F45—TRACK-1 DAT: The values encoded on the card's Track 1 data in ISO 7813 format are sent including the field separators, together with the start and end sentinels, but excluding the LRC (Longitudinal Redundancy Check) character. It is 76 characters long.
The F45 format is as follows:
| Subelement | Length | Description |
| Start Sentinel | an-1 | |
| Format Code | an-1 | Literal character “B” |
| PAN | n…19 | |
| Field Separator | ans-1 | |
| Cardholder Name | ans…26 | |
| Field Separator | ans-1 | |
| Expiration Date | n-4 | In “YYMM” format |
| Service Code | n-3 | |
| Discretionary Data | n…23 | Optional |
| End Sentinel | n-1 | |
| LRC | n-1 |
Difference between Track 1 and Track 2
A magnetic stripe has three tracks. Payment cards generally use Track 1 and Track 2. The main differences between the two tracks are as follows:
- Track 1: Can contain alphanumeric characters. In addition to the card number and expiration date, it also contains the cardholder's name.
- Track 2: Contains only digits and a few special characters. It does not include the cardholder's name.
Why is F35 more common?
F35 (Track 2) is mostly used in authorization messages. Track 2 has a simpler structure, is easy to transmit because it is shorter, and can be read by almost all terminals. Since the cardholder's name is not required for the authorization decision, Track 1 data is not sent in most transactions. Some networks and card schemes, however, also accept Track 1 data for additional checks.
What does format code B mean?
The format code “B” in the table above indicates that the data is in the standard format defined for financial cards. By reading this character, the terminal knows how to parse the data.
From a security perspective
Track 1 data, like Track 2, is sensitive data. Under the PCI DSS standard, it must not be stored after the transaction has been authorized, and it must be encrypted in transit.
