Editing Canadian football (section)

===Officials and fouls===
{{See also|Official (Canadian football)|Chain crew|Penalty (gridiron football)}}

Officials are responsible for enforcing game rules and monitoring the clock. All officials carry a [[whistle]] and wear black-and-white striped shirts and black caps except for the referee, whose cap is white.{{clarify |date=March 2020 |reason=Are these colours used in amateur play? }} Each carries a [[Penalty flag|weighted orange flag]] that is thrown to the ground to signal that a [[Penalty (gridiron football)|foul]] has been called. An official who spots multiple fouls will throw their cap as a secondary signal.<ref name="American Football Officials">{{cite web|url=http://www.dummies.com/how-to/content/american-football-officials.html|title=American Football Officials|last1=Long|first1=Howie|last2=Czarnecki|first2=John|author-link1=Howie Long|publisher=[[For Dummies|Dummies.com]]|access-date=November 22, 2012|archive-url=https://web.archive.org/web/20121127034309/http://www.dummies.com/how-to/content/american-football-officials.html|archive-date=November 27, 2012|url-status=live|df=mdy-all}}</ref> The seven officials (of a standard seven-man crew; lower levels of play up to the university level use fewer officials) on the field are each tasked with a different set of responsibilities:<ref name="American Football Officials" />
[[File:First down marker.png|thumb|upright|alt=Photograph of a down indicator box on a pole | A modern down indicator box is mounted on a pole and is used to mark the current line of scrimmage. The number on the marker is changed using a dial.]]
* The '''referee''' is positioned behind and to the side of the offensive backs. The referee is charged with oversight and control of the game and is the authority on the score, the down number, and any rule interpretations in discussions among the other officials. The referee announces all penalties and discusses the infraction with the offending team's captain, monitors for illegal hits against the quarterback, makes requests for first-down measurements, and notifies the head coach whenever a player is ejected. The referee positions themselves to the passing arm side of the quarterback. In most games, the referee is responsible for spotting the football prior to a play from scrimmage.
* The '''umpire''' is positioned in the defensive backfield. The umpire watches play along the line of scrimmage to make sure that no more than 12 offensive players are on the field before the snap. The umpire monitors contact between offensive and defensive linemen and calls most of the [[Holding (American football)|holding]] penalties. The umpire records the number of timeouts taken and the winner of the coin toss and the game score, assists the referee in situations involving possession of the ball close to the line of scrimmage, determines whether player equipment is legal, and dries wet balls prior to the snap if a game is played in rain.
* The '''back judge''' is positioned deep in the defensive backfield, behind the umpire. The back judge ensures that the defensive team has no more than 12 players on the field and determines whether catches are legal, whether field goal or extra point attempts are good, and whether a [[pass interference]] violation occurred. The back judge is also responsible for the play clock, the time between each play, when a visible play clock is not used.
* The '''head linesman'''/'''down judge''' is positioned on one end of the line of scrimmage. The head linesman/down judge watches for any line-of-scrimmage and holding violations and assists the line judge with illegal procedure calls. The head linesman/down judge also rules on out-of-bounds calls that happen on their side of the field, oversees the chain crew and marks the forward progress of a runner when a play has been whistled dead.
* The '''side judge''' is positioned 20 yards downfield of the head linesman. The side judge mainly duplicates the functions of the field judge. On field goal and extra point attempts, the side judge is positioned lateral to the umpire.
* The '''line judge''' is positioned on the end of the line of scrimmage, opposite the head linesman. They supervise player substitutions, the line of scrimmage during punts, and game timing. The line judge notifies the referee when time has expired at the end of a quarter and notifies the head coach of the home team when five minutes remain for halftime. In the CFL, the line judge also alerts the referee when [[three-minute warning|three minutes remain in the half]]. If the clock malfunctions or becomes inoperable, the line judge becomes the official timekeeper.
* The '''field judge''' is positioned 20 yards downfield from the line judge. The field judge monitors and controls the [[play clock]], counts the number of defensive players on the field and watches for offensive pass interference and holding violations by offensive players. The field judge also makes decisions regarding catches, recoveries and the ball spot when a player goes out of bounds. On field goal and extra-point attempts, the field judge is stationed under the upright opposite the back judge.

Another set of officials, the [[chain crew]], is responsible for moving the chains. The chains, consisting of two large sticks with a 10-yard-long chain between them, are used to measure for a first down. The chain crew stays on the sidelines during the game, but if requested by the officials they will briefly bring the chains on to the field to measure. The chain crew work under the direction of the head linesman and will typically consist of at least three people—two members of the chain crew will hold either of the two sticks, while a third will hold the down marker. The down marker, a large stick with a dial on it, is flipped after each play to indicate the current down and is typically moved to the approximate spot of the ball. The chain crew system has been used for over 100 years and is considered to be an accurate measure of distance, rarely subject to criticism from either side.<ref name="The Orchestration of the Chain Gang">{{cite news|url=https://www.nytimes.com/2009/01/01/sports/football/01chainside.html|title=The Orchestration of the Chain Gang|last=Branch|first=John|date=December 31, 2008|work=[[The New York Times]]|access-date=December 19, 2012|archive-url=https://web.archive.org/web/20121229055115/http://www.nytimes.com/2009/01/01/sports/football/01chainside.html|archive-date=December 29, 2012|url-status=live|df=mdy-all}}</ref>