DE 11 - SYSTEMS TRACE AUDIT NUMBER: A 6-digit unique numeric value generated by the message originator that enables the transaction to be uniquely tracked.
How is STAN generated?
STAN (System Trace Audit Number) is generally generated by incrementing by 1 for each new transaction by the system that initiates the message. The value cycles between 000001 and 999999. When the value 999999 is reached, the counter rolls back to the beginning. Therefore, STAN is not a permanently unique value on its own. It is unique only for a certain time period and for a certain sender.
It remains the same throughout the transaction
The STAN value is the same in both the request message and the response message belonging to a transaction. The sending system uses this value to match the incoming response to the corresponding request. In cancellation (reversal) and advice messages belonging to the same transaction, the original STAN value is also used in field F90 to identify the original transaction.
Used together with other fields for uniqueness
Different institutions can generate the same STAN value at the same time. Therefore, to definitively identify a transaction, STAN is generally evaluated together with the following fields:
- F7: Transmission date and time
- F32: Identity of the institution initiating the message
- F41: Terminal number
STAN on the POS side
POS devices also keep their own STAN counters. The transaction number that appears on the POS receipt is often this value. It should be noted that the counter may also reset to the beginning when the terminal is replaced or reset.
