RE: DHTML show/hide sections & screen readers

Lets just remember that we need to separate the responsibility of the 
screen reader and assistive technologies from that of the web content and 
the user's preferences and configuration.  Each component has a 
responsibility to make the web accessible.

In other words, in this expand/collapse example the software developer 
just uses the standards windows control file system and each of the screen 
readers and magnifiers handle it as they are designed, some with more or 
less usability, advanced features, and/or customization.  Open or common 
standards in this case allow the screen reader vendors to compete on 
design and ease of use features while still supporting the so-called 
standard window file view control.  With some of the design solution 
responsibilities in the AT, then the power user can have their settings 
different from the novice user.  If the recommendations are too prescribed 
in the content to the point that nothing can be customized, then some user 
set will be disadvantaged.  Not all users use their software the same way.

The "essential components of Web accessibility" are explained in a W3C WAI 
piece at http://www.w3.org/WAI/intro/components

Regards,
Phill Jenkins
IBM Worldwide Accessibility Center
http://www.ibm.com/able