Edit comment LC-2791 for Accessibility Guidelines Working Group

Previous: LC-2800 Next: LC-2792

Comment LC-2791: Comment Shortname:; Commenter: Laura Carlson <laura.lee.carlson@gmail.com>; Message-id:; Section of the document concerned:

or; Refinement of the section concerned:; Status:
assigned to; Type:; Resolution status:
Response drafted Resolution implemented Reply sent to commenter; Response status:
No response from Commenter yet Commenter approved disposition Commenter objected to disposition
Commenter's response (URI):; Comment:
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">

<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.; Related issues: (space separated ids); WG Notes: AWK updated respoonse; Resolution: Thank you for your comment. The WG agrees that an example detailing this method may help people understand how this works and what limitations exist. We will add an additional paragraph to the description and example 2 will be added as follows: [DONE] description new second paragraph: Authors can provide a description for an image by including text in a separate resource or within the text of the page containing the image. An advantage of providing the description within the same page as the image is that all users can access the description. A limitation of this method, as well as in providing multiple descriptions on a single separate page, is that current implementations supporting longdesc read all text on the page that follows the start of the long description. As a result, an end user may hear the long description and all content on the page following it, without knowing where the long description is intended to end unless authors provide text to help users identify the end-point of the description. [DONE] Example 1: Using longdesc to refer to a long description contained on a separate resource. (title of example changed to clarify) [DONE] Example 2: Using longdesc to refer to a long description within the same page. <img longdesc="thispage.html#desc" alt="Line graph of the number of subscribers" src="http://www.company/images/graph.png"> <div id="desc">  <div>; (Please make sure the resolution is adapted for public consumption)