>well, and what about using simple utilities, e.g. ipv6calc not to make a
>mistake? you can find it in pkgsrc as net/ipv6calc.  it is as easy as
>type:
>
> ~> ipv6calc -r 3ffe:80e8:200::1
> 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.8.e.0.8.e.f.f.3.ip6.int

Hey wow, now that's pretty useful.  That's getting installed for sure.
Thanks!

--Ken