I'm reading the RFCs related to MIME types and the process to apply
for one.

My read of Section 2.2.4 of RFC 2048 would exclude a joint application
for "application/rss+xml" by the RSS Advisory Board and RSS-DEV
Working Group (or any other shared type).

The section:

"2.2.4. Canonicalization and Format Requirements

"All registered media types must employ a single, canonical data
format, regardless of registration tree.

"A precise and openly available specification of the format of each
media type is required for all types registered in the IETF tree and
must at a minimum be referenced by, if it isn't actually included in,
the media type registration proposal itself."

ftp://ftp.isi.edu/in-notes/rfc2048.txt

Does anyone else have a different take on this?