Request for clarification: implicit ARIA semantics of headers

Folks,

There is a discussion going on at [1] about ReSpec and its support of
ARIA.  During that discussion there is an implicit assumption that elements
such as "H1" have both strong native semantics AND some implicit ARIA
semantics.  However, my reading of [2] leads me to believe that while there
maybe SHOULD be some implicit semantics for "H*" elements, they are not
specified.

So my questions are:

1) I see that the default @role for "H*" elements is heading.  I also see
that (in HTML5) this is marked as "do not set".  Why is it improper to set
"heading" on an H* element?

2) What is the default value of the property "aria-level" for such
elements?  Presumably it is the 'N' in the 'HN' element.

3) If I set an @role of heading on an H* element and do NOT specify an
explicit aria-level, how should this be processed by conforming UAs and ATs?

4) Where is this specified?



[1] https://github.com/w3c/respec/issues/370
[2] http://www.w3.org/TR/html5/dom.html#sec-strong-native-semantics

-- 
Shane McCarron
Managing Director, Applied Testing and Technology, Inc.