Readiness

Once a rally has ended, the players are given a reasonable amount of time (according to the judgment of the referee) to return to their respective positions, and then the score is called. If the server or receiver is, in the referees opinion, taking too much time in commencing play, that player will be assessed with a Loss of point penalty.
i) The 10 second rule applies to the server and receiver simultaneously. Collectively, they are allowed up to 10 seconds after the score is called to serve or be ready to receive. It is the servers responsibility to look and be certain the receiver is ready. If a receiver is not ready, they must signal by raising the racquet above the head or completely turning the back to the server. These are the only two acceptable signals.
ii) Serving while the receiving player/team is signaling not ready shall be replayed with no penalty and the server shall be warned to check the receiver. If the server serves a second consecutive time without checking the receiver, the referee will assess a fault serve.
iii) After the score is called, if the server looks at the receiver and the receiver is not signaling not ready, the server may then serve. If the receiver attempts to signal not ready after that point, the signal shall not be acknowledged and the serve becomes legal.