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Techniques for WCAG 2.0 H45 longdesc: Missing on-page description example

From: Laura Carlson <laura.lee.carlson@gmail.com>
Date: Mon, 15 Jul 2013 06:43:59 -0500
Message-ID: <CAOavpvf05d2iRAvPi9i13MmCW_MxXv7C9HkhvBga8H3iSAtL-A@mail.gmail.com>
To: public-comments-wcag20@w3.org
Cc: Charles McCathieNevile <w3b@chaals.com>
Hi WCAG,

1. Title of the document

H45: Using longdesc

2. Location within the document

"Examples"
http://www.w3.org/WAI/GL/2013/WD-WCAG20-TECHS-20130711/H45.html#H45-examples

3. Concern

H45 is missing example longdesc syntax for an on-page description. If
the long text alternative of an image is useful to all users, keeping
it in plain view in the same document and using longdesc for screen
reader users to programmatically obtain it is a good option. That way
everyone can read it.

4. Suggested change

Add something like:

If the long text alternative of an image is useful to all users,
keeping it in plain view in the same document and using longdesc for
screen reader users to programmatically obtain it is a good option.
That way everyone can read it. By using a fragment identifier,
longdesc may be used to link to a description within the same
document. The syntax is:

<img
 longdesc="#desc"
 alt="Line graph of the number of subscribers"
 src="http://www.company/images/graph.png">
<div id="desc">
 <!-- Full Description of Graph -->
<div>

4. Additional rationale for the comment

This technique is specified in the HTML5 Image Description Extension (longdesc).

Use Case:
"Linking to a description included within a page
If an image already has a description included within a page, making
the linkage explicit can provide further clarity for a user who is not
able to interpret the default layout. For example this happens when
users force a re-layout of the page elements because they have
magnified the content, or because they do not see the default visual
relationship between the element and its description.
This practice also enables description to be provided for all users.
By keeping the association clear the content maintainer can more
easily check that the description and link are actually correct."
http://dvcs.w3.org/hg/html-proposals/raw-file/default/longdesc1/longdesc.htm#use-cases

Example:
http://dvcs.w3.org/hg/html-proposals/raw-file/default/longdesc1/longdesc.html#intro

Please add an explanation and example to Techniques for WCAG 2.0 document H45.

Thank you.

Best Regards,
Laura
--
Laura L. Carlson
Received on Monday, 15 July 2013 11:45:42 UTC

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