This is the third part of a four-part series on the officiating crew. Our first article, we introduced what is required to become a member of a FCS-level officiating crew. In the second, we reviewed the officiating crew positions and their pre-snap responsibilities.

At this point in our series, the teams have lined up to start the play. The offensive set is a Pro Set, with the strength to the lineman's side of the field as shown in the figure after the jump. Officiating crew field positions are shown as well.

In the Pro Set formation, the officiating crew has the following responsibilities:

Referee: Quarterback, backs and tackles.

Umpire: Interior lineman (guards and centers)

Linesman: third eligible receiver from the sideline to the linesman's side of the field. In this case, it's the back on his side of the field. During a passing down, the head linesman will work his way down the field 7 to 9 yards.

Side Judge: Widest eligible receiver on the side judge's side of the field, in this case, the flanker.

Line judge: Normally the third eligible receiver from the sideline to the line judge's side of the formation, but if there are only two eligible receivers on the line judge's side of the field, the key here is the inside receiver. In the pro set as shown, the line judge watches the back on his side. The line judge will hold the line during pass plays so he can determine if the QB is across the line when the ball is released or if there are any ineligible receiver's down field.

Field Judge: Widest eligible receiver on the field judge's side of the field, in this case the split end.

Back Judge: Second eligible receiver on the strong side of the field, in this case the tight end. If the formation is balanced, the Back Judge will favor the line judge's side.There are ten different offensive alignments that the officiating crew must be aware of to determine their keys to watch during the play. The different offensive alignments are defined are as follows (We're not going to bother with kicking, punting, onside kick formations, or goal line situations, but consider the possibilities):

Pro Set, Strength to Lineman's Side
Motion Man Inside Tackle at Snap
Motion Man Outside Tackle at Snap
Motion Man is Widest at Snap
Double Tight End, Balanced Formation
Trips, Empty Backfield
Four Receivers, Unaligned
Four Receivers, Stacked
Double Wing, Balanced Formation
Motion into Trips

To cover all the formations and respective keys would be more exhaustive than I desire to be, and probably more than you want to read. The bottom line is that each member of the crew must correctly identify the formation, then determine which player they are responsible to watch throughout the play.

If the offensive team goes into motion or switches formation, then the keys change and each member of the crew must pick up their new key before the ball is snapped and play begins.

Let's look at what happens during a running play from the perspective of a single official - the line judge.

The ball is snapped and the offensive team runs a sweep to the line judge's side of the field. The line judge has been watching the line to make sure there are no false starts. As the play starts, the line judge moves from the ball to the offensive tackle on his side (can't block below the waist, clip, or hold a defensive end), then they move to their key (the inside receiver).

The line judge has taken two steps into the offensive backfield to get a better view of blocking. As the play moves forward the line judge watches the blocking behind the runner. If the runner is stopped the line judge's job is to determine forward progress. If the run continues, the line judge continues to follow the runner until his forward progress is stopped.

If the side judge's view is blocked, he will receive help from the referee, who is trailing the play, and the umpire, who has turned to watch the play from the defensive point of view. (Keep in mind the umpire can't exactly run into the play, or he's going to get killed. The NFL recently adjusted the position of the umpire due to so many injuries.)

Consider the number of formations and the variations of plays that can be run from those formations, and that all of this is happening at football speed, and you get an idea of why FCS-level officials must learn for years before they're allowed to officiate college football games. The complexity is amazing.

Next up, we'll put everything together and talk about the most controversial calls that the officiating crew has to make (holding) and some of the philosophical reasons as to why they make them.