Officials
A hurling match is watched over by 8 officials:
The referee
Two linesmen
Sideline Official/Standby Linesman (inter-county games only)
Four umpires (two at each end)
The referee is responsible for starting and stopping play, recording the score, awarding frees and booking and sending off players.
Linesmen are responsible for indicating the direction of line balls to the referee.
The fourth official is responsible for overseeing substitutions, and also indicating the amount of stoppage time (signalled to him by the referee) and the players substituted using an electronic board.
The umpires are responsible for judging the scoring. They indicate to the referee whether a shot was: wide (spread both arms), a 65 m puck (raise one arm), a point (wave white flag), or a goal (wave green flag).
All officials are also supposed to indicate to the referee anything he may have missed, although this is a rare occurrence. The referee can over-rule any decision by a linesman or umpire.