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Merchant & POS
The System Trace Audit Number (STAN) is a number assigned by the third-party system (ATM or POS) to help uniquely identify a transaction. It is generated in the range 000001 to 999999. Each new authorization message needs a new STAN; retries reuse the original STAN.
ISO 8583
DE 11 - SYSTEMS TRACE AUDIT NUMBER: A 6-digit unique numeric value generated by the message originator, enabling unique tracking of the transaction. How is STAN generated?
ISO 8583
F37-RETRIEVAL REFERENCE NUMBER is a code generated by the bank that initiates a transaction, used to uniquely track it. It is a 12-character alphanumeric value.
Online & Authorization
Many fields are sent in the authorization message of a card transaction, one of the most important being the authorization code. On its own it is not enough; together with the STAN and transaction date, the transaction can be found directly.
Payment Systems
Every payment transaction completes in seconds, yet dozens of controls run behind the scenes. This post covers the precautions for authorization and clearing, the critical role of reversals, and the financial loss scenarios most often seen in the field.
ISO 8583
We covered the ISO 8583 basics in an earlier article. This post explains the ISO 8583 message structure in detail: every ISO 8583 message consists of three main parts - the MTI (Message Type Indicator), the Bitmap, and the Data Elements.
ISO 8583
F90 - ORIGINAL DATA ELEMENTS: the data elements from an original message, designed to identify the transaction in correction or reversal transactions. Subfields: Original MTI, Original DE 11 (STAN), Original DE 7, Original DE 32, Original DE 33.
Merchant & POS
In daily credit card purchases, the POS produces two receipts: the Customer Copy and the Merchant Copy. The cardholder gets the customer copy; the merchant keeps its own copy by law.
ISO 8583
F7 - TRANSMISSION DATE AND TIME: the field containing the moment the initiating party started the transaction. It is a 10-character numeric value in MMDDhhmmss format.