Various combinations of penalties may also result in matchups such as 5-on-3, 4-on-3, 4-on-4 or even 3-on-3; in a four-on-four or three-on-three penalty combination, icing will still be enforced. A team, however, may not have fewer than four players (including the goaltender) on the ice at any point in the game. Power play in overtime If a penalty is called on a team in overtime, the matchups in that period cannot become 3-on-2, as there cannot be less than three skaters on the ice for a team. Instead, the power play team gets a 4-on-3 power play. When that power play ends, the matchups temporarily become 4-on-4 until the play is blown dead, after which the matchups return to 3-on-3. Team roster The maximum number of players on an NHL roster is 20. A team can have a maximum of 50 signed players and a total of 90 players (unsigned and signed). Potential rule changes In August 2010, the NHL held an "R & D camp" at the Toronto Maple Leafs’ practice facility, where rule changes under consideration were given trial runs. Scrimmages at the camp, featuring some top players eligible for the 2011 NHL Entry Draft, experimented with changes such as two-on-two overtime, shallower goal nets, a referee viewing the play from an elevated off-ice platform, and a rink with three face-off circles instead of the traditional five. Table of comparison In 2021 IIHF adopted a new rule book which is based on NHL rules, however, some differences remain. The following table lists some of the key differences between NHL and IIHF rules. References Notes External links NHL Official Rules 2022-2023 Ice hockey rules Rules