MIME Media Type Suffixes for XML-based Document Types
Even if this doesn't do *much* good, I see little harm in it.
The document would need to explain the choice of a suffix
rather than a prefix (text/xml.blah vs. text/blah-xml),
give a list of generic XML processing that might apply
(use of XPointer and XLink?), address the charset issue
(XML types either need to be UTF8 or else allow an explicit
charset parameter).
This would then be issued as a BCP, updating the registration
procedure BCP.
Larry