XML root-level MIME type?

This is probably not the right place to be asking this, so please direct me
to the right place.

Is there an effort underway to add XML as a root-level MIME type? As in,
XSLT and XSL would be xml/xsl, svg could be xml/svg. (Although image/svg
works) XHTML could be xml/xhtml. I think this is a good idea because
compressing all the possible XML formats into "text/xml" and
"application/xml" seems squished. And xml is really not just text.

Jeffrey Yasskin