контекст таков:
NOTE:
1. Please fax the copy of both sides of the card to MCI Middle East LLC., Fax: +971 4 3419177
Email: FIATA2007@mci-group.com
2. Rates in USD are for your reference.
3. Payment is settled in AED according to the exchange rate of the day when the above credit card is debited by
the Congress Organisation.
4. A 3.5 % of the total amount as credit card surcharge will be paid by the card holder.

почему? потому что расчёты ведутся в AED (лень смотреть, что за валюта)

The Emirati dirham (AED) is the official currency of the United Arab Emirates

according to the exchange rate of the day when the above credit card is debited ...
... по обменному курсу на день списания средств с кредитной карты