Returns true if the variable we are setting has a RepNotify AND was defined in a blueprint The 'defined in a blueprint' is to avoid natively defined RepNotifies being called unintentionally. Most (all?) native rep notifies are intended to be client only. We are moving away from this paradigm in blueprints So for now this is somewhat of a hold over to avoid nasty bugs where a K2 set node is calling a native function that the designer has no idea what it is doing.