Referee. Assume a position where he can see the ball and the offensive tackle on his side of the ball at the snap. WATCHES THE QUARTERBACK, AND HELPS WITH THE TACKLE ON HIS SIDE.

Umpire. Insure legal snap and ineligibles on the line of scrimmage. WATCHES INTERIOR LINEMEN.

Linesman and Line Judge. KEY ON WIDEST ELIGIBLE RECEIVER IN THE FORMATION ON YOUR SIDE OF THE FIELD. Also take the second eligible receiver in, for formations with two wideouts to the strong side of the field opposite you. In 4-man crews, both wideouts are always your keys. Remain with your keys up the field for two to three seconds (3 to 5 yards) then pivot to check the play.

Back Judge. Key on TIGHT END in normal formations, or the man in motion. Key on the second man in with two wideouts to the strong side of the field.

Linesman, Line Judge, and Back Judge. Must be ready to SWITCH KEYS when a formation shift occurs.

All. Stay with your keys for the initial charge of the formation, then switch to zone responsibility. CAUTION: After the snap, do not release too quickly and assume zone responsibility.