From Section 4(5) of the sticky:
Originally Posted by Austinrunner
If an itinerary has an open jaw consisting of the originating city and the final city, then no stopover is allowed in the final city earlier in the itinerary. For example, assume the itinerary is as follows:
DFW (start of itinerary) - LAX - SYD - PER - MEL - HKG - LAX (end of itinerary)
No stopover in LAX upon arrival from DFW would be allowed. The one allowed stopover in LAX would occur at the end of the itinerary.