RE: v6 & DSL / Cable modems [was: Private use of non-RFC1918 IP space

Considering that RFC1918 says nothing about IPv at all,

That may technically be true, but it does explicitly reference IPv4 addresses. Oh, and when RFC1918 (or more correctly, RFC1597) was written, "IP", "TCP/IP", etc. all directly meant IPv4. (RFC1597 @ 03/94 ... RFC1883 @ 12/95)