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Payment Systems
The rules in this guide relate to the processing of Transactions and Payment Transactions made with Mastercard-branded cards. Here are the key definitions and where to find the document.
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.
Merchant & POS
CAVV and AAV are verification codes used in 3D Secure transactions to ensure transaction integrity and security. CAVV is used by Visa, while AAV is used by Mastercard.
Merchant & POS
Terminal Verification Results (TVR): a sequence of bits produced when a terminal reads an EMV card, based on logical checks such as an expired card. This data object is used to decide whether a payment transaction should be accepted online, declined, or allowed to proceed.
Payment Systems
The Address Verification Service (AVS) is a fraud prevention system that, when used effectively, can help limit fraud and chargebacks. This post lists the AVS response codes used by AMEX, Mastercard and Visa, with a description of each.
Security
Forgery in card payments means transactions made with card details without the cardholder's knowledge, or purchases with counterfeit or stolen cards. Merchants cannot eliminate fraud and chargeback risk, but they should aim to reduce it to reasonable levels.
Credit Card
KKB was established, under banking law, to enable the exchange of all kinds of information and documents among at least five banks, and it also shares credit information about customers. The Credit Bureau of Turkey also serves deposit banks, participation banks, financial institutions, and more.
Payment Systems
TCR stands for Transaction Record Component, the packets that carry transaction information in a clearing system. Transaction types in a clearing file are distinguished by transaction code and usage code values, and this data is sent inside TCR packets.
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.
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.
Merchant & POS
Almost all of us carry at least one credit card. Imagine losing your wallet with all your cards inside, and someone with bad intentions finding it and using the cards without a PIN. Who bears the responsibility?
EMV
The Visa EAS Server (Extended Access Service) is a server used in Visa’s authentication infrastructure. It was developed to run the cardholder authentication process securely between banks and the Visa network, particularly within Visa Secure (3-D Secure 2.x).