Yeah, a lot of them are similar to what I thought. Although I think I have NAR as 'Naval Auxiliary Reserve' potentially?
Didn't think of NSP 'Science Program', so yes, that seems fairly elegant.
There's a variety of freighter prefixes, plus BDT for the S.S Santa Maria, for example
And I've invented a whole new one, inspired by Starfleet Battles - which is NCP, for a patrol/perimetre ship, for a number of designs with awkward registry overlaps (like potentially, the Okinawa, Akula, Akyazi or Jester-classes, or the Orca-class corvette, and so forth)
The alternative being that some registries are just constantly reused, that is (such as NCC-100-300, 500-800, and 1000-1100, and so on)
Non Federation Transport is also pretty intuitive... but then why bother registering it, in the Federation, if so (hmmm)...?