A - Theoretical Surface Normal
B - Measured Point
C - Theo Point
D - Gap
E - Theoretical Approach Vector
The Gap Only check box is available when dimensioning edge points. When you select the Gap Only check box, and an edge point is measured, the location axes are calculated by:
Projecting the measured point (1) to the theoretical surface.
Projecting this new point on to the theoretical approach vector.
Any location axes are then calculated from this new point.
A - Theoretical Surface Normal
B - Measured Point
C - Theo Point
D - Gap
E - Theoretical Approach Vector