I'm a kick starter on the character generator, I've spent a lot of time thinking/guessing what those P,C,M stands for, but i failed to figure anything out.
and what's more, i am curious why the "rearhair1" is not shown in the variation of "kid"
Maybe it doesn't appear because you didn't put anything in the "Variation" Folder.
The "p" just defines the position of the piece in the generator, and it's used to identify it.
I don't actually know what "c" and "m" stand for; but I suppose they are related to layers or things like that.