Field hockey - Wikipedia
https://en.wikipedia.org/wiki/Field_hockeyThe game is played between two teams of eleven, 10 field players and one goal keeper, are permitted to be on the pitch at any one time. The remaining players may be substituted in any combination. There is an unlimited number of times a team can sub in and out. Substitutions are permitted at any point in the game, apart from between the award and end of a penalty corner; two exceptions to this rule is for injury or suspension of the defending goalkeeper, which is not allowe…