Displacement Map which gray shade up?

I created Displacement Map in gray scale and loaded in my texture. In Materials Button, Map To tab, I selected [Nor] button and increased number on [Nor] slider. The Displacement Map does work but it is reversed; black shade up and white shade down. I thought it was other way around. Is there a button I can push to reveres this?

Also top row of buttons in Map To tab has 3 click able settings; off position, on 1 and on 2. What are they?

Click the Nor button again to reverse the displacement.

Richard

Oh, ok so that was the extra click on those buttons! Thanks.