"Ian Hickson" <ian@hixie.ch>
> If one UA considers section A to start at point X and end at point Y, but
> a second UA considers section A to start at point X and end at point Z,
> and they are both conforming implementations, then obviously the user is
> not going to be guarenteed to receive the intent of the author.

Ian,

I agree that it's under specified, almost all of XHTML 2 is, my comment 
though was based purely on:

" request that the XHTML2 specification include an algorithm that exactly
defines how to obtain a document outline from a given XHTML2 document"

Perhaps it's us having a different idea of what a "document outline" is, but 
whilst I want Hx/h/section to be well defined, I don't want a specific 
algorithm for creating document outlines, a user agent should be free to use 
any piece of content etc. in creating a document outline to present the 
user.  Of course if by document outline you mean something different to me, 
then fair enough!

Cheers,

Jim.