A (semi) always includes air brakes here I believe, B (straight truck) I believe is the one that may or may not include air brakes. C (regular car/van/pickup) as CDL only exists for placardable vehicles (hazmat). M is an add on motorcycle class.
I have a class AM license with TX endorsements and AP restriction. T=double/triple, X=tank and hazmat, A=corrective lenses (contacts), P=hazmat endorsement expiration different from license expiration (1yr sooner).