[html5] embedded xml parsing rules

[Rand McRanderson]

One of the original promises of HTML5 was that arbitrary xml could be 
embedded without losing the data structure. I think that is no longer 
exactly true, but I'm curious about a few things.
A. If xml is embedded in an HTML5 document or an XHTML5 document, would 
it be better to always use empty tags or not? I'm not sure if my 
terminology is right, by empty tag I mean a tag ending with "/>", or do 
you need to be attentive to what the tag names are specified as empty by 
the HTML5 specification. Part of my concern is if we have such a 
document and say it has a tag <data-source> and HTML5 adds such a tag 
sometime in the future, could my old tag break?
B. If xml is embedded within a <script> tag is it parsed?
C. Is it possible to give instructions to a parser outside of a 
javascript-context instructions to parse the contents of a script-tag as 
xml (obviously I could devise my own way, but I'm asking if there's a 
standard way)

-John Thomas