Editing Canadian football (section)

=== Game timing ===
The game consists of two 30-minute halves, each of which is divided into two 15-minute quarters. The clock counts down from 15:00 in each quarter. Timing rules change when there are three minutes remaining in a half.
A short break interval of 2 minutes occurs after the end of each quarter (a longer break of 15 minutes at halftime), and the two teams then change goals.

In the first 27 minutes of a half, the clock stops when:
* Points are scored,
* The ball goes out of bounds,
* A forward pass is incomplete,
* The ball is dead and a penalty flag has been thrown,
* The ball is dead and teams are making substitutions (e.g., possession has changed, punting situation, short yardage situation),
* The ball is dead and a player is injured, or
* The ball is dead and a captain or a coach calls a [[sport time-out|time-out]].

The clock starts again when the referee determines the ball is ready for scrimmage, except for team time-outs (where the clock starts at the snap), after a time count foul (at the snap) and kickoffs (where the clock starts not at the kick but when the ball is first touched after the kick).

In the last three minutes of a half, the clock stops whenever the ball becomes dead. On kickoffs, the clock starts when the ball is first touched after the kick. On scrimmages, when it starts depends on what ended the previous play. The clock starts when the ball is ready for scrimmage except that it starts on the snap when on the previous play:
* The ball was kicked off,
* The ball was punted,
* The ball changed possession,
* The ball went out of bounds,
* There were points scored,
* There was an incomplete forward pass,
* There was a penalty applied (not declined), or
* There was a team time-out.

During the last three minutes of a half, the penalty for failure to place the ball in play within the 20-second play clock, known as a "time count violation" (this foul is known as "delay of game" in American football), is dramatically different from during the first 27 minutes. Instead of the penalty being 5 yards with the down repeated, the base penalty (except during convert attempts) becomes loss of down on first or second down, and 10 yards on third down with the down repeated. In addition, as noted previously, the referee can give possession to the defence for repeated deliberate time count violations on third down.

The clock does not run during convert attempts in the last three minutes of a half. If the 15 minutes of a quarter expire while the ball is live, the quarter is extended until the ball becomes dead. If a quarter's time expires while the ball is dead, the quarter is extended for one more scrimmage. A quarter cannot end while a penalty is pending: after the penalty yardage is applied, the quarter is extended one scrimmage. The non-penalized team has the option to ''decline'' any penalty it considers disadvantageous, so a losing team cannot indefinitely prolong a game by repeatedly committing infractions.