This person tweeted their AA boarding pass back in April 2010. I decoded this using my old Windows Mobile 6.5 phone using an app.

http://bit.ly/SNhryv

Knowing that all AA tickets start with 001 I thought that the last 14 digits prior to the "AA AA" Advantage number was the ticket number plus a check digit. In this case it's zero. Are we now saying that it's 3 if you are pre selected for PreCheck?