ARIA role restrictictions in HTML5

I was looking at the latest draft version of the HTML5 specification and
noticed in the implicit aria semantics table it indicates that only a
limited set of ARIA roles can be used with certain elements such as the
anchor element to conform to the HTML5 specification.  Specifically you
could not use a role of button, radio button, etc. on anchor elements.
This seems problematic but makes good semantic sense.  One advantage of
using anchors with hrefs for diverse ARIA roles is there is some
progressive enhancement support.



http://www.w3.org/html/wg/drafts/html/master/dom.html#sec-implicit-aria-semantics



Jonathan