That's the list straight from Brian Harmer's email.
R1: AM, BM, DM, EM, XP, CP, FP
R2: DP, EP, CM, FM
One of the issues with PAX for prosolo bump classes is that it's course dependent. If you end up with a Corvette course, you don't want to toss Miatas in with corvettes in the same bump class because the index can't account for that. It's even more of an issue this year because ProSolo is using Rick Ruth's standard PAX/RTP and it doesn't account for 60ft times.
One way to reduce the course and launch dependencies and level the playing field is to structure the bump classes around course dependency archetypes- put the high power cars in one bump class and the low power cars in another. PAX/RTP then compensates for the relative performance difference between each class in the bump class. This is not new; the ProSolo and Match Tour bump classes already account somewhat for surface dependencies by keeping street tire cars separate from r-comps.