A special type of combination in which two round trip fares are combined to produce a complete itinerary.
In this example, the passenger buys a round trip ticket from AAA to BBB (Rule 1), and a separate round trip fare from BBB to CCC (Rule 2). The net effect is to travel from AAA to CCC, but breaking the fare at BBB, which may in some cases be less expensive than the round trip (through) fare from AAA to CCC.