Understanding the Structure and Data Content of Financial Transaction Cards

Financial transaction cards, such as credit and debit cards, are standardized to ensure compatibility and security across various payment systems. One of the key standards governing these cards is ISO/IEC 7813, which specifies the physical characteristics and magnetic track data structures of financial transaction cards.

Magnetic Stripe Tracks: Structure and Content

Financial transaction cards typically feature a magnetic stripe containing up to three tracks, each serving distinct purposes:

• Track 1: Designed to store up to 79 alphanumeric characters, Track 1 is primarily used in the United States and Canada.
• Track 2: Capable of holding up to 40 numeric or special characters, Track 2 is widely utilized in Europe and other regions.
• Track 3: While it can store up to 107 numeric characters, Track 3 is virtually unused by major worldwide networks and is often absent on payment cards.

Detailed Breakdown of Track Formats

Track 1:

Track 1 is formatted to accommodate a variety of data elements essential for transaction processing. The general structure includes:

• Start Sentinel: Indicates the beginning of the track data, typically represented by the "%" character.
• Format Code: Identifies the data format; "B" is commonly used for standard data.
• Primary Account Number (PAN): The card number, which can be up to 19 digits.
• Field Separator: Separates different data fields; commonly the "^" character.
• Cardholder Name: The name of the cardholder, formatted with surname and given name.
• Expiration Date: The card's expiration date, usually in MMYY format.
• Service Code: Indicates interchange and usage restrictions.
• Discretionary Data: Additional data defined by the card issuer, which may include security information.
• End Sentinel: Marks the end of the track data, typically represented by the "?" character.
• Longitudinal Redundancy Check (LRC): A checksum used to verify data integrity.

Track 2:

Track 2 is structured differently, focusing on numeric data elements:

• Start Sentinel: Denotes the beginning of the track, usually the ";" character.
• Primary Account Number (PAN): The card number, up to 19 digits.
• Field Separator: Separates data fields; typically the "=" character.
• Expiration Date: Card expiration date in YYMM format.
• Service Code: Three-digit code specifying interchange and usage rules.
• Discretionary Data: Issuer-specific data, which may include security information.
• End Sentinel: Indicates the end of the track, generally the "?" character.
• Longitudinal Redundancy Check (LRC): Ensures data integrity through a checksum.

Track 3:

Track 3 shares similarities with Track 2 but offers a higher data capacity:

• Start Sentinel: Marks the beginning of the track data.
• Primary Account Number (PAN): The card number, up to 19 digits.
• Field Separator: Separates data fields.
• Expiration Date: Card expiration date.
• Service Code: Interchange and usage rules.
• Discretionary Data: Additional data as defined by the issuer.
• End Sentinel: Denotes the end of the track data.
• Longitudinal Redundancy Check (LRC): Verifies data integrity.

It's important to note that while Track 3 has the capacity for more data, it is seldom utilized in major payment networks and may not be present on all cards.

Service Code Values in Financial Cards

The Service Code is a critical component in Tracks 1 and 2, providing information about the card's usage and interchange restrictions. The three-digit Service Code is structured as follows:

• First Digit: Specifies interchange rules.
• Second Digit: Indicates authorization processing requirements.
• Third Digit: Defines service restrictions, such as cash access or PIN requirements.

For example, a Service Code of "201" would denote specific interchange and authorization rules, as well as service restrictions, according to the definitions provided in the ISO/IEC 7813 standard.

Conclusion

Understanding the structure and data content of financial transaction cards is essential for professionals involved in payment processing, security, and card manufacturing. The ISO/IEC 7813 standard provides a comprehensive framework that ensures interoperability and security across diverse payment systems globally. For detailed specifications and further information, refer to the official ISO/IEC 7813:2006 standard.

Understanding Service Codes in Financial Cards

Service codes in financial cards are critical elements that define the rules for a particular card’s use. These codes are typically found in Track 1 and Track 2 data and are made up of three digits. Each digit in the service code has a specific purpose, which can be broken down as follows:

First Digit: Interchange Rules

The first digit of the service code specifies the rules governing the interchange of the card, particularly whether the card can be used internationally, whether it requires a chip, or if it’s restricted to specific regions.

• 1: International interchange is allowed. The card can be used globally across networks.
• 2: International interchange is allowed, but the card uses an IC chip (Integrated Circuit) for enhanced security.
• 5: National interchange only. This means the card can only be used within the issuing country unless otherwise agreed upon in a bilateral agreement between countries.
• 6: National interchange, with the option to use IC chip technology where feasible.
• 7: The card can only be used in a closed-loop system, meaning it’s restricted to specific merchants or services.

Second Digit: Authorization Processing

The second digit of the service code indicates the processing requirements for authorization, specifying how the card should be authenticated or how the transaction should be handled.

• 0: Normal processing. No special restrictions on the authorization process.
• 2: Contact the issuer online. The merchant should reach out to the card issuer to confirm authorization online.
• 4: Contact issuer online, but only allowed under specific bilateral agreements.

Third Digit: Service Restrictions

The third digit of the service code defines the specific restrictions related to the type of services the card can access. It can specify access to cash, goods, and services, whether a PIN is required, or if there are any other service limitations.

• 0: No restrictions. The card can be used for all types of transactions.
• 1: No restrictions, but PIN is not required for most transactions.
• 2: Goods and services only, no cash access.
• 3: ATM use only, PIN is required.
• 4: Cash only transactions allowed.
• 5: Goods and services only, PIN is required.
• 6: No restrictions, but PIN is required where feasible.
• 7: Goods and services only, PIN is required when feasible.

Track Formats: Examples and Data Structure

Tracks on magnetic cards contain essential data used to process transactions. There are three tracks: Track 1, Track 2, and Track 3, though Track 3 is rarely used.

Track 1 Format (Alpha-Numeric Data)

Track 1 stores up to 79 characters of data, including alphabetic text, which can contain both letters and numbers. This track is primarily used in the United States and Canada.

%1234567890123456^DOE/JOHN^23051210000000000000?

Track 2 Format (Numeric Data)

Track 2 is mainly used for numeric data and is more common in Europe and other regions. It can store up to 40 characters.

;1234567890123456=23051210000000000000?

Track 3 Format (Rarely Used)

Track 3 has the capacity to store 107 characters of data, but it is rarely used by modern payment networks. Its structure is similar to Track 2, but with additional data capacity for specialized systems.

12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890?

Conclusion

The service code and track data formats are essential parts of card data processing and help ensure that card transactions can be authenticated, processed, and authorized correctly across different regions and networks.