CCW is short for counter clockwise. The alternative is an advancement that is not rotational.
A counter clockwise rotation gives the posibility to have the chin advanced without advancing the maxilla as much as would be needed else. So if you have a retruded chin, but your maxilla is not, or only slightly retruded, you can swing the chin forward and have more degree of freedome on what maxilla/mandible advancement ratio you want.
CCW rotation is not always the answear.