A few are like Airline codes but alpha numeric characters and shorter than below. (Example: 12A34B56C)

A few are a few digits plus a letter then some digits then a letter and then more than a few digits (Example: 12345A1B12345678)

most are a few digits plus a letter then a lots of digits (Example: 12345A1234567890)

just one of my reservation has the original confirmation number.

none of these reservations will pull up if using manual lookup without login