Technically it's not open time because schedules aren't final. The ALPA scheduling committee builds X amount lines depending on how many block hours need to be covered for that month. The top X pilots bid on those lines. Any conflicts are dropped from the lineholders' trip. The trips dropped are traded or dropped by the lineholders for a 24 hour period on a first come first served basis instantly over the Internet. At that point, the lineholders' schedule is pretty much final. Then the ALPA scheduling committee looks at the amount of open trips left by the lineholders and estimates X amount of relief lines needed to cover those trips. They then publish a secondary bid for the reserve pilots with X amount of releif lines to cover the open trips. The top X reserve pilots that want one can bid a releif line. The remainder bid on the reserve lines. Once that bid is awarded, the releif lineholders have their schedules constructed by the ALPA scheduling committee out of the open trips left over from the lineholders' trip touching/conflicts using their stated preferences. At the end there is not that much open time left over and at least 10% reserve coverage. Once the releif lines are final, whatever is left over is there for anyone to pick up or trade.

This is the model that you hear XJT pilots saying they will never give up.