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RE: Agenda + [2.4] CORRECT version of 2.4 proposal

From: John M Slatin <john_slatin@austin.utexas.edu>
Date: Thu, 5 May 2005 11:25:25 -0500
Message-ID: <6EED8F7006A883459D4818686BCE3B3B0124836E@MAIL01.austin.utexas.edu>
To: "Tim Boland" <frederick.boland@nist.gov>
Cc: <w3c-wai-gl@w3.org>

Tim asked some very detailed questions about exactly what I had in mind
in using the phrases "visual display order" and "CSS positioning" in an
earlier post on this thread.  He then wrote:

<blockquote>
I think that
the "interaction" of values of "display", "position", and "float" 
properties (as well as
applicable values of "top", "right", "bottom", "left", "direction", 
"clear", and
  "z-index" properties) may have accessibility implications pertaining
to the discussion 
</blockquote>

Tim, your knowledge of CSS is far more comprehensive than mine and I
can't honestly say I had in mind all the very specific properties you
listed (see below if you want the full text).   But based on the text
excerpted above I believe we're talking about the same set of problems,
though you're doing it with a specificity I can't match.

If you have time, I'd certainly appreciate your spelling out the
"accessibility implications" you allude to above.

Thanks so much!
John
"Good design is accessible design." 
John Slatin, Ph.D.
Director, Accessibility Institute
University of Texas at Austin
FAC 248C
1 University Station G9600
Austin, TX 78712
ph 512-495-4288, f 512-495-4524
email jslatin@mail.utexas.edu
web http://www.utexas.edu/research/accessibility/


 



-----Original Message-----
From: Tim Boland [mailto:frederick.boland@nist.gov] 
Sent: Thursday, May 05, 2005 10:46 am
To: John M Slatin
Cc: w3c-wai-gl@w3.org
Subject: RE: Agenda + [2.4] CORRECT version of 2.4 proposal


By "visual display order" and "CSS positioning" (in excerpted text
following), are you specifically referencing
  implementations of the CSS2.1 visual
  rendering model, in which each element in the document tree generates
zero
  or more rectangular boxes in the rendering structure, as well as the
visual rendering model aspects,  the box model (describing the
generation of such boxes, controlled by the "display" property), and 
the visual
flow model, describing how each box receives its final position, based
upon relationships of source elements in the document tree, box
dimensions, and canvas dimensions (and including the "position" and
"float 
properties)?     I think that
the "interaction" of values of "display", "position", and "float" 
properties (as well as
applicable values of "top", "right", "bottom", "left", "direction", 
"clear", and
  "z-index" properties) may have accessibility implications pertaining
to the discussion excerpted following..




>my lifetime.  But the replacement-- CSS positioning-- raises the same 
>possible problems because it *does* (or can) separate content and 
>structure from presentaition (even if the boundary gets blurred 
>sometimes).  Mostly that's a good thing for accessibility-- it means 
>that the visual display order and the auditory sequence can be 
>different and each be "tuned" to the needs of a different segment of 
>the audience. But the decoupling can be problematic if the order of the

>content in the delivery unit doesn't work as a linear sequence-- even 
>if the order in the source follows the visual order.
Received on Thursday, 5 May 2005 16:25:31 UTC

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