[momofpnm]

If I understand what you are asking, this explanation from violetpretty may help. It's the best one I've seen:

I like to think of the first bid list as a "box". If you're in the box, order doesn't matter. If you're in the box you can be matched to that chapter. You stay in the box until you are matched somewhere. If you're not in the box, you "wait in line" (aka the second bid list). You stand in line in order. If you are the next one in line to go in the box, you can only move into the box if someone already in the box matches elsewhere.

If you're asking how to decide, look at "indecisive recruitment help" for some great advice! Let us know how it goes and good luck!