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Re: How to describe Flowcharts, Schematics, etc

From: Leonard R. Kasday <kasday@acm.org>
Date: Thu, 12 Aug 1999 17:39:11 -0400
Message-Id: <>
To: w3c-wai-ig@w3.org
Steven McCaffrey had some suggestions on describing flowcharts, schematics,
etc that we chatted about offline and I wanted to bring back to the list.
Hs proposal is that ALT text or even LONG DESCRIPTION is not always enough:
interactivity is needed.

The thread is as follows:
>Hi Len:
>That's an excellent question and well worth bringing up at this time.
>Since I am totally blind myself and use such technology and have seen such
diagrams in the past during my undergrad days (esp. data structure diagrams
in computer science classes)  when I had sight, I may have some overall
>Whenever I have discussed this topic with sighted individuals familiar
with such diagrams, my question is really a simple one.  What information
are you seeking via the diagram that you could not get as easily or at all
without it?  It's often surprising that I usually get a long pause in
>I try to clarify by saying "What questions are you asking yourself in your
mind when you look at the diagram?  What information is conveyed by knowing
relative (i.e. relational )position (e.g. "at a higher/lower  level than"
or "is a sibbling of" on")"  How do you find the answers to these questions
with your eyes (i.e. describe the algorithm you are, perhaps unconsciously
so perhaps difficult, using).  The computer code behind such diagrams can
do the same thing.  
>So, that's it in a nutshell.  Ask yourself what questions you put to the
diagram.  Ask how you find the answers with your eyes.  I would design the
page with questions as links.  That's my half-baked idea at the moment.

>> "Leonard R. Kasday" <kasday@acm.org> 08/11 5:29 PM >>>
Thanks for the suggestions Steve.

What you're suggesting sounds like more than just ALT text or even a long
description.  It sounds like something that needs to be interactive.  

Could be done with links as you suggest.  In fact, I tried something like
that for table access.  It listed table cells and by choosing links you
could navigate by row or column and announce where you were.  It's at
http://astro.temple.edu/~kasday/web_access/table_access/ if you're curious.

Could modify this to walk a tree for example.

It would be better I think to always have defined keys to do the actions.
Actually, this could be kluged by using ACCESSKEY and jumping to new pages,
but would be quite slow.  Best to be interactive at the client level.

Hmmm.  Might work with javascript if it changed the whole page and the
screenreader could follow it.

On  Thu, 12 Aug 1999 07:42:38 "Steven McCaffrey" wrote:
Hi Len:
You are quite welcome and thank you for bringing this under discussed topic
to a wider audience.  Yes, I do think it needs to be highly interactive at
the client level.  Tree traversal was exactly what I was thinking. Since,
of course, all particular instances of tree structures can be represented
by the same, what used to be called, "abstract data type", my idea was to
have subject-specific terminology correspond to the abstract operation.  To
take a very simple example, if I have an organization chart, I might ask
"Who is the director of the organization?"  or "Who is the head of my
department/division?" or "Who is my counterpart in office x?"etc.  These
are just some generic questions I can think of at the moment.  The
particular questions chosen must come from the person(s) who put the chart
out on the web.  What information do they want the viewers of that chart to
obtain?  These are just ordinary information design considerations applied
to the specific question of what any given diagram/chart is for.  As I
remarked earlier, this is a little more difficult, because in many cases,
the knowledge of what information is conveyed by a diagram/chart is, I
think, often on an subconscious level and probably someone trained in
information engineering might be able to help turn implicit questions into
explicit ones.  However, I think anyone can do this with a little
Your table structure sounds interesting and I'll check it out soon.  
Sure, feel free to repost my response to the list.  I am never quite sure
how much depth to post to a list on this topic.  It happens to be both very
important and interesting to me but I have not seen a wide discussion on
this to date.  I would like to see this discussed in some depth since I
think this kind of material is going to be more ubiquitous soon and is not
easily transformed into an accessible format.
Steven McCaffrey
Information Technology Services

Leonard R. Kasday, Ph.D.
Universal Design Engineer, Institute on Disabilities/UAP, and
Adjunct Professor, Electrical Engineering
Temple University

Ritter Hall Annex, Room 423, Philadelphia, PA 19122
(215) 204-2247 (voice)
(800) 750-7428 (TTY)
Received on Thursday, 12 August 1999 17:36:36 UTC

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