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Re: New issue: IMG section of HTML5 draft contradicts WCAG 1 & WCAG 2 (draft)

From: Christophe Strobbe <christophe.strobbe@esat.kuleuven.be>
Date: Mon, 14 Apr 2008 17:26:31 +0200
Message-Id: <>
To: W3C WAI-XTECH <wai-xtech@w3.org>

Dear Henri Sivonen,

At 15:08 14/04/2008, Henri Sivonen wrote:
>In summary:
>Requiring alt to have a value when a proper value is not available
>leads to developers of HTML generators to put junk into the alt value
>when a proper value *is not available* to the software. Putting junk
>there is information loss compared to signaling the unavailability.
>Information loss is bad, because then UAs have less information to
>work with in order to function to the benefit of users. To avoid this
>badness, alt must be allowed to be absent when the piece of software
>that would generate it doesn't have the data that it should put there.
>(Insisting that a page not be generated at all when alternative text
>is not available is not realistic.)
>>So the previous input concluded  that the draft should be fixed to
>>_keep_ it required until an alternate plan for providing the
>>required by WCAG is available,
>The whole point is that there are HTML generators that *do not have*
>the information that would be needed to generate a WCAG-compliant page
>because someone else did not provide it. Why require the impossible
>(generating a page with information that doesn't exist to the
>generator software)? Why not admit that HTML *syntax* and
>accessibility are different things and that some generators at least
>under some circumstances produce HTML that is syntactically correct
>(i.e. no typos in markup) but is not accessible for everyone?

If HTML 5 were to specify certain values (e.g. "_notsupplied" and 
"_decorative") that would need to be used when real text alternative 
cannot be provided (as John Foliot proposed at 
<http://lists.w3.org/Archives/Public/wai-xtech/2008Apr/0094.html> and 
these values could be a technique to meet the last item of success 
criterion 1.1 of WCAG 2.0 
(<http://www.w3.org/TR/2007/WD-WCAG20-20071211/#text-equiv-all> in 
the current draft):
"If it [= non-text content] is pure decoration, or used only for 
visual formatting, or if it is not presented to users, then it is 
implemented in a way that it can be ignored by assistive technology."

This would not "require the impossible". It would allow us to keep 
the alt attribute as a required attribute in HTML 5, and allow sites 
with file upload functions to meet success criterion 1.1 of WCAG 2.0.

Best regards,


>Henri Sivonen

Please don't invite me to LinkedIn, Facebook, Quechup or other 
"social networks". You may have agreed to their "privacy policy", but 
I haven't.

Christophe Strobbe
K.U.Leuven - Dept. of Electrical Engineering - SCD
Research Group on Document Architectures
Kasteelpark Arenberg 10 bus 2442
B-3001 Leuven-Heverlee
tel: +32 16 32 85 51

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Received on Monday, 14 April 2008 15:27:26 UTC

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