The field has no boundaries, but is usually enclosed by existing borders, such a trees, a track or fences. The Referee's Role Uses a whistle to denote a foul. When a player receives a yellow card, she is warned that she is in danger of being ejected from the game. If a player is given a red card, she is ejected. When a foul is committed, the referee will blow the whistle and determine whether the foul is major or minor.
Penalties are more severe for major fouls than minor ones.
Referees can require a longer distance if the foul was reckless.