The Crawford rule (named for John R. Crawford) is an optional rule for match play that states: if a player attains a match score one game short of victory, the next game of the match is to be played without a doubling cube. This one game in which neither player may double is called the Crawford game.

For example, if you are playing a five point match and win a game to take a 4-1 lead, the next game is the Crawford game, and the doubling cube is not allowed. If your opponent wins a single point game (the score is then 4-2), the doubling cube is in effect for the remaining games of the match.

You can specify whether you prefer to play matches with the Crawford rule in effect. Most players on FIBS do choose to play with the Crawford rule, and by default it is enabled. Both players must disable this option to disable the Crawford rule, so either player may force the Crawford rule to be in effect.