My mileage runs typically show the return starting in a connecting city. For example, some years ago, EWR-HKG-SIN-HKG-EWR, showed EWR-HKG as the outbound, then HKG-SIN-HKG-EWR as the return. Just recently EWR-SFO-SIN-NRT-EWR showed up as a EWR-NRT trip with two connections, probably since there were fewer than 12 hours in SIN, then NRT-EWR as the return trip.