AH is just "other information." There's no O&G-specific standard that says "this item should be called AH2."

If you tell me what information you have, I can probably tell you the significance of it. If the amounts are material, it's not a PTP / MLP, and your client is not obviously the designated sucker in the deal, I will probably also tell you that you're doing your client a disservice by preparing the return, but most of the time one of those three outs apply.