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Re: Request for review of alt and alt value for authoring or publishing tools

From: Ian Hickson <ian@hixie.ch>
Date: Tue, 15 Apr 2008 18:20:14 +0000 (UTC)
To: Laura Carlson <laura.lee.carlson@gmail.com>
Cc: Jutta.treviranus@utoronto.ca, jimallan@tsbvi.edu, jan.richards@utoronto.ca, shadi@w3.org, Alfred.S.Gilman@ieee.org, wai-xtech@w3.org, wai-liaison@w3.org, cooper@w3.org, public-html@w3.org
Message-ID: <Pine.LNX.4.62.0804151756510.3690@hixie.dreamhostps.com>

On Tue, 15 Apr 2008, Laura Carlson wrote:
> 
> As PFWG is aware [1], the HTML 5 working group is questioning and 
> debating the need for the alt attribute on "critical content".

This is a blatent mischaracterisation of the debate. Nobody is questioning 
or debating the need of the attribute. The spec goes to extreme lengths to 
require that the attribute be included, and even provides over 20 examples 
of how to write alternative text. The debate is over whether the alt="" 
attribute should be included (with a forcibly bogus value) in the rare 
cases where the author (typically an automated tool) simply does not know 
what the image represents and cannot write appropriate and accessibility- 
improving alternative text, or whether in such cases the ATs should be 
given a signal that the image, despite its importance, does not have a 
proper substitute provided.


> In particular one case in the HTML 5 Draft states:

The text you quote is obsolete; the spec has been updated several times 
since then. It is now even more forceful about requiring alt="" text.

The actual text is here:

   http://www.whatwg.org/specs/web-apps/current-work/multipage/section-embedded0.html#alt

In particular, scroll down to "A key part of the content".


> a. No alt attribute provided as stated in the current draft <img 
> src="vexed.jpg">
> 
> b. An alt attribute with some type of standardized reserved value to 
> indicate that the image is "critical content" but the author has not 
> supplied a text alternative. (example value for the purposes of 
> illustration only) <img src="vexed.jpg" alt="?">or <img src="vexed.jpg" 
> alt="_none">
> 
> c. An attribute separate from the alt that serves to indicate that the 
> image is "critical content", but no text alternative has been provided. 
> <img src="vexed.jpg" alt="" noalt> or <img src="vexed.jpg" noalt>

All of the above are, from an accessibility point of view, equivalent, 
they are merely syntactic variants of each other.


> d. A null alt <img src="vexed.jpg" alt="">

This would be significantly worse than the above, as it labels a critical 
image as decorative. That anyone who claims to be interested in 
accessibility even suggests this is worrisome.


> e. Further potential solutions are listed at:
> http://esw.w3.org/topic/HTML/IssueAltAttribute#head-27468e7ee9afd1f9e07186c8d74f0b0168b3975a

The only actual solution suggestion I see there is alt="1", alt="2", etc, 
but it is unclear how that would improve accessibility. The other options 
are either non-options, e.g. requiring the image to be described, or 
merely ways to move the problem elsewhere, e.g. saying the document is 
"unready", or that the image isn't Web content and therefore doesn't need 
to be accessible (!).


> Your expert review and advice regarding this edge-case scenario, as well 
> as your ideas for other solutions would be indispensable to HTML5.

Any input on how to handle images for which alternative text is simply not 
available would be very welcome.

In particular, it would also be good if the WCAG documents could be 
updated to handle this case.

Note that in many of these cases, putting the caption or other metadata in 
the alt="" attribute would be harmful as it would merely duplicate 
information already available elsewhere on the page. (I mention this 
merely because WCAG does currently suggest giving such text in some cases, 
but this doesn't help when such text is already available outside of the 
<img> element.)

Thanks in advance for any feedback,
-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Tuesday, 15 April 2008 18:21:10 GMT

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