The Umpire is judge of the conduct of the players, and his decision is final regarding such fouls as are not specifically placed within the jurisdiction of the Referee.
The Umpire is judge of charging, and of the positions of players whenever the ball is put in play.
He may appeal to both the Referee and Linesman for testimony in cases of fouls seen by them, and it shall be their duty to volunteer testimony concerning violations of Rule 27 (c and f).
NOTE - Captains and players, however, may not appeal to the Referee or Linesman for their testimony upon the points just mentioned.
The Umpire shall not signal with his horn or bell, except to declare a foul committed.
Whenever the Umpire notices or is informed by the Referee or Linesman that a substitute or any other person not participating in the game is coaching, he shall immediately exclude the offender for the remainder of the game from the neighborhood of the field of play; i. e., send the offender behind the ropes or fence surrounding the field of play.
Furthermore, he shall exact the penalty as provided in Rule 28.
NOTE - The Referee should use a whistle to indicate cessation of play on downs, fair catches and fouls, and the Umpire (and Linesman) should use a horn or a bell of some kind, distinguishable from the Referee's whistle, to indicate that a foul has been committed.