Notes:
As an example, suppose that a round-trip journey on American Airlines consists of the three flights shown, nonstop from San Francisco to Boston, then back to San Francisco through Dallas, and that American Airlines publishes the 3 fares listed in the table. For example, the $1000 “Y” fare can be used to pay for travel from BOS to SFO or from SFO to BOS. Then, assuming the Y fare’s rules are satisfied, one way to pay for this journey is by using the Y to pay for the single outbound flight, and the Y again to pay for both return flights, for a total price of $2000.