Originally Posted by jsloan

They've started to add this to some of their fare templates, not because they're trying to discourage mileage runs, per se, but because they're trying to enforce price discipline in other markets. The intent is to disallow people from using an LAX-SIN fare for a cheap trip to Tokyo. (LAX-NRT / NRT-SIN-LAX, priced using a RT LAX-SIN fare with a stopover).