Workplane specifies the axis system used to create the toolpath
Create Workplane — Select an option to create a new workplane. This becomes the active workplane.
Active Workplane — Select the active workplane. If no workplane is displayed, then the transform (global coordinate system) is used. Selecting one of the workplanes from the list makes it the active workplane.
Edit Workplane — Click to edit the active workplane. This displays the Workplane Editor tab. This is the same tab displayed when you create or edit a workplane and enables you to edit the workplane location and orientation.