This is correct...and true with BMW and Mercedes, at least on the older cars...must be a German thing!
Also, for a little more info, the top slider on the HVAC control panel controls air flow for the defrost vents. The bottom slider controls air flow to the floor vents. The vertical slide with the little defrost logo at the top will open or shut the main "in your face" vents. By different combinations of positions of all of the various levers, you can direct air flow where it's needed. Most of the time, you'll end up with a spring/summer setting and a fall/winter setting and then use the magic defrost button to clear the windshield. Hope that helps.
- Darryl