Where is this clock that is used to serve? In books and magazines and on this board I have read about the racket moving from something like 7 o’clock to 1 o’clock, but nowhere have I seen the clock defined. Am I the only one that wonders about this? Here is what I think is the position of the clock: The clock is in the vertical plane that is perpendicular to the planned flight of the ball. For example, if the server is at the center, by the hash mark and serving down the center, the clock would be in the plane of the back court line. If the server moves to either side on the center to serve wide, the clock would rotate with the direction of he serve. Is this correct? Am I correct that the plane is vertical? And why is there only one clock? It has been a long time since I studied geometry, but I doubt that geometry has changed. Movement in one direction on one plane is only part of what it takes to define movement.