The switch with picture of a child on it inhibits the rear power window operation, the 'child door lock' switch is a small lever near to the door latch, seen when the door is open.
The W202 rally car had it on the inner "lip" of the door (i.e. inacessible when the door is closed).
Open the door, flip a switch, and hey presto the door can't be opened from inside... (pain in the @$$ when you're in the middle of nowhere sleeping on the back seat and someone does that as a prank as they leave the car.... )