It even gets more convoluted than that which is described above. However, the STAR and One World carriers have attempted some coordination of their respective fare codes.

Some booking codes may be for multiple purposes, ie, "A" may be for award F, as well as upgrade F, as well as discounted F, even within the same airline. One airline may use a certain inventory on another airline to get partner awards ... this may NOT be the same inventory that the partner's own members receive awards from. Also, a certain inventory may be that from which a consolidator gets seats for resale, but already has a contracted price with the airline.