I am using the Distance Tool to measure between two vehicles in EDSMAC4. When I select a point on one vehicle and then on the other vehicle, I see the Distance Tool dialog indicates a Z height and Zenith angle. Why?

No matter which system software you are using, the Distance Tool provides information between two selected points on the geometries of vehicles or the environment.  Vehicles in HVE-2D and HVE-CSI have 3-dimensional shape to them, which are reflected in the coordinates of the points selected on each object.  You may have selected the roof of one vehicle and the lower front fender of the other vehicle.  There will be an elevation difference between the two selected points, which will be displayed in the results.  If you want to see the absolute horizontal distance between any two points using the Distance Tool, simply edit the From/To Z coordinates for both points to be exactly the same. When you press Apply, you'll see that the Z distance and the zenith angle results are now shown as 0.0.