Long description and image on same page (was RE: [techs] Summary of techniques teleconference 22 September 2004)

Sailesh writes
<blockquote>
Hello John /  Gez,
Gez asked
Does it still give the same results if the longdesc attribute was
marked up with the page name, along with the document fragment
identifier?
Sailesh:
Nope. Even WinEyes does not recognize longdesc on same page. Both JAWS
and WinEyes do nothing even if you give full path of longdesc  that
links to same page.
Actually, I wonder why one should give detailed description of the img
on the same page.  It is text equivalent info meant for those who cannot
see the image. So it will clutter up the page  if it is on the same page
and might be a usability issue for sighted users unless of course the
longdesc contains some explanation of the image etc. which serves all
users. Then why use longdesc... just link to it. 
[JMS] </blockquote>
You've got it, Sailesh: there are many cases where description and
explanation/interpretation of a complex imageis the entire point of a
document-- this is true in fields like art history, film studies,
descriptive bibliography (sometimes, anyway), archaeology,
architecture... sometimes in historical writing... sometimes in
scientific writing.
 
It's entirely possible that longdesc isn't the best technique to use,
and in fact an explicit text link might not always be the best thing
either-- I would be interested in finding/learning about techniques that
would establish an explicit association between an image and its
description that don't necessarily employ a linking technique, rather
something that a user agent could identify and report (at the user's
discretion, for example). My thought was prompted by the note about RDF
techniques, which I infer could provide a way to designate a block of
text as a description for a given image, so that the two items could
"travel" together.
 
Hope that makes sense.
John