6/ ONLY ONE INTERNATIONAL DEPARTURE AND ONE INTERNATIONAL ARRIVAL FROM/TO THE COUNTRY OF ORIGIN IS PERMITTED EXCEPT AS PROVIDED BELOW. FOR THESE EXCEPTIONS TRAVEL MAY BE VIA THE POINT OF ORIGIN PROVIDED NO STOPOVER IS TAKEN THERE.
EXCEPTION 1 - PASSENGERS ORIGINATING IN BRAZIL OR US/CA - INCLUDING PR/VI - MAY HAVE TWO INTERNATIONAL DEPARTURES AND TWO INTERNATIONAL ARRIVALS IN THE COUNTRY OF ORIGIN. ALSO- TRAVEL BETWEEN THE U.S. AND CANADA IS NOT COUNTED AS AN INTERNATIONAL ARRIVAL/DEPARTURE.
The US-Canada stuff is stated for cases like the following. I'll use examples to make it easy to understand.
Say you had an OWE ex-Japan. You can start your journey as NRT-HKG-LAX..., right? However, you can't do NRT-HKG-x/KIX-DFW..., because you're violating the "ONLY ONE INTERNATIONAL DEPARTURE AND ONE INTERNATIONAL ARRIVAL FROM/TO THE COUNTRY OF ORIGIN IS PERMITTED" rule by comming back to Japan at KIX.
What if you had an ex-Canada OWE? Can you do YVR-DFW-x/YYZ-LHR...? With the "TRAVEL BETWEEN THE U.S. AND CANADA IS NOT COUNTED AS AN INTERNATIONAL ARRIVAL/DEPARTURE" exception, you can re-enter Canada, therefore, the routing is permitted.
Hope that clarifies.