draft-ietf-ipngwg-addr-arch-v3-0x.txt
In -03, Section 2.5.6 (excerpt from RFC2374)‘described fields and their widths are not a fundamental part of the IPv6 architecture’
But implementations should not need to know
Ops community and RIRs deal with this, it is policy
Old-style TLA/NLA/SLA boundaries as example
|n bits| m bits | p bits | 128-n-m-p bits |+------+-------------------+-----------+----------------------------+| 001 | routing prefix | subnet ID | interface ID |+------+-------------------+-----------+----------------------------+