If there is a sense in which a card game can have an "official" set of rules, it is when that card game has an "official" governing body. For example, the rules of tournament bridge are governed by the World Bridge Federation, and by local bodies in various countries such as the American Contract Bridge League in the U.S., and the English Bridge Union in England. The rules of skat are governed by The International Skat Players Association and, in Germany, by the "Deutscher Skatverband" which publishes the "Skatordnung". The rules of French tarot are governed by the Fédération Française de Tarot. The rules of Poker's variants are largely traditional, but enforced by the World Series of Poker and the World Poker Tour organizations which sponsor tournament play. Even in these cases, the rules must only be followed exactly at games sanctioned by these governing bodies; players in less formal settings are free to implement agreed-upon supplemental or substitute rules at will.