From reading the mailing lists and looking at the specification I cannot tell what the limits of HTML5 are as a software or programmatic technology. I have seen where they have attempted to standardize video and audio formats in HTML5 and it seems they may be writing the definitions for XHTML5 into the HTML5 specification. It also appears the specification is extremely lengthy and covers topics far outside the mere definitions and minimally required processing instructions of a markup language.
With version 5 is HTML now an application interface opposed to just a markup language? If so then what are the boundaries and defined limits of the technology? If not, then why are so many topics irrelevant to the processing of markup taking such a spotlight in the development process of the technology? When do the boundaries of a markup language end and the application preferences of a user-agent application begin? With HTML5 that separation does not appear very clear, but as an industry standard it should be crystal clear, right?
You're not the first person wondering about this. See the discussion between Rob Sayre and the HTML5 editor (hixie): http://blog.mozilla.com/rob-sayre/2008/02/19/bloaty-parts-of-the-whatwg-html5-specification-that-should-be-removed/#comment-7559
My understanding is this: there is a number of
If hixie is interested in them and no other editor steps up to maintain a separate specification, hixie prefers to keep them in HTML5, "[rephrased] paying the price of a bloated specification for not stalling the web progress".
BTW, if you want an authoritative answer, you should ask hixie himself or in the HTML5 discussion forums.
[edit] found an addition e-mail from hixie on splitting stuff from the HTML5 spec: http://lists.w3.org/Archives/Public/public-html/2008Oct/0127.html