Yes, it is possible to add an attribute to a common registry.
On the other hand it is possible to realign what entries go in which
registry according to:
- "reservations" to be in the "main" registry, using a working
definition of a "reservation" as something that all implementations
of the protocol have to honour.
- all other IANA special purpose address assignments to be placed in
this special purpose registry (including, for example RFC1918 space,
6to4 relays, etc), and the RFC to document the process of special
purpose assignment.
an N-ary attribute or N lists, semantically about the same, syntax seems
a matter of taste. i agree with the distinction, and am happy with
either syntax.
randy