R 3-2-5

The game clock shall be stopped when each half ends, for a charged team timeout, for an injury timeout or at the Referee’s discretion.
Within the last 2 minutes of each half the clock shall stop:

1. To award a first down, also after a change of team possession.
2. To complete a penalty.
3. When the ball or the runner goes out of bounds.
4. When a pass or fumble (forward or backward) strikes the ground.
5. When a teammate of the fumbler touches the ball.
6. When a score is made and during and after the following try.
7. When a charged timeout is granted.

The game clock shall not run during an extension of a half or overtime.