UDD (Unpaid Direct Debit)

Expiry Date is the month and year printed on a payment card, indicating when the card becomes invalid and must be replaced.

ZKP is a cryptographic method that allows one party to prove knowledge of information without revealing the information itself, used in advanced authentication and privacy-preserving payment solutions.

ZIP is a buy now, pay later (BNPL) service offering instalment-based payments for online and in-store purchases.

The secure deletion of cryptographic keys and sensitive data from hardware security modules (HSMs) or other secure devices to prevent unauthorised use.

Refers to goods or services that are taxed at a 0% VAT rate, affecting invoice and payment calculations.

An authorisation request for a value of £0 used to validate a card before charging it. It confirms card validity without reserving funds.