Concerns over restrictions of GL 4.1 SC1

I have a concern with Guideline 4.1 Success Criteria 1:

Level 1 Success Criteria for Guideline 4.1
1.      Except where the site has documented that a specification was 
violated for backward compatibility or compatibility with assistive 
technology, the technology has: [I] 
a.      passed validity tests for the version of the technology in use 
(whether it be conforming to a schema, Document Type Definition (DTD), or 
other tests described in the specification),
b.      structural elements and attributes are used as defined in the 
specification.


What about web applications that make use of HTML attributes supported by 
the browsers but not part of the specification/DTD?  Often these 
attributes are used to create DHTML widgets that are accessible but were 
not created specifically to support accessibility?   An example is the 
tabindex attribute. In Internet Explorer and Mozilla 1.8, this attribute 
can be used to allow focus to be given to any element.  A tabindex equal 
to 0 puts the element into the tab order, a tabindex of greater than 0 
puts the element in a specific tab order;  a tabindex of less than 0 does 
not put the element in the tab order but allows programmatic focus to the 
element.  Thus, the following example will put the <div> element into the 
default tab order of the page:

<div  tabindex="0" onclick="doMouseAction();" 
onkeypress="doKeyAction();">content of the div</div>

But, a page using tabindex in this manner will not pass HTML 4.01 
validation since tabindex is not supported on the <div> tag.   Technically 
this example could pass GL 4.1 SC 1 since putting the div into the tab 
order does make it keyboard accessible and thus does make it compatible 
with assistive technology. But, that is not always the specific reasoning 
for using tabindex.  I think we should relax this success criteria in 
order to allow the use of browser extensions even if their purpose is not 
strictly for "backward compatibility or compatibility with assistive 
technology".  The real criteria should be that the result of using the 
technology remains accessible.    Disallowing the used of these browser 
extension could severely limit web application development.

thoughts,
-becky


Becky Gibson
Web Accessibility Architect
                                                       
IBM Emerging Internet Technologies
5 Technology Park Drive
Westford, MA 01886
Voice: 978 399-6101; t/l 333-6101
Email: gibsonb@us.ibm.com