W3C home > Mailing lists > Public > public-html@w3.org > July 2007

Re: unifying alternate content across embedded content element types

From: Gregory J. Rosmaita <oedipus@hicom.net>
Date: Sat, 14 Jul 2007 11:30:46 -0400
To: public-html@w3.org
Cc: Robert Burns <rob@robburns.com>, Andrew Sidwell <takkaria@gmail.com>
Message-Id: <20070714151303.M64866@hicom.net>

robert burns wrote, quote:
> As an example, think of an <img> that has a @longdesc attached 
> to it.  According to current recommendations, the @alt attribute 
> is still  required. Its not that we require @alt or @longdesc. 
> Rather we  require @alt even if there is a @longdesc value. Is 
> that simply an  oversight? Or have these attributes evolved to 
> serve distinct  purposes: distinct purposes worth using for 
> other embedded content [WINDOWS-1252?]—  for other element types?
unquote

@alt and @longdesc provide distinct purposes:

1. alt text enables the user who -- for whatever reason -- cannot 
process images (text-only browser, for example); often the alt 
text is not an exact duplication of the graphic (say a mailbox)
but a description of what the iconic link will do when activated
(in the case of the mailbox example, i would never encourage 
anyone to use alt="mailbox" but rather, alt="Send Email to Webmaster"

2. the purpose of long description is to provide an equivalent 
user experience if a user cannot -- for whatever reason -- cannot 
process the image, especially when that image is part of the 
illustrative content of a page; longdescriptions can be brief 
and to the point (the icon shows the word Valid XHTML with a 
red check-mark next to it, indicating that it has passed 
validation) -- there is no law that says someone must read the 
entire contents of the longdesc -- they are free to read what 
portion of the longdesc they find most germane, which is why 
verbosity in longdesc isn't a problem, in as much as the reader 
can either decide to get more granular information by listening 
to/reading/feeling the entire longdesc, or can simply stop 
listening and return to the document in which the longdesced 
image is located, if the user feels that the portion of the 
long description heard/read/felt is sufficient, then he or she 
is free to return to the document instance in which the image
being described is located.

so, yes, ALT and LONGDESC serve 2 distinct purposes; alt needs 
to be required in order to avoid perceptual black holes; however,
i wouldn't feel bound to provide a longdesc for the conformance 
logo, as its meaning is "this page is valid -- go ahead, check 
for yourself" -- of course, on the pages that the validity icons 
are archived, each MUST have a longdesc describing the icon, so 
that the page author can make an informed decision about which 
icon to use...

i do strongly agree with robert burns, however, on the need for 
making the mechanics of equivalent text uniform across all media 
types, which would lead not only to a richer user experience, but
which lowers the burden on the page author and increases the 
chances that the exposition of equivalent content will be supported 
by user agents, in a manner specified by the user...

just my 2 cents (american),
gregory.

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   Gregory J. Rosmaita, oedipus@hicom.net or gregory@ubats.org
UBATS - United Blind Advocates for Talking Signs: http://ubats.org/
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Received on Saturday, 14 July 2007 15:30:58 GMT

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