
+    content:    "WebIDL";
+    display:    block;
+    width:      8ex;
+    background: #90b8de;
+    color:  #fff;
+    font-family:    initial;
+    padding:    3px;
+    font-weight:    bold;
+    margin: -1em 0 1em -1em;
+}
+.idlType {
+    color:  #ff4500;
+    font-weight:    bold;
+    text-decoration:    none;
+}
+/*.idlInterface*/
+.idlInterfaceID, .idlDictionaryID, .idlCallbackID, .idlEnumID {
+    font-weight:    bold;
+    color:  #005a9c;
+}
+.idlSuperclass {
+    font-style: italic;
+    color:  #005a9c;
+}
+/*.idlAttribute*/
+.idlAttrType, .idlFieldType, .idlMemberType {
+    color:  #005a9c;
+}
+.idlAttrName, .idlFieldName, .idlMemberName {
+    color:  #ff4500;
+}
+.idlAttrName a, .idlFieldName a, .idlMemberName a {
+    color:  #ff4500;
+    border-bottom:  1px dotted #ff4500;
+    text-decoration: none;
+}
+
+.extAttr {
+    color:  #666;
+}
+/*.idlConst*/
+.idlConstType {
+    color:  #005a9c;
+}
+.idlConstName {
+    color:  #ff4500;
+}
+.idlConstName a {
+    color:  #ff4500;
+    border-bottom:  1px dotted #ff4500;
+    text-decoration: none;
+}
+
+.idlImplements a {
+    font-weight:    bold;
+}
+dl.attributes, dl.methods, dl.constants, dl.fields, dl.dictionary-members {
+    margin-left:    2em;
+}
+.attributes dt, .methods dt, .constants dt, .fields dt, .dictionary-members dt {
+    font-weight:    normal;
+}
+.attributes dt code, .methods dt code, .constants dt code, .fields dt code, .dictionary-members dt code {
+    font-weight:    bold;
+    color:  #000;
+    font-family:    monospace;
+}
+.attributes dt code, .fields dt code, .dictionary-members dt code {
+    background:  #ffffd2;
+}
+.attributes dt .idlAttrType code, .fields dt .idlFieldType code, .dictionary-members dt .idlMemberType code {
+    color:  #005a9c;
+    background:  transparent;
+    font-family:    inherit;
+    font-weight:    normal;
+    font-style: italic;
+}
+
+.attributes dd, .methods dd, .constants dd, .fields dd, .dictionary-members dd {
+    margin-bottom:  1em;
+}
+
+/*]]>*/
+</style>
+<link href="https://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css" /><!--[if lt IE 9]><script src='undefined://www.w3.org/2008/site/js/html5shiv.js'></script><![endif]-->
+<style type='text/css'>
+.diff-old-a {
+  font-size: smaller;
+  color: red;
+}
+
+.diff-new { background-color: yellow; }
+.diff-chg { background-color: lime; }
+.diff-new:before,
+.diff-new:after
+    { content: "\2191" }
+.diff-chg:before, .diff-chg:after
+    { content: "\2195" }
+.diff-old { text-decoration: line-through; background-color: #FBB; }
+.diff-old:before,
+.diff-old:after
+    { content: "\2193" }
+:focus { border: thin red solid}
+</style>
+</head>
+<body>
+<div class="head">
+<p>
+<a href="http://www.w3.org/">
+<img alt="W3C" src="http://www.w3.org/Icons/w3c_home" height="48" width="72" />
+</a>
+</p>
+<h1 class="title" id="title">
+<del class="diff-old">HTML
+</del>
+<ins class="diff-chg">HTML5
+</ins>
+Image
+Description
+Extension
+</h1>
+<h2 id="w3c-working-draft-20-september-2012">
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+<del class="diff-old">First
+Public
+Working
+</del>
+<ins class="diff-chg">Editors'
+</ins>
+Draft
+<del class="diff-old">12
+March
+</del>
+<ins class="diff-chg">17
+May
+</ins>
+2013
+</h2>
+<dl>
+<dt>
+<del class="diff-old">This
+version:
+http://www.w3.org/TR/2013/WD-html-longdesc-20130312/
+</del>
+Latest
+published
+version:
+</dt>
+<dd>
+<del class="diff-old">http://www.w3.org/TR/html-longdesc/
+</del>
+<a href="http://www.w3.org/TR/HTML-longdesc">
+<ins class="diff-chg">http://www.w3.org/TR/HTML-longdesc
+</ins>
+</a>
+</dd>
+<dt>
+Latest
+editor's
+draft:
+</dt>
+<dd>
+<a href="http://dvcs.w3.org/hg/html-proposals/raw-file/default/longdesc1/longdesc.html">
+http://dvcs.w3.org/hg/html-proposals/raw-file/default/longdesc1/longdesc.html
+</a>
+</dd>
+<dt>
+<del class="diff-old">Editor:
+</del>
+<ins class="diff-chg">Editors:
+</ins>
+</dt>
+<dd>
+<a href="mailto:[email protected]">
+Charles
+<del class="diff-old">McCathie
+</del>
+<ins class="diff-chg">(McCathie)
+</ins>
+Nevile
+</a>,
+<del class="diff-old">Яндекс.
+</del>
+<a href="http://www.yandex.ru">
+<ins class="diff-chg">Яндекс
+</ins></a><ins class="diff-chg">
+—
+</ins><a href="http://yandex.com"><ins class="diff-chg">
+Yandex
+</ins>
+</a>
+</dd>
+</dl>
+<p class="copyright">
+<a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">
+Copyright
+</a>

+<del class="diff-old">2013
+</del>
+<ins class="diff-chg">2012-2013
+</ins>
+<a href="http://www.w3.org/">
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+</a>
+<sup>

+</sup>
+(
+<a href="http://www.csail.mit.edu/">
+<abbr title="Massachusetts Institute of Technology">
+MIT
+</abbr>
+</a>,
+<a href="http://www.ercim.eu/">
+<abbr title="European Research Consortium for Informatics and Mathematics">
+ERCIM
+</abbr>
+</a>,
+<a href="http://www.keio.ac.jp/">
+Keio
+</a>,
+<a href="http://ev.buaa.edu.cn/">
+Beihang
+</a>
+),
+All
+Rights
+Reserved.
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+<a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">
+liability
+</a>,
+<a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">
+trademark
+</a>
+and
+<a href="http://www.w3.org/Consortium/Legal/copyright-documents">
+document
+use
+</a>
+rules
+apply.
+</p>
+<hr />
+</div>
+<section class="introductory" id="abstract">
+<h2>
+Abstract
+</h2>
+<p>
+This
+specification
+defines
+a
+<code>
+longdesc
+</code>
+attribute
+to
+link
+extended
+descriptions
+with
+images
+in
+HTML5-based
+content.
+</p>
+</section>
+<section class="introductory" id="sotd">
+<h2>
+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="http://www.w3.org/TR/">
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+technical
+reports
+index
+</a>
+at
+http://www.w3.org/TR/.
+</em>
+</p>
+<p>
+This
+document
+<del class="diff-old">was
+developed
+through
+the
+HTML
+Accessibility
+Task
+Force
+,
+and
+</del>
+is
+<del class="diff-old">published
+by
+</del>
+<ins class="diff-chg">an
+editors'
+draft
+proposed
+to
+</ins>
+the
+HTML
+Working
+Group
+<del class="diff-old">with
+approval
+by
+the
+Protocols
+and
+Formats
+</del>
+<ins class="diff-chg">Accessibility
+Task
+Force
+for
+publication
+as
+a
+</ins>
+Working
+<del class="diff-old">Group
+.
+Bugs
+can
+</del>
+<ins class="diff-chg">Draft,
+which
+would
+</ins>
+be
+<del class="diff-old">filed
+directly
+into
+</del>
+<ins class="diff-chg">proposed
+as
+</ins>
+the
+<del class="diff-old">W3C
+Bug
+tracker
+</del>
+<ins class="diff-chg">basis
+</ins>
+for
+<del class="diff-old">this
+specification
+.
+This
+document
+was
+published
+by
+the
+HTML
+Working
+Group
+as
+</del>
+a
+<ins class="diff-new">Last
+Call
+Working
+Draft.
+Following
+feedback
+on
+the
+</ins><a href="http://www.w3.org/TR/2013/WD-html-longdesc-20130312/">
+First
+Public
+Working
+<del class="diff-old">Draft.
+This
+document
+is
+intended
+to
+become
+</del>
+<ins class="diff-chg">Draft
+</ins></a>,
+a
+<del class="diff-old">W3C
+Recommendation.
+</del>
+<ins class="diff-chg">number
+of
+</ins><a href="https://www.w3.org/Bugs/Public/buglist.cgi?product=HTML%20WG&amp;amp;component=HTML%20Image%20Description%20Extension"><ins class="diff-chg">
+bugs
+were
+raised
+and
+resolved
+</ins></a>.
+If
+you
+wish
+to
+make
+comments
+regarding
+this
+document,
+please
+send
+them
+to
+<a href="mailto:[email protected]">
[email protected]
+</a>
+(
+<a href="mailto:[email protected]?subject=subscribe">
+subscribe
+</a>,
+<a href="http://lists.w3.org/Archives/Public/public-html-a11y/">
+archives
+</a>
+).
+All
+<del class="diff-old">comments
+are
+</del>
+<ins class="diff-chg">feedback
+is
+</ins>
+welcome.
+<ins class="diff-new">Bugs
+can
+also
+be
+filed
+directly
+into
+the
+</ins><a href= "https://www.w3.org/Bugs/Public/buglist.cgi?product=HTML%20WG&amp;amp;component=HTML%20Image%20Description%20Extension"><ins class="diff-new">
+W3C
+Bug
+tracker
+for
+this
+specification
+</ins></a>.</p><p><ins class="diff-new">
+This
+document
+is
+intended
+to
+become
+a
+</ins><abbr title="World Wide Web Consortium"><ins class="diff-new">
+W3C
+</ins></abbr><ins class="diff-new">
+Recommendation,
+either
+on
+its
+own
+or
+merged
+into
+an
+HTML
+Recommendation.
+</ins>
+</p>
+<p>
+Publication
+as
+a
+<del class="diff-old">First
+Public
+</del>
+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 href="http://www.w3.org/Consortium/Patent-Policy-20040205/">
+5
+February
+2004
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+Patent
+Policy
+</a>.
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+maintains
+a
+<a href="http://www.w3.org/2004/01/pp-impl/42538/status" 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="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">
+Essential
+Claim(s)
+</a>
+must
+disclose
+the
+information
+in
+accordance
+with
+<a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">
+section
+6
+of
+the
+<abbr title="World Wide Web Consortium">
+W3C
+</abbr>
+Patent
+Policy
+</a>.
+</p>
+</section>
+<section id="toc">
+<h2 class="introductory">
+Table
+of
+Contents
+</h2>
+<ul class="toc">
+<li class="tocline">
+<a class="tocxref" href="#intro">
+Introduction
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#conformance">
+<span class="secno">
+1.
+</span>
+Conformance
+</a>
+<ul class="toc">
+<li class="tocline">
+<a class="tocxref" href="#dependencies">
+<span class="secno">
+1.1
+</span>
+Dependencies
+</a>
+</li>
+</ul>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#UCnR">
+<span class="secno">
+2.
+</span>
+Use
+Cases
+and
+Requirements
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#longdesc">
+<span class="secno">
+3.
+</span>
+The
+<code>
+longdesc
+</code>
+Attribute
+</a>
+<ul class="toc">
+<li class="tocline">
+<a class="tocxref" href="#extensions-to-the-element-interface">
+<span class="secno">
+3.1
+</span>
+Extensions
+to
+the
+<code>
+HTMLImageElement
+</code>
+interface
+</a>
+<ul class="toc">
+<li class="tocline">
+<a class="tocxref" href="#attributes">
+<span class="secno">
+3.1.1
+</span>
+<del class="diff-old">Attributes
+</del>
+<ins class="diff-chg">Attribute
+</ins>
+</a>
+</li>
+</ul>
+</li>
+</ul>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#acknowledgements">
+<span class="secno">
+A.
+</span>
+Acknowledgements
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#references">
+<span class="secno">
+B.
+</span>
+References
+</a>
+<ul class="toc">
+<li class="tocline">
+<a class="tocxref" href="#normative-references">
+<span class="secno">
+B.1
+</span>
+Normative
+references
+</a>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#informative-references">
+<span class="secno">
+<ins class="diff-new">B.2
+</ins></span><ins class="diff-new">
+Informative
+references
+</ins></a></li>
+</ul>
+</li>
+<li class="tocline">
+<a class="tocxref" href="#changes">
+<span class="secno">
+<ins class="diff-new">C.
+</ins></span><ins class="diff-new">
+Change
+History
+</ins></a></li>
+</ul>
+</section>
+<section id="intro" class="introductory">
+<h1>
+Introduction
+</h1>
+<p>
+HTML
+4
+provided
+a
+<code>
+longdesc
+</code>
+attribute
+for
+the
+<code>
+img
+</code>
+element.
+This
+enabled
+a
+machine-discoverable
+description
+of
+an
+image
+to
+be
+linked
+to
+the
+image.
+This
+extension
+specification
+defines
+the
+same
+functionality
+for
+HTML5-based
+content.
+</p>
+<del class="diff-old">      &lt;!-- The description is somewhere on the same page as the image --&gt;
+&lt;img src="http://example.com/graph1" alt="(The trend is for drinks to get sweeter)" title="Figure One" &gt;
+&lt;!-- The description is a page on its own --&gt;
+</del>
+<pre class="example">
+<code><br /><br />&lt;!-- The description is somewhere on the same page as the image --&gt;
+<ins class="diff-chg">&lt;img src="http://example.com/graph1" alt="(Drinks are getting sweeter)" title="Figure One" <strong>longdesc="#graph1Explained"</strong>&gt;
+&lt;!-- The description is a page on its own --&gt;
+</ins>
+&lt;img src="figure1" alt="figure 1" <strong>longdesc="http://example.com/desc1"</strong>&gt;
+<del class="diff-old">&lt;!-- The description is one of several within an external page --&gt;
+&lt;img
+src="ExampleImage"
+alt="example"
+longdesc="http://example.com/descs#item3"
+&gt;
+</del>
+<ins class="diff-chg">
+&lt;!-- The description is one of several within an external page --&gt;
+&lt;img src="ExampleImage" alt="example" <strong>longdesc="http://example.com/descs#item3"</strong>&gt;
+&lt;!-- The description is included in a data: URI --&gt;
+&lt;img src="logo" alt="W3C" <strong>longdesc="data:text/html;charset=utf-8;,%3C!DOCTYPE%20html%3E%3Chtml%3E%3Chead%3E
+%3Ctitle%3EDescription%20of%20the%20W3C%20Logo%3C/title%3E%3C/head%3E%3Cbody%3E%3Cp%3EA%20blue%20capital%20letter<br />%20%22W%22%20with%20kerning%20so%20it%20touches%20a%20blue%203%2C%20followed%20by%20a%20black%20shadow%20<br />of%20a%20white%20capital%20letter%20C%20all%20on%20a%20white%20background%3C/body%3E%3C/html%3E"</strong>&gt;</code>
+</ins>
+</pre>
+</section>
+<section id="conformance">
+<h2>
+<span class="secno">
+1.
+</span>
+Conformance
+</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>
+The
+key
+words
+<em title="must" class="rfc2119">
+must
+</em>,
+<em title="should" class="rfc2119">
+should
+</em>,
+and
+<em title="may" class="rfc2119">
+may
+</em>
+in
+this
+specification
+are
+to
+be
+interpreted
+as
+described
+in
+[
+<cite>
+<a class="bibref" href="#bib-RFC2119">
+RFC2119
+</a>
+</cite>
+].
+</p>
+<section id="dependencies">
+<h3>
+<span class="secno">
+1.1
+</span>
+Dependencies
+<ins class="diff-new">and
+definitions
+</ins>
+</h3>
+<p>
+The
+IDL
+fragments
+in
+this
+specification
+<em title="must" class="rfc2119">
+must
+</em>
+be
+interpreted
+as
+required
+for
+conforming
+IDL
+fragments,
+as
+described
+in
+the
+Web
+IDL
+specification.
+[
+<cite>
+<a class="bibref" href="#bib-WEBIDL">
+WEBIDL
+</a>
+</cite>
+]
+</p>
+<p>
+<del class="diff-old">Some
+of
+the
+</del>
+<ins class="diff-chg">The
+</ins>
+terms
+<ins class="diff-new">"
+</ins><a href="http://www.w3.org/TR/HTML5/#valid-url-potentially-surrounded-by-spaces"><ins class="diff-new">
+valid
+non-empty
+URL
+potentially
+surrounded
+by
+spaces
+</ins></a><ins class="diff-new">
+",
+"
+</ins><a href="http://www.w3.org/TR/HTML5/#hyperlink"><ins class="diff-new">
+hyperlink"
+</ins></a>,<ins class="diff-new">
+and
+"
+</ins><a href="http://www.w3.org/TR/HTML5/#reflect"><ins class="diff-new">
+reflect
+</ins></a><ins class="diff-new">
+",
+</ins>
+used
+in
+this
+specification
+are
+defined
+in
+[
+<cite>
+<del class="diff-old">DOM4
+],
+[
+</del>
+<a class="bibref" href="#bib-HTML5">
+HTML5
+</a>
+</cite>
+<del class="diff-old">]
+</del>
+<ins class="diff-chg">].
+</ins></p><p><ins class="diff-chg">
+This
+document
+does
+not
+define
+the
+term
+"accessible"
+nor
+accessibility,
+but
+uses
+them
+with
+the
+sense
+they
+have
+in
+[
+</ins><a href="#bib-WCAG"><ins class="diff-chg">
+WCAG
+</ins>
+</a>
+<del class="diff-old">.
+</del>
+<ins class="diff-chg">]
+</ins>
+</p>
+</section>
+</section>
+<section id="UCnR">
+<h2>
+<span class="secno">
+2.
+</span>
+Use
+Cases
+and
+Requirements
+</h2>
+<p>
+There
+are
+many
+ways
+users
+can
+successfully
+interact
+with
+content
+even
+if
+they
+cannot
+see,
+or
+see
+well,
+images
+included
+in
+that
+content.
+The
+<code>
+alt
+</code>
+attribute
+is
+designed
+to
+ensure
+that
+for
+everyday
+work,
+a
+user
+has
+enough
+information
+to
+replace
+an
+image,
+and
+often
+this
+is
+more
+helpful
+than
+a
+detailed
+description
+of
+every
+image.
+The
+<code>
+longdesc
+</code>
+attribute
+is
+designed
+to
+complement
+this
+functionality,
+to
+meet
+the
+following
+use
+cases.
+</p>
+<h3>
+Use
+Cases
+</h3>
+<dl>
+<dt>
+<del class="diff-old">Describing
+</del>
+<ins class="diff-chg">Identifying
+</ins>
+a
+well-known
+image
+</dt>
+</dl>
+<dl>
+<dd>
+There
+are
+many
+well-known
+images
+which
+are
+widely
+reproduced
+<del class="diff-old">-
+Mona
+Lisa,
+Washington
+crossing
+some
+river,
+the
+Da
+Vinci
+picture
+of
+the
+guy
+in
+a
+square
+</del>
+and
+<del class="diff-old">a
+circle,
+Gerníka,
+</del>
+<ins class="diff-chg">well
+known.
+In
+some
+cases,
+such
+as
+"Mona
+Lisa",
+"Gerníka",
+</ins>
+Cubbin's
+"Lost",
+Leunig's
+"ramming
+the
+<del class="diff-old">shears".
+While
+</del>
+<ins class="diff-chg">shears",
+the
+most
+effective
+way
+to
+refer
+identify
+an
+image
+to
+another
+person
+is
+by
+the
+creator,
+title,
+and
+similar
+information
+that
+would
+be
+found
+in
+a
+catalogue.
+But
+</ins>
+different
+people
+know
+the
+images
+by
+different
+titles,
+and
+some
+images
+have
+no
+widely
+known
+<del class="diff-old">titles,
+visually
+recognising
+the
+</del>
+<ins class="diff-chg">titles.
+Identifying
+an
+</ins>
+image
+is
+often
+an
+important
+part
+of
+framing
+a
+discussion.
+Where
+the
+image
+itself
+cannot
+be
+seen,
+a
+description
+can
+often
+be
+used
+to
+offer
+<ins class="diff-new">easier
+recognition
+than
+</ins>
+the
+<del class="diff-old">same
+recognition.
+</del>
+<ins class="diff-chg">cataloguing
+information,
+for
+example
+"Washington
+crossing
+some
+river,
+standing
+heroically
+in
+the
+boat,
+while
+soldiers
+do
+the
+hard
+work",
+or
+"the
+Da
+Vinci
+picture
+of
+the
+guy
+in
+a
+square
+and
+a
+circle".
+</ins>
+</dd>
+<dd>
+<em>
+Requires
+</em>:
+Discoverability
+</dd>
+<dd>
+<em>
+Helped
+by
+</em>:
+Inline,
+Reuse
+</dd>
+<dt>
+Describing
+a
+complex
+diagram
+</dt>
+<dd>
+In
+many
+environments
+diagrams
+are
+used
+to
+explain
+a
+concept
+or
+transmit
+information
+efficiently.
+Where
+a
+user
+has
+a
+reduced
+ability
+to
+see
+the
+image
+(poor
+contrast
+vision
+and
+other
+conditions
+are
+as
+relevant
+here
+as
+a
+complete
+lack
+of
+vision),
+a
+description
+can
+enable
+that
+user
+to
+understand
+the
+information
+being
+presented
+</dd>
+<dd>
+<em>
+Requires
+</em>:
+Structured
+Markup,
+Inline,
+Reuse,
+Simple
+Return
+</dd>
+<dt>
+Teaching
+Accessible
+Development
+</dt>
+<dd>
+In
+many
+environments
+producing
+content
+that
+is
+accessible
+to
+users
+regardless
+of
+disability
+is
+a
+legal
+and/or
+market
+requirement.
+</dd>
+<dd>
+<em>
+Requires
+</em>:
+Maintenance,
+Backwards
+compatibility
+</dd>
+<dt>
+A
+self-describing
+artistic
+work
+</dt>
+<dd>
+For
+many
+pages
+the
+visual
+design
+of
+the
+page
+is
+an
+important
+part
+of
+the
+message
+it
+conveys
+to
+a
+fully-sighted
+user,
+but
+the
+author
+would
+like
+to
+convey
+as
+much
+of
+that
+design
+as
+possible
+to
+a
+user
+with
+low
+or
+no
+vision
+available.
+</dd>
+<dd>
+<em>
+Requires
+</em>:
+No
+visual
+encumbrance,
+Structured
+Markup
+</dd>
+<dd>
+<em>
+Helped
+by
+</em>:
+Reuse,
+Simple
+Return
+</dd>
+<dt>
+Referring
+to
+an
+existing
+description
+</dt>
+<dd>
+Many
+well-known
+images
+are
+already
+described
+by
+other
+sources.
+The
+copyright
+on
+those
+sources
+may
+not
+be
+compatible
+with
+re-publishing
+the
+description,
+but
+there
+is
+little
+value
+in
+making
+a
+new
+one.
+</dd>
+<dd>
+<em>
+Requires
+</em>:
+Reuse,
+Structured
+Markup,
+Simple
+Return,
+Optional
+Consumption
+</dd>
+<dd>
+<em>
+Helped
+by
+</em>:
+No
+Visual
+Encumbrance
+</dd>
+<dt>
+Linking
+to
+a
+description
+included
+within
+a
+page
+</dt>
+<dd>
+In
+some
+cases
+an
+image
+already
+has
+a
+description
+included
+within
+a
+page.
+Making
+the
+linkage
+explicit
+can
+provide
+further
+clarity
+for
+a
+user
+navigating
+the
+page
+who
+is
+not
+able
+to
+interpret
+the
+default
+layout,
+e.g.
+because
+they
+have
+forced
+a
+re-layout
+of
+the
+page
+elements,
+or
+because
+they
+do
+not
+see
+the
+default
+visual
+relationship
+between
+the
+element
+and
+its
+description.
+</dd>
+<dd>
+This
+practice
+also
+enables
+description
+to
+be
+provided
+for
+all
+users.
+</dd>
+<dd>
+By
+keeping
+the
+association
+clear
+the
+content
+maintainer
+can
+more
+easily
+check
+that
+the
+description
+and
+link
+are
+actually
+correct.
+</dd>
+<dd>
+<em>
+Requires
+</em>:
+Inline,
+Simple
+Return,
+Structured
+Markup,
+Optional
+Consumption
+</dd>
+<dt>
+<ins class="diff-chg">Localising
+descriptions
+</ins></dt><dd><ins class="diff-chg">
+When
+content
+is
+localised
+to
+multiple
+languages,
+it
+is
+important
+that
+metadata
+intended
+for
+human
+consumption,
+such
+as
+image
+descriptions,
+can
+be
+readily
+localised.
+</ins></dd><dd><em><ins class="diff-chg">
+Helped
+by
+</ins></em>:<ins class="diff-chg">
+Structured
+Markup,
+Reuse,
+Maintenance.
+</ins>
+</dd>
+</dl>
+<h3>
+Requirements
+<ins class="diff-new">for
+an
+Image
+Description
+functionality
+</ins>
+</h3>
+<dl>
+<dt>
+No
+visual
+encumbrance
+</dt>
+<dd>
+It
+<em class="rfc2119">
+must
+</em>
+be
+possible
+to
+provide
+a
+description
+for
+an
+image
+without
+any
+visual
+encumbrance
+on
+the
+page.
+</dd>
+<dt>
+Structured
+Markup
+</dt>
+<dd>
+It
+<em class="rfc2119">
+must
+</em>
+be
+possible
+to
+include
+rich
+markup
+(e.g.
+HTML5)
+in
+the
+description
+of
+the
+image.
+</dd>
+<dt>
+Inline
+</dt>
+<dd>
+It
+<em class="rfc2119">
+must
+</em>
+be
+possible
+to
+associate
+a
+description
+in
+the
+body
+of
+a
+page
+with
+an
+image
+in
+that
+page.
+</dd>
+<dt>
+Reuse
+</dt>
+<dd>
+It
+<em class="rfc2119">
+must
+</em>
+be
+possible
+to
+re-use
+a
+single
+description
+for
+multiple
+occurrences
+of
+an
+image.
+</dd>
+<dt>
+Maintenance
+</dt>
+<dd>
+It
+<em class="rfc2119">
+must
+</em>
+be
+simple
+to
+maintain
+a
+library
+of
+images
+and
+descriptions
+for
+dynamic
+assembly,
+or
+dis-assembly
+and
+re-assembly,
+of
+content.
+</dd>
+<dt>
+Discoverability
+</dt>
+<dd class="rfc2119">
+It
+<em class="rfc2119">
+must
+</em>
+be
+simple
+for
+a
+user
+agent
+to
+automatically
+discover
+a
+description
+provided
+for
+a
+given
+image.
+</dd>
+<dd>
+A
+user
+<em class="rfc2119">
+should
+</em>
+be
+able
+to
+determine
+that
+there
+is
+a
+description
+available
+for
+a
+given
+image.
+</dd>
+<dt>
+Optional
+consumption
+</dt>
+<dd>
+A
+user
+<em class="rfc2119">
+must
+</em>
+be
+able
+to
+choose
+not
+to
+read
+the
+long
+description
+of
+a
+given
+image.
+</dd>
+<dt>
+Simple
+return
+</dt>
+<dd>
+A
+user
+<em class="rfc2119">
+must
+</em>
+be
+able
+to
+return
+from
+the
+description
+to
+the
+image.
+</dd>
+<dt>
+Backwards
+Compatibility
+</dt>
+<dd>
+It
+<em class="rfc2119">
+should
+</em>
+be
+possible
+to
+use
+existing
+tools
+and
+techniques
+to
+associate
+an
+image
+with
+its
+description.
+</dd>
+</dl>
+</section>
+<section id="longdesc">
+<h2>
+3.
+The
+<code>
+longdesc
+</code>
+attribute
+</h2>
+<h3>
+<ins class="diff-new">3.0
+Implementation
+</ins></h3><h4><ins class="diff-new">
+3.0.1
+Authors
+and
+Conformance
+checkers
+</ins></h4>
+<section id="parsing">
+<p class="rfc2119">
+<ins class="diff-new">Zero
+or
+one
+</ins><code><ins class="diff-new">
+longdesc
+</ins></code><ins class="diff-new">
+attributes
+</ins><em class="rfc2119"><ins class="diff-new">
+may
+</ins></em><ins class="diff-new">
+be
+added
+to
+any
+</ins><code><ins class="diff-new">
+img
+</ins></code><ins class="diff-new">
+element.
+</ins></p>
+<p>
+The
+<code>
+longdesc
+</code>
+attribute
+<em class="rfc2119">
+must
+</em>
+contain
+a
+<a href="http://dev.w3.org/html5/spec/urls.html#valid-url-potentially-surrounded-by-spaces">
+valid
+<ins class="diff-new">non-empty
+</ins>
+URL
+potentially
+surrounded
+by
+spaces
+</a>.
+The
+URL
+is
+a
+<a href="http://dev.w3.org/html5/spec/links.html#hyperlink">
+hyperlink
+</a>
+to
+a
+description
+of
+the
+image
+that
+its
+parent
+<code>
+img
+</code>
+element
+represents.
+</p>
+<p>
+<ins class="diff-new">The
+linked
+description
+</ins><em class="rfc2119"><ins class="diff-new">
+should
+</ins></em><ins class="diff-new">
+be
+a
+broadly
+accessible
+format.
+(For
+example,
+a
+link
+to
+another
+version
+of
+the
+image
+is
+almost
+certainly
+not
+a
+useful
+description,
+and
+plain
+text
+is
+an
+extremely
+limiting
+format).
+</ins></p><div class="note"><p><em><ins class="diff-new">
+This
+section
+is
+informative
+</ins></em></p><p><ins class="diff-new">
+Best
+practices
+for
+checking
+descriptions
+of
+images
+are
+beyond
+the
+scope
+of
+this
+document,
+but
+there
+are
+many
+resources
+available.
+For&#160;
+further
+guidance
+tool
+developers
+can
+consult
+e.g.
+[
+</ins><a href="#bib-ATAGB3"><ins class="diff-new">
+ATAGB3
+</ins></a><ins class="diff-new">
+].
+</ins><span class="issue"><ins class="diff-new">
+ISSUE:
+This
+doesn't
+seem
+a
+great
+reference
+-
+is
+there
+anything
+better?
+This
+is
+tracked
+in
+</ins><a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=21501"><ins class="diff-new">
+bug
+21501
+</ins></a><ins class="diff-new">
+and
+its
+dependent
+bugs.
+Unless
+a
+proposal
+is
+made
+and
+accepted
+for
+improvement
+this
+bug
+will
+simply
+be
+closed
+after
+Last
+Call.
+</ins></span></p></div><h4><ins class="diff-new">
+3.0.2
+Authors
+</ins></h4><p>
+Authors
+<em class="rfc2119">
+should
+</em>
+put
+descriptions
+within
+an
+element
+which
+is
+the
+target
+of
+a
+fragment
+link
+(e.g.
+<code>
+longdesc="example.html#description"
+</code>
+)
+if
+a
+description
+is
+only
+part
+of
+the
+target
+document.
+</p>
+<div class="note">
+<p>
+<em>
+<ins class="diff-new">This
+section
+is
+informative
+</ins></em></p><p><ins class="diff-new">
+Best
+practices
+for
+full
+descriptions
+of
+images
+are
+beyond
+the
+scope
+of
+this
+document,
+but
+there
+are
+many
+resources
+available.
+</ins></p><p><ins class="diff-new">
+This
+document
+does
+not
+define
+the
+term
+"accessible"
+nor
+accessibility.
+For
+further
+guidance
+on
+making
+an
+accessible
+document,
+authors
+can
+consult
+e.g.
+[
+</ins><a href="#bib-WCAG2"><ins class="diff-new">
+WCAG
+</ins></a><ins class="diff-new">
+].
+</ins></p></div><h4><ins class="diff-new">
+3.0.3
+User
+Agents
+</ins></h4>
+<p>
+<ins class="diff-new">If
+the
+</ins><code><ins class="diff-new">
+longdesc
+</ins></code><ins class="diff-new">
+value
+is
+valid,
+</ins>
+User
+agents
+<em class="rfc2119">
+<del class="diff-old">should
+</del>
+<ins class="diff-chg">must
+</ins>
+</em>
+make
+the
+link
+available
+to
+all
+users
+through
+the
+regular
+user
+<del class="diff-old">interface.
+</del>
+<ins class="diff-chg">interface(s).&#160;
+</ins>
+</p>
+<p>
+<ins class="diff-new">If
+the
+</ins><code><ins class="diff-new">
+longdesc
+</ins></code><ins class="diff-new">
+value
+is
+valid,
+</ins>
+User
+agents
+<em class="rfc2119">
+<del class="diff-old">should
+</del>
+<ins class="diff-chg">must
+</ins>
+</em>
+expose
+the
+link
+to
+relevant
+APIs,
+especially
+accessibility-oriented
+APIs.
+</p>
+<p>
+User
+agents
+<em class="rfc2119">
+should
+</em>
+enable
+users
+to
+discover
+when
+images
+in
+a
+page
+contain
+a
+long
+description.
+</p>
+<del class="diff-old">If
+a
+longdesc
+attribute
+has
+invalid
+content,
+user
+agents
+may
+make
+that
+content
+available
+to
+the
+user.
+This
+is
+because
+a
+common
+authoring
+error
+is
+to
+include
+the
+text
+of
+a
+description,
+instead
+of
+the
+URL
+of
+a
+description,
+as
+the
+value
+of
+the
+attribute.
+</del>
+<div class="note">
+<p>
+<em>
+This
+section
+is
+informative
+</em>
+</p>
+<p>
+<del class="diff-old">Best
+</del>
+<ins class="diff-chg">Complete
+documentation
+of
+best
+</ins>
+practices
+for
+<del class="diff-old">full
+descriptions
+of
+images
+are
+</del>
+<ins class="diff-chg">implementation
+is
+</ins>
+beyond
+the
+scope
+of
+this
+<del class="diff-old">document,
+but
+there
+</del>
+<ins class="diff-chg">document.
+However
+the
+following
+notes
+</ins>
+are
+<del class="diff-old">many
+resources
+available.
+</del>
+<ins class="diff-chg">offered
+to
+help
+repair
+a
+common
+authoring
+mistake
+and
+avoid
+a
+common
+user
+agent
+mistake.
+</ins>
+</p>
+<p>
+<del class="diff-old">Best
+practices
+for
+implementation
+are
+beyond
+</del>
+<ins class="diff-chg">One
+of
+</ins>
+the
+<del class="diff-old">scope
+</del>
+<ins class="diff-chg">most
+common
+mistakes
+authors
+make
+that
+is
+easily
+repaired
+by
+user
+agents
+is
+to
+use
+a
+description,
+instead
+</ins>
+of
+<ins class="diff-new">a
+URL
+that
+links
+to
+a
+description.
+This
+means
+there
+is
+often
+plain
+text
+description
+in
+the
+content
+of
+an
+invalid
+longdesc
+attribute.
+Converting
+such
+attributes
+to
+data
+URLs
+is
+a
+simple
+repair
+strategy
+that
+can
+help
+recover
+from
+cases
+where
+authors
+have
+made
+</ins>
+this
+<del class="diff-old">document.
+</del>
+<ins class="diff-chg">mistake.
+</ins></p><p>
+Since
+some
+images
+with
+long
+description
+are
+also
+normal
+link
+content,
+it
+is
+important
+for
+implementations
+to
+ensure
+that
+users
+can
+activate
+both
+behaviours.
+Likewise,
+it
+is
+generally
+helpful
+when
+the
+behaviour
+for
+finding,
+reading,
+and
+returning
+from
+a
+long
+description
+to
+the
+image
+described
+is
+a
+consistent
+experience.
+</p>
+<p>
+<ins class="diff-new">Obviously,
+it
+is
+important
+that
+access
+to
+the
+long
+description
+is
+accessible
+to
+users.
+Further
+information
+on
+how
+to
+do
+this
+can
+be
+found
+in
+[
+</ins><a href="#bib-UAAG"><ins class="diff-new">
+UAAG
+</ins></a><ins class="diff-new">
+].
+</ins></p>
+</div>
+</section>
+<section id="extensions-to-the-element-interface">
+<h3>
+<span class="secno">
+3.1
+</span>
+Extension
+to
+the
+<code>
+<a title="element" class="externalDFN" data-spec="HTML5">
+HTMLImageElement
+</a>
+</code>
+interface
+</h3>
+<del class="diff-old">        partial interface &lt;span
+class="idlInterfaceID"&gt;HTMLImageElement {
+ &lt;span
+class="idlAttrName"&gt;&lt;a
+href="#widl-Element-longdesc"&gt;longdesc
+};
+</del>
+<pre class="idl">
+<span class="idlInterface" id="idl-def-Element">partial interface <span class="idlInterfaceID">HTMLImageElement</span> {
+<span class="idlAttribute">             attribute <span class="idlAttrType"><a>DOMStringa></span> <span class="idlAttrName"><a href="#widl-Element-longdesc">longdesc</a></span>;</span>
+<ins class="diff-chg">};</span>
+</ins>
+</pre>
+<section id="attributes">
+<h4>
+<span class="secno">
+3.1.1
+</span>
+Attribute
+</h4>
+<dl class="attributes">
+<dt id="widl-Element-longdesc">
+<code>
+longdesc
+</code>
+of
+type
+<span class="idlAttrType">
+<a>
+DOMString
+</a>
+</span>
+</dt>
+<dd>
+<p class="rfc2119">
+The
+<dfn id="dfn-dom-element-longdesc">
+<code>
+longdesc
+</code>
+</dfn>
+IDL
+attribute
+<em class="rfc2119">
+must
+</em>
+be
+a
+valid
+non-empty
+URL
+potentially
+surrounded
+by
+spaces.
+It
+represents
+a
+hyperlink
+to
+a
+detailed
+description
+of
+the
+image
+its
+parent
+<code>
+<a title="element" class="externalDFN" data-spec="DOM4">
+HTMLImageElement
+</a>
+</code>
+represents.
+</p>
+</dd>
+<dd>
+<p>
+<ins class="diff-new">The
+</ins><code><ins class="diff-new">
+longdesc
+</ins></code><ins class="diff-new">
+IDL
+attribute
+</ins><em class="rfc2119"><ins class="diff-new">
+must
+</ins></em><a href="http://www.w3.org/TR/html5/infrastructure.html#reflect"><ins class="diff-new">
+reflect
+</ins></a><ins class="diff-new">
+the
+HTML
+content
+attribute
+</ins><code><ins class="diff-new">
+longdesc
+</ins></code>.</p></dd><dd>
+<dl class="domintro">
+<dt>
+<var>
+image
+</var>.
+<code title="dom-Element-innerHTML">
+longdesc
+</code>
+[
+=
+<var>
+value
+</var>
+]
+</dt>
+<dd>
+<p>
+Returns
+a
+DOMString
+that
+represents
+the
+attribute's
+contents.
+</p>
+<p>
+Can
+be
+set,
+to
+replace
+the
+contents
+of
+the
+attribute
+with
+the
+given
+string.
+</p>
+</dd>
+</dl>
+</dd>
+</dl>
+<pre class="example">
+<del class="diff-old">//Make
+the
+first
+internal
+longdesc
+reference
+absolute
+var
+baseURL
+=
+document.location.origin
++
+document.location.pathname
+var
+someImage
+=
+document.querySelector('img[longdesc^=#]');
+someImage.longdesc
+=
+baseURL
++
+someImage.longdesc;
+</del>
+<code>//Make the first internal longdesc reference absolute
+<ins class="diff-chg">
+var baseURL = document.location.origin + document.location.pathname
+var someImage = document.querySelector('img[longdesc^=#]');
+someImage.longdesc = baseURL + someImage.longdesc;</code>
+</ins>
+</pre>
+<pre class="example">
+<del class="diff-old">//Open
+new
+windows
+for
+each
+longdesc
+found
+var
+describedImages
+=
+document.querySelectorAll('img[longdesc]');
+for
+(i
+in
+describedImages)
+{
+if
+(i.
+longdesc
+)
+//there
+are
+a
+couple
+of
+extra
+things
+matched
+window.open(i.
+longdesc
+);
+}
+</del>
+<code>//Open new windows for each longdesc found
+<ins class="diff-chg">
+var describedImages = document.querySelectorAll('img[longdesc]');
+for (i in describedImages) {
+  if (i.<strong>longdesc</strong>)
+    window.open(i.<strong>longdesc</strong>);
+}</code>
+</ins>
+</pre>
+<pre class="example">
+<code>//Tries to repair errors where the longdesc isn't a URI
+<ins class="diff-new">
+var describedImages = document.querySelectorAll('img[longdesc]');
+for (i in describedImages) {
+  if (i.longdesc &amp;&amp; !(validURL(i.longdesc)) { //assumes some URL validating function
+    var theData = encodeURIComponent(i.longdesc);
+    i.longdesc = "data:text/plain;charset=";
+    i.longdesc += document.charset;
+    i.longdesc += theData;
+  }
+}</code>
+</ins></pre>
+</section>
+</section>
+<section class="appendix" id="acknowledgements">
+<h2>
+<span class="secno">
+A.
+</span>
+Acknowledgements
+</h2>
+<p>
+Thanks
+to
+the
+HTML
+Working
+group
+of
+the
+late
+1990s
+for
+the
+original
+specification
+of
+longdesc,
+<ins class="diff-new">to
+those
+who
+have
+implemented
+it
+in
+various
+kinds
+of
+software,
+</ins>
+and
+to
+many
+many
+people
+involved
+with
+the
+development
+of
+HTML5
+(including
+but
+not
+limited
+to
+those
+who
+discussed
+"ISSUE-30"
+in
+the
+HTML
+Working
+Group,
+the
+Protocols
+and
+Formats
+Working
+Group,
+the
+W3C
+Advisory
+Board,
+and
+around
+countless
+dinner
+tables,
+coffee
+breaks,
+and
+elsewhere)
+for
+the
+<ins class="diff-new">ideas,
+</ins>
+discussions
+and
+contributions
+that
+led
+to
+<ins class="diff-new">the
+initial
+draft
+of
+</ins>
+this
+specification.
+With
+the
+exception
+of
+Laura
+Carlson,
+who
+did
+far
+more
+very
+valuable
+work
+than
+it
+took
+me
+to
+produce
+this
+specification,
+I
+haven't
+named
+them:
+the
+list
+might
+be
+larger
+than
+the
+content
+of
+the
+specification.
+</p>
+<p>
+<ins class="diff-new">For
+specific
+comments
+and
+suggestions
+that
+led
+to
+improvements
+over
+successive
+drafts
+of
+this
+specification,
+thanks
+to
+the
+W3C's
+HTML
+Accessibility
+Task
+Force,
+the
+W3C
+Internationalisation
+Working
+Group,
+and
+to
+Jonathan
+Avila,
+Robin
+Berjon,
+James
+Craig,
+Steve
+Faulkner,
+John
+Foliot,
+Geoff
+Freed,
+Richard
+Ishida,
+Anne
+van
+Kesteren,
+David
+MacDonald,
+Chris
+Mills,
+Jay
+Munro,
+Devarshi
+Pant,
+Leif
+Halvard
+Silli,
+Mathew
+Turvey
+and
+Boris
+Zbarsky.
+Any
+errors
+are
+despite,
+not
+as
+a
+result
+of,
+their
+efforts.
+</ins></p>
+</section>
+<section class="appendix" id="references">
+<h2>
+<span class="secno">
+B.
+</span>
+References
+</h2>
+<section id="normative-references">
+<h3>
+<span class="secno">
+B.1
+</span>
+Normative
+references
+</h3>
+<dl class="bibliography">
+<del class="diff-old">[DOM4]
+Anne
+van
+Kesteren;
+Aryeh
+Gregor;
+Lachlan
+Hunt;
+Ms2ger.
+DOM4
+.
+6
+December
+2012.
+W3C
+Working
+Draft.
+URL:
+http://www.w3.org/TR/2012/WD-dom-20121206
+</del>
+<dt id="bib-HTML5">
+[HTML5]
+</dt>
+<dd>
+Robin
+Berjon
+et.
+al.,
+eds.
+<a href="http://www.w3.org/TR/html5">
+<cite>
+HTML5.
+</cite>
+</a>
+W3C
+Working
+Draft.
+(Work
+in
+progress.)
+URL:
+<a href="http://www.w3.org/TR/html5">
+http://www.w3.org/TR/html5
+</a>
+</dd>
+<dt id="bib-RFC2119">
+[RFC2119]
+</dt>
+<dd>
+S.
+Bradner.
+<a href="http://www.ietf.org/rfc/rfc2119.txt">
+<cite>
+Key
+words
+for
+use
+in
+RFCs
+to
+Indicate
+Requirement
+Levels.
+</cite>
+</a>
+March
+1997.
+Internet
+RFC
+2119.
+URL:
+<a href="http://www.ietf.org/rfc/rfc2119.txt">
+http://www.ietf.org/rfc/rfc2119.txt
+</a>
+</dd>
+<dt id="bib-WEBIDL">
+[WEBIDL]
+</dt>
+<dd>
+Cameron
+McCormack.
+<a href="http://www.w3.org/TR/2011/WD-WebIDL-20110927/">
+<cite>
+Web
+IDL.
+</cite>
+</a>
+27
+September
+2011.
+W3C
+Working
+Draft.
+(Work
+in
+progress.)
+URL:
+<a href="http://www.w3.org/TR/2011/WD-WebIDL-20110927/">
+http://www.w3.org/TR/2011/WD-WebIDL-20110927/
+</a>
+</dd>
+<del class="diff-old">[XML10]
+</del>
+</dl>
+</section>
+<section id="informative-references">
+<h3>
+<span class="secno">
+<ins class="diff-chg">B.2
+</ins></span><ins class="diff-chg">
+Informative
+references
+</ins></h3><dl class="bibliography"><dt id="bib-ATAGB3"><ins class="diff-chg">
+[ATAGB3]
+</ins>
+</dt>
+<dd>
+<del class="diff-old">C.
+M.
+Sperberg-McQueen
+et
+al.
+</del>
+<ins class="diff-chg">Jutta
+Treviranus
+et.
+al.,
+eds.
+</ins><a href="http://www.w3.org/TR/ATAG20-TECHS/#principle_b3">
+<cite>
+<del class="diff-old">Extensible
+Markup
+Language
+(XML)
+1.0
+(Fifth
+Edition)
+</del>
+<ins class="diff-chg">Implementing
+ATAG
+2.0
+</ins>
+</cite>
+<del class="diff-old">.
+26
+November
+</del>
+</a>,
+<ins class="diff-chg">Principle
+B3
+"Authors
+must
+be
+supported
+in
+improving
+the
+accessibility
+of
+existing
+content"
+October
+2011.
+W3C
+Working
+Draft.
+URL:
+</ins><a href="http://www.w3.org/TR/ATAG20-TECHS/#principle_b3"><ins class="diff-chg">
+http://www.w3.org/TR/ATAG20-TECHS/#principle_b3
+</ins></a></dd><dt id="bib-WCAG2"><ins class="diff-chg">
+[WCAG]
+</ins></dt><dd><ins class="diff-chg">
+Ben
+Caldwell
+et.
+al.,
+eds.
+</ins><a href="http://www.w3.org/TR/2008/REC-WCAG20-20081211/"><cite><ins class="diff-chg">
+Web
+Content
+Accessibility
+Guidelines
+2.0
+</ins></cite></a>,<ins class="diff-chg">
+December
+</ins>
+2008.
+W3C
+Recommendation.
+URL:
+<del class="diff-old">http://www.w3.org/TR/2008/REC-xml-20081126/
+</del>
+<a href="http://www.w3.org/TR/2008/REC-WCAG20-20081211/">
+<ins class="diff-chg">http://www.w3.org/TR/2008/REC-WCAG20-20081211/
+</ins></a></dd><dt id="bib-UAAG"><ins class="diff-chg">
+[UAAG]
+</ins></dt><dd><ins class="diff-chg">
+Ian
+Jacobs
+et.
+al.,
+eds.
+</ins><a href="http://www.w3.org/TR/2002/REC-UAAG10-20021217/"><cite><ins class="diff-chg">
+User
+Agent
+Accessibility
+Guidelines
+2.0
+</ins></cite></a>,<ins class="diff-chg">
+December
+2002.
+W3C
+Recommendation.
+URL:
+</ins><a href="http://www.w3.org/TR/2002/REC-UAAG10-20021217/"><ins class="diff-chg">
+http://www.w3.org/TR/2002/REC-UAAG10-20021217/
+</ins></a>.<ins class="diff-chg">
+A
+draft
+for
+a
+version
+2.0
+is
+available
+at
+</ins><a href="http://www.w3.org/TR/UAAG20/"><ins class="diff-chg">
+http://www.w3.org/TR/UAAG20/
+</ins>
+</a>
+</dd>
+</dl>
+</section>
+<section class="appendix" id="changes">
+<h2>
+<span class="secno">
+<ins class="diff-new">C.
+</ins></span><ins class="diff-new">
+Change
+History
+</ins></h2><p><ins class="diff-new">
+(This
+section
+is
+not
+normative)
+</ins></p><p><ins class="diff-new">
+Since
+the
+</ins><a href="http://www.w3.org/TR/2013/WD-html-longdesc-20130312/"><ins class="diff-new">
+First
+Public
+Working
+Draft
+</ins></a><ins class="diff-new">
+substantive
+changes
+include:
+</ins></p><ul><li><ins class="diff-new">
+Added
+a
+requirement
+that
+the
+destination
+of
+a
+</ins><code><ins class="diff-new">
+longdesc
+</ins></code><em class="rfc2119"><ins class="diff-new">
+should
+</ins></em><ins class="diff-new">
+be
+"accessible".
+</ins></li><li><ins class="diff-new">
+The
+requirement
+to
+present
+content
+through
+the
+standard
+User
+Interace
+was
+changed
+from
+</ins><em class="rfc2119"><ins class="diff-new">
+should
+</ins></em><ins class="diff-new">
+to
+</ins><em class="rfc2119"><ins class="diff-new">
+must
+</ins></em>.</li><li><ins class="diff-new">
+The
+requirement
+to
+present
+content
+through
+the
+standard
+User
+Interace
+was
+narrowed
+to
+apply
+only
+to
+valid
+values
+of
+</ins><code><ins class="diff-new">
+longdesc
+</ins></code>.</li><li><ins class="diff-new">
+The
+requirement
+to
+present
+content
+through
+the
+Accessibiltiy
+APIs
+was
+changed
+from
+</ins><em class="rfc2119"><ins class="diff-new">
+should
+</ins></em><ins class="diff-new">
+to
+</ins><em class="rfc2119"><ins class="diff-new">
+must
+</ins></em>.</li><li><ins class="diff-new">
+The
+requirement
+to
+present
+content
+through
+the
+Accessibility
+APIs
+was
+narrowed
+to
+apply
+only
+to
+valid
+values
+of
+</ins><code><ins class="diff-new">
+longdesc
+</ins></code>.</li><li><ins class="diff-new">
+The
+IDL
+attribute
+</ins><code><ins class="diff-new">
+longdesc
+</ins></code><ins class="diff-new">
+was
+changed
+to
+</ins><a href="http://www.w3.org/TR/html5/infrastructure.html#reflect"><ins class="diff-new">
+reflect
+</ins></a><ins class="diff-new">
+the
+HTML
+content
+attribute
+</ins><code><ins class="diff-new">
+longdesc
+</ins></code>.</li></ul><p><ins class="diff-new">
+Editorial
+changes
+include:
+</ins></p><ul><li><ins class="diff-new">
+Clarifying
+that
+the
+document
+does
+not
+define
+"accessible",
+except
+that
+it
+is
+used
+in
+the
+sense
+that
+it
+is
+used
+in
+[
+</ins><a href="#bib-WCAG2"><ins class="diff-new">
+WCAG
+</ins></a><ins class="diff-new">
+].
+</ins></li><li><ins class="diff-new">
+Sectioning
+requirements
+according
+to
+whom
+they
+apply.
+</ins></li><li><ins class="diff-new">
+Removed
+the
+statement
+that
+User
+Agents
+</ins><em title="may" class="rfc2119"><ins class="diff-new">
+may
+</ins></em><ins class="diff-new">
+present
+descriptions
+which
+are
+erroneously
+included
+in
+the
+content
+instead
+of
+a
+link.
+</ins></li><li><ins class="diff-new">
+Added
+more
+examples
+</ins></li></ul></section>
+</section>
+</section>
+
--- a/longdesc1/longdesc.html	Sat Jun 01 17:07:17 2013 +0200
+++ b/longdesc1/longdesc.html	Wed Jun 19 10:32:41 2013 +0200
@@ -1,13 +1,12 @@
-<!DOCTYPE html>
<html dir="ltr" lang="en">
  <head>
    <meta content="text/html; charset=UTF-8" http-equiv="content-type">
    <title>HTML Image Description Extension</title>
    <style>
      .issue {border: dashed red 2px; background-color: #ffd}
      .example, .example code {color: #404; background-color:#eee}
      .example::before {float:left;
        margin-top: -.2em;
        background-color: white;
            display: block;
            border: 1px solid black;
            color: #404;
            padding: 2px;
        content: "Example: (non-normative)"}
      
      .example:first-child {padding-top:1em}
      
        /* Make these stand-out more... */
        .externalDFN {
            font-style: italic;
            background-color: #fff9d6;
        }
        /* Switch statement */
        dl.switch dt::before {
            content: "↪ ";
            margin-left: 1em;
        }
        /* Better spacing around various lists (implied paragraph children) */
        ol > li, section:not(#toc) ul > li, section dl > dt {
            margin: 1em 0;
        }
        /* domintro styling */
        dl.domintro {
            background-color: rgb(221, 255, 221);
            padding: 1em 0.5em 1em 2em;
            clear: both;
        }
        dl.domintro dt {
            color: black;
        }
        dl.domintro > dd {
            color: green;
        }
        dl.domintro::before {
            float: right;
            background-color: white;
            display: block;
            border: 2px solid black;
            color: green;
            margin-top: -20px;
            padding: 2px;
            content: "This box is non-normative.";
        }
        /* Fancy table stuff */
        table {
            border-collapse: collapse;
        }
        thead tr {
            border-bottom: 2px solid black;
        }
        tbody tr:not(:last-child) {
            border-bottom: 1px solid black;
        }
        td {
            border-left: 1px solid black;
            padding: 4px;
        }

/*****************************************************************
 * ReSpec 3 CSS
 * Robin Berjon - http://berjon.com/
 *****************************************************************/

/* --- INLINES --- */
em.rfc2119 { 
    text-transform:     lowercase;
    font-variant:       small-caps;
    font-style:         normal;
    color:              #900;
}

h1 acronym, h2 acronym, h3 acronym, h4 acronym, h5 acronym, h6 acronym, a acronym,
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;
}

cite .bibref {
    font-style: normal;
}

code {
    color:  #ff4500;
}

/* --- TOC --- */
.toc a, .tof a {
    text-decoration:    none;
}

a .secno, a .figno {
    color:  #000;
}

ul.tof, ol.tof {
    list-style: none outside none;
}

.caption {
    margin-top: 0.5em;
    font-style:   italic;
}


/* --- DL --- */
.section dd > p:first-child {
    margin-top: 0;
}

.section dd > p:last-child {
    margin-bottom: 0;
}

.section dd {
    margin-bottom:  1em;
}

.section dl.attrs dd, .section dl.eldef dd {
    margin-bottom:  0;
}
/* --- ISSUES/NOTES --- */
div.note-title {
    padding-right:  1em;
    min-width: 7.5em;
    color: #b9ab2d;
}

div.note-title { color: #52e052; }
div.note-title span {
    text-transform: uppercase;
}
div.note {
    margin-top: 1em;
    margin-bottom: 1em;
}
.note > p:first-child { margin-top: 0 }
.note {
    padding: .5em;
    border-left-width: .5em;
    border-left-style: solid;
}
div.note {
    padding: 0.5em;
    margin: 1em 0;
    position: relative;
    clear: both;
}
span.note { padding: .1em .5em .15em; }

.note {
    border-color: #52e052;
    background: #e9fbe9;
}


pre.idl {
    border-top: 1px solid #90b8de;
    border-bottom: 1px solid #90b8de;
    padding:    1em;
    line-height:    120%;
}

pre.idl::before {
    content:    "WebIDL";
    display:    block;
    width:      8ex;
    background: #90b8de;
    color:  #fff;
    font-family:    initial;
    padding:    3px;
    font-weight:    bold;
    margin: -1em 0 1em -1em;
}

.idlType {
    color:  #ff4500;
    font-weight:    bold;
    text-decoration:    none;
}

/*.idlInterface*/
.idlInterfaceID, .idlDictionaryID, .idlCallbackID, .idlEnumID {
    font-weight:    bold;
    color:  #005a9c;
}

.idlSuperclass {
    font-style: italic;
    color:  #005a9c;
}

/*.idlAttribute*/
.idlAttrType, .idlFieldType, .idlMemberType {
    color:  #005a9c;
}
.idlAttrName, .idlFieldName, .idlMemberName {
    color:  #ff4500;
}
.idlAttrName a, .idlFieldName a, .idlMemberName a {
    color:  #ff4500;
    border-bottom:  1px dotted #ff4500;
    text-decoration: none;
}



.extAttr {
    color:  #666;
}

/*.idlConst*/
.idlConstType {
    color:  #005a9c;
}
.idlConstName {
    color:  #ff4500;
}
.idlConstName a {
    color:  #ff4500;
    border-bottom:  1px dotted #ff4500;
    text-decoration: none;
}


.idlImplements a {
    font-weight:    bold;
}

dl.attributes, dl.methods, dl.constants, dl.fields, dl.dictionary-members {
    margin-left:    2em;
}

.attributes dt, .methods dt, .constants dt, .fields dt, .dictionary-members dt {
    font-weight:    normal;
}

.attributes dt code, .methods dt code, .constants dt code, .fields dt code, .dictionary-members dt code {
    font-weight:    bold;
    color:  #000;
    font-family:    monospace;
}

.attributes dt code, .fields dt code, .dictionary-members dt code {
    background:  #ffffd2;
}

.attributes dt .idlAttrType code, .fields dt .idlFieldType code, .dictionary-members dt .idlMemberType code {
    color:  #005a9c;
    background:  transparent;
    font-family:    inherit;
    font-weight:    normal;
    font-style: italic;
}



.attributes dd, .methods dd, .constants dd, .fields dd, .dictionary-members dd {
    margin-bottom:  1em;
}



</style> <link href="https://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet">
    <!--[if lt IE 9]><script src='undefined://www.w3.org/2008/site/js/html5shiv.js'></script><![endif]-->
  </head>
  <body>
    <div class="head">
      <p> <a href="http://www.w3.org/"><img alt="W3C" src="http://www.w3.org/Icons/w3c_home"
            height="48"
            width="72"></a>
      </p>
      <h1 class="title" id="title">HTML5 Image Description Extension</h1>
      <h2 id="w3c-working-draft-20-september-2012"><abbr title="World Wide Web Consortium">W3C</abbr>
        Editors' Draft 17 May 2013</h2>
      <dl>
        <dt>Latest published version:</dt>
        <dd><a href="http://www.w3.org/TR/HTML-longdesc">http://www.w3.org/TR/HTML-longdesc</a></dd>
        <dt>Latest editor's draft:</dt>
        <dd> <a href="http://dvcs.w3.org/hg/html-proposals/raw-file/default/longdesc1/longdesc.html">http://dvcs.w3.org/hg/html-proposals/raw-file/default/longdesc1/longdesc.html</a></dd>
        <dt>Editors:</dt>
        <dd><a href="mailto:[email protected]">Charles (McCathie) Nevile</a>,
          <a href="http://www.yandex.ru">Яндекс</a>—<a href="http://yandex.com">Yandex</a></dd>
      </dl>
      <p class="copyright"> <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
        © 2012-2013 <a href="http://www.w3.org/"><abbr title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup>
        (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>,
        <a href="http://www.ercim.eu/"><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>,
        <a href="http://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</a>),
+<html dir="ltr" lang="en">
  <head>
    <meta content="text/html; charset=UTF-8" http-equiv="content-type">
    <style>
      .issue {border: dashed red 2px; background-color: #ffd}
      .example, .example code {color: #404; background-color:#eee}
      .example::before {float:left;
        margin-top: -.2em;
        background-color: white;
            display: block;
            border: 1px solid black;
            color: #404;
            padding: 2px;
        content: "Example: (non-normative)"}
      
      .example:first-child {padding-top:1em}
      
        /* Make these stand-out more... */
        .externalDFN {
            font-style: italic;
            background-color: #fff9d6;
        }
        /* Switch statement */
        dl.switch dt::before {
            content: "↪ ";
            margin-left: 1em;
        }
        /* Better spacing around various lists (implied paragraph children) */
        ol > li, section:not(#toc) ul > li, section dl > dt {
            margin: 1em 0;
        }
        /* domintro styling */
        dl.domintro {
            background-color: rgb(221, 255, 221);
            padding: 1em 0.5em 1em 2em;
            clear: both;
        }
        dl.domintro dt {
            color: black;
        }
        dl.domintro > dd {
            color: green;
        }
        dl.domintro::before {
            float: right;
            background-color: white;
            display: block;
            border: 2px solid black;
            color: green;
            margin-top: -20px;
            padding: 2px;
            content: "This box is non-normative.";
        }
        /* Fancy table stuff */
        table {
            border-collapse: collapse;
        }
        thead tr {
            border-bottom: 2px solid black;
        }
        tbody tr:not(:last-child) {
            border-bottom: 1px solid black;
        }
        td {
            border-left: 1px solid black;
            padding: 4px;
        }

/*****************************************************************
 * ReSpec 3 CSS
 * Robin Berjon - http://berjon.com/
 *****************************************************************/

/* --- INLINES --- */
em.rfc2119 { 
    text-transform:     lowercase;
    font-variant:       small-caps;
    font-style:         normal;
    color:              #900;
}

h1 acronym, h2 acronym, h3 acronym, h4 acronym, h5 acronym, h6 acronym, a acronym,
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;
}

cite .bibref {
    font-style: normal;
}

code {
    color:  #ff4500;
}

/* --- TOC --- */
.toc a, .tof a {
    text-decoration:    none;
}

a .secno, a .figno {
    color:  #000;
}

ul.tof, ol.tof {
    list-style: none outside none;
}

.caption {
    margin-top: 0.5em;
    font-style:   italic;
}


/* --- DL --- */
.section dd > p:first-child {
    margin-top: 0;
}

.section dd > p:last-child {
    margin-bottom: 0;
}

.section dd {
    margin-bottom:  1em;
}

.section dl.attrs dd, .section dl.eldef dd {
    margin-bottom:  0;
}
/* --- ISSUES/NOTES --- */
div.note-title {
    padding-right:  1em;
    min-width: 7.5em;
    color: #b9ab2d;
}

div.note-title { color: #52e052; }
div.note-title span {
    text-transform: uppercase;
}
div.note {
    margin-top: 1em;
    margin-bottom: 1em;
}
.note > p:first-child { margin-top: 0 }
.note {
    padding: .5em;
    border-left-width: .5em;
    border-left-style: solid;
}
div.note {
    padding: 0.5em;
    margin: 1em 0;
    position: relative;
    clear: both;
}
span.note { padding: .1em .5em .15em; }

.note {
    border-color: #52e052;
    background: #e9fbe9;
}


pre.idl {
    border-top: 1px solid #90b8de;
    border-bottom: 1px solid #90b8de;
    padding:    1em;
    line-height:    120%;
}

pre.idl::before {
    content:    "WebIDL";
    display:    block;
    width:      8ex;
    background: #90b8de;
    color:  #fff;
    font-family:    initial;
    padding:    3px;
    font-weight:    bold;
    margin: -1em 0 1em -1em;
}

.idlType {
    color:  #ff4500;
    font-weight:    bold;
    text-decoration:    none;
}

/*.idlInterface*/
.idlInterfaceID, .idlDictionaryID, .idlCallbackID, .idlEnumID {
    font-weight:    bold;
    color:  #005a9c;
}

.idlSuperclass {
    font-style: italic;
    color:  #005a9c;
}

/*.idlAttribute*/
.idlAttrType, .idlFieldType, .idlMemberType {
    color:  #005a9c;
}
.idlAttrName, .idlFieldName, .idlMemberName {
    color:  #ff4500;
}
.idlAttrName a, .idlFieldName a, .idlMemberName a {
    color:  #ff4500;
    border-bottom:  1px dotted #ff4500;
    text-decoration: none;
}



.extAttr {
    color:  #666;
}

/*.idlConst*/
.idlConstType {
    color:  #005a9c;
}
.idlConstName {
    color:  #ff4500;
}
.idlConstName a {
    color:  #ff4500;
    border-bottom:  1px dotted #ff4500;
    text-decoration: none;
}


.idlImplements a {
    font-weight:    bold;
}

dl.attributes, dl.methods, dl.constants, dl.fields, dl.dictionary-members {
    margin-left:    2em;
}

.attributes dt, .methods dt, .constants dt, .fields dt, .dictionary-members dt {
    font-weight:    normal;
}

.attributes dt code, .methods dt code, .constants dt code, .fields dt code, .dictionary-members dt code {
    font-weight:    bold;
    color:  #000;
    font-family:    monospace;
}

.attributes dt code, .fields dt code, .dictionary-members dt code {
    background:  #ffffd2;
}

.attributes dt .idlAttrType code, .fields dt .idlFieldType code, .dictionary-members dt .idlMemberType code {
    color:  #005a9c;
    background:  transparent;
    font-family:    inherit;
    font-weight:    normal;
    font-style: italic;
}



.attributes dd, .methods dd, .constants dd, .fields dd, .dictionary-members dd {
    margin-bottom:  1em;
}



</style> <link href="https://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet">
    <!--[if lt IE 9]><script src='undefined://www.w3.org/2008/site/js/html5shiv.js'></script><![endif]-->
  </head>
  <body><br>
    <div class="head">
      <p> <a href="http://www.w3.org/"><img alt="W3C" src="http://www.w3.org/Icons/w3c_home"
            height="48"
            width="72"></a>
      </p>
      <h1 class="title" id="title">HTML5 Image Description Extension</h1>
      <h2 id="w3c-working-draft-20-september-2012"><abbr title="World Wide Web Consortium">W3C</abbr>
        Editors' Draft 17 May 2013</h2>
      <dl>
        <dt>Latest published version:</dt>
        <dd><a href="http://www.w3.org/TR/HTML-longdesc">http://www.w3.org/TR/HTML-longdesc</a></dd>
        <dt>Latest editor's draft:</dt>
        <dd> <a href="http://dvcs.w3.org/hg/html-proposals/raw-file/default/longdesc1/longdesc.html">http://dvcs.w3.org/hg/html-proposals/raw-file/default/longdesc1/longdesc.html</a></dd>
        <dt>Editors:</dt>
        <dd><a href="mailto:[email protected]">Charles (McCathie) Nevile</a>,
          <a href="http://www.yandex.ru">Яндекс</a>—<a href="http://yandex.com">Yandex</a></dd>
      </dl>
      <p class="copyright"> <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
        © 2012-2013 <a href="http://www.w3.org/"><abbr title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup>
        (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>,
        <a href="http://www.ercim.eu/"><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>,
        <a href="http://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</a>),
         All Rights Reserved. <abbr title="World Wide Web Consortium">W3C</abbr>
        <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
        <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
        and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
-          use</a> rules apply. </p>
      <hr> </div>
    <section class="introductory" id="abstract">
      <h2>Abstract</h2>
      <p>This specification defines a <code>longdesc</code> attribute to link
        extended descriptions with images in HTML5-based content.</p>
    </section>
    <section class="introductory" id="sotd">
      <h2>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="http://www.w3.org/TR/"><abbr title="World Wide Web Consortium">W3C</abbr>
            technical reports index</a> at http://www.w3.org/TR/.</em> </p>
      <p> This document is an editors' draft proposed to the HTML Working Group
        Accessibility Task Force for publication as a Working Draft, which would
        be proposed as the basis for a Last Call Working Draft. Following
        feedback on the <a href="http://www.w3.org/TR/2013/WD-html-longdesc-20130312/">First
-          Public Working Draft</a>, a number of <a href="https://www.w3.org/Bugs/Public/buglist.cgi?product=HTML%20WG&amp;amp;component=HTML%20Image%20Description%20Extension">bugs
-          were raised and resolved</a>. If you wish to make comments regarding
        this document, please send them to <a href="mailto:[email protected]">[email protected]</a>
        (<a href="mailto:[email protected]?subject=subscribe">subscribe</a>,
        <a href="http://lists.w3.org/Archives/Public/public-html-a11y/">archives</a>).
-        All feedback is welcome. Bugs can also be filed directly into the <a href="https://www.w3.org/Bugs/Public/buglist.cgi?product=HTML%20WG&amp;amp;component=HTML%20Image%20Description%20Extension">W3C
-          Bug tracker for this specification</a>.</p>
      <p>This document is intended to become a <abbr title="World Wide Web Consortium">W3C</abbr>
        Recommendation, either on its own or merged into an HTML Recommendation.
      </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 href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5
          February 2004 <abbr title="World Wide Web Consortium">W3C</abbr>
          Patent Policy</a>. <abbr title="World Wide Web Consortium">W3C</abbr>
        maintains a <a href="http://www.w3.org/2004/01/pp-impl/42538/status" 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="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
-          Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
-          6 of the <abbr title="World Wide Web Consortium">W3C</abbr> Patent
          Policy</a>. </p>
    </section>
    <section id="toc">
      <h2 class="introductory">Table of Contents</h2>
      <ul class="toc">
        <li class="tocline"><a class="tocxref" href="#intro"><span class="secno">
            </span>Introduction</a></li>
        <li class="tocline"><a class="tocxref" href="#conformance"><span class="secno">1.
+          use</a> rules apply. </p>
      <hr> </div>
    <section class="introductory" id="abstract">
      <h2>Abstract</h2>
      <p>This specification defines a <code>longdesc</code> attribute to link
        descriptions to images in HTML5-based content.</p>
    </section>
    <section class="introductory" id="sotd">
      <h2>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="http://www.w3.org/TR/"><abbr title="World Wide Web Consortium">W3C</abbr>
            technical reports index</a> at http://www.w3.org/TR/.</em> </p>
      <p> This document is an editors' draft proposed to the HTML Working Group
        Accessibility Task Force for publication as a Last Call Working Draft.
        Following feedback on the <a href="http://www.w3.org/TR/2013/WD-html-longdesc-20130312/">First
+          Public Working Draft</a>, a number of <a href="https://www.w3.org/Bugs/Public/buglist.cgi?product=HTML%20WG&amp;amp;component=HTML%20Image%20Description%20Extension">bugs</a>
        were raised and resolved and a Second Public Working Draft was published
        for review. Review of this draft did not produce any new substantive
        issues. Significant changes between successive public drafts are tracked
        in the Change History section.</p>
      <p>If you wish to make comments regarding this document, please send them
        to <a href="mailto:[email protected]">[email protected]</a>
        (<a href="mailto:[email protected]?subject=subscribe">subscribe</a>,
        <a href="http://lists.w3.org/Archives/Public/public-html-a11y/">archives</a>).
+All
+        feedback is welcome. Bugs can also be filed directly into the <a href="https://www.w3.org/Bugs/Public/buglist.cgi?product=HTML%20WG&amp;amp;component=HTML%20Image%20Description%20Extension">W3C
+          Bug tracker for this specification</a>.</p>
      <section class="introductory" id="sotd">
        <p>This document is intended to become a <abbr title="World Wide Web Consortium">W3C</abbr>
          Recommendation, either on its own or merged into an HTML
          Recommendation. </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 href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5
            February 2004 <abbr title="World Wide Web Consortium">W3C</abbr>
            Patent Policy</a>. <abbr title="World Wide Web Consortium">W3C</abbr>
          maintains a <a href="http://www.w3.org/2004/01/pp-impl/42538/status"
            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="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
+            Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
            6</a> of the <abbr title="World Wide Web Consortium">W3C</abbr>
          Patent Policy. </p>
      </section>
    </section>
    <section id="toc">
      <h2 class="introductory">Table of Contents</h2>
      <ul class="toc">
        <li class="tocline"><a class="tocxref" href="#intro"><span class="secno">
            </span>Introduction</a></li>
        <li class="tocline"><a class="tocxref" href="#conformance"><span class="secno">1.
               </span>Conformance</a>
          <ul class="toc">
            <li class="tocline"><a class="tocxref" href="#dependencies"><span class="secno">1.1
                   </span>Dependencies</a></li>
          </ul>
        </li>
        <li class="tocline"><a class="tocxref" href="#UCnR"><span class="secno">2.
               </span>Use Cases and Requirements</a></li>
        <li class="tocline"><a class="tocxref" href="#longdesc"><span class="secno">3.
@@ -18,15 +17,16 @@
               </span>References</a>
          <ul class="toc">
            <li class="tocline"><a class="tocxref" href="#normative-references"><span
                  class="secno">B.1
                   </span>Normative references</a></li>
            <li class="tocline"><a class="tocxref" href="#informative-references"><span
                  class="secno">B.2
                   </span>Informative references</a></li>
          </ul>
        </li>
        <li class="tocline"><a class="tocxref" href="#changes"><span class="secno">C.
-              </span>Change History</a></li>
      </ul>
    </section>
    <section id="intro" class="introductory">
      <h1>Introduction</h1>
      <p>HTML 4 provided a <code>longdesc</code> attribute for the <code>img</code>
        element. This enabled a machine-discoverable description of an image to
        be linked to the image. This extension specification defines the same
        functionality for HTML5-based content.</p>
      <pre class="example"><code><br><br>&lt;!-- The description is an element on the same page as the image, with the id "graph1Explained" --&gt;
&lt;img src="http://example.com/graph1" alt="(Drinks are getting sweeter)" title="Figure One" <strong>longdesc="#graph1Explained"</strong>&gt;

&lt;!-- The description is a page on its own --&gt;
&lt;img src="figure1" alt="figure 1" <strong>longdesc="http://example.com/desc1"</strong>&gt;

&lt;!-- The description is one of several within an external page --&gt;
&lt;img src="ExampleImage" alt="example" <strong>longdesc="http://example.com/descs#item3"</strong>&gt;

&lt;!-- The description is included in a data: URI --&gt;
&lt;img src="logo" alt="W3C" <strong>longdesc="data:text/html;charset=utf-8;,%3C!DOCTYPE%20html%3E%3Chtml%3E%3Chead%3E
%3Ctitle%3EDescription%20of%20the%20W3C%20Logo%3C/title%3E%3C/head%3E%3Cbody%3E%3Cp%3EA%20blue%20capital%20letter<br>%20%22W%22%20with%20kerning%20so%20it%20touches%20a%20blue%203%2C%20followed%20by%20a%20black%20shadow%20<br>of%20a%20white%20capital%20letter%20C%20all%20on%20a%20white%20background%3C/body%3E%3C/html%3E"</strong>&gt;</code></pre>
    </section>
    <section id="conformance">
      <h2><span class="secno">1. </span>Conformance</h2>
      <p> As well as sections marked as non-normative, all diagrams, examples,
        and notes in this specification are non-normative. Everything else in
        this specification is normative. </p>
      <p> The key words <em title="must" class="rfc2119">must</em>, <em title="should"
          class="rfc2119">should</em>,
        <em title="should not" class="rfc2119"></em><em title="recommended" class="rfc2119"></em>and
-        <em title="may" class="rfc2119">may</em><em title="optional" class="rfc2119"></em>
        in this specification are to be interpreted as described in [<cite><a class="bibref"
            href="#bib-RFC2119">RFC2119</a></cite>].</p>
      <section id="dependencies">
        <h3><span class="secno">1.1 </span>Dependencies and definitions</h3>
        <p>The IDL fragments in this specification <em title="must" class="rfc2119">must</em>
          be interpreted as required for conforming IDL fragments, as described
          in the Web IDL specification. [<cite><a class="bibref" href="#bib-WEBIDL">WEBIDL</a></cite>]</p>
        <p>The terms "<a href="http://www.w3.org/TR/HTML5/#valid-url-potentially-surrounded-by-spaces">valid
-            non-empty URL potentially surrounded by spaces</a>", "<a href="http://www.w3.org/TR/HTML5/#hyperlink">hyperlink"</a>,
          and "<a href="http://www.w3.org/TR/HTML5/#reflect">reflect</a>", used
          in this specification are defined in [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>].</p>
        <p>This document does not define the term "accessible" nor
          accessibility, but uses them with the sense they have in [<a href="#bib-WCAG">WCAG</a>]</p>
      </section>
    </section>
    <section id="UCnR">
      <h2><span class="secno">2. </span>Use Cases and Requirements</h2>
      <p>There are many ways users can successfully interact with content even
        if they cannot see, or see well, images included in that content. The <code>alt</code>
        attribute is designed to ensure that for everyday work, a user has
        enough information to replace an image, and often this is more helpful
        than a detailed description of every image. The <code>longdesc</code>
        attribute is designed to complement this functionality, to meet the
        following use cases. </p>
      <h3>Use Cases</h3>
      <dl>
        <dt>Identifying a well-known image</dt>
      </dl>
      <dl>
        <dd>There are many well-known images which are widely reproduced and
          well known. In some cases, such as "Mona Lisa", "Gerníka", Cubbin's
          "Lost", Leunig's "ramming the shears", the most effective way to refer
          identify an image to another person is by the creator, title, and
          similar information that would be found in a catalogue. But different
          people know the images by different titles, and some images have no
          widely known titles. Identifying an image is often an important part
          of framing a discussion. Where the image itself cannot be seen, a
          description can often be used to offer easier recognition than the
          cataloguing information, for example "Washington crossing some river,
          standing heroically in the boat, while soldiers do the hard work", or
          "the Da Vinci picture of the guy in a square and a circle".</dd>
        <dd><em>Requires</em>: Discoverability</dd>
        <dd><em>Helped by</em>: Inline, Reuse</dd>
        <dt>Describing a complex diagram</dt>
        <dd>In many environments diagrams are used to explain a concept or
          transmit information efficiently. Where a user has a reduced ability
          to see the image (poor contrast vision and other conditions are as
          relevant here as a complete lack of vision), a description can enable
          that user to understand the information being presented</dd>
        <dd><em>Requires</em>: Structured Markup, Inline, Reuse, Simple Return</dd>
        <dt>Teaching Accessible Development</dt>
        <dd>In many environments producing content that is accessible to users
          regardless of disability is a legal and/or market requirement. </dd>
        <dd><em>Requires</em>: Maintenance, Backwards compatibility</dd>
        <dt>A self-describing artistic work</dt>
        <dd>For many pages the visual design of the page is an important part of
          the message it conveys to a fully-sighted user, but the author would
          like to convey as much of that design as possible to a user with low
          or no vision available. </dd>
        <dd><em>Requires</em>: No visual encumbrance, Structured Markup</dd>
        <dd><em>Helped by</em>: Reuse, Simple Return</dd>
        <dt>Referring to an existing description</dt>
        <dd>Many well-known images are already described by other sources. The
          copyright on those sources may not be compatible with re-publishing
          the description, but there is little value in making a new one. </dd>
        <dd><em>Requires</em>: Reuse, Structured Markup, Simple Return, Optional
          Consumption </dd>
        <dd><em>Helped by</em>: No Visual Encumbrance</dd>
        <dt>Linking to a description included within a page</dt>
        <dd>In some cases an image already has a description included within a
          page. Making the linkage explicit can provide further clarity for a
          user navigating the page who is not able to interpret the default
          layout, e.g. because they have forced a re-layout of the page
          elements, or because they do not see the default visual relationship
          between the element and its description.</dd>
        <dd>This practice also enables description to be provided for all users.</dd>
        <dd>By keeping the association clear the content maintainer can more
          easily check that the description and link are actually correct.</dd>
        <dd><em>Requires</em>: Inline, Simple Return, Structured Markup,
          Optional Consumption </dd>
        <dt>Localising descriptions</dt>
        <dd>When content is localised to multiple languages, it is important
          that metadata intended for human consumption, such as image
          descriptions, can be readily localised.</dd>
        <dd><em>Helped by</em>: Structured Markup, Reuse, Maintenance.</dd>
      </dl>
      <h3>Requirements for an Image Description functionality </h3>
      <dl>
        <dt>No visual encumbrance</dt>
        <dd>It <em class="rfc2119">must</em> be possible to provide a
          description for an image without any visual encumbrance on the page.</dd>
        <dt>Structured Markup</dt>
        <dd>It <em class="rfc2119">must</em> be possible to include rich markup
          (e.g. HTML5) in the description of the image.</dd>
        <dt>Inline</dt>
        <dd>It <em class="rfc2119">must</em> be possible to associate a
          description in the body of a page with an image in that page. </dd>
        <dt>Reuse</dt>
        <dd>It <em class="rfc2119">must</em> be possible to re-use a single
          description for multiple occurrences of an image.</dd>
        <dt>Maintenance</dt>
        <dd>It <em class="rfc2119">must</em> be simple to maintain a library of
          images and descriptions for dynamic assembly, or dis-assembly and
          re-assembly, of content. </dd>
        <dt>Discoverability </dt>
        <dd class="rfc2119">It <em class="rfc2119">must</em> be simple for a
          user agent to automatically discover a description provided for a
          given image.</dd>
        <dd>A user <em class="rfc2119">should</em> be able to determine that
          there is a description available for a given image. </dd>
        <dt>Optional consumption</dt>
        <dd>A user <em class="rfc2119">must</em> be able to choose not to read
          the long description of a given image.</dd>
        <dt>Simple return</dt>
        <dd>A user <em class="rfc2119">must</em> be able to return from the
          description to the image. </dd>
        <dt>Backwards Compatibility </dt>
        <dd>It <em class="rfc2119">should</em> be possible to use existing
          tools and techniques to associate an image with its description. </dd>
      </dl>
    </section>
    <section id="longdesc">
      <h2><span class="secno"></span>3. The <code>longdesc</code> attribute</h2>
      <h3>3.0 Implementation</h3>
      <h4>3.0.1 Authors and Conformance checkers</h4>
      <section id="parsing">
        <p class="rfc2119">Zero or one <code>longdesc</code> attributes <em class="rfc2119">may</em>
          be added to any <code>img</code> element.</p>
        <p>The <code>longdesc</code> attribute <em class="rfc2119">must</em>
          contain a <a href="http://dev.w3.org/html5/spec/urls.html#valid-url-potentially-surrounded-by-spaces">valid
+              </span>Change History</a></li>
      </ul>
    </section>
    <section id="intro" class="introductory">
      <h1>Introduction</h1>
      <p>HTML 4 provided a <code>longdesc</code> attribute for the <code>img</code>
        element. This enabled a machine-discoverable description of an image to
        be linked to the image. This extension specification defines the same
        functionality for HTML5-based content.</p>
      <pre class="example"><code><br><br>&lt;!-- The description is somewhere on the same page as the image --&gt;
&lt;img src="http://example.com/graph1" alt="(Drinks are getting sweeter)" title="Figure One" <strong>longdesc="#graph1Explained"</strong>&gt;

&lt;!-- The description is a page on its own --&gt;
&lt;img src="figure1" alt="figure 1" <strong>longdesc="http://example.com/desc1"</strong>&gt;

&lt;!-- The description is one of several within an external page --&gt;
&lt;img src="ExampleImage" alt="example" <strong>longdesc="http://example.com/descs#item3"</strong>&gt;

&lt;!-- The description is included in a data: URI --&gt;
&lt;img src="logo" alt="W3C" <strong>longdesc="data:text/html;charset=utf-8;,%3C!DOCTYPE%20html%3E%3Chtml%3E%3Chead%3E
%3Ctitle%3EDescription%20of%20the%20W3C%20Logo%3C/title%3E%3C/head%3E%3Cbody%3E%3Cp%3EA%20blue%20capital%20letter<br>%20%22W%22%20with%20kerning%20so%20it%20touches%20a%20blue%203%2C%20followed%20by%20a%20black%20shadow%20<br>of%20a%20white%20capital%20letter%20C%20all%20on%20a%20white%20background%3C/body%3E%3C/html%3E"</strong>&gt;</code></pre>
    </section>
    <section id="conformance">
      <h2><span class="secno">1. </span>Conformance</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>The key words <em title="must" class="rfc2119">must</em>, <em title="should"
          class="rfc2119">should</em>,
        <em title="should not" class="rfc2119"></em><em title="recommended" class="rfc2119"></em>and
+        <em title="may" class="rfc2119">may</em><em title="optional" class="rfc2119"></em>
        in this specification are to be interpreted as described in [<cite><a class="bibref"
            href="#bib-RFC2119">RFC2119</a></cite>].</p>
      <section id="dependencies">
        <h3><span class="secno">1.1 </span>Dependencies and definitions</h3>
        <p>The IDL fragments in this specification <em title="must" class="rfc2119">must</em>
          be interpreted as required for conforming IDL fragments, as described
          in the Web IDL specification. [<cite><a class="bibref" href="#bib-WEBIDL">WEBIDL</a></cite>]</p>
        <p>The terms "<a href="http://www.w3.org/TR/html5/infrastructure.html#valid-url-potentially-surrounded-by-spaces">valid
+            non-empty URL potentially surrounded by spaces</a>", "<a href="http://www.w3.org/TR/html5/links.html#hyperlink">hyperlink"</a>,
          and "<a href="http://www.w3.org/TR/html5/infrastructure.html#reflect">reflect</a>",
+          used in this specification are defined in [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>].</p>
        <p>This document does not define the term "accessible" nor
          accessibility, but uses them with the sense they have in [<a href="#bib-WCAG2">WCAG</a>]</p>
      </section>
    </section>
    <section id="UCnR">
      <h2><span class="secno">2. </span>Use Cases and Requirements</h2>
      <p>There are many ways users can successfully interact with content even
        if they cannot see, or see well, images included in that content. The <code>alt</code>
        attribute is designed to ensure that for everyday work, a user has
        enough information to replace an image, and often this is more helpful
        than a detailed description of every image. The <code>longdesc</code>
        attribute is designed to complement this functionality, to meet the
        following use cases. </p>
      <h3 id="use-cases">Use Cases</h3>
      <dl>
        <dt>Identifying a well-known image</dt>
      </dl>
      <dl>
        <dd>There are many well-known images which are widely reproduced and
          well known. In some cases, such as "Mona Lisa", "Gerníka", Cubbin's
          "Lost", Leunig's "ramming the shears", the most effective way to refer
          identify an image to another person is by the creator, title, and
          similar information that would be found in a catalog. But different
          people know the images by different titles, and some images have no
          widely known titles. Identifying an image is often an important part
          of framing a discussion. Where the image itself cannot be seen, a
          description can often be used to offer easier recognition than the
          cataloging information, for example "Washington crossing some river,
          standing heroically in the boat, while soldiers do the hard work", or
          "the Da Vinci picture of the guy in a square and a circle".</dd>
        <dd><em>Requires</em>: Discoverability</dd>
        <dd><em>Helped by</em>: Inline, Reuse</dd>
        <dt>Describing a complex diagram</dt>
        <dd>In many environments diagrams are used to explain a concept or
          transmit information efficiently. Where a user has a reduced ability
          to see the image (poor contrast vision and other conditions are as
          relevant here as a complete lack of vision), a description can enable
          that user to understand the information being presented.</dd>
        <dd><em>Requires</em>: Structured Markup, Inline, Reuse, Simple Return</dd>
        <dt>Teaching Accessible Development</dt>
        <dd>In many environments producing content that is accessible to users
          regardless of disability is a legal and/or market requirement. </dd>
        <dd><em>Requires</em>: Maintenance, Backwards compatibility</dd>
        <dt>A self-describing artistic work</dt>
        <dd>For many pages the visual design of the page is an important part of
          the message it conveys to a fully-sighted user, but the author would
          like to convey as much of that design as possible to a user with low
          or no vision available. </dd>
        <dd><em>Requires</em>: No visual encumbrance, Structured Markup</dd>
        <dd><em>Helped by</em>: Reuse, Simple Return</dd>
        <dt>Referring to an existing description</dt>
        <dd>Many well-known images are already described by other sources. The
          copyright on those sources may not be compatible with re-publishing
          the description, but there is little value in making a new one. </dd>
        <dd><em>Requires</em>: Reuse, Structured Markup, Simple Return, Optional
          Consumption </dd>
        <dd><em>Helped by</em>: No Visual Encumbrance</dd>
        <dt>Linking to a description included within a page</dt>
        <dd>In some cases an image already has a description included within a
          page. Making the linkage explicit can provide further clarity for a
          user navigating the page who is not able to interpret the default
          layout, e.g. because they have forced a re-layout of the page
          elements, or because they do not see the default visual relationship
          between the element and its description.</dd>
        <dd>This practice also enables description to be provided for all users.</dd>
        <dd>By keeping the association clear the content maintainer can more
          easily check that the description and link are actually correct.</dd>
        <dd><em>Requires</em>: Inline, Simple Return, Structured Markup,
          Optional Consumption </dd>
        <dt>Localizing descriptions</dt>
        <dd>When content is localized to multiple languages, it is important
          that metadata intended for human consumption, such as image
          descriptions, can be readily localized.</dd>
        <dd><em>Helped by</em>: Structured Markup, Reuse, Maintenance.</dd>
      </dl>
      <h3 id="requirements">Requirements for an Image Description functionality</h3>
      <dl>
        <dt>No visual encumbrance</dt>
        <dd>It <em class="rfc2119">must</em> be possible to provide a
          description for an image without any visual encumbrance on the page.</dd>
        <dt>Structured Markup</dt>
        <dd>It <em class="rfc2119">must</em> be possible to include rich markup
          (e.g. HTML5) in the description of the image.</dd>
        <dt>Inline</dt>
        <dd>It <em class="rfc2119">must</em> be possible to associate a
          description in the body of a page with an image in that page. </dd>
        <dt>Reuse</dt>
        <dd>It <em class="rfc2119">must</em> be possible to re-use a single
          description for multiple occurrences of an image.</dd>
        <dt>Maintenance</dt>
        <dd>It <em class="rfc2119">must</em> be simple to maintain a library of
          images and descriptions for dynamic assembly, or dis-assembly and
          re-assembly, of content. </dd>
        <dt>Discoverability </dt>
        <dd class="rfc2119">It <em class="rfc2119">must</em> be simple for a
          user agent to automatically discover a description provided for a
          given image.</dd>
        <dd>A user <em class="rfc2119">should</em> be able to determine that
          there is a description available for a given image. </dd>
        <dt>Optional consumption</dt>
        <dd>A user <em class="rfc2119">must</em> be able to choose not to read
          the long description of a given image.</dd>
        <dt>Simple return</dt>
        <dd>A user <em class="rfc2119">must</em> be able to return from the
          description to the image. </dd>
        <dt>Backwards Compatibility </dt>
        <dd>It <em class="rfc2119">should</em> be possible to use existing
          tools and techniques to associate an image with its description. </dd>
      </dl>
    </section>
    <section id="longdesc">
      <h2><span class="secno"></span>3. The <code>longdesc</code> attribute</h2>
      <h3 id="implementation">3.0 Implementation</h3>
      <h4 id="authors-and-conformance-checkers">3.0.1 Authors and Conformance
        checkers</h4>
      <section id="parsing">
        <p class="rfc2119">Zero or one <code>longdesc</code> attributes <em class="rfc2119">may</em>
          be added to any <code>img</code> element.</p>
        <p>The <code>longdesc</code> attribute <em class="rfc2119">must</em>
          contain a <a href="http://www.w3.org/TR/html5/infrastructure.html#valid-url-potentially-surrounded-by-spaces">valid
             non-empty URL potentially surrounded by spaces</a>. The URL is a <a
            href="http://dev.w3.org/html5/spec/links.html#hyperlink">hyperlink</a>
          to a description of the image that its parent <code>img</code>
          element represents. </p>
        <p>The linked description <em class="rfc2119">should</em> be a broadly
          accessible format. (For example, a link to another version of the
          image is almost certainly not a useful description, and plain text is
          an extremely limiting format).</p>
        <div class="note">
          <p><em>This section is informative</em></p>
          <p>Best practices for checking descriptions of images are beyond the
            scope of this document, but there are many resources available.
            For&nbsp; further guidance tool developers can consult e.g. [<a href="#bib-ATAGB3">ATAGB3</a>].
             <span class="issue">ISSUE: This doesn't seem a great reference - is
              there anything better? This is tracked in <a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=21501">bug
-                21501</a> and its dependent bugs. Unless a proposal is made and
              accepted for improvement this bug will simply be closed after Last
              Call.</span>. These notes are offered to help avoid common
            mistakes.</p>
          <p>A common mistake has been putting a description as the content of
            the attribute. Detecting invalid URLs can help to identify this
            problem, and as noted below conversion to a data: URL is one
            possible repair strategy.</p>
          <p>Similarly, </p>
        </div>
        <h4>3.0.2 Authors</h4>
        <p>Authors <em class="rfc2119">should</em> put descriptions within an
          element which is the target of a fragment link (e.g. <code>longdesc="example.html#description"</code>)
          if a description is only part of the target document. </p>
        <div class="note">
          <p><em>This section is informative</em></p>
          <p>Best practices for full descriptions of images are beyond the scope
            of this document, but there are many resources available. These
            notes are offered to help avoid common mistakes.</p>
          <p>This document does not define the term "accessible" nor
            accessibility. For further guidance on making an accessible
            document, authors can consult e.g. [<a href="#bib-WCAG2">WCAG</a>].</p>
        </div>
        <h4>3.0.3 User Agents</h4>
        <p>If the <code>longdesc</code> value is valid, User agents <em class="rfc2119">must</em>
          make the link available to all users through the regular user
          interface(s).&nbsp; </p>
        <p class="note">Some images with long descriptions are used inside
          hyperlinks. This provision is a wilful violation of HTML's stipulation
          that a hyperlink cannot be nested. </p>
        <p>If the <code>longdesc</code> value is valid, User agents <em class="rfc2119">must</em>
          expose the link to relevant APIs, especially accessibility-oriented
          APIs. </p>
        <p>User agents <em class="rfc2119">should</em> enable users to discover
          when images in a page contain a long description.</p>
        <div class="note">
          <p><em>This section is informative</em></p>
          <p>Complete documentation of best practices for implementation is
            beyond the scope of this document. These notes are offered to help
            minimise the impact of common mistakes.</p>
          <p>A common mistake in the past has been to use a description, instead
            of a URL that links to a description. Converting such values to
            data: URLs is a repair strategy for user agents that can help users
            to recover in cases where authors have made this mistake. </p>
          <p>It is usually helpful when the behaviour for finding, reading, and
            returning from a long description to the image described is a
            consistent experience.</p>
          <p>Further information on making user agents accessible can be found
            in [<a href="#bib-UAAG">UAAG</a>].</p>
        </div>
      </section>
      <section id="extensions-to-the-element-interface">
        <h3><span class="secno">3.1 </span>Extension to the <code><a title="element"
              class="externalDFN"
              data-spec="HTML5">HTMLImageElement</a></code>
          interface</h3>
        <pre class="idl"><span class="idlInterface" id="idl-def-Element">partial interface <span
class="idlInterfaceID">HTMLImageElement</span> {
<span class="idlAttribute">             attribute <span class="idlAttrType"><a>DOMString</a></span> <span
class="idlAttrName"><a
href="#widl-Element-longdesc">longdesc</a></span>;</span>
};</span></pre>
        <section id="attributes">
          <h4><span class="secno">3.1.1 </span>Attribute</h4>
          <dl class="attributes">
            <dt id="widl-Element-longdesc"><code>longdesc</code> of type <span
                class="idlAttrType"><a>DOMString</a></span></dt>
            <dd>
              <p class="rfc2119">The <dfn id="dfn-dom-element-longdesc"><code>longdesc</code></dfn>
                IDL attribute <em class="rfc2119">must</em> be a valid
                non-empty URL potentially surrounded by spaces. It represents a
                hyperlink to a detailed description of the image its parent <code><a
                    title="element"
                    class="externalDFN"
                    data-spec="DOM4">HTMLImageElement</a></code>
                represents.</p>
            </dd>
            <dd>
              <p>The <code>longdesc</code> IDL attribute <em class="rfc2119">must</em>
                <a href="http://www.w3.org/TR/html5/infrastructure.html#reflect">reflect</a>
                the HTML content attribute <code>longdesc</code>. </p>
            </dd>
            <dd>
              <dl class="domintro">
                <dt><var>image</var>.<code title="dom-Element-innerHTML">longdesc</code>
                  [ = <var>value</var> ] </dt>
                <dd>
                  <p>Returns a DOMString that represents the attribute's
                    contents. </p>
                  <p>Can be set, to replace the contents of the attribute with
                    the given string.</p>
                </dd>
              </dl>
            </dd>
          </dl>
          <pre class="example"><code>//Make the first internal longdesc reference absolute

var baseURL = document.location.origin + document.location.pathname
var someImage = document.querySelector('img[longdesc^=#]');

someImage.longdesc = baseURL + someImage.longdesc;</code></pre>
          <pre class="example"><code>//Open new windows for each longdesc found

var describedImages = document.querySelectorAll('img[longdesc]');

for (i in describedImages) {
  if (i.<strong>longdesc</strong>)
    window.open(i.<strong>longdesc</strong>);
}</code></pre>
          <pre class="example"><code>//Tries to repair errors where the longdesc isn't a URI

var describedImages = document.querySelectorAll('img[longdesc]');

for (i in describedImages) {
  if (i.longdesc &amp;&amp; !(validURL(i.longdesc)) { //assumes some URL validating function
    var theData = encodeURIComponent(i.longdesc);
    i.longdesc = "data:text/plain;charset=";
    i.longdesc += document.charset;
    i.longdesc += theData;
  }
}</code></pre>
        </section>
      </section>
      <section class="appendix" id="acknowledgements">
        <h2><span class="secno">A. </span>Acknowledgements</h2>
        <p>Thanks to the HTML Working group of the late 1990s for the original
          specification of longdesc, to those who have implemented it in various
          kinds of software, and to many many people involved with the
          development of HTML5 (including but not limited to those who discussed
          "ISSUE-30" in the HTML Working Group, the Protocols and Formats
          Working Group, the W3C Advisory Board, and around countless dinner
          tables, coffee breaks, and elsewhere) for the ideas, discussions and
          contributions that led to the initial draft of this specification.
          With the exception of Laura Carlson, who did far more very valuable
          work than it took me to produce this specification, I haven't named
          them: the list might be larger than the content of the specification.</p>
        <p>For specific comments and suggestions that led to improvements over
          successive drafts of this specification, thanks to the W3C's HTML
          Accessibility Task Force, the W3C Internationalisation Working Group,
          and to Jonathan Avila, Robin Berjon, James Craig, Steve Faulkner, John
          Foliot, Geoff Freed, Richard Ishida, Anne van Kesteren, David
          MacDonald, Chris Mills, Jay Munro, Devarshi Pant, Silvia Pfeiffer,
          Leif Halvard Silli, Mathew Turvey and Boris Zbarsky. Any errors are
          despite, not as a result of, their efforts.</p>
      </section>
      <section class="appendix" id="references">
        <h2><span class="secno">B. </span>References</h2>
        <section id="normative-references">
          <h3><span class="secno">B.1 </span>Normative references</h3>
          <dl class="bibliography">
            <dt id="bib-HTML5">[HTML5]</dt>
            <dd>Robin Berjon et. al., eds. <a href="http://www.w3.org/TR/html5"><cite>HTML5.</cite></a>
              W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/html5">http://www.w3.org/TR/html5</a>
            </dd>
            <dt id="bib-RFC2119">[RFC2119]</dt>
            <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
+                21501</a> and its dependent bugs. Unless a proposal for
              improvement is made and accepted this bug will simply be closed
              after Last Call.</span></p>
        </div>
        <h4 id="authors">3.0.2 Authors</h4>
        <p>Authors <em class="rfc2119">should</em> put descriptions within an
          element which is the target of a fragment link (e.g. <code>longdesc="example.html#description"</code>)
          if a description is only part of the target document. </p>
        <div class="note">
          <p><em>This section is informative</em></p>
          <p>Best practices for full descriptions of images are beyond the scope
            of this document, but there are many resources available.</p>
          <p>This document does not define the term "accessible" nor
            accessibility. For further guidance on making an accessible
            document, authors can consult e.g. [<a href="#bib-WCAG2">WCAG</a>].</p>
        </div>
        <h4 id="user-agents">3.0.3 User Agents</h4>
        <p>If the <code>longdesc</code> value is valid, User agents <em class="rfc2119">must</em>
          make the link available to all users through the regular user
          interface(s).&nbsp; </p>
        <p>If the <code>longdesc</code> value is valid, User agents <em class="rfc2119">must</em>
          expose the link to relevant APIs, especially accessibility-oriented
          APIs. </p>
        <p>User agents <em class="rfc2119">should</em> enable users to discover
          when images in a page contain a long description.</p>
        <div class="note">
          <p><em>This section is informative</em></p>
          <p>Complete documentation of best practices for implementation is
            beyond the scope of this document. These notes are offered to help
            minimise the impact of common mistakes.</p>
          <p>A common mistake in the past has been to use a description, instead
            of a URL that links to a description. Converting such values to
            data: URLs is a repair strategy for user agents that can help users
            to recover in cases where authors have made this mistake. </p>
          <p>It is usually helpful when the behaviour for finding, reading, and
            returning from a long description to the image described is a
            consistent experience.</p>
          <p>Further information on making user agents accessible can be found
            in [<a href="file:///Users/chaals/Documents/w3c/html-proposals/longdesc1/longdesc.html#bib-UAAG">UAAG</a>].</p>
        </div>
      </section>
      <section id="extensions-to-the-element-interface">
        <h3><span class="secno">3.1 </span>Extension to the <code><a title="element"
              class="externalDFN"
              data-spec="HTML5">HTMLImageElement</a></code>
          interface</h3>
        <pre class="idl"><span class="idlInterface" id="idl-def-Element">partial interface <span
class="idlInterfaceID">HTMLImageElement</span> {
<span class="idlAttribute">             attribute <span class="idlAttrType"><a>DOMString</a></span> <span
class="idlAttrName"><a
href="#widl-Element-longdesc">longdesc</a></span>;</span>
};</span></pre>
        <section id="attributes">
          <h4><span class="secno">3.1.1 </span>Attribute</h4>
          <dl class="attributes">
            <dt id="widl-Element-longdesc"><code>longdesc</code> of type <span
                class="idlAttrType"><a>DOMString</a></span></dt>
            <dd>
              <p class="rfc2119">The <dfn id="dfn-dom-element-longdesc"><code>longdesc</code></dfn>
                IDL attribute <em class="rfc2119">must</em> be a valid
                non-empty URL potentially surrounded by spaces. It represents a
                hyperlink to a detailed description of the image its parent <code><a
                    title="element"
                    class="externalDFN"
                    data-spec="DOM4">HTMLImageElement</a></code>
                represents.</p>
            </dd>
            <dd>
              <p>The <code>longdesc</code> IDL attribute <em class="rfc2119">must</em>
                <a href="http://www.w3.org/TR/html5/infrastructure.html#reflect">reflect</a>
                the HTML content attribute <code>longdesc</code>. </p>
            </dd>
            <dd>
              <dl class="note">
                <dt>
                  <p><em>This section is informative</em></p>
                  <p><var>image</var>.<code title="dom-Element-innerHTML">longdesc</code>
                    [ = <var>value</var> ]</p>
                </dt>
                <dd>
                  <p>Returns a DOMString that represents the attribute's
                    contents. </p>
                  <p>Can be set, to replace the contents of the attribute with
                    the given string.</p>
                </dd>
              </dl>
            </dd>
          </dl>
          <pre class="example"><code>//Make the first internal longdesc reference absolute

var baseURL = document.location.origin + document.location.pathname
var someImage = document.querySelector('img[longdesc^=#]');

someImage.longdesc = baseURL + someImage.longdesc;</code></pre>
          <pre class="example"><code>//Open new windows for each longdesc found

var describedImages = document.querySelectorAll('img[longdesc]');

for (i in describedImages) {
  if (i.<strong>longdesc</strong>)
    window.open(i.<strong>longdesc</strong>);
}</code></pre>
          <pre class="example"><code>//Tries to repair errors where the longdesc isn't a URI

var describedImages = document.querySelectorAll('img[longdesc]');

for (i in describedImages) {
  if (i.longdesc &amp;&amp; !(validURL(i.longdesc)) { //assumes some URL validating function
    var theData = encodeURIComponent(i.longdesc);
    i.longdesc = "data:text/plain;charset=";
    i.longdesc += document.charset;
    i.longdesc += theData;
  }
}</code></pre>
        </section>
      </section>
      <section class="appendix" id="acknowledgements">
        <h2><span class="secno">A. </span>Acknowledgements</h2>
        <p>Thanks to the HTML Working Group of the late 1990s for the original
          specification of longdesc, to those who have implemented it in various
          kinds of software, and to many many people involved with the
          development of HTML5 (including but not limited to those who discussed
          "ISSUE-30" in the HTML Working Group, the Protocols and Formats
          Working Group, the W3C Advisory Board, and around countless dinner
          tables, coffee breaks, and elsewhere) for the ideas, discussions and
          contributions that led to the initial draft of this specification.
          With the exception of Laura Carlson, who did far more very valuable
          work than it took me to produce this specification, I haven't named
          them: the list might be larger than the content of the specification.</p>
        <p>For specific comments and suggestions that led to improvements over
          successive drafts of this specification, thanks to the W3C's HTML
          Accessibility Task Force, the W3C Internationalization Working Group,
          and to Jonathan Avila, Robin Berjon, James Craig, Steve Faulkner, John
          Foliot, Geoff Freed, Richard Ishida, Anne van Kesteren, David
          MacDonald, Chris Mills, Jay Munro, Devarshi Pant, Silvia Pfeiffer,
          Leif Halvard Silli, Mathew Turvey and Boris Zbarsky. Any errors are
          despite, not as a result of, their efforts.</p>
      </section>
      <section class="appendix" id="references">
        <h2><span class="secno">B. </span>References</h2>
        <section id="normative-references">
          <h3><span class="secno">B.1 </span>Normative references</h3>
          <dl class="bibliography">
            <dt id="bib-HTML5">[HTML5]</dt>
            <dd>Robin Berjon et. al., eds. <a href="http://www.w3.org/TR/html5/"><cite>HTML5.</cite></a>
              W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/html5/">http://www.w3.org/TR/html5/</a>
            </dd>
            <dt id="bib-RFC2119">[RFC2119]</dt>
            <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
                   words for use in RFCs to Indicate Requirement Levels.</cite></a>
              March 1997. Internet RFC 2119. URL: <a href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a></dd>
            <dt id="bib-WEBIDL">[WEBIDL]</dt>
            <dd>Cameron McCormack. <a href="http://www.w3.org/TR/2011/WD-WebIDL-20110927/"><cite>Web
                   IDL.</cite></a> 27 September 2011. W3C Working Draft. (Work in
              progress.) URL: <a href="http://www.w3.org/TR/2011/WD-WebIDL-20110927/">http://www.w3.org/TR/2011/WD-WebIDL-20110927/</a></dd>
          </dl>
        </section>
        <section id="informative-references">
          <h3><span class="secno">B.2 </span>Informative references</h3>
          <dl class="bibliography">
            <dt id="bib-ATAGB3">[ATAGB3]</dt>
            <dd>Jutta Treviranus et. al., eds. <a href="http://www.w3.org/TR/ATAG20-TECHS/#principle_b3"><cite>Implementing
                   ATAG 2.0</cite></a>, Principle B3 "Authors must be supported
              in improving the accessibility of existing content" October 2011.
              W3C Working Draft. URL: <a href="http://www.w3.org/TR/ATAG20-TECHS/#principle_b3">http://www.w3.org/TR/ATAG20-TECHS/#principle_b3</a></dd>
            <dt id="bib-WCAG2">[WCAG]</dt>
            <dd>Ben Caldwell et. al., eds. <a href="http://www.w3.org/TR/2008/REC-WCAG20-20081211/"><cite>Web
                   Content Accessibility Guidelines 2.0</cite></a>, December
              2008. W3C Recommendation. URL: <a href="http://www.w3.org/TR/2008/REC-WCAG20-20081211/">http://www.w3.org/TR/2008/REC-WCAG20-20081211/</a></dd>
            <dt id="bib-UAAG">[UAAG]</dt>
            <dd>Ian Jacobs et. al., eds. <a href="http://www.w3.org/TR/2002/REC-UAAG10-20021217/"><cite>User
-                  Agent Accessibility Guidelines 2.0</cite></a>, December 2002.
              W3C Recommendation. URL: <a href="http://www.w3.org/TR/2002/REC-UAAG10-20021217/">http://www.w3.org/TR/2002/REC-UAAG10-20021217/</a>.
              A draft for a version 2.0 is available at <a href="http://www.w3.org/TR/UAAG20/">http://www.w3.org/TR/UAAG20/</a></dd>
          </dl>
        </section>
        <section class="appendix" id="changes">
          <h2><span class="secno">C. </span>Change History</h2>
          <p>(This section is not normative)</p>
          <p>Since the <a href="http://www.w3.org/TR/2013/WD-html-longdesc-20130312/">First
-              Public Working Draft</a> substantive changes include:</p>
          <ul>
            <li>Added a requirement that the destination of a <code>longdesc</code>
              <em class="rfc2119">should</em> be "accessible".</li>
            <li>The requirement to present content through the standard User
              Interace was changed from <em class="rfc2119">should</em> to <em
                class="rfc2119">must</em>.
            </li>
            <li>The requirement to present content through the standard User
              Interace was narrowed to apply only to valid values of <code>longdesc</code>.</li>
            <li>The requirement to present content through the Accessibiltiy
              APIs was changed from <em class="rfc2119">should</em> to <em class="rfc2119">must</em>.
            </li>
            <li>The requirement to present content through the Accessibility
              APIs was narrowed to apply only to valid values of <code>longdesc</code>.</li>
            <li>The IDL attribute <code>longdesc</code> was changed to <a href="http://www.w3.org/TR/html5/infrastructure.html#reflect">reflect</a>
              the HTML content attribute <code>longdesc</code>.</li>
          </ul>
          <p>Editorial changes include:</p>
          <ul>
            <li>Clarifying that the document does not define "accessible",
              except that it is used in the sense that it is used in [<a href="#bib-WCAG2">WCAG</a>].</li>
            <li>Sectioning requirements according to whom they apply.</li>
            <li>Removed the statement that User Agents <em title="may" class="rfc2119">may</em><em
                title="optional"
                class="rfc2119"></em>
              present descriptions which are erroneously included in the content
              instead of a link.</li>
            <li>Added more examples</li>
          </ul>
        </section>
      </section>
    </section>
  </body>
</html>
\ No newline at end of file
+                  Agent Accessibility Guidelines 1.0</cite></a>, December 2002.
              W3C Recommendation. URL: <a href="http://www.w3.org/TR/2002/REC-UAAG10-20021217/">http://www.w3.org/TR/2002/REC-UAAG10-20021217/</a>.
              A draft for a version 2.0 is available at <a href="http://www.w3.org/TR/UAAG20/">http://www.w3.org/TR/UAAG20/</a></dd>
          </dl>
        </section>
        <section class="appendix" id="changes">
          <h2><span class="secno">C. </span>Change History</h2>
          <p>(This section is not normative)</p>
          <p>Since the <a href="http://www.w3.org/TR/2013/WD-html-longdesc-20130312/">First
+              Public Working Draft</a> substantive changes include:</p>
          <ul>
            <li>Added a requirement that the destination of a <code>longdesc</code>
              <em class="rfc2119">should</em> be "accessible".</li>
            <li>The requirement to present content through the standard User
              Interface was changed from <em class="rfc2119">should</em> to <em
                class="rfc2119">must</em>.
            </li>
            <li>The requirement to present content through the standard User
              Interface was narrowed to apply only to valid values of <code>longdesc</code>.</li>
            <li>The requirement to present content through the Accessibility
              APIs was changed from <em class="rfc2119">should</em> to <em class="rfc2119">must</em>.
            </li>
            <li>The requirement to present content through the Accessibility
              APIs was narrowed to apply only to valid values of <code>longdesc</code>.</li>
            <li>The IDL attribute <code>longdesc</code> was changed to <a href="http://www.w3.org/TR/html5/infrastructure.html#reflect">reflect</a>
              the HTML content attribute <code>longdesc</code>.</li>
          </ul>
          <p>Editorial changes include:</p>
          <ul>
            <li>Clarifying that the document does not define "accessible",
              except that it is used in the sense that it is used in [<a href="#bib-WCAG2">WCAG</a>].</li>
            <li>Sectioning requirements according to whom they apply.</li>
            <li>Removed the statement that User Agents <em title="may" class="rfc2119">may</em><em
                title="optional"
                class="rfc2119"></em>
              present descriptions which are erroneously included in the content
              instead of a link.</li>
            <li>Added more examples</li>
          </ul>
        </section>
      </section>
    </section>
  </body>
</html>
\ No newline at end of file