REF AND SUBS 

A soccer team can choose to substitute a new player for one who has been playing at any point during a game. When the coach decides to make a substitution, he or she tells an official who hangs out near the team benches, and that official signals the referee. At the next dead ball (a stop in play that occurs when the ball goes out-of-bounds for a throw-in or goal-kick but not for a corner kick or a foul) the ref stops the game and allows the substitution to be made. There are two somewhat picky rules about this process. The substitute is supposed to wait at the side of the field at exactly the half-way line until the player who is being substituted for leaves the field completely. Refs are allowed to discipline (by giving yellow or red cards) players who violate these rules. 

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