I don't have much detail available, only what is printed on my Citi AAdvantage card statement:
"Save money! Use your City(R) AAdvantage(R) card to buy an American Airlines ticket and receive 5% discount, visit aa.com and enter promotion code CBAA when making your reservation. Offer expires March 31, 2002."
Since most of my tickets are booked through my travel department I've only used it once for personal travel. Worked without problems though.