I don't have any problems with IIDs being different :-) But i was more
trying to understand the compatibility problem. Multi6 module anyway
has to do different processing if the address is a HBA address or
if it is a CGA/HBA address. Now you can still use the same format for
generating a single IID for all the prefixes e.g. using all zeroes or all
ones for the subnet prefix field of the CGA parameters data structure.
(but including the multi-prefix extension at the end as specified now)
Assuming we can find such a thing, would it be considered simpler ?