I'm curious about this. The way Travelterminal explains it (
http://www.travelterminal.com/glossary.shtml#end_on_end ), it sounds like nested ticketing. Same thing or not?
Here's the specific explanation:
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 B, which may in some cases be less expensive than the round trip fare from AAA to CCC. Fare rules usually specify whether end-on-end combinations are allowed.