Some software allow users to zoom via a middle mouse wheel. Occasionally the direction that zooms IN may be the opposite in one application verses another.
With the ZOOMWHEEL system variable in CIVIL 3D we can control which direction, towards us or away from us, zooms IN.
The default setting for ZOOMWHEEL is 0, which reacts with: moving wheel forward zooms in; moving wheel backwards zooms out. Effectively we are moving ourselves with the mouse.
Changing this value to 1, reacts with: Move wheel forward zooms out; moving wheel backwards zooms in. Think of this as you are moving the object with the mouse.
This NEW system variable allows us to perhaps make different applications function slightly more consistently.
Try it. See if you have a preference.