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Re: Call for Review: HTML5 Image Description Extension (longdesc) Last Call

From: Charles McCathie Nevile <chaals@yandex-team.ru>
Date: Wed, 11 Dec 2013 14:15:18 +0400
To: "HTML Accessibility Task Force" <public-html-a11y@w3.org>, "Matthew Turvey" <mcturvey@gmail.com>, "James Craig" <jcraig@apple.com>
Message-ID: <op.w7xarsepy3oazb@dhcp-219-197-wifi.yandex.net>
James, Matt,

Thank you for your feedback. I apologise for the length of time it has  
taken to provide a formal response, but here it is.

We agree that it would be inappropriate to rely solely on longdesc where  
standards exist to support accessibility more directly, instead of e.g.  
providing a MathML version of mathematical content, or using the native  
accessibility features of SVG. However, even in these cases many users of  
current-generation technologies which don't support those standards well  
can benefit from the discoverability and access provided by longdesc.

We disagree that an "ordinary" link provides the same discoverability as  
longdesc in the general case.

We have added the following text to the section on Authoring requirements  
to further clarify when longdesc is appropriate:

Suggested Spec Addition:

"Authors SHOULD NOT rely solely on longdesc where standards exist to  
provide direct, structured access. Note: (informative) For example a  
MathML version of mathematical content, or an SVG image that uses the  
accessibility features of SVG, can provide better accessibility to users  
with appropriate technology. In such cases, it is appropriate to use  
longdesc as a fallback strategy, in combination with more modern  

Please let us know if you are satisfied with this resolution, or would  
like to maintain a formal objection.


TF co-coordinator

On Tue, 16 Jul 2013 22:19:40 +0400, Matthew Turvey <mcturvey@gmail.com>  

> On 16 July 2013 18:40, James Craig <jcraig@apple.com> wrote:
>> I have an additional suggestion that I believe would help the  
>> acceptance of this document within the general working group. Add an  
>> informative section detailing several of the many cases where it is  
>> inappropriate to use @longdesc. For example…
>> 1. @longdesc is inappropriate when an EPUB footnote is sufficient.
>> 2. @longdesc is inappropriate for Math. Use MathML instead.
>> 3. @longdesc is inappropriate for SVG graphics. Make the SVG DOM  
>> accessible instead.
>> 4. @longdesc is inappropriate for graphics of tabular data. Use an  
>> accessible table instead.
>> More examples at http://cookiecrook.com/longdesc/
>> These should probably be added to the WCAG 2.0 Techniques documents as  
>> well.
> I'd also add:
> 5. @longdesc is inappropriate when a normal link is sufficient. Example:
> <a href="descrip"><img src="pic" alt="*the purpose of the link*"></a>
> -Matt

Charles McCathie Nevile - Consultant (web standards) CTO Office, Yandex
       chaals@yandex-team.ru         Find more at http://yandex.com
Received on Wednesday, 11 December 2013 10:15:48 UTC

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