MIME type for detached signatures?

Hi!

I'd like to sign an XHTML document using XML-SIG detached
signatures. The document will have a link pointing to the
signature.

However, XML-SIG didn't define a MIME type for detached signatures.
I could use application/xml and do some snooping, but it would
be more efficient if I could use something like application/xsig+xml.

xml-encryption does have its own MIME type. pgp, pkcs, and pkix
have several[1]. Is there any reason
why this wasn't taken into account for XML-SIG? It seems
it could be useful for both detached and enveloping signatures.

Thanks!

-jose

[1] http://www.iana.org/assignments/media-types/application/