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RE: Support for LONGDESC

From: John Foliot - bytown internet <foliot@bytowninternet.com>
Date: Tue, 6 Aug 2002 10:31:31 -0400
To: "Brian Kelly" <b.kelly@ukoln.ac.uk>, <w3c-wai-ig@w3.org>
Message-ID: <GKEFJJEKDDIMBHJOGLENGEMMCJAA.foliot@bytowninternet.com>

>
> It's interesting in your guidelines that you say "Avoid use of popups".
> I did wonder whether browser vendors would implement longdesc support
> using some type of pop-up, along the lines of support for ALT and TITLE
> attributes.  Is it mandated in the user-agent guidelines how support
> should be implemented?

Not actually sure.  As a web developer though I don't worry too much about
developing to specific user agents, but rather to code standards. (Let's not
start that flame war again readers!)

>
> It's not clear from your example, whether the "Return to referring page"
> link is generated by the browser or is in the longdesc file.  Looking at
> your longdesc file -
> http://www.bytowninternet.com/examples/ctry_usage.html
> I think the link is hardcoded - which will not be what's needed if you
> want a single description linked to from many images.  You could use
> some JavaScript to generate the link to the referrer page, or this could
> be provided by the browser's implementation of longdesc support - but
> you wouldn't want to do both.

You are correct, it is hard coded in the example (it's an example <grin>).
There are of course many other ways of doing this, including JavaScript, but
if JS is not supported, then what?  You could probably use some form of
Server Side scripting (Perl, ASP, etc.) and take advantage of the HTTP
referrers, but specifics would change from site to site.  Not being a Perl
author myself I don't have a code sample handy, but a quick google should
produce something, or perhaps somebody on this list???

>
> Also, as the longdesc file is handled as a standard HTML file using HTTP
> by the browser, it is liable to be indexed by indexing spiders, so
> potentially could be found as a result of a search query, without
> appropriate context, navigational bars, etc.  (I appreciate that it can
> be useful to find such information - I'm trying to think through the
> implications).

Again could be handled a couple of different ways, via robots.txt,
.htaccess, <meta name="Robots" content="noindex,nofollow" />, etc.  All
three if you're really paranoid! <grin>

>
> Thanks for the suggestion of getting a colleague to describe an image.
> Something I've been wondering about is how to provide multiple
> descriptions of an image for multiple purposes, using a unidirectional
> technique such as longdesc.  i.e. how can multiple language descriptions
> be provided, descriptions for different groups of users, etc.
>
> Thanks again for your comments.
>
> Brian
>
> ---------------------------------------
> Brian Kelly
> UK Web Focus
> UKOLN
> University of Bath
> BATH
> BA2 7AY
> Email: B.Kelly@ukoln.ac.uk
> Web: http://www.ukoln.ac.uk/
> Phone: 01225 38 3943
>
> > > -----Original Message-----
> > > From: w3c-wai-ig-request@w3.org [mailto:w3c-wai-ig-request@w3.org]On
> > > Behalf Of Brian Kelly
> > > Sent: August 6, 2002 6:47 AM
> > > To: w3c-wai-ig@w3.org
> > > Cc: b.kelly@ukoln.ac.uk
> > > Subject: Support for LONGDESC
> > >
> > >
> > >
> > > I'm giving a talk on web accessibility shortly.  I'd like
> > to know the
> > > status of mainstream browser support for LONGDESC.  I've
> > searched the
> > > WAI-IG list archives and used Google to search Web pages.  From my
> > > searching my understanding is that LONGDESC is not supported by
> > > mainstream browsers (cab on the Mac is an exception) -
> > although if you
> > > use XSLT you could reformulate LONGDESC to supported HTML element
> > > (thanks to Kynn for this suggestion).
> > >
> > > Is this currently correct?
> > >
> > > Also what formats can the longdesc file be in?  The HTML 4 spec [1]
> > > states that:
> > >
> > > longdesc = uri [CT]
> > > This attribute specifies a link to a long description of the image.
> > > This description should supplement the short description provided
> > > using the alt attribute.
> > >
> > > But doesn't say whether the file can be HTML, XHTML, plain
> > text, etc.
> > > (or that it shouldn't be PDF, GIF, etc.!), can contains JavaScript,
> > > etc. Although the example give a file with a .html extension.
> > >
> > > If use of longdesc is needed to future-proof Web resources for when
> > > browser support is available, are their any guidelines on using
> > > longdesc?
> > >
> > >
> > > References
> > >
> > > 1 http://www.w3.org/TR/html4/struct/objects.html
> > >
> > >
> > > ---------------------------------------
> > > Brian Kelly
> > > UK Web Focus
> > > UKOLN
> > > University of Bath
> > > BATH
> > > BA2 7AY
> > > Email: B.Kelly@ukoln.ac.uk
> > > Web: http://www.ukoln.ac.uk/
> > > Phone: 01225 38 3943
> > >
> >
> >
>
Received on Tuesday, 6 August 2002 10:39:33 GMT

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