IANA registration of RFC 1767 mime types?

[Dale_Moberg@xxxxxxxxxxxx]

     Hi,
     
     According to RFC 1521, the IANA is to maintain a list of all content 
     types and subtypes, character sets and content transfer types for mime 
     mail. Shouldn't the RFC 1767 types (application/edifact etc.) be
     on this list? They aren't (as a vendor of X.400 gateways recently
     pointed out to me). How/who can update the IANA list so that these
     types are included? Or is there some reason to exclude these from
     official registration?
     
     Bye
     Dale Moberg
     Sterling Commerce