Hi. I learned from some players today, after seeing a serve curve to the opposite after impact with the ground, that there are at least two undocumented effects which can be added with buttons 'z' and 'x'. Apparently, the 'x' key can be held down on a serve to cause it to curve, and the 'z' key can give a wildly looping effect to a forehand. Also, I think that the 'z' key will create a booming serve. Are there any other undocumented keys that we new players should know about

Thanks!