The general system is to be hit anywhere from 1" below the wrist to 1" above the knee with sufficient force (yes things can be too light) If you are hit in a limb you lose the use of the limb, if you are hit in the head, neck, body, or crotch you have lost for you are "dead". If a mass weapon (Axe, Mace, Poleweapon, 2 handed sword) hits you in the shoulder or hip you are also dead.
We also do pas d'arms with counted blows and other things too but the above is the general system.