Continuing Education Requirement--required for certification by USFS and administrated by PSA. "A" and "B" differ in terms of the course/test requirements. "B" is usually just the basics and for coaches who for whatever reason ($$$, teaching only group lessons), don't want/need to take the extra courses. Put me down as someone who is not very impressed by CERs. The proof is in the pudding, not whether you can pass the online courses (and the coaches on this board must agree that some of those courses are awfully lame).