Move the Witness Line for Permanent Dimensions

When you want to change the reference for a permanent dimension, move its witness line.

1. Select a permanent dimension.
2. Right-click the blue circle control in the middle of the witness line, and click Move Witness Line.
   
3. Drag the witness line to the element to be referenced.
Note: Left-click the witness line control to change the reference point for that element. For example, for a wall, left-clicking the control toggles the reference point among the centerline, the interior face, and the exterior face of the wall.