Dynamic currency conversion (DCC) or cardholder preferred currency (CPC) is a process whereby the amount of a credit card transaction is converted at the point of sale, ATM or internet to the currency of the card's country of issue. DCC is generally provided by third party operators in association with the merchant, and not by a card issuer. Card issuers permit DCC operators to offer DCC in accordance with the card issuers' processing rules. However, using DCC, the customer is usually charged an amount in excess of the transaction amount converted at the normal exchange rate, though this may not be obviously disclosed to the customer at the time. The merchant, the merchant's bank or ATM operator usually impose a markup on the transaction, in addition to the exchange rate that would normally apply, sometimes by as much as 18%.