For games you require
A referee
Two Assistant referees to run the line
A reserve official .
Another official (known as the "fourth official") to ensure that all the above positions are filled, and replace the referee in cases where the referee is unable to complete the game. This used the duty of the primary lineman. He is also required to act as an independent timekeeper, which was previously the duty of the referee and ensure that players and staff not on the field of play, are acting within the laws of the game.
I have also wondered why if there is a forth official and his duty is to be a time keeper to add time on for injuries, goals, subs, ect - why can't there be a stopping clock like in rugby, this would put a stop to time wasting.
