Originally Posted by
magredvet
Actually, they're required by law in Europe. When you are parked on an unlit street at night, in the direction of traffic flow, you're supposed to show lights front and back, on the side furthest from the kerb. Hence one side for RHD (England) the other side for LHD, (rest of Europe), and they're known as parking lamps.
They should only come on when the ignition is off.
I can't comment for Europe, but the UK rules don't mention only having lights lit on the side furthest from the kerb. Every car I've driven has had side (parking) lights, but the Xfire is the only one that allows left/right selection.