W3C home > Mailing lists > Public > public-html-a11y@w3.org > August 2013

FW: longdesc extension question

From: Andrew Kirkpatrick <akirkpat@adobe.com>
Date: Fri, 23 Aug 2013 16:09:08 +0000
To: "public-html-a11y@w3.org" <public-html-a11y@w3.org>
Message-ID: <EE43A638A0C5E34E80AF78EFE940FC2C10B9720D3C@nambx09.corp.adobe.com>
Forwarding to HTML A11Y TF per Chaals's suggestion.


Andrew Kirkpatrick
Group Product Manager, Accessibility
Adobe Systems 



-----Original Message-----
From: Charles McCathie Nevile [mailto:chaals@yandex-team.ru] 
Sent: Thursday, August 22, 2013 6:00 AM
To: Andrew Kirkpatrick
Subject: Re: longdesc extension question

Hi Andrew

(this is a good question, and I would love to have it in public - feel free to forward my response...)

On Wed, 21 Aug 2013 00:57:54 +0500, Andrew Kirkpatrick <akirkpat@adobe.com> wrote:

> Hi Chaals,
> I'm looking at the longdesc extension and also a couple of the WCAG 
> techniques and have a question.  It seems that a key problem with the 
> implementations of longdesc today (well, at least JAWS and NVDA) is 
> that when you activate the longdesc feature for an image they load the 
> page with the longdesc and start reading at the required place.  As 
> some people are advocating for same-page references or many longdesc 
> descriptions on a single separate page this is a problem because JAWS 
> and NVDA don't know where the longdesc stops, just where it starts. As 
> a result, a user listening to the longdesc for all three images in the 
> following example would hear information about "a" once, "b" twice, 
> and "c" three times.
> So the question is:  Is there anything in the spec that requires that 
> user agents read only the content contained within the HTML object 
> with the matching id reference?

No, but there is a "should" requirement on authors:

'Authors should put descriptions within an element which is the target of a fragment link (e.g. longdesc="example.html#description") if a description is only part of the target document.'

which is intended to allow for such behaviour.

In general the spec tries to go lightly on requirements for user agents - it was somewhat controversial to require that they actually make the longdesc available to users in the first place ;(



> Sample.html
> <img alt="a" longdesc="descs.html#a">
> <img alt="b" longdesc="descs.html#b">
> <img alt="c" longdesc="descs.html#c">
> Descs.html
> <div id="a"><p>This is my longdesc for a</p></div> <div id="b"><p>This 
> is my longdesc for b</p></div> <div id="c"><p>This is my longdesc for 
> c</p></div>
> Thanks,
> Andrew Kirkpatrick
> Group Product Manager, Accessibility
> Adobe Systems
> akirkpat@adobe.com<mailto:akirkpatrick@adobe.com>
> http://twitter.com/awkawk

> http://blogs.adobe.com/accessibility


Charles McCathie Nevile - Consultant (web standards) CTO Office, Yandex
       chaals@yandex-team.ru         Find more at http://yandex.com

Received on Tuesday, 27 August 2013 17:09:51 UTC

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