Rules of Hockey
11.1 Two umpires control the match, apply the Rules and are the
judges of fair play.
11.2 Each umpire has primary responsibility for decisions in one
half of the field for the duration of the match.
11.3 Each umpire is responsible for decisions on free hits in the circle,
penalty corners, penalty strokes and goals in one half of the field.
For a few years now I have been advocating that the number of officials officiating a hockey match ought to be increased to five. I give my reasons via the videos in this article. Please watch the videos, navigating back to the WordPress article is a simple matter of closing a tab or using the back button.
https://martinzigzag.com/2018/06/19/the-number-and-p…-match-officials/
The second part of this same article also suggests the introduction of the use of a second whistle to restart play when an umpire has blown the whistle to award penalty or a side-line ball has to be taken.
11.6 Umpires blow the whistle to:
a start and end each quarter of the match
b start a bully
c enforce a penalty
d stop the time after the awarding of a penalty corner
e re-start the time before the taking of a penalty corner
f start and end a penalty stroke
g indicate a goal
h re-start the match after a goal has been scored
i re-start the match after a penalty stroke when a goal was not scored
j stop the match for the substitution onto or off the field of a fully equipped goalkeeper and to restart the match on completion of the substitution
k stop the match for any other reason and to re-start it
l indicate, when necessary, that the ball has passed wholly outside the field.
It amuses me to see this ‘comprehensive’ list of reasons for an umpire to blow the whistle presented, while in other areas the Rules Committee have declared such comprehensive listing to be unnecessary (too wordy) or too difficult.
Rules of Hockey 
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