To split an Outline part (for example, to split a line or a curve so a new part (like an arc) can be inserted, or to reassign parts to different surfaces):
• Enter an Outline mode (line, arc, spline, etc.).
• Find the location on the Outline where split is to occur (note that only Outline Lines and Splines can be split (not arcs, circles, or fillets)).
• Right click and pick ‘Split Outline’ from the menu.
• Move the mouse to place the split end point and click.