Can't find language file for AVS error

I need to change the language for the AVS mismatch error during check-out. A search using the Developers Tool Kit does not find it.

Where do I change 'The transaction has been declined because of an AVS mismatch. The address provided....'

This is for the Authorize.net module

Upon further investigation, it appears the message is a combination of Zen and a.net.

This comes from a.net
The transaction has been declined because of an AVS mismatch. The address provided does not match billing address of cardholder.

This comes from Zen.

• Your credit card could not be authorized for this reason. Please correct any information and try again or contact us for further assistance.