I know many states are different, but many are also the same as Texas. After getting my Class A Operators license, I called the DMV and asked about an air brake endorsement, for the future possibility of getting a DP. I was told that it is not an "endorsement", It is a "restriction" on a CDL if you don't take the air brake portion of the exam. He then asked me if my Class A Operators had an air brake restriction and I told him "No". He said that is because it only applies to CDL's.
Scotty and Kristen, Airedales Dagny and Wyatt
2007 Newmar Mountain Aire 4528, 450 HP ISM, Allison 4000, 8 Trojan T-105's
2014 F150 4x4 Crew Cab Platinum 157" WB
Roadmaster Blackhawk 2, RVI2 Brake System