Open jaw also includes the turnaround point--e.g YYZ - LHR, CDG - YYZ.

One caveat on circle trip. A fare that allows stopovers can create a multi-city itinerary that is, in fact, a point-to-point.

For example, the J fare from YYZ to HKG allows unlimited stopovers. So you go YYZ-ORD-LAX-HKG-YVR-YYZ.

This looks like a circle fare. But in fact, the fare calculation will show YYZHKG and HKGYYZ.