Materials  -  M i n M a x

Think of MinMax as a kind of "range remapper".   It lets you take an input and slide it higher or lower, or even stretch it, then output the result.  Here is what the formula looks like:  min + (max-min)* value    As an example of what that means, let's try it out.

Incoming value:  0.6
Min setting:
-0.5
Max setting:
0.5

That gives us this equation and result:      -0.5 + (0.5 - (-0.5)) * 0.6 = 0.1

If, for example, you're using Zbrush (or other image maps), you have the ability to create dents as well as bumps on the surface of your model.  Dents should produce negative values in order to "sink in" the surface, and bumps should have a positive value to "protrude from" the surface.  But because the 16bit image data is likely unsigned (i.e. all positive values... 0.0,1.0), the displacement will always protrude from the surface.  It may have the appearance of dents, but your model will look "swollen" compared to what you see in Zbrush.

So, you need to decide, based on what you've produced in Zbrush, how far the dents should sink into the surface.   Also, messiah already handles signed data.  If Zbrush is eventually able to output its maps as "signed" 16bit images, then you won't need MinMax, you would just control the level of bump on the Material.