Payment Glossary

CAVV	Cardholder Authentication Verification Value. A base64-encoded string sent back with Verified by Visa-enrolled cards that specifically identifies the transaction with the issuing bank and Visa. Standard for collecting and sending AAV data for Verified by Visa transactions. See AAV.
CAVV algorithm	A one-digit reply passed back when the PARes status is a Y or an A. If your processor is ATOS, this must be passed in the authorization, if available.
CVV	Card Verification Value. Security feature for credit cards and debit cards. This feature consists of two values or codes: one that is encoded in the magnetic strip and one that is printed on the card. Usually the CVV is a 3-digit number on the back of the card. The CVV for American Express cards is a 4-digit number on the front of the card. CVVs are used as an extra level of validation by issuing banks.

AAV	Account Authentication Value. Unique 32-character transaction token for a 3-D Secure transaction. For MasterCard SecureCode, the AAV is named the UCAF.For Verified by Visa, the AAV is named the CAVV

Reference : 

1. http://apps.cybersource.com/library/documentation/dev_guides/Payer_Authentication_SO_API/html/wwhelp/wwhimpl/common/html/wwhelp.htm#href=glossary.html&single=true
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