W3C home > Mailing lists > Public > public-html@w3.org > September 2012

RE: Proposed rewording of ISSUE-204 text to address outstanding technical issues

From: John Foliot <john@foliot.ca>
Date: Mon, 10 Sep 2012 19:30:39 -0700
To: "'Maciej Stachowiak'" <mjs@apple.com>
Cc: "'Edward O'Connor'" <eoconnor@apple.com>, <public-html@w3.org>, "'HTML Accessibility Task Force'" <public-html-a11y@w3.org>
Message-ID: <008c01cd8fc5$70f6bc80$52e43580$@ca>
Maciej Stachowiak wrote:
> 
> To provide further context: how is this context being referenced? Is it
> via a <td headers=""> attribute? Via <img usemap="">? Or something
> else? If it just appears in the document without being referenced at
> all, the proposal is pretty clear that it would not be presented in any
> modality.
> 
> I think that might affect the answers to your questions.

Sure.  Here is some real, live code:

<tr>
  <th colspan="6" style="text-align:left;" id="dv"> 
    <a
href="http://www.w3.org/WAI/PF/HTML/wiki/Media_Accessibility_Requirements#De
scribed_video" class="external text">Described video</a>
  </th>
</tr>
<tr>
  <th headers="dv ref" id="dv1"> (DV-1)</th>
  <td headers="dv req"> Provide an indication that descriptions are
available, and are active/non-active.</td>
  <td headers="dv tech"> UX</td>
  <td headers="dv wcag"> AA <br /><a
href="http://www.w3.org/TR/2008/REC-WCAG20-20081211/#navigation-mechanisms-d
escriptive" class="external text"
title="http://www.w3.org/TR/2008/REC-WCAG20-20081211/#navigation-mechanisms-
descriptive" rel="nofollow">2.4.6 </a></td>
  <td headers="dv uaag"> A <br /><a
href="http://www.w3.org/TR/UAAG20/#gl-access-alternative-content"
class="external text"
title="http://www.w3.org/TR/UAAG20/#gl-access-alternative-content"
rel="nofollow">UAAG 3.1.1</a></td>
  <td headers="dv msm"> must</td>
</tr>

Source: http://www.w3.org/WAI/PF/HTML/wiki/Media_Accessibility_Checklist 

As James noted, he has seen instances where certain <th>s have been hidden
visually, yet still referenced by screen readers.  

Use-Case:
What would happen if, in the first row above, either the row (<tr>) or the
header (<th>) took the @hidden attribute?

A screen reader could use the headers/id association here: "<td headers="dv
msm"> must</td>", and the hyperlink to the named anchor that is referenced
in Described Video would be spoken aloud as part of the "full semantic"
expression, but where would the visible tab focus be shown? 


Moving on here, Ted and James have taken pains to not include ARIA in the
new text, simply suggesting that something that is hidden could still take
semantic 'fullness'.  They have brought forth 2 examples: <td headers="">,
<img usemap="">), but leave the door open for others - but what others would
there be?  What other elements use a mechanism that references IDs without
invoking ARIA?  If all we have is headers= and usemap=, then why not just
say so?

And what *if* an author did something as above, and used a @hidden header
with a hyperlink in it? Would Safari/VoiceOver expose the link in the modal
dialog you explained earlier? Is this what we should expect consistently in
User Agents that would support this technique? 

As I have previously noted, there is a tension between under-specification
and over-specification, and left too under-specified here delivers us to a
situation similar to @longdesc: a good idea that was initially
under-specified in its implementation, and thus pilloried and derided down
the road.  

I don't want to see that happen to something that is supposed to benefit
accessibility ever again!

JF
Received on Tuesday, 11 September 2012 02:31:11 GMT

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