The World Curling Federation Secretariat relocated from Edinburgh to Perth, Scotland, in May 2000. Wheelchair curling debuted in the World Handi Ski Championships in Crans-Montana, Switzerland, in 2000. Switzerland and Sweden were the only competitors. The event was held for only one year because of lack of interest from other countries. Wheelchair curling is a form of boccia played by people with physical disabilities. An ice rink is required, as well as wheelchairs and some kind of brake for each player. The game is similar to wheelchair basketball but uses a sheet of ice instead of a basketball court. In addition to the rules applicable to traditional curling, players must follow certain guidelines when using their brakes: no more than six points of contact with the ice at any one time; no faster than five miles per hour; and no driving on the ice during play. There are three types of shots in wheelchair curling: the hammer throw, the rock shot, and the sweep shot. During the hammer throw, also called the house shot, the player throws his or her hammer into the air by bending at the waist. The hammer must be kept in the throwing position until it is caught behind the head with both hands. The rock must be thrown with force enough to make a sound when it hits the ice. There is a limit to how far a player can throw a hammer.