The current double miles according to united.com allows us to "Earn double Mileage Plus® miles when you purchase and fly a qualifying roundtrip on United and United Express®. Offer valid for travel between October 4 and December 15, 2001."

My question is: if I begin a roundtrip on December 13 but don't complete it until December 28th, do I get double miles for the outbound portion?

The way I read the promotion, the answer would be "yes, for all travel completed through December 15," but the "round trip" requirement seems odd to me. Does the double miles not apply to one-way or multi-segment itineraries?