In Shanxi Province 2004. Master Yang Fansheng expounds upon XY's Ji Tui (Rooster perches on one Leg = knee striking) method of stepping on your enemy with the foot or bumping him with the knee when entering to break his structure and for simultaneous hi and lo attack when coordinated with the hands. When you must step back, the lead leg is violently lifted up and backwards, "shovelling" the enemy's crotch while going back - dirty zero range stuff. He also shows me some ideas on Che style Zuan Jin (Drilling Power) and the importance of mixing high, mid, and low attacks, and how if you want knee your opponent you should put a hand in his face so he wont see the knee coming.