I am not certain as to its accuracy.

I do know that just as in many res systems, it shows how many tickets authorized to sell, but only a single digit. So, if there are 20 seats left, and 25 tickets authorized to oversell the flight by 5 tickets, it will show 9. If there are -2 seats left, and 12 tickets authorized yet, to oversell the flight by 14, it will show 9. In general, if it shows anything less than 9, its not good. But as I said, I'm not sure of its accuracy.

And all the different letters are different fare classes. If theres 5 letters with a 9, its 9, not 45.