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Re: Is longdesc a good solution? (was: Acessibility of <audio> and <video>)

From: James Craig <jcraig@apple.com>
Date: Fri, 5 Sep 2008 19:56:59 -0700
Cc: public-html@w3.org, W3C WAI-XTECH <wai-xtech@w3.org>
Message-Id: <B9B7EE3D-9E25-4D73-9F4E-6E1857A39C3F@apple.com>
To: Justin James <j_james@mindspring.com>

Justin James wrote:

> James Craig wrote:
>> I'd disagree with you on the usefulness of longdesc as a standard
>> description mechanism. There is a better, in-document alternative  
>> now:
>> ARIA's describedby property, which is also implemented in more
>> browsers than longdesc.
>
> I'm not an ARIA expert (which is why I didn't consider it for this),  
> but I
> *am* an ARIA convert. If ARIA supports identical information as  
> longdesc
> does, I am in favor of it over using an attribute, simply because I  
> think
> that "people who really care" will be using ARIA, and overall I find  
> the
> system practical.

I would call it "equivalent," rather than "identical" functionality,  
since longdesc is intended to be an external resource, and aria- 
describedby is intended to be internal resource. For example, a DIV  
representing an image could be marked to indicate that the caption  
text is its long description:

<div role="img" aria-labelledby="myImage" aria-describedby="myCaption">
	<img id="myImage" src="img.png" alt="Chart showing Candidate X's 12%  
lead."  />
	<p id="myCaption">
		Chart shows the breakdown of counties supporting Candidate X and  
Candidate Y.
		Candidate X is leading in all but three counties, with a 12% lead  
overall.
	</p>
</div>

That said, there is nothing to stop you using it in a similar way to  
longdesc, where aria-describedby would pointed to a link that  
referenced an external file. It'd be interesting to see if browsers  
and AT supported using it in this way though.

<div role="img" aria-labelledby="myImage" aria- 
describedby="myLongDescription">
	<img id="myImage" src="img.png" alt="Chart showing Candidate X's 12%  
lead."  />
	<a id="myLongDescription" href="fullData.html" rel="longdesc">
		Spreadsheet including full data set referenced in this chart.
	</a>
</div>

Cheers,
James
Received on Saturday, 6 September 2008 02:57:43 UTC

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