Under IIHF rules, each team may carry a maximum of 20 players and two goaltenders on their roster. NHL rules restrict the total number of players per game to 18, plus two goaltenders. In the NHL, the players are usually divided into four lines of three forwards, and into three pairs of defencemen. On occasion, teams may elect to substitute an extra defenceman for a forward. The seventh defenceman may play as a substitute defenceman, spend the game on the bench, or if a team chooses to play four lines then this seventh defenceman may see ice-time on the fourth line as a forward.