Looks for possible false start by offensive linemen. Observes legality of contact by both offensive linemen while blocking and by defensive players while they attempt to ward off blockers. Is prepared to call rule infractions if they occur on offense or defense. Moves forward to line of scrimmage when pass play develops in order to insure that interior linemen do not move illegally downfield. If offensive linemen indicate screen pass is to be attempted, Umpire shifts his attention toward screen side, picks up potential receiver in order to insure that he will legally be permitted to run his pattern and continues to rule on action of blockers.
Umpire is to assist in ruling on incomplete or trapped passes when ball is thrown overhead or short.
Head Linesman Primarily responsible for ruling on offside, encroachment, and actions pertaining to scrimmage line prior to or at snap. Keys on closest setback on his side of the field. On pass plays, Linesman is responsible to clear his receiver approximately seven yards downfield as he moves to a point five yards beyond the line. Linesman s secondary responsibility is to rule on any illegal action taken by defenders on any delay receiver moving downfield. Has full responsibility for ruling on sideline plays on his side, e.g., pass receiver or runner in or out of bounds.