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POS terminal device used to process chip card payments

Merchant & POS

What is Application Usage Control (AUC)?

AUC (Application Usage Control) specifies restrictions that limit an application by geography or by specific transaction types. It is a 2-byte data element in Tag 9F07. If present, the terminal performs checks such as whether the transaction is at an ATM.

Illustration of the Alipay super app connecting payments, merchants and financial services

Closed-Loop Payments

Alipay: Payment System or Digital Economy? | Closed-Loop Payments #5

Is Alipay a payment system, or a digital economy? In the previous post we discussed how Starbucks shows that payment systems can evolve into a different structure. At first the goal was to make payment easier for the customer. As the system grew, loyalty programs...

Illustration showing how an Application Identifier (AID) is used in a chip card transaction

EMV

What is an Application Identifier (AID)?

The AID tells the terminal which applications are present on a chip during a POS or ATM transaction. What does the AID do? It lets the terminal determine whether it supports an application on the chip. In Tag 9F06, it is 5-16 digits long.

Diagram illustrating the EMV Tag-Length-Value (TLV) data structure used in card transactions

Online & Authorization

What are EMV Tags?

In EMV, data is stored in Tag-Length-Value (TLV) format, and it is carried between the card, the POS terminal, and the authorization system in this same format. This post lists every EMV Tag, its type, and its description.

Exterior of the Takasbank headquarters building

Payment Systems

What is Takasbank?

Takasbank (Istanbul Settlement and Custody Bank) exists to increase the competitiveness of Turkey's markets by providing clearing and custody services, financial services, and other economic activities under the relevant legislation.

Table listing ISO 4217 currency codes, numeric codes, and minor units for countries worldwide

ATM

What is ISO 4217?

ISO 4217, also known as the currency code standard, defines the three-letter abbreviations assigned to currencies. The ISO 4217 code list is used extensively in banking and business. In some countries, exchange offices rely on these codes alone.

Illustration representing electronic payment systems

Payment Systems

What are Payment Systems?

Let's talk about payment systems, which we have heard more about since the internet entered our lives, and the basic structures behind them. The first credit card in the world was used in America in the 1920s.