Used for checking if the player is inside an arena or if it's a rated match

isArena, isRegistered = IsActiveBattlefieldArena();

Parameters

Returns

isArena 

Integer - 1 if the player is inside an arena, nil if they aren't

isRegistered 

Integer - 1 if the player is playing a rated arena match, nil if they aren't

Details

If you are in waiting room and/or countdown is going on, it will return false.