By the rules of the game, the agreed meanings of all calls must be public and known to the opponents. In normal club or home play, the opponents are entitled, at their turn to make a call, to ask the partner of the bidder about the meaning of the call. In high-level tournaments, where screens are used, the procedure is to ask the screen-mate about their calls as well as their partner's calls. In serious online tournaments, the procedure is for the player making the call to self-alert it, but the explanation is visible only to the opponents.