profileTypeId parameter in NPRML querystring

[bdivver]

I've noticed in another flavor of the NPRML feed that I use for a non WP site, there is a parameter called profileTypeId. In using this, I'm getting a more robust result of the data I'm looking for than just the id. Does anyone know/recall how they are determined? I've been poking around the nprstations.org and can't find any documentation. I'm hoping to find a list. Any help is appreciated.