What is ISO-8583 and how many its parts are there ?

ISO 8583 : Financial transaction card originated messages

Interchange message specifications is the International Organization for Standardization standard for systems that exchange electronic transactions made by cardholders using payment cards.

It has three parts :

1. Messages, data elements and code values.

2. Application and registration procedures for Institution Identification Codes (IIC)

3. Maintenance procedures for messages, data elements and code values.

A card-based transaction typically travels from a transaction acquiring device, such as a point-of-sale terminal or an ATM, through a series of networks, to a card issuing system for authorization against the card holder's account.

The card issuing system will either authorize or decline the transaction and generate a response message which must be delivered back to the terminal in a timely manner.

ISO 8583 defines a message format and a communication flow so that different systems can exchange these transactions. The vast majority of transactions made at ATMs use ISO 8583.

Cardholder-originated transactions include purchase, withdrawal,deposit, refund, reversal, balance inquiry, payments and inter-account transfers.