Originally Posted by Uncle_Al
More like parking lights. They don't blink. They use them in Europe for on street parking where they hang out in the street.
^Also this. They are actually the parking lights, it just allows you to turn on one side or the other instead of both. Also, the interior (dash) lights will remain off.
Most Mercedes that I've been in have this switch in them. Kinda tells you where it came from.