pTLAs missing in action

[richdr@microsoft.com (Richard Draves)]

> While an interesting exercise, your "inactive" pTLAs are dependent on
> your IPv4 unicast reachability.
>
> 3FFE:800:0:C620:920B::0  

The 5 pTLAs were just those for which I know no v6 addresses to try pinging,
and have not heard confirmation from the pTLA admin that the pTLA is
offline.

This is very different from a list of pTLAs unreachable by me, which would
be much longer.

Now that I have an address in 3ffe:800::/24 to add to my list, I'm down to 4
"missing" pTLAs.

Thanks,
Rich