In my opinion, the critical bit on a notation packet should mean
that the implementation needs to recognize that particular notation,
not just notation packets in general. Otherwise we would have no way
of expressing the requirement that the particular notation packet be
understood.
I also wouldn't say that human-readable means that it is enough to display
it. My interpretation of human-readable is that it is OK to display it
to a person, i.e. that the data is in UTF-8, but not that displaying it
to a person is sufficient to claim full support of the packet.
Hal Finney