W3C home > Mailing lists > Public > w3c-wai-gl@w3.org > July to September 1999

RE: longdesc media type concern

From: Gregg Vanderheiden <gv@trace.wisc.edu>
Date: Sun, 5 Sep 1999 23:04:31 -0500
To: "'Charles McCathieNevile'" <charles@w3.org>, "'Jason White'" <jasonw@ariel.ucs.unimelb.EDU.AU>, "'GL - WAI Guidelines WG (E-mail)'" <w3c-wai-gl@w3.org>
Cc: "'WAI Protocols and Formats'" <w3c-wai-pf@w3.org>
Message-ID: <004001bef7da$79d843a0$c934fea9@gregg>

I'm still thinking about what should be allowed off of a LONGDESC.

I am averse to using an element for something other than its intended
purpose just because it could be.

SO.  That leaves me thinking..

-What is the purpose of LONGDESC?

- What are the other uses that are being considered for it?

- Could they be done other ways?  Would that not be better?
(e.g.  if other descriptive information could be attached to a LONGDESC
link... why not have that info on the home page.

_- Of PRIMARY concern, is the ability to easily and automatically pull a
text description from the LONGDESC link on the main page without having to
go through multiple links or search another page to find it.  I'm not seeing
that in the descriptions I've heard..



-- ------------------------------
Gregg C Vanderheiden Ph.D.
Professor - Human Factors
Dept of Ind. Engr. - U of Wis.
Director - Trace R & D Center
Gv@trace.wisc.edu, http://trace.wisc.edu/
FAX 608/262-8848
For a list of our listserves send "lists" to listproc@trace.wisc.edu

 -----Original Message-----
From: 	w3c-wai-pf-request@w3.org [mailto:w3c-wai-pf-request@w3.org]  On
Behalf Of Charles McCathieNevile
Sent:	Thursday, August 26, 1999 11:17 PM
To:	Jason White
Cc:	WAI Protocols and Formats
Subject:	Re: longdesc media type concern

There are a couple of things at work here.

longdesc is a specific fix provided for IMG to allow it to handle (by
reference) multiple types of content. For HTML until version 4.0 IMG is the
only element available to include mutlimedia content. Although the
specification talks exclusively about images, there are blurred lines. For
example, animated gifs are pretty common on the web. Although most of them
are a few frames, I have watched video clips of more than a hunndred frames
rendered with an animated gif. There does not seem to be a clear line
an image and a video presentation.

So I did a straw poll among a group of people who are not representative of
anything really, and the consensus seemed to be that there is not a problem
using IMG to include a video (although the person I asked who knows HTML
wanted to know why you didn't use object).

Gregg expressed a concern in the meeting that a longdesc could be used to
present something more than the IMG which it describes. I think that it is a
mistake to rely on longdesc to include content which is not reproduced in
general - that should be clear from the guidelines. But there is a judgement
call on how much information the object referred to by the IMG represents.

So I would be unhappy about the idea that longdesc should be text. I could
live with it being hypertext, because that allows the inclusion of multiple
media. And I think that the IMG element should be deprecated and we should
look to better solutions for the problem such as SMIL and the object
In the current specifications nothing is said about the resource type which
is expected from a longdesc, and I think that is how it should be.

charles McCN

--Charles McCathieNevile            mailto:charles@w3.org
phone: +1 617 258 0992   http://www.w3.org/People/Charles
W3C Web Accessibility Initiative    http://www.w3.org/WAI
MIT/LCS  -  545 Technology sq., Cambridge MA, 02139,  USA
Received on Monday, 6 September 1999 00:05:26 UTC

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