In this draft : http://www.ietf.org/id/draft-ietf-mile-rfc5070-bis-10.txt

there is an entire chapter (10.2) about Enumerated Value Registries "to be managed" by IANA.

"This document creates xx identically structured registries to be
managed by IANA:

o  Name of the parent registry: "Incident Object Description Exchange
      Format v2 (IODEF)"

o  URL of the registry: http://www.iana.org/assignments/iodef2"

Although I didn't find anything on the IANA site at the url given in the document this is exactly what we were thinking about for IDMEF RFC where ENUM should also be managed by something like IANA.

It would be a good thing to see how it works for IODEF and try something similar on IDMEF.