Base: Always measures the distance from the first point you select to each of the additional points you select.
Continuous: Measures the distance from one point to the next.
Select two points to display the distance between the points.
Select another point. If you selected Base, Autodesk Civil 3D displays the distance from first (or base) point to the new point. If you selected Continuous, Autodesk Civil 3D displays the distance from the last point to the new point.
When you finish selecting points, press Enter to view the total of the distances.