Rigger adaptation?

I know the rigger interface is an item that you buy and install in vehicle so you can remote control it, but what is a rigger adaptation? I checked the Double Clutch book, and both the rigger interface and rigger adaptation are mentioned. Vehicles that have them always have either, but not both, and the rigger adaptation is listed under Standard Equipment (on the vehicle stats). However, I don't see any cost, rating or any game mechanics for the rigger adaptation.