This is the second part of a three-part series on officiating. This part will deal with the officiating crew and their keys - or what their responsibilities are on each play. The first part dealt with what it takes to become a FCS-level official. The third part will deal with post-snap responsibilities, and the fourth will deal with how calls are made.

There are seven members of the officiating crew in the NFL and college football (although some smaller colleges will use only six, without the back judge). Below are the definitions of each crew member, along with their pre-snap keys. This should be considered light reading, still laying the ground work for the complexity that's yet to come.

Referee or Head Referee

The referee or head referee positions himself in the offensive backfield before the snap. He's the guy with the white cap, and he is the head of the officiating crew. If there are any disputes, he's the guy who makes the final decision.

The referee is responsible for counting the offense while in the huddle and then after they break huddle to make sure there are 11 guys on the field. He watches the quarterback, and makes sure that any motion is legal.

Umpire

The umpire stands on the defensive side of the ball near the linebackers. He's most likely to be run over by players. The umpire counts offensive players in the same way as the referee, and both must confirm the count is legal before the play.

The umpire watches the interior linemen (center and guards, and assists with tackles) to make sure there is no illegal movement and makes sure the snap is legal. He makes sure the defense doesn't use any words or signals to disrupt the offense. He must be aware of which players are ineligible receivers, and must be aware of the position of the ball relative to the field so that the ball can be returned to the previous spot if necessary.

Head Linesman And Line Judge

The head linesman is on the sideline opposite the press box, where the chain crew (the sticks) are located. The line judge is opposite the head linesman.

Both are responsible for determining if the formation is legal. This used to involve determining how many players are on the line of scrimmage, but due to rule changes they simply count how many players are in the backfield. If there are four or less, it's an illegal formation. Both watch for encroachment by the defense, and false starts by offensive linemen, particularly the tackles. They also watch any players in motion to determine that it's legal.

Field Judge

The field judge is located behind the defensive secondary on the same side as the line judge. He counts the defensive players, determines which receivers are eligible and monitors defensive substitutions.

Side Judge

The side judge is located behind the defensive secondary on the side of the head linesman. He counts the defensive players, He has the same responsibilities as the field judge, but on his side of the field. Along with those, he monitors the game clock and calls time out if there is a problem, notifying the referee.

Back Judge

The back judge is behind the defensive secondary, favoring the strong side of the field (determined by the number of eligible receivers). He also counts the defensive players, and is responsible for the 25/40-second play clock.

Conclusion

At this point, the teams are lined up, and the ball has not yet been snapped. Things for the officiating crew don't appear to be too complicated, but what you don't realize is that the crew is determining their keys - the players to watch. That's next.