How do they determine the priority order for VDB (bumps)? I recently asked 5 different Gate Agents and got 4 different answers.

One GA said they first ask every pax on the "oversell" list (i.e. confirmed pax with no seat assignment) if they will take a later flight. If the flight is still oversold, then they make an announcement to solicit volunteers.

Another GA said it's ordered by status and (within status) by time of volunteering. If you're a Plat and #1 on the volunteer list, and if an EXP later volunteers, you're suddenly #2.

Another GA said it's ordered by time of checkin. If you're the #1 volunteer and then someone new volunteers who checked in before you did, you're suddenly #2.

Two different GA's (both at DFW) said it's ordered strictly according to whoever volunteered first. First come first served, regardless of status.

In actual practice yesterday, I handed over our BPs and the GA said we were #5 and 6. I asked her how it was ordered and she said by time of checkin. I told her I checked in online more than 24 hours in advance (because this was our second flight of the day). She verified this fact on her screen, then moved us to #1 and #2. She actually wrote VOL 1 and VOL 2 on our BPs then changed the writing on all the other BPs.

In fact she ended up bumping 5 people. If I had not reminded her that we checked in far in advance, either companion or I would have missed this bump.

The flight we were bumped to was also oversold. They already had two or three volunteers and I handed over our BPs. I asked how they ordered the volunteer list. She said it was by status. I replied "Great, I'm EXP". She put my BP on top of the stack. They ended up bumping one volunteer ... me.

My question is: are there any rules or procedures to prioritize the volunteer list? Or do they (as I expect) order the list however they feel like ordering it that particular day?