Conditional effects on a model

Folks, how do make an effect only be visible during taxi? Or during sleep? I would like the following for my AI boats: Sleep Pre-Taxi Taxi ClearanceRunning Lights: Off On On OffAnchor Light: On On Off OnI note that AI aircraft turn on their lights at pre-taxi, turn on landing lights when landing, so I 'm hopeful there's a way to do this.I presume there's a way to do this, as AI aircraft turn on their landing lights at certain times, etc. I've heard rumours about the possibility of triggering on engine RPM.This is an original gmax model I'm working on.Jon