Magnetic Stripe Track Data

Track 1 and Track 2

ISO/IEC 7813 defines two record formats for the magnetic stripe. Track 1 is alphanumeric and carries the cardholder name. Track 2 is numeric and carries the PAN, expiry, service code and discretionary data. Both begin with a sentinel character, separate fields with a separator and end with a terminator.

• Track 1 is alphanumeric and includes the cardholder name
• Track 2 is numeric and omits the name
• Each record starts with a sentinel and ends with a terminator
• Fields are separated by a single delimiter
• Both encode the PAN and the expiry

Field layout

Track 1 fields run format code, primary account number, name, expiry, service code and discretionary data. Track 2 fields run primary account number, expiry, service code and discretionary data. The service code occupies a fixed three-digit position and controls whether the card may be used for local or international transactions.

• Track 1: format code, PAN, name, expiry, service code, discretionary
• Track 2: PAN, expiry, service code, discretionary
• The service code is a fixed three-digit field
• The first service code digit governs international use
• The second governs local use

Expiry and service codes

The expiry is stored as a two-digit year and a two-digit month, and in Track 1 the two digits are reversed compared with Track 2. The service code tells the terminal what the card is authorised for, which is why a card with a restricted service code behaves differently at different terminals.

• Expiry is stored as YYMM
• Track 1 reverses the expiry digit order relative to Track 2
• Service code digit one controls international use
• Service code digit two controls local use
• Digit three indicates PIN support and interchange requirements

Reading a record safely

A parser should validate structure before trusting content: correct sentinel, correct field count, correct separators, a PAN that passes the Luhn check, and a plausible expiry. Records that fail these checks are malformed, and malformed records are a strong indicator of a bad or tampered source.

• Validate the sentinel and terminator
• Check the field count and separators
• Confirm the PAN passes the Luhn check
• Confirm the expiry is plausible
• Reject records that fail any structural check