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 Schafkopf are laid down by the Schafkopfschule in Munich. Even in these cases, the rules must only be followed at games sanctioned by these governing bodies or where the tournament organisers specify them. Players in informal settings are free to implement agreed supplemental or substitute rules. For example, in Schafkopf there are numerous local variants sometimes known as "impure" Schafkopf and specified by assuming the official rules and describing the additions e.g. "with Geier and Bettel, tariff 5/10 cents".
