I think it was an OCS Tactics class, the instructor told us about giving the bodies on the ground a "double tap" when you advance through the kill zone. If you pass a fallen enemy and he is still alive, you are obligated to provide him with medical attention. It is such a narrow distinction, but that is in the Geneva Convention. The thought there was, if someone was playing dead, you get to keep them honest. But if you pass someone and they are wounded, then they have lost the desire to fight and should be treated as a Prisoner of War, albeit an injured one.