In order to register for U6/U7 training classes, or request U6/U7 game assignments in R85 you must have a R85 Ref # and Pin #.
You will initially be issued a temporary Ref # (> 7000) which will allow you to register for classes and update your personal information, e.g. email address, Pin #, etc., but will not allow you to signup for games.
When you are certified as a referee you will be issued a permanent Ref #. If you no longer wish to referee in R85 you can make yourself inactive, or permanently delete your Ref #.