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Re: LONGDESC: some current problems and a proposed solution added to the wiki

From: Lachlan Hunt <lachlan.hunt@lachy.id.au>
Date: Sat, 30 Jun 2007 21:35:20 +1000
Message-ID: <46863FF8.70802@lachy.id.au>
To: Peter Krantz <peter.krantz@gmail.com>
CC: public-html@w3.org

Peter Krantz wrote:
> Problems with the current longdesc method:
> - Assistive devices need to make an extra HTTP request to retrieve the 
> content. A risk for availability problems.

I don't think that's a major issue, since the risk of being unable to 
access a long description is equal to the risk of being unable to access 
the content of any other page that is linked to.

> - It is unclear how the web page containing the extended description
> should look. If it includes the web site navigation toolbars and
> headers it increases the time to reach the content for the user.

This issue can be be resolved by giving guidance in the spec and/or 
other accessibility related guidelines.

> - Search engines need to make an extra request to get information
> about the image.

Do search engines bother to make use of longdesc?  I don't believe they 
do.  Even if they did, why is that an issue?

> - It is difficult to script usage of the extended content to e.g.
> display it in a popup when hovering the image.
> - Forcing the user to navigate to a separate page increase the risk
> for usability problems (do they know they can click the image?).

The method used to reveal the long description is up to the assistive 
technology.  It doesn't need to navigate away from the page as if 
following an ordinary link, it could reveal it in a separate context 
instead (e.g. a side bar or popup).  Authors certainly shouldn't attempt 
to override the UAs behaviour by using scripts in this case, since 
interfering with that is likely to cause more problems that it solves. 
Just let the UA do its job and deal with the issue of how to give the 
user access to the page.

Lachlan Hunt
Received on Saturday, 30 June 2007 11:35:37 UTC

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