Reference > Payments subsystem > Payments subsystem > Payments subsystem architecture
A payment instruction is the instance of a payment method with the details necessary to perform payment actions. For example, if a payment method name is Visa, then the payment instruction consists of Visa, the payment amount, cardholder's name, billing address, account number, and expiration date.
A shopper adds a payment instruction during the checkout flow. When the payment instruction is added, the PIAdd command runs and persists payment information to the payment tables. A payment instruction is created in the EDPPAYINST and PPCPAYINST tables. The protocol data is stored in the PPCEXTDATA table.
Payment configuration files
RefundMethodConfigurations XML file
Payment, refund and return payment business policies
PaymentMethodConfigurations XML file