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Device Independence

From: Gregg Vanderheiden <gv@trace.wisc.edu>
Date: Mon, 03 Mar 2003 00:15:31 -0600
To: "'WCAG List'" <w3c-wai-gl@w3.org>
Message-id: <004e01c2e14c$4e411f50$046fa8c0@TOSHIBATABLET>
The term "device independence" keeps coming up.    So I would like to write
something here to spur a dialog that will let us clear this concept up as it
relates to accessibility.

 

 

 The term device independence has always been a very confusing term.    If
device independence means anything other than

 "usable by a keyboard or keyboard interface if the function or its result
can be concisely expressed in words"  

 then I do not think that we want or need it.   In fact I do not see how it
could even be possible. 

 

If the goal is to allow content to be accessed from PDAs, by Voice, by
keyboard etc. then 

"usable by a keyboard or keyboard interface if the function or its result
can be concisely expressed in words"  

will get you this.

 

If you would like to ALSO add mouse control to make some tasks easier. That
is fine.  But we should not require it - and, as I said above, I don't even
think it is possible.   

 

Since text input is sometimes required as a part of web content interaction,
it would mean that text input would have to be possible using just a mouse.
This in turn  would require that every single page that required text input
have a keyboard on the page and a  script to drive it.   If an external
on-screen keyboard is used - then you are using keyboard input to the
content - not mouse.    And if a keyboard on the page is used then you are
requiring that a script be used and the page would fail if the script did
not run.    

 

Help me here.   

 

1) what does "device independence"  mean?

 

2) independence from what?

 

3) does it require that all content be usable with a mouse only?

(if so - how could this be done?  Remember an on screen keyboard that is not
part of the content is just a keyboard and the content would be receiving
keyboard input.) 

 

4) does it require that all content be usable with a keyboard only?

 

5) does it require anything else?

 

 

How does device independence make things any more accessible than

"usable by a keyboard or keyboard interface if the function or its result
can be concisely expressed in words"  

 

(I am presuming that device independence does not mean "also support a mouse
where that is a good interface practice".   That would make the pages more
accessible but does not sound like device independence because it doesn't
make the content independent of any device or input method.   It is just
good user interface design practice that makes the page more usable).

 

Help me if you can.   Am I missing something?

 

Thanks

 

 
Gregg

 -- ------------------------------ 
Gregg C Vanderheiden Ph.D. 
Professor - Ind. Engr. & BioMed Engr.
Director - Trace R & D Center 
University of Wisconsin-Madison 

 
Received on Monday, 3 March 2003 01:15:44 GMT

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