In AD&D 2nd edition, fighters gain experience bonuses from damage they've done. Experience=(Damage/8)*10. Compared to rogues or mages that gain exp from spells, it's a lot less.
My question is: Suppose an enemy has 1 hit die, and he had 1 health point left, and a fighter does a critical hit of 17 damage. Does he gain experience from the 17 damage, or for the 1 point of health the enemy had left?
UPDATE: Verified with my DM, this is a modification from the rule from the DM Handbook mentioned on the answer given: "The fighter gets 10 * 1 (level of orcs) * 3 (number of orcs) XP on top, although he didn't even act before it all was over" What its doing, is making the assumption of enemies having a hit die of 8 (which is why its doing the calculation of dividing by 8). And then it does the multiply by 10 as the rule specifies.
So it seems its a modification of an existing rule, so the answer is that there is no answer. So I guess its up to DM's call.
Thank you for the answer and the help.