A gridiron official is a referee responsible for officiating a football game. The three-letter abbreviation for this position is 'REF'. An UMPIRE is a gridiron official who is responsible for monitoring the line of scrimmage and making rulings on plays. The six-letter abbreviation for this position is 'UMPIRE'. A back judge is a gridiron official who is responsible for monitoring the defensive backfield and making rulings on pass interference. The nine-letter abbreviation for this position is 'BACKJUDGE'. Finally, a side judge is a gridiron official who is responsible for monitoring the offensive backfield and making rulings on illegal motion. The nine-letter abbreviation for this position is 'SIDEJUDGE'.