Its pretty complicated - here is the readers digest version for more than 12 hours. The ones people seem to care most about are bolded.

1. Recovery slips
2. White slips
3. Long call reserves
4. Short Call reserves
5. Reserve Pilots on an X day
6. OOBWS
7-17. Arcane combinations of long and short call pilots in and out of base
18. Greenslips
19. IP Greenslips
20. OOBGS
21. Rerouting pilots flying
22-29 Interrupted X days, assignments, and conflicts
30. Anyone that they can get.

Scoop