Collin is technically "the" referee, but a handful of other professors have been given referee rights to share the load a little. During games, everyone but Collin and the person refereeing are wiped from the ref list.

+tossup [Team1]/[Team2]
Put in the names of the two teams as their three-letter abbreviations (GRY for Gryffindor, HFL for Hufflepuff, RAV for Ravenclaw and SLY for Slytherin), and the code will announce who gets the chance to go first, as well as display rosters for those playing and wipe the ref list. Only 'official' referees may use this command, which include Collin, Dumbledore and Hogwarts Teachers.
(Full game only - NOT available during practice)

+foul [the team that committed the foul]
   Fouls can be called for many, many reasons, and it is up to the Referee to spot them and use this command. Once enacted, the team which has been victimised will be permitted to use the +penalty command. The game is put on hold while a selected Chaser ICly soars from the middle of the field to go one-on-one with the opposing Keeper. Once the shot is taken, the Quaffle is automatically relocated and the game continues as normal.
A penalty with precedence on our game is when there are too many Chasers in the scoring area. If there is, for example, a Hufflepuff Chaser in the Ravenclaw scoring area preparing to score, no other Chaser may touch the Quaffle regardless of their team. Other Hufflepuff Chasers may not use +protect and Ravenclaw Chasers may not try to steal the ball. If one team fouls in this manner, the other receives a penalty shot. (Hufflepuff +protects and Ravenclaw gets a penalty shot. Ravenclaw +steals and Hufflepuff gets a penalty shot.) Any Chaser on the team may take a penalty shot, and the shot does not count as that team's turn for the round. The command to take the shot is +penalty.
Please note if you sight anything happening that you feel could constitute a foul, you may call it. You're the referee, after all. Too many Chasers in the scoring area is only one rule to break.

+add ref
Add yourself as a referee. This is mainly to be used during practices so that team captains and members can watch each other, as anyone currently playing in a game may not be set as a referee.
(Practice code only - NOT available during games)

+rem ref
Remove yourself as a referee.
(Practice code only - NOT available during games)

+list refs
List the current referees.
(Practice code only - NOT available during games)