I think this is what you're asking - example

10 displacements for 76T CAP out of DEN

The displacement are initially assigned to the bottom 10 pilots on the DEN 76T CAP list. Every pilot senior to these 10 can volunteer for the displacement. Let's say that 10 guys senior to them volunteer then the guys initially assigned the displacement stay in place(not displaced). If only 5 senior guys volunteer for the displacement then they and the bottom 5 on the initial displacement list will be displaced. The top 5 guys on the displacement list will stay in place.