Reference

Payment Certification Levels

A practical guide to EMVCo L1 / L2 / L3 terminal certifications, PCI DSS merchant compliance tiers, and the standards that govern every card-present transaction.

ISO 8583 Financial Transaction Protocol

The international standard for electronic financial transactions between terminals, acquirers, switches, and issuers. Defines message framing, bitmap encoding, and 128 Data Elements (DEs) used in authorization, financial, reversal, and network management messages.

Message Type Indicator (MTI)

Position 1
Version
  • 0 ISO 1987
  • 1 ISO 1993
  • 2 ISO 2003
  • 9 Private use
Position 2
Message Class
  • 0 Authorization
  • 1 Financial
  • 2 File Action
  • 3 Reversal
  • 4 Reconciliation
  • 5 Administration
  • 6 Fee Collection
  • 7 Network Mgmt
Position 3
Message Function
  • 0 Request
  • 1 Request Response
  • 2 Advice
  • 3 Advice Response
  • 4 Notification
  • 5 Notification Ack
Position 4
Message Origin
  • 0 Acquirer
  • 1 Acquirer Repeat
  • 2 Issuer
  • 3 Issuer Repeat
  • 4 Other
  • 5 Other Repeat
MTI Pair
Name
Use
0100 / 0110
Authorization Request / Response
Real-time auth for card-present and CNP
0120 / 0130
Authorization Advice / Response
Issuer-initiated auth completion confirmation
0200 / 0210
Financial Transaction Request / Response
Debit/credit with immediate posting
0201 / 0211
Financial Transaction Advice / Response
Forced financial (offline TC submission)
0400 / 0410
Reversal Request / Response
Cancel a prior authorization or financial
0420 / 0430
Reversal Advice / Response
Forced reversal notification
0500 / 0510
Reconciliation Request / Response
Batch totals reconciliation between terminal and host
0800 / 0810
Network Management Request / Response
Sign-on, sign-off, echo test, key exchange

Bitmap Mechanics

Primary bitmap (8 bytes = 64 bits): bit N set means DE N is present. Bit 1 = DE1 = secondary bitmap present.
Secondary bitmap (bits 65–128): present only when bit 1 of primary is set.
Primary Bitmap — 64 bit positions (DE1–DE64)
DE1
DE2
DE3
DE4
DE5
DE6
DE7
DE8
DE9
DE10
DE11
DE12
DE13
DE14
DE15
DE16
DE17
DE18
DE19
DE20
DE21
DE22
DE23
DE24
DE25
DE26
DE27
DE28
DE29
DE30
DE31
DE32
DE33
DE34
DE35
DE36
DE37
DE38
DE39
DE40
DE41
DE42
DE43
DE44
DE45
DE46
DE47
DE48
DE49
DE50
DE51
DE52
DE53
DE54
DE55
DE56
DE57
DE58
DE59
DE60
DE61
DE62
DE63
DE64
Example primary: 7238 0001 28C1 8E00 — DEs present: 2, 3, 4, 7, 11, 12, 13, 22, 32, 37, 39, 41, 42, 49, 52…

Key Data Elements

DE
Name
Format
Max Len
Notes
DE2
PAN
n
19
Primary Account Number
DE3
Processing Code
n
6
First 2 digits = transaction type, second 2 = from account, last 2 = to account
DE4
Amount, Transaction
n
12
Transaction amount in minor currency units
DE7
Transmission Date & Time
n
10
MMDDhhmmss — UTC timestamp
DE11
STAN
n
6
System Trace Audit Number — unique per terminal per day
DE12
Local Transaction Time
n
6
hhmmss local time at terminal
DE13
Local Transaction Date
n
4
MMDD local date at terminal
DE14
Card Expiration Date
n
4
YYMM format
DE18
Merchant Category Code
n
4
ISO 18245 MCC — determines interchange category
DE22
POS Entry Mode
n
3
PAN entry method + PIN capability indicator
DE23
Card Sequence Number
n
3
Differentiates multiple cards on same PAN
DE25
POS Condition Code
n
2
Describes POS environment (attended, unattended, etc.)
DE32
Acquiring Institution ID
n
11
Acquirer BIN / institution code
DE35
Track 2 Equivalent Data
z
37
Magnetic stripe Track 2 data (PAN + expiry + service code)
DE37
Retrieval Reference Number
an
12
Terminal-assigned transaction ID; returned in response
DE38
Authorization ID Response
an
6
Authorization / approval code from issuer
DE39
Response Code
an
2
00=Approved, 05=Do Not Honor, 51=Insufficient Funds…
DE41
Card Acceptor Terminal ID
ans
8
Unique terminal identifier assigned by acquirer
DE42
Card Acceptor ID Code
ans
15
Merchant ID assigned by acquirer
DE43
Card Acceptor Name/Location
ans
40
Merchant name + city + country for receipt/statement
DE48
Additional Data — Private Use
ans
999
Network-specific subelements (Visa SE, MC SE, Amex data)
DE49
Transaction Currency Code
n
3
ISO 4217 numeric currency code
DE52
PIN Data
b
8
Encrypted PIN block (ISO 9564 format)
DE55
ICC System Related Data
b
255
EMV TLV data: ARQC, ATC, TVR, IAD, cryptogram info…
DE70
Network Management Info Code
n
3
001=Sign-on, 002=Sign-off, 301=Echo
DE90
Original Data Elements
n
42
MTI + STAN + Date + Acquirer/Fwd IDs of original transaction (reversals)
DE95
Replacement Amounts
n
42
Corrected amounts in partial reversal
DE102
Account Identification 1
ans
28
From-account identifier (EFT / ACH routing)

Processing Code (DE3)

Pair 1 — Transaction Type
  • 00 Purchase
  • 01 Cash Withdrawal
  • 09 Purchase + Cashback
  • 20 Return / Refund
  • 28 Payment
  • 31 Balance Inquiry
  • 38 Reversal
Pair 2 — From Account
  • 00 Default / Unspecified
  • 10 Checking
  • 20 Savings
  • 30 Credit
  • 40 Universal
Pair 3 — To Account
  • 00 Default / Unspecified
  • 10 Checking
  • 20 Savings
  • 30 Credit
  • 40 Universal

Network Variations

Visa BASE I
  • DE48 carries Visa-specific subelements (SE 01–93)
  • DE104–DE107 for Visa private-use extensions
  • DE63 for network routing data and token indicators
Mastercard BankNet
  • DE48 carries Mastercard subelements (SE 20, 37, 48…)
  • DE127 extended data element for BankNet-specific data
  • DE63 carries BankNet reference number and date
American Express
  • Uses a subset of ISO 8583 DEs
  • DE48 carries Amex-specific private data
  • Extended response codes (M0, B1) for special approvals

Related Tools

Use these tools to work with the cryptographic primitives that underpin terminal and card security.

🗝️ DUKPT Key Derivation🔢 PIN Block Encoder🧮 ARQC Calculator🔓 EMV TLV Decoder🏷️ MAC Calculator🔐 DES / 3DES Calculator