No. 4 Referees
No. 4 (and 5) referees are responsible for managing player substitutions during a match. The only games which regularly have No.4 referees appointed in Brisbane are Representative and Premier matches, but at finals time all matches will have No. 4 referees appointed.
The best source of information for referees wanting to learn more about the role of No. 4 referee is the World Rugby Technical Zone Program, which can be found on the World Rugby website at this link.
Some useful resources for No. 4 Referees are: