Extrusion tab for objects
Origin and Normal: Define the 3D base plane for the extrusion object, typically the reflection plane. These values are typically set using the 3D Import tool on the Object page or the Copy From button.
Copy From: Copies the plane definition from another object to use as the reflection plane.
Plane and Extrusion Curve are Valid: This box is checked if you assigned a valid reflection plane and defined the extrusion intersection curve using the [Edit Model] tool .