Mask naming conventions

Hello all

I think I'm seeing a pattern in the naming of some of the masks out there, but I'm not able to put it together. Some start with F, others with N, and some have an i at the end. Is there a list of what all that means somewhere?

Thanks

Resmed's newer basic masks are prefixed F for full face, N for nasal cushion,
or P for nasal pillows. The suffix "i" is reserved for additional features--
(Improvements?)
I am aware of no official "list", and other manufacturers have their own names.

F usually means full face
N usually means some sort of nasal mask...can be traditional over the nose cushion or even under the nose cradle type of cushion
P usually means some sort of nasal pillow type of mask

I have never seen any sort of "list" though.

Still trying to figure out what "i" means...unless it has to do with the special frame and hose connection at the top somehow with ResMed masks. Since all the "i" masks are with the frame that has the air going in the frame itself and hose connects at the top of the head.

Thank you. That helps.