The basic analysis says the idea is to grab an opponent's arm say with one hand and pull it one way while using your other arm on his body to move him in the opposite direction, thus shearing/tearing/rending/dividing the opponent. He also notes that your leg "should be places so that it blocks the opponent from retreating or kicking". The one "downing the enemy" application listed says you block a left punch with your left hand, leading it away to the left, moving your right leg in to protect against a kick, then stepping the right leg behind the enemy's right leg (that he stepped forward on the punch) and raise your right arm under the enemy's left armpit. He can then be forced down by rotating to the right and pushing against his right knee with your leg. The listed qin na application is to do the same steps up to the felling action then pull down with your left hand and push up with your right shoulder, bend the enemy's left elbow and wrist, then bring your right hand over to the enemy's held left hand and use both hands to bend his wrist. How's that for a start to this thread? 
