Just to second 29palms, EVERY airline does things a little different, has different agreements with other carriers, and has different requirements in order to get space available travel. If you're curious how a specific type of travel pass (ID90, ZED, etc) is used, this is a good place to come. If you're wanting to know how to book/obtain those passes, you need to see your (your wife's) employer (i.e. Pass Bureau).