Thank you very much for that detailed information.
Those are indeed quite a few base pointer special registers. I would be a bit sad to see the cpReg and cppReg go though. I can think of at least one use case where they would allow for elegant implementation of Haskell thunks/closures, where the closure memory layout/parameter description meta-data and the code thunk should be accessible via the same offset/pointer but must of course reside in different access permissions and thus need different bases.
No idea if those “levels of display” would cover this, because I have no idea what that means in this context here.