Defining the Movement Plane
When modifying a surface, you can select one of the following Movement Plane options on the Modify Surface dialog box:
• Dynamic Plane—The movement plane is a tangent plane that passes through the selected point. The dynamic movement plane follows the selected point.
• Defined Plane—Selects a datum plane to be the movement plane.
• Original Plane—The movement plane is a tangent plane that passes through the original location of the selected point.