The CLEARP command (Insert | Parameter Change | Clearance Planes) allows you to define a clearance plane value for the current workplane. Clearance planes, in essence, create an envelope around a part where the probe will always travel to when it moves from one feature to another.
The Clearance Plane tab of the Parameters dialog box allows you to turn clearance planes on globally. The CLEARP command only defines the clearance plane for the first hit of a feature. To set additional clearance planes for a feature, open a new line at the desired location, and type the command: CLEARP.
For an in-depth discussion on how to define and work with clearance planes, see "Parameter Settings: Clearance Plane tab" in the "Setting Your Preferences" chapter.