Discover is unique in how they label reason codes in that they use an alpha and alpha-numeric labeling system. In some cases the use of letters groups chargebacks into a category, such as with the six chargeback reason codes beginning with UA which stands for Unauthorized. In many cases the letters used in the reason code are hints to convey the chargeback description, such as with DP representing Duplicate Processing and DA representing Declined Authorization. Other times the lettered reason code system is random or arbitrary, such as with reason code AA being for Cardholder Does Not Recognize chargebacks.