What is the role of a disengaged hockey umpire?

Answer 1

The engaged umpire is the one currently in control of play, normally because the ball is within their circle or 23 metre area.

The disengaged umpire is, simply enough, the other umpire on the field, their coumpire.

Their role is to provide asistance to the engaged umpire, to cover any areas of the field in which they are unsighted, and to maintain supervision of off-the-ball players. If necessary, the disengaged umpire should also focus on the timekeeping aspects (i.e. calling the end of halves) while their coumpire is distracted.