The System Trace Audit Number (STAN) is a 6-digit identifier assigned by the acquirer. Prefer network_data.transaction_id if present, unless you have special requirements.
Unique identifier for the authorization assigned by the card network used to match subsequent messages, disputes, and transactions.
Identifier assigned to the acquirer by the card network. Sometimes this value is not provided by the network; in this case, the value will be
null.