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Foundation for text techniques

From: Adam Victor Reed <areed2@calstatela.edu>
Date: Thu, 6 Dec 2001 20:34:52 -0800
To: w3c-wai-gl@w3.org
Message-ID: <20011206203452.A11780@uranus.calstatela.edu>
I am planning to write the techniques document on accessibility text
(alt, title and longdesc parameters of tags presenting content that
would not be universally accessible without those parameters) over the
winter break, so this discussion cames just in time. I am not claiming
that my current understanding of the relevant issues is necessarily
correct, but if I my understanding diverges either from relevant facts
or from the concensus of this group, I need to know it now. So please
comment on the following summary:

1. The default (pictorial or animated) content and the ALT text are
alternatives: when one is presented, the other isn't. Thus the
ALT parameter contains text which IS presented whenever the
corresponding visual is NOT being accessed, and that is NOT
normally presented when the visual IS being acccessed.

Constraint: In common ("visual") browsers, the presentation of the
ALT text normally uses the same real-estate that would contain, if
the user chose to load images, the corresponding visual. To maximize
the likelihood of fitting in the reserved area, the ALT text should
be as brief as possible.

2. According to the HTML recommendation,
<http://www.w3.org/TR/REC-html40/struct/global.html#adef-title>,
the TITLE parameter's function is to "offer advisory information
about the element". This means that the TITLE text is an optional
addition to whatever content (visual or ALT) is already displayed.
The presentation of the TITLE text in the user agent usually depends
on user actions, or on user-specified browser options. In visual
browsers, the TITLE text is normally available as a "tool tip", that
is, as text which pops up when the mouse cursor is positioned over
the element area, regardless of whether the element area contains the
default element or its ALT text.

In non-visual (text, auditory etc) browsers, the presentation of the
TITLE text may depend on whether an ALT text string is also available.
Such browsers may present the TITLE text automatically if ALT is not
found. If ALT text is available, the presentation of TITLE text
depends on a user-set option, or on user input. Users of text browsers
generally prefer that if ALT and TITLE are both displayed, the TITLE
be presented in parentheses after the ALT. (I'd like input from list
users on what is preferred by users of auditory and other browsers.)

4. LONGDESC is a separate resource which provides, for users unable to
access the visual in full detail, all the information that a user to
whom the visual is fully accessible would be able to extract from it
if she examined the visual exhaustively. It should be usable not only
by users who require ALT, but also by users who can extract casually
adequate information but not complete detail from the visual itself.
For example, a colored image might convey information equivalent to an
adequate ALT even to a color-blind user, but this user then might use
the LONGDESC resource for access to details that others could deduce
from colors in the image. The LONGDESC resource should be available
through a user action, such as a link in a menu displayed when the
menu button is depressed over the image in a visual browser. (How do
users of auditory browsers prefer to access LONGDESC?)

Is the above a reasonable starting point for the techniques document?
-- 
				Adam Reed
				areed2@calstatela.edu
				 
Context matters. Seldom does *anything* have only one cause.
Received on Thursday, 6 December 2001 23:34:59 GMT

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