AFL (Application File Locator) is the field that shows where on the card the data the terminal will use in the authorization transaction is located.
AFL is a list of the application data records found on the card, and the terminal uses the AFL to read the application data from the card. AFL also indicates (if any) which of the data records should be used by the terminal as input for the data authentication process.
In EMV Tag 94, it is a piece of data 0-252 characters in length.
How does the terminal get the AFL?
When the terminal sends the GET PROCESSING OPTIONS (GPO) command to the card, the card returns two important pieces of information in its response. One of these is the AIP, which shows the functions supported by the card, and the other is the AFL, which shows the location of the records to be read.
The structure of the AFL
The AFL consists of 4-byte entries. Each entry contains the following information:
- The short identifier of the file to be read (SFI)
- The number of the first record to be read
- The number of the last record to be read
- How many of these records will be used in offline data authentication
How does the terminal use the AFL?
The terminal sends the READ RECORD command for each entry in the AFL and reads the specified records in sequence. These records contain data such as the card number, expiration date, the list of cardholder verification methods, action codes (IAC), and the certificates required for offline authentication.
Error conditions
If a record specified in the AFL cannot be read, or if the AFL is in an incorrect format, the terminal terminates the transaction. Such errors usually stem from mistakes made during the personalization of the card and need to be detected during the card's testing processes.
