Please contact your processor for the most up to date AVS code matrix.
All Card Types:
Y - Match (street address and 5-digit zip both match)
A - Partial Match (street address, but not zip code)
Z - Partial Match (5-digit zip code matches, but not street address)
N - No Match (neither zip nor address match)
U - System Unavailable
U can mean the information wasn't available, or that data is a non US address, or that the bank couldn't verify.
Visa Specific:
E - AVS data is invalid
MasterCard Specific:
X - Match (street address and 9-digit zip match)
MasterCard & Discover:
W - Partial Match (9-digit zip is a match, but street address does not)
Visa, MasterCard and AMEX
R - System unavailable, retry if possible