I'm a little confused as to the functioning of the F-15's VSD radar scope. My understanding is that the bottom scale represents azimuth to target, while the side represents range. In that case, why exactly is it called a vertical situation display? To me the name implies that it would show azimuth and elevation to a radar contact (i.e. a vertical plane representation, like the HUD), while an azimuth-range representation (i.e. view from the top) is what I would consider a horizontal situation.