I've just finished scanning in a few hundred boarding passes from my travel over the past three years. Original plan was to try and keep track of where, when and how often I've been to different places.

Once I had the data I started looking at the other fields in the boarding pass barcode. One of the fields is the "compartment code" which seems to be one of: Q, Y, C, J, X, F (for my AA flights). This looks useful for calculating how much of my travel has been in economy vs the other cabin(s). But I have noticed a few occasions where the compartment code in the barcode is Y but the printed class is X and the seat is in first class. I've also noticed the opposite where the compartment code is X but the seat and text are for Y. I'm being nosy now, but does anyone know why this would be out of sync (esp. given the barcode and text are printed together) and what its purpose is?

I was also intrigued by the "passenger status" field which seems to be: 1, 2, 3 or 7. 2 seems to be used for priority verification cards from a desk, whereas 1 is used for confirmed flights as well as priority verification cards from a self check in machine. Can anyone shed any more light on the meaning of these? Note: seems unrelated to the "selectee" identifier.