See W3C user agent bug: http://www.w3.org/Bugs/Public/show_bug.cgi?id=6653 ARIAAttrModified? During some discussion over IRC yesterday Olli Pettay suggested that a performant way of implementing DOM attribute mutations might be to have separate but similar API to DOMAttrModified. Note DOMAttrModified would serve the same purpose, but having the browser create DOM mutation events for all mutations is going to slow the web experience. ARIAAttrModified is tabled as a way of only creating mutation events for aria attributes. Background: why do we need these mutations? In the case that an aria-attribute is modified, not by the web developer (perhaps through platform API), for example aria-sort is set to "true", the web developer is supposed to respond to that change (a dom attr mutation), and put his web application into a state that corresponds with the aria-sort="true" semantic.

Engaging wai-xtech: http://lists.w3.org/Archives/Public/wai-xtech/2009Mar/0066.html

Will monitor in W3C spec land, but no action needed for now.