ISO 8583
The foundational financial transaction message standard used by ATMs, POS terminals, card switches, and payment gateways worldwide. Every card payment you make passes through this protocol.
Network Variations
Each card network extends ISO 8583 with proprietary data elements, subelement structures, and processing rules. Understanding these variations is essential when building or certifying against a specific network.
Visa BASE I / VisaNet
Visa's authorization network uses ISO 8583 with extensive DE48 subelements and DE63 for routing. Key structures:
| Field | Subelement | Description |
|---|---|---|
DE48Additional Data | SE01 | POS Environment — terminal type, attendance, capability flags |
| SE22 | CAVV — 3DS authentication value for card-not-present transactions | |
| SE23 | ECI — Electronic Commerce Indicator (05=full auth, 06=attempt, 07=no auth) | |
| SE31 | Merchant category — enhanced MCC data | |
| SE42 | Electronic commerce security level / 3DS version | |
| SE92 | CPS (Custom Payment Service) condition code | |
DE63Network Data | — | Visa routing data: transaction ID, validation code, network ID, and transaction lifecycle identifiers |
DE55 | — | EMV chip data — standard TLV structure across all schemes |
Mastercard BankNet
Mastercard uses similar DE48 subelement structure plus DE63 for BankNet reference data. Key differences:
| Field | Subelement / Data | Description |
|---|---|---|
DE48 | TCC (Transaction Category Code) | Single-char code: T=retail, R=restaurant, H=hotel, F=fuel |
| SE26 | Wallet Program Data — for digital wallet transactions (Apple Pay, Google Pay) | |
| SE43 | Universal Cardholder Authentication Field — authentication data | |
| SE92 | CPS condition code equivalent for Mastercard | |
DE63 | BankNet Reference Number | Mastercard's unique transaction reference assigned by BankNet. Used in clearing and dispute matching. |
DE127 | Extended Network Data | Mastercard extension beyond the standard 128 DEs for additional clearing and settlement data. |
Common Extensions (All Networks)
DE55 (EMV Chip Data) is standardized by EMVCo and has the same TLV structure across all networks. The content includes ARQC, AIP, ATC, TVR, IAD, unpredictable number, and terminal capabilities. Each network validates ARQC using issuer-derived session keys.
DE104-DE107 are Visa private-use extensions typically used in reconciliation and clearing messages for counts and amounts of credits, debits, and reversals in a settlement batch.