From TSYS and VISA:
Visa is introducing an authorization requirement for return (cardholder refund) transactions. Authorizing a return enables the card issuer to validate the cardholder account, decline potentially fraudulent cards, and minimize chargebacks if the account does not exist or is closed. The return authorization message is intended to improve the return process by enabling cardholders to view a credit/return on their online banking statement in real time, as well as support other issuer services such as text alerts, in order to improve the cardholder experience and minimize return inquiries.
