- The spec goes on to say that new media types can 'also' be used, so things like text/xsl is fine.

The caveat here is that text/xsl currently isn't a registered MIME type
and therefore in violation of the MIME type grammar (unregistered types
have to start with an "x-" prefix).

- Mozilla is fine with text/xml and application/xml...and something I didnt know (from Jarno's post) apparantly uses text/xsl as well