Sunday’s New York Jets-New England Patriots game on Kickoff Weekend was an example of how the NFL’s explicit "third quarterback" rule works.

For the game, the Jets designated starter VINNY TESTAVERDE and TOM TUPA, who also punts, as their two active quarterbacks. RICK MIRER was designated as the Jets’ "third quarterback."

In the second quarter, Testaverde was injured and determined to be out for the game. Tupa took his place at quarterback, and also punted.

In the fourth quarter, the Jets brought Mirer into the game at quarterback.

The reason the Jets waited until the fourth quarter to use Mirer is that if he was inserted before the fourth quarter, Tupa would not be allowed to continue in the game, even as a punter.

The third quarterback rule states that if a third quarterback is inserted before the fourth quarter, a team’s first two quarterbacks cannot be used in the game at any position.

Another aspect of the rule is sometimes misunderstood. It is a coach’s decision as to whether a third quarterback will be used. The active quarterbacks do not have to be injured for a team to use its third quarterback.