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Re: [text] starter draft of clarification on alt validation, for discussion

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Tue, 26 Apr 2011 16:54:44 +0200
To: Richard Schwerdtfeger <schwer@us.ibm.com>
Cc: Judy Brewer <jbrewer@w3.org>, HTML Accessibility Task Force <public-html-a11y@w3.org>, faulkner.steve@gmail.com
Message-ID: <20110426165444395471.74225202@xn--mlform-iua.no>
Richard Schwerdtfeger, Tue, 26 Apr 2011 08:33:42 -0500:
> Judy,
> Steve and I met on the alt="" and role="presentation" discussion. Please
> make the following change to the response:
> <change>
  [ snip ]
> </change>
> <to>
> The default semantics for and image with alt="" is role="presentation". The
> accessibility API mapping is such that, when alt="", the <img> element is
> removed from the accessibility API tree to improve assistive technology
> performance as well as browser performance in that the browser is not
> maintaining accessible objects for these presentational elements.
> Applications, such as those from IBM, have used role="presentation" to
> remove these objects from the accessibility tree as HTML4 does not have the
> same mapping as we have specified for HTML 5. So, not allowing alt="" and
> role="presentation" to be used interchangeably violates consistency with
> the default HTML 5 semantics and is inconsistent with the ARIA
> specification.
> </to>

This only gives a justification from an ARIA point of view. The 
validator is also supposed to help the author avoid wasting his/her 
time. E.g. to avoid the problem that the user agent auto-generates a 
'Image' text for the lacking @alt. The intent of the author can of 
course be spotted by the validator when he/she adds role=presentation. 
So the validator should ask the author to add empty alt. I would 
recommend to explain why the validator should only have ARIA supporting 
AT in mind when it decides what validataes.

It is unclear to me how permission to add @role=presentation without 
simultaneously adding @alt "violates consistency with the default HTML 
5 semantics". I also don't see how it is inconsistent with ARIA. How is 
it inconsistent with ARIA?
leif halvard silli
Received on Tuesday, 26 April 2011 14:55:18 UTC

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