steve: added info about use of null alt attribute

steve: added info about use of null alt attribute

http://dev.w3.org/cvsweb/html5/alt-techniques/Overview.html?r1=1.53&r2=1.54&f=h

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RCS file: /sources/public/html5/alt-techniques/Overview.html,v
retrieving revision 1.53
retrieving revision 1.54
diff -u -d -r1.53 -r1.54
--- Overview.html 22 Jul 2010 13:06:18 -0000 1.53
+++ Overview.html 16 Aug 2010 10:53:11 -0000 1.54
@@ -158,7 +158,7 @@
  </head>
 <body>
 <div class="head"><p><a href="http://www.w3.org/"><img width="72" height="48" src="http://www.w3.org/Icons/w3c_home" alt="W3C"></a></p><h1 class="title" id="title">HTML5:  Techniques for providing useful text alternatives</h1>
-<h2 id="w3c-working-draft-05-may-2010"><acronym title="World Wide Web Consortium">W3C</acronym> Editor's Draft 6 July 2010</h2>
+<h2 id="w3c-working-draft-05-may-2010"><acronym title="World Wide Web Consortium">W3C</acronym> Editor's Draft 16 August 2010</h2>
 <dl><!-- <dt>This version:</dt>
 <dd><a href="http://www.w3.org/TR/2010/WD-html-alt-techniques-20100624/">http://www.w3.org/TR/2010/WD-html-alt-techniques-20100624/</a></dd><dt>Latest published version:</dt> -->
   <!-- <dd><A href="http://www.w3.org/TR/html-alt-techniques/">http://www.w3.org/TR/html-alt-techniques/</A> </dd> --><dt>Latest editor's draft:</dt><dd><a href="http://dev.w3.org/html5/alt-techniques/">http://dev.w3.org/html5/alt-techniques/</a></dd>
@@ -306,13 +306,13 @@
   <li>An image is not meant to be <a href="#img-not-for-user">visible to any user</a>.</li>
   <li>An image consists of text that is repeated as text or a <a href="#icons">graphical symbol</a> whose meaning is conveyed as text, immediately before or after the image.</li>
   <li>The image is part of a <a href="#imgslices">group of images</a> that  form a single larger picture and one of the other images in the group has a text alternative which serves as the text alternative for the single larger picture.</li>
-  <li>The image is included as the content of a link and there is <a href="#hav">other content included</a> that clearly describes the link target.</li>
+  <li>The image is included as the content of a link and there is <a href="#hba">other content included</a> that clearly describes the link target.</li>
 </ul>
 <p>Circumstances in which <strong>it is not</strong> appropriate to use an empty or null <code>alt</code> attribute:</p>
 <ul>
-  <li>An image is contained within a <code>figure</code> element and has an associated caption provided using the <code>figcaption</code> element.</li>
-  <li>An image contains relevant information not available in the same document as text.</li>
-  <li>An image contains relevant information,  an interpretation of which is available in the same document as structured text.</li>
+  <li>An image is contained within a <code>figure</code> element and has an associated caption provided using the <code>figcaption</code> element. Using an empy alt attribute hides an image from some users. If an image has a caption the image needs to be discoverable by users, otherwise a caption is present that refers to nothing for some users.</li>
+  <li>An image contains relevant information not available in the same document as text. Using an empy alt attribute hides an image from some users, in order to have the possibility of interrogating the image, the image must be discoverable.</li>
+  <li>An image contains relevant information,  an interpretation of which is available in the same document as structured text. Using an empy alt attribute hides an image from some users. If a description of an image is provided in a document, a <a href="#hpa">programmatic association</a> between the image and the descriptive text is required, using an empty alt attribute on the image effectively precludes the assigning of a programmatic association.</li>
   <li class="note">to do</li>
 </ul>
 <h6 id="he">How long should a short text alternative be?</h6>
@@ -1127,6 +1127,8 @@
 <p>Hardware and/or software that acts as a user agent, or along with a mainstream user agent, to provide functionality to meet the requirements of users with disabilities that go beyond those offered by mainstream user agents. A more <a href="http://www.w3.org/TR/WCAG20/#atdef">detailed explanation of assistive technology</a> is provided in the WCAG 2.0 glossary.</p>
 <h3 id="hbr">content (Web content) </h3>
 <p>Information and sensory experience to be communicated to the user by means of a user agent such as a web browser, including code or markup that defines the content's structure, presentation, and interactions. </p>
+<h3 id="hpa">programmatic association</h3>
+<p>It must  be possible for people using assistive technologies to find   the text alternative for an image when they encounter the image that they cannot   use. To accomplish this,  the text must be "programmatically   associated" with the image. This means that the user must be able to   use their assistive technology to find the alternative text (that they can use)   when they land on the image (that they can't use).</p>
 <h3 id="hbs">non-text content </h3>
 <p>Any content that is not a sequence of characters that can be programmatically determined or where the sequence is not expressing something in human language </p>
 <p>Note: This includes ASCII Art (which is a pattern of characters), emoticons, leetspeak (which uses character substitution), and images representing text. </p>

Received on Monday, 16 August 2010 10:54:00 UTC