NRL: schemaType for schemas in XML

Hopefully this is the place for discussion about NRL as well.

According to James Clark's NRL document the "validate" element's
"schemaType" attribute is meant to indicate the type of the specified
schema iff its not in XML. Otherwise its type can be automatically
detected from the schema's namespace URI.

While this is certainly true I wonder whether it's worthwhile to allow
for an (optional) indication of a schema's type even in case of a XML
schema. Thus a validator can e.g. reject a schema of unknown type before
fetching a copy from a remote server.

I envision somthing like RDDL's use of XLink's "role" attribute to
indicate the nature or type of the schema specified. Thus one can write

<validate schema="xhtml.rnc"
 schemaType="http://www.isi.edu/in-notes/iana/assignments/media-types/
 application/x-rnc">

as well as

<validate schema="xhtml.rng"
 schemaType="http://relaxng.org/ns/structure/1.0">

Any comments?

Regards,

Andreas Sewe