Abstract: A tennis court wherein the different playing zones thereof defined by the rules of tennis are distinguished by color, as opposed to the conventional use of white stripes to define zone boundaries.

Abstract: A line monitoring apparatus is disclosed which is particularly adapted for use in determining whether a ball lands inside or outside of an area having a premarked boundary, such as a line on a tennis court. The apparatus incorporates electrical circuitry which distinguishes between a player's foot or a ball activating the switching means monitoring so that a player cannot activate an audio or visual indicator. An embodiment of the system includes pressure operated switching means for monitoring the boundary, as well as a service foot fault detector.