Unknown tractor codes ?

[SteveP 0]

I was researching some info for my brother who just picked up a 7116 (1690475). So I was in the engine cross reference section off the home page and ran into some codes that I don’t understand and can not find the secret decoder ring. These code appear after the tractor number and there is an “A” prefix (1981 update): HOT HOA GOA E M PP There is more but this is enough. I guess that the H = Hydro and M = Manual but what the do the rest of codes stand for?