From the Edit menu, point to Graphic Display Window, and choose Lighting, Materials. Click on the Clip Planes tab.
Once you have the clipping plane inserted, you can adjust it by:
Clicking the Flip IJK push button to invert the IJK. This is useful when surface vectors from a CAD selection were incorrect, a relatively common problem with IGES files.
Manually editing XYZ location and IJK vector information by typing in new values.
Using the Move clipping plane along above IJK area.
The Move clipping plane along above IJK area contains two rows of boxes and up and down arrow buttons. The boxes define increments that the clipping plane uses to move along the defined vector when you click the up or down arrow buttons for that box.
The top row allows you to move the clipping plane along the IJK vector in small adjustments.
The bottom row allows you to also move the clipping plane along the IJK vector, in larger increments.