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Background documentationISO 8583 Protocol Overview Locate this document in the navigation structure

 

This section provides a brief introduction to the ISO 8583 standard.

Note Note

For details on ISO 8583, refer to your standard ISO 8583 documentation.

End of the note.

ISO 8583 is a standard for systems that exchange electronic transactions made by cardholders using payment cards. Cardholder-originated transactions include purchase, withdrawal, deposit, refund, reversal, balance inquiry, payments and inter-account transfers. The standard defines:

  • A message format and a communication flow so that different systems can exchange these transactions

  • System-to-system messages for secure key exchanges, reconciliation of totals, and other administrative purposes

Structure

Although ISO 8583 defines a common standard, it is not typically used directly by systems. Instead, each system adapts the standard for its own use with custom fields and custom usages. The placement and use of fields in different versions of the standard varies.

An ISO 8583 message is made of the following parts:

  • Message Type Indicator (MTI). Unfortunately, not all ISO 8583 implementations interpret the meaning of an MTI in the same way.

  • One or more bitmaps, indicating which data elements are present.

  • Data Elements; the individual fields which carrying the substantive information about the transaction itself.

    The standard specifies set of the standard fields, which varies in different versions of the standard, while the message format remains unchanged. Each data element is described in a standard format which defines:

    • The permitted content of the field (for example, numeric or binary).

    • The field length (variable or fixed). If variable, the length of the field is preceded by a length indicator.

The EFT framework supports interfaces which determine conversion of the inbound predefined XML messages into an ISO 8583 compliant format, or other message formats, as required. An ISO message definition in the ISO message space can be considered as an XML schema in the XML space. From this perspective, the EFT framework deals with conversion of messages defined by the XML schema into the messages defined by the ISO message format.

There is no one-to-one correspondence for many XML fields in the ISO standard. However, the standard defines some private use fields such as Field 62 and Field 63 for such use. The EFT framework facilitates processing of such fields through Private Fieldst. The examples of such fields are CVV2 field or Pin Block One for Debit transactions. For more information, see XML to ISO Mapping.

The inbound XML messages mimic the messages defined by the standard and determine protocol between client of the Transnet and the framework. For more information on inbound XML messages, see Transnet Financial XML Messages.