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Accessibility Supported and Programatically Determined

From: Wayne Dick <wed@csulb.edu>
Date: Thu, 31 May 2007 10:52:33 -0700
To: <w3c-wai-eo@w3.org>
Message-ID: <web-13476250@remus.csulb.edu>

Sometimes we work too hard to avoid 
real scientific concepts in the 
pursuit of simplicity, even when that 
is precisely what we must address to 
be clear and simple. I'm thinking of 
"accessibility support" and 
"programmatically determined".  These 
are good concepts, but they are not 
measurable as defined.  I think twenty 
experts could in good faith come up 
with different answers when confronted 
with the same set of technologies.

Accessibility support is a special 
case of programmatically determined. 
 It requires programmatic 
determination by assistive technology 
programs. Hence, defining 
accessibility support depends on a 
clear definition of programmatically 
determined, a formal linguistic 

Now here is the situation.  Computers 
cannot comprehend natural human 
language.  To communicate with 
computers we invented formal 
languages.  They are much simpler. 
 They lack ambiguity and idioms, and 
lots of other stuff that makes human 
communication fun. However, computers 
can recognize formal language with 
100% accuracy.  So the definition is 

Information can be programmatically 
determined whenever it is expressed in 
a formal language that is constructed 
to be recognized by programs.  This 
brings us to our final definition for 
accessibility supported.  An 
information technology is 
accessibility supported whenever the 
POUR criteria are supported by the 
technology itself or the communication 
interface of the technology can be 
programmatically determined by 
assistive technologies that support 

This definition is both accurate and 
verifiable.  It is exact because the 
program interface must be constructed 
to be determined by accessible 
technology, and the POUR must be 
supported.  Support for POUR is 
delineated exactly and measurably in 
the WCAG 2.0 Guidelines.
Received on Thursday, 31 May 2007 17:52:54 UTC

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