Originally Posted by
wyseson
...it seems that if one books using a codeshare flight #, both the codeshare carrier and the operating carrier has to be partners of UA. Is this policy spelled out anywhere?
That would be Krect™, and though it isn't spelled out anywhere, it follows logic:
1) You can only receive mileage credit when booking your travel on a partner airline (implicit to the rules); and
2) In the case of partner flights operated by other carriers, the operating carrier must also be a partner (easily inferred from the rules).
ergo: both the booking partner (code) and operating carrier (metal) have to be partners in order to accrue miles (and the accrual is based on the partnership agreements with the operating carrier).