ARIA role: do not use namespaced role attribute on HTML elements

ARIA authors: please change any ARIA content to use plain |role| instead
of |xhtml:role| or |xhtml2:role|. Do not use setAttributeNS() when
setting the role -- you can still use setAttribute() or add the role
attribute directly in markup.
This note only applies to the role attribute, not the other ARIA properties.

Support for the namespaced role attribute is going to be removed. We are
simplifying ARIA to make it more palatable for other browsers to
implement it, and less confusing for authors.

If you need to be compatible with Firefox 2, do:
<div role="wairole:menuitem" aaa:checked="true">  <!-- In FF2 still use
setAttributeNS() for aaa:checked -->

If Firefox 3 support is good enough for you, do:
<div role="menuitem" aria-checked="true">  <!-- In FF3 all of ARIA can
be declared directly in markup-->
Firefox 3 is scheduled to be shipped by January.

Notice that in both cases you use |role|, and not |xhtml:role| or
|xhtml2:role|
The hardcoded "wairole:" prefix for the role value is still available
for use in text/html, but is no longer required in Firefox 3. The WAI
roles can now be accessed directly without a prefix.

- Aaron

Aaron Leventhal
IBM web accessibility architect
Mozilla accessiblity lead
http://www.mozilla.org/access