Why ISO 8583 still runs card payments
The message standard behind card networks has outlasted several generations of technology. That is a reason to rely on it.
ISO 8583 is the international standard for the messages that card payment systems exchange. A purchase at a POS machine, a withdrawal at an ATM and a transfer in an app can all be carried as ISO 8583 messages.
Each message says what kind of message it is, which fields it carries, and then the fields themselves: the amount, the card, the terminal, the response code and so on.
Because institutions and switches share the standard, a bank, an EMI and a PI can exchange transactions without agreeing a private format with each other first.
The Baran platform fully supports ISO 8583, and Baran Switch uses it for its connection to APS, the national switch.