PA, PNI, PI, MSV, etc. "bow"

[Rory M Larson]

I wonder if I could get a quick clarification from the Algonquianists on
what all "Algonquian" and "Proto-Algonquian" covers.

My understanding, picked up in bits and pieces over the years, is that
Algonquian is divided into four major branches: Blackfoot; Cheyenne;
Arapaho; and eastern or Great Lakes Algonquian, which includes all the
rest.  Blackfoot is supposed to be especially divergent.  The big eastern
group is supposed to be divided between a northeastern seaboard group and a
more central Great Lakes/subarctic/prairie/eastern woodlands group.  I've
also heard that there are supposed to be a couple of small
Algonquian-related languages in California.

So when we talk about Proto-Algonquian, are we talking about the
protolanguage of all the Algonquians, or just of the big eastern group?  Or
is my information/classification as given above notably incorrect?

Thanks for any quick tutorials on this!

Rory