[ppml] [address-policy-wg] Those pesky ULAs again

aside from the difficulties pointed out during this thread regarding
enforcement of ULA terms vs. PI terms, there are two other things that
prevent me from thinking well of ULA.

first, ARIN does not currently consider routability when allocating
address space.  non-routable space comes from ietf/iana, not the RIRs.
so, for ARIN to start allocating nonroutable space is a big change.  we
would have to define "routable", we could face implied liability for
routability on "normal address space" (even if we continue to disclaim
it in the NRPM as we do now), and we would then walk the slippery slope
of the changing definition "largest" with respect to breidbart's maxim:

	>> But what *IS* the internet?
	> It's the largest equivalence class in the reflexive transitive
	> symmetric closure of the relationship "can be reached by an IP
	> packet from".		--Seth Breidbart

second, even with the rampant EUI64 wastage of the bottom 64 bits of the
IPv6 address space, there's still a lot of space, and it's not hard to
get.  it's perfectly reasonable for all addresses to be unique even if
some are never expected to be "routed" or are only "privately routed" or
whatever.  so while i think that ietf/iana ought to allocate a "private"
block of space for IPv6 since a lot of the world loves their IPv4 NAT and
wants to be able to do the same thing with IPv6, one block ought to be
enough.  (heck, maybe the old site-local prefix is still available.)