When using the API to process a transaction you are required to specify the transaction type as follows: CC.DB . Here the first 2 alphabets specify the payment method i.e. CC stands for credit card and the next two alphabets specify the type of transaction i.e. DB stands for Debit. Please refer to article on Transaction types for more detail on those codes.

Following are the various payment methods supported and their codes:

CCCredit Card
CTCredit Transfer
DCDebit Card
DDDirect Debit
ODCash on Delivery
OTOnline Transfer
RMRisk Management
UAUser Account
VAVirtual Account
WAWallet Account