I recently checked a PNR mostly out of curiosity. I had a case where due to an UA error they needed to reprice an itin (the FCCs weren't properly applied). The result was a comedy of errors - the original price was gone, all the seats in the bucket were taken, it involved a leg on TK, it went on and on. I was on the phone for about an hour being bounced around while they worked to untangle the mess. The PNR records showed, line my line, what they'd had to do. At least a hundred lines. Some of these things aren't simple, and I learned something about the UA processes. They had to reprice to the original fare with a supervisor override, open up seats, put back my FCCs which they had been marked as "used" but they weren't applied and then apply to the new ticket, cancel and rebook the TK leg, even the fraud department checked in to approve it all. Fascinating. In the end the phone agent said "I think its all sorted, I even got your original seats, I'm hitting the button" and breathed a sigh of relief when it actually went through.

I could see each of these steps in the PNR.