Comment by viraptor

> That seems oddly rigid though.

We're past that for a decade, but various services have not caught up yet https://datatracker.ietf.org/doc/html/rfc6177

         The actual intention has always been that there be no hard-
         coded boundaries within addresses, and that Classless Inter-
         Domain Routing (CIDR) continues to apply to all bits of the
         routing prefixes.