Recently there has been a number of concerns from umpires and players regarding the Stoppage Rule. Please find clarification of this rule below for your information:

If a player asks the umpire for stoppage time due to illness, injury or blood the umpire will hold time. This player MUST leave the court and has 30 seconds to leave the court to receive treatment.  Even if the injury can be dealt with within the 30 seconds, they MUST leave the court. Substitutions and team changes can be made by both teams during this 30 seconds.  If the Primary Carer (First Aider) feels that the injured player requires more time to leave the court, they can appeal to the umpire to extend this time.

During this stoppage, if no substitution is made, the position will remain vacant until the next goal is scored, and after notifying the Umpire, a substitute or the injured player may return to the court, but must fill the vacant position.
Further reading for this rule:  RULE 9.3 STOPPAGES, PAGE 45