In Germany, the StVZO (Road Traffic Licensing Regulations) calls for a different function provided by these lights: with the vehicle's ignition switched off, the operator may activate a low-intensity white light at the front and red light at the rear on either the left or right side. This function is used when parking in narrow unlit streets to provide parked-vehicle conspicuity to approaching drivers. This function, which is optional under UN and US regulations, is served passively in the United States by mandatory side marker retroreflectors.
