ISO 8583

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ISO 8583 is an international standard for financial transaction card originated interchange messaging. It is the International Organization for Standardization standard for systems that exchange electronic transactions initiated by cardholders using payment cards.

ISO 8583 defines a message format and a communication flow so that different systems can exchange these transaction requests and responses. The vast majority of transactions made when a customer uses a card to make a payment in a store (EFTPOS) use ISO 8583 at some point in the communication chain, as do transactions made at ATMs. In particular, both the MasterCard and Visa networks base their authorization communications on the ISO 8583 standard, as do many other institutions and networks.

Although ISO 8583 defines a common standard, it is not typically used directly by systems or networks. It defines many standard fields (data elements) which remain the same in all systems or networks, and leaves a few additional fields for passing network-specific details. These fields are used by each network to adapt the standard for its own use with custom fields and custom usages.

Introduction[edit]

The ISO 8583 specification has three parts:

  • Part 1: Messages, data elements, and code values[1]
  • Part 2: Application and registration procedures for Institution Identification Codes (IIC)[2]
  • Part 3: Maintenance procedures for the aforementioned messages, data elements and code values[3]

Message format[edit]

A card-based transaction typically travels from a transaction-acquiring device, such as a point-of-sale terminal or an automated teller machine (ATM), through a series of networks, to a card issuing system for authorization against the card holder's account. The transaction data contains information derived from the card (e.g., the account number), the terminal (e.g., the merchant number), the transaction (e.g., the amount), together with other data which may be generated dynamically or added by intervening systems. Based on this information, the card issuing system will either authorize or decline the transaction and generate a response message which must be delivered back to the terminal within a predefined time period.

An ISO 8583 message is made of the following parts:

  • Message type indicator (MTI)
  • One or more bitmaps, indicating which data elements are present
  • Data elements, the actual information fields of the message

The placements of fields in different versions of the standard varies; for example, the currency elements of the 1987 and 1993 versions of the standard are no longer used in the 2003 version, which holds currency as a sub-element of any financial amount element. As of June 2017, however ISO 8583:2003 has yet to achieve wide acceptance. ISO 8583 messaging has no routing information, so is sometimes used with a TPDU header.

Cardholder-originated transactions include purchase, withdrawal, deposit, refund, reversal, balance inquiry, payments and inter-account transfers. ISO 8583 also defines system-to-system messages for secure key exchanges, reconciliation of totals, and other administrative purposes.

Message type indicator (MTI)[edit]

The message type indicator is a four-digit numeric field which indicates the overall function of the message. A message type indicator includes the ISO 8583 version, the Message Class, the Message Function and the Message Origin, as described below.

ISO 8583 version[edit]

The first digit of the MTI indicates the ISO 8583 version in which the message is encoded.

Code Meaning
0xxx ISO 8583:1987
1xxx ISO 8583:1993
2xxx ISO 8583:2003
3xxx Reserved by ISO
4xxx
5xxx
6xxx
7xxx
8xxx National use
9xxx Private use

Message class[edit]

Position two of the MTI specifies the overall purpose of the message.

Code Meaning Usage
x0xx Reserved by ISO
x1xx Authorization message Determine if funds are available, get an approval but do not post to account for reconciliation. Dual message system (DMS), awaits file exchange for posting to the account.
x2xx Financial messages Determine if funds are available, get an approval and post directly to the account. Single message system (SMS), no file exchange after this.
x3xx File actions message Used for hot-card, TMS and other exchanges
x4xx Reversal and chargeback messages Reversal (x4x0 or x4x1): Reverses the action of a previous authorization.
Chargeback (x4x2 or x4x3): Charges back a previously cleared financial message.
x5xx Reconciliation message Transmits settlement information message.
x6xx Administrative message Transmits administrative advice. Often used for failure messages (e.g. message reject or failure to apply).
x7xx Fee collection messages
x8xx Network management message Used for secure key exchange, logon, echo test and other network functions.
x9xx Reserved by ISO

Message function[edit]

Position three of the MTI specifies the message function which defines how the message should flow within the system. Requests are end-to-end messages (e.g., from acquirer to issuer and back with time-outs and automatic reversals in place), while advices are point-to-point messages (e.g., from terminal to acquirer, from acquirer to network, from network to issuer, with transmission guaranteed over each link, but not necessarily immediately).

Code Meaning Notes
xx0x Request
xx1x Request response
xx2x Advice
xx3x Advice response
xx4x Notification
xx5x Notification acknowledgement
xx6x Instruction ISO 8583:2003 only
xx7x Instruction acknowledgement
xx8x Reserved for ISO use Some implementations (such as MasterCard) use for positive acknowledgment.[4]
xx9x Some implementations (such as MasterCard) use for negative acknowledgement.[5]

Message origin[edit]

Position four of the MTI defines the location of the message source within the payment chain.

Code Meaning
xxx0 Acquirer
xxx1 Acquirer repeat
xxx2 Issuer
xxx3 Issuer repeat
xxx4 Other
xxx5 Other repeat
xxx6 Reserved by ISO
xxx7
xxx8
xxx9

Examples[edit]

Given an MTI value of 0110, the following example lists what each position indicates:

  • 0xxx → version of ISO 8583 (0 = 1987 version)
  • x1xx → class of the message (1 = authorization message)
  • xx1x → function of the message (1 = response)
  • xxx0 → who began the communication (0 = acquirer)

Therefore, MTI 0110 is an authorization response message sent by the acquirer.

Bearing each of the above four positions in mind, an MTI will completely specify what a message should do, and how it is to be transmitted around the network. Unfortunately, not all ISO 8583 implementations interpret the meaning of an MTI in the same way. However, a few MTIs are relatively standard:

MTI Meaning Usage
0100 Authorization Request Request from a point-of-sale terminal for authorization for a cardholder purchase
0110 Authorization Response Request response to a point-of-sale terminal for authorization for a cardholder purchase
0120 Authorization Advice When the point-of-sale device breaks down and you have to sign a voucher
0121 Authorization Advice Repeat If the advice times out
0130 Issuer Response to Authorization Advice Confirmation of receipt of authorization advice
0200 Acquirer Financial Request Request for funds, typically from an ATM or pinned point-of-sale device
0210 Issuer Response to Financial Request Issuer response to request for funds
0220 Acquirer Financial Advice e.g. Checkout at a hotel. Used to complete transaction initiated with authorization request
0221 Acquirer Financial Advice Repeat If the advice times out
0230 Issuer Response to Financial Advice Confirmation of receipt of financial advice
0320 Batch Upload File update/transfer advice
0330 Batch Upload Response File update/transfer advice response
0400 Acquirer Reversal Request Reverses a transaction
0510 Batch Settlement response Card acceptor reconciliation request response
0800 Network Management Request Hypercom terminals initialize request. Echo test, logon, logoff etc.
0810 Network Management Response Hypercom terminals initialize response. Echo test, logon, logoff etc.
0820 Network Management Advice Key change

Bitmaps[edit]

In ISO 8583, a bitmap is a field or subfield within a message, which indicates whether other data elements or data element subfields are present elsewhere in the message.

A field is considered to be present only when the corresponding bit in the bitmap is set. For example, a hex with value 0x82 (decimal 130) is binary 1000 0010, which means fields 1 and 7 are present in the message and fields 2, 3, 4, 5, 6 and 8 are not.

The bitmap may be represented as 8 bytes of binary data or as 16 hexadecimal characters (0-9, A-F) in the ASCII or EBCDIC character sets. A message will contain at least one bitmap, called the primary bitmap, which indicates which of data elements 1 to 64 are present. The presence of an optional secondary bitmap is also indicated by the first bit in the primary bitmap. If present, the secondary bitmap indicates whether data elements 65 to 128 are present. Similarly, a tertiary bitmap can be used to indicate the presence of fields 129 to 192, although these data elements are rarely used.

Examples[edit]

Given a bitmap value of 22 10 00 11 02 C0 48 04,

0x22 = 0010 0010 (counting from the left, the third and seventh bits are 1, indicating that fields 3 and 7 are present)
0x10 = 0001 0000 (the first bit corresponds to field 9, so the fourth bit here indicates field 12 is present)
0x00 = 0000 0000 (no fields present)
0x11 = 0001 0001 (fields 28 and 32 are present)
0x02 = 0000 0010 (field 39 is present)
0xC0 = 1100 0000 (fields 41 and 42 are present)
0x48 = 0100 1000 (fields 50 and 53 are present)
0x04 = 0000 0100 (field 62 is present)
nth bit 0 10 20 30 40 50 60
1234567890 1234567890 1234567890 1234567890 1234567890 1234567890 1234
Bitmap 0010001000 0100000000 0000000100 0100000010 1100000001 0010000000 0100

Therefore, the given bitmap defines the following fields present in the message:
3, 7, 12, 28, 32, 39, 41, 42, 50, 53, 62

Data elements[edit]

Data elements are the individual fields carrying the transaction information. There are up to 128 data elements specified in the original ISO 8583:1987 standard, and up to 192 data elements in later releases. The 1993 revision added new definitions, deleted some, while leaving the message format itself unchanged.

While each data element has a specified meaning and format, the standard also includes some general purpose data elements and system- or country-specific data elements which vary enormously in use and form from implementation to implementation.

Each data element is described in a standard format which defines the permitted content of the field (numeric, binary, etc.) and the field length (variable or fixed), according to the following table:

Abbreviation Meaning
a Alpha, including blanks
n Numeric values only
s Special characters only
an Alphanumeric
as Alpha & special characters only
ns Numeric and special characters only
ans Alphabetic, numeric and special characters.
b Binary data
z Tracks 2 and 3 code set as defined in ISO/IEC 7813 and ISO/IEC 4909 respectively
. or .. or ... variable field length indicator, each . indicating a digit.
x or xx or xxx fixed length of field, or maximum length in the case of variable length fields.

Additionally, each field may be either fixed or variable length. If variable, the length of the field will be preceded by a length indicator.

Type Meaning
Fixed no field length used
LLVAR or (..xx) Where 0 < LL < 100, means two leading digits LL specify the field length of field VAR
LLLVAR or (...xxx) Where 0 < LLL < 1000, means three leading digits LLL specify the field length of field VAR
LL and LLL are hex or ASCII. A VAR field can be compressed or ASCII depending of the data element type. LL can be one or two bytes. For example, if compressed as one hex byte, '27x means there are 27 VAR bytes to follow. If ASCII, the two bytes '32x, '37x mean there are 27 bytes to follow. Three-digit field length LLL uses two bytes with a leading '0' nibble if compressed, or three bytes if ASCII. The format of a VAR data element depends on the data element type. If numeric it will be compressed, e.g. 87456 will be represented by three hex bytes '087456x. If ASCII then one byte for each digit or character is used, e.g. '38x, '37x, '34x, '35x, '36x.

Examples[edit]

Field Definition Meaning
n 6 Fixed length field of six digits
n.6 LVAR numeric field of up to 6 digits in
a..11 LLVAR alpha field of up to 11 characters in length
b...999 LLLVAR binary field of up to 999 bits in length

ISO-defined data elements[edit]

Data field Type Usage
1 b 64 Second Bitmap
2 n ..19 Primary account number (PAN)
3 n 6 Processing code
4 n 12 Amount, transaction
5 n 12 Amount, settlement
6 n 12 Amount, cardholder billing
7 n 10 Transmission date & time
8 n 8 Amount, cardholder billing fee
9 n 8 Conversion rate, settlement
10 n 8 Conversion rate, cardholder billing
11 n 6 System trace audit number (STAN)
12 n 6 Local transaction time (hhmmss)
13 n 4 Local transaction date (MMDD)
14 n 4 Expiration date
15 n 4 Settlement date
16 n 4 Currency conversion date
17 n 4 Capture date
18 n 4 Merchant type, or merchant category code
19 n 3 Acquiring institution (country code)
20 n 3 PAN extended (country code)
21 n 3 Forwarding institution (country code)
22 n 3 Point of service entry mode
23 n 3 Application PAN sequence number
24 n 3 Function code (ISO 8583:1993), or network international identifier (NII)
25 n 2 Point of service condition code
26 n 2 Point of service capture code
27 n 1 Authorizing identification response length
28 x+n 8 Amount, transaction fee
29 x+n 8 Amount, settlement fee
30 x+n 8 Amount, transaction processing fee
31 x+n 8 Amount, settlement processing fee
32 n ..11 Acquiring institution identification code
33 n ..11 Forwarding institution identification code
34 ns ..28 Primary account number, extended
35 z ..37 Track 2 data
36 n ...104 Track 3 data
37 an 12 Retrieval reference number
38 an 6 Authorization identification response
39 an 2 Response code
40 an 3 Service restriction code
41 ans 8 Card acceptor terminal identification
42 ans 15 Card acceptor identification code
43 ans 40 Card acceptor name/location (1-23 street address, 24-36 city, 37-38 state, 39-40 country)
44 an ..25 Additional response data
45 an ..76 Track 1 data
46 an ...999 Additional data (ISO)
47 an ...999 Additional data (national)
48 an ...999 Additional data (private)
49 a or n 3 Currency code, transaction
50 a or n 3 Currency code, settlement
51 a or n 3 Currency code, cardholder billing
52 b 8 Personal identification number data
53 n 16 Security related control information
54 an ...120 Additional amounts
55 ans ...999 ICC data – EMV having multiple tags
56 ans ...999 Reserved (ISO)
57 ans ...999 Reserved (national)
58 ans ...999
59 ans ...999
60 ans ...999 Reserved (national) (e.g. settlement request: batch number, advice transactions: original transaction amount, batch upload: original MTI plus original RRN plus original STAN, etc)
61 ans ...999 Reserved (private) (e.g. CVV2/service code   transactions)
62 ans ...999 Reserved (private) (e.g. transactions: invoice number, key exchange transactions: TPK key, etc.)
63 ans ...999 Reserved (private)
64 b 16 Message authentication code (MAC)
65 b 1 Extended bitmap indicator
66 n 1 Settlement code
67 n 2 Extended payment code
68 n 3 Receiving institution country code
69 n 3 Settlement institution country code
70 n 3 Network management information code
71 n 4 Message number
72 n 4 Last message's number
73 n 6 Action date (YYMMDD)
74 n 10 Number of credits
75 n 10 Credits, reversal number
76 n 10 Number of debits
77 n 10 Debits, reversal number
78 n 10 Transfer number
79 n 10 Transfer, reversal number
80 n 10 Number of inquiries
81 n 10 Number of authorizations
82 n 12 Credits, processing fee amount
83 n 12 Credits, transaction fee amount
84 n 12 Debits, processing fee amount
85 n 12 Debits, transaction fee amount
86 n 16 Total amount of credits
87 n 16 Credits, reversal amount
88 n 16 Total amount of debits
89 n 16 Debits, reversal amount
90 n 42 Original data elements
91 an 1 File update code
92 an 2 File security code
93 an 5 Response indicator
94 an 7 Service indicator
95 an 42 Replacement amounts
96 b 64 Message security code
97 x+n 16 Net settlement amount
98 ans 25 Payee
99 n ..11 Settlement institution identification code
100 n ..11 Receiving institution identification code
101 ans ..17 File name
102 ans ..28 Account identification 1
103 ans ..28 Account identification 2
104 ans ...100 Transaction description
105 ans ...999 Reserved for ISO use
106 ans ...999
107 ans ...999
108 ans ...999
109 ans ...999
110 ans ...999
111 ans ...999
112 ans ...999 Reserved for national use
113 ans ...999
114 ans ...999
115 ans ...999
116 ans ...999
117 ans ...999
118 ans ...999
119 ans ...999
120 ans ...999 Reserved for private use
121 ans ...999
122 ans ...999
123 ans ...999
124 ans ...999
125 ans ...999
126 ans ...999
127 ans ...999
128 b 64 Message authentication code

Processing code[edit]

The following is a table specifying the message type and processing code for each transaction type.

Transaction Message type Processing code
Authorization 0100 00 a0 0x
Balance inquiry 31 a0 0x
Sale 0200 00 a0 0x
Cash 01 a0 0x
Void 02 a0 0x
Mobile topup 57 a0 0x

Response code[edit]

The following table shows response codes and their meanings.

Code Meaning
00 Successful approval/completion or that VIP PIN verification is valid
01 Refer to card issuer
02 Refer to card issuer, special condition
03 Invalid merchant or service provider
04 Pickup
05 Do not honor
06 General error
07 Pickup card, special condition (other than lost/stolen card)
08 Honor with identification
09 Request in progress
10 Partial approval
11 VIP approval
12 Invalid transaction
13 Invalid amount (currency conversion field overflow) or amount exceeds maximum for card program
14 Invalid account number (no such number)
15 No such issuer
16 Insufficient funds
17 Customer cancellation
19 Re-enter transaction
20 Invalid response
21 No action taken (unable to back out prior transaction)
22 Suspected Malfunction
25 Unable to locate record in file, or account number is missing from the inquiry
28 File is temporarily unavailable
30 Format error
41 Merchant should retain card (card reported lost)
43 Merchant should retain card (card reported stolen)
51 Insufficient funds
52 No checking account
53 No savings account
54 Expired card
55 Incorrect PIN
57 Transaction not permitted to cardholder
58 Transaction not allowed at terminal
59 Suspected fraud
61 Activity amount limit exceeded
62 Restricted card (for example, in country exclusion table)
63 Security violation
65 Activity count limit exceeded
68 Response received too late
75 Allowable number of PIN-entry tries exceeded
76 Unable to locate previous message (no match on retrieval reference number)
77 Previous message located for a repeat or reversal, but repeat or reversal data are inconsistent with original message
78 ’Blocked, first used’—The transaction is from a new cardholder, and the card has not been properly unblocked.
80 Visa transactions: credit issuer unavailable. Private label and check acceptance: Invalid date
81 PIN cryptographic error found (error found by VIC security module during PIN decryption)
82 Negative CAM, dCVV, iCVV, or CVV results
83 Unable to verify PIN
85 No reason to decline a request for account number verification, address verification, CVV2 verification; or a credit voucher or merchandise return
91 Issuer unavailable or switch inoperative (STIP not applicable or available for this transaction)
92 Destination cannot be found for routing
93 Transaction cannot be completed, violation of law
94 Duplicate transmission
95 Reconcile error
96 System malfunction, System malfunction or certain field error conditions
B1 Surcharge amount not permitted on Visa cards (U.S. acquirers only)
N0 Force STIP
N3 Cash service not available
N4 Cashback request exceeds issuer limit
N7 Decline for CVV2 failure
P2 Invalid biller information
P5 PIN change/unblock request declined
P6 Unsafe PIN
Q1 Card authentication failed
R0 Stop payment order
R1 Revocation of authorization order
R3 Revocation of all authorizations order
XA Forward to issuer
XD Forward to issuer
Z3 Unable to go online

See also[edit]

References[edit]