Box lacrosse 1998, the NLL entered into the Canadian market for the first time with the Ontario Raiders. Although 5 of the league's 9 teams are based in American cities, more than two-thirds of the players are Canadian. During play, a team consists of six players: a goaltender and five "runners". A runner is any non-goalkeeper position player, including forwards, transition players, and defenders. Runners usually specialize in one of these roles and substitute off the field when the ball moves from one end to the other. When the sport originated teams played with six runners. However, in 1953 the sixth runner,
Field lacrosse member William George Beers codified the modern game. He established the Canadian Lacrosse Association and created the first written rules for the game, "Lacrosse: The National Game of Canada". The book specified field layout, lacrosse ball dimensions, lacrosse stick length, number of players, and number of goals required to determine the match winner. Field lacrosse involves two teams, each competing to shoot a lacrosse ball into the opposing team's goal. A lacrosse ball is made out of solid rubber, measuring 7.75 to 8 inches (19.7–20 cm) in circumference and weighing 5 to 5.25 ounces (140–149 g). Each team plays with