iNTERFACEWARE™ Inc.

NACK Messages

Negative Acknowledgments, known as NACKs, let the sending system know that there was an error while processing the message.

If there were problems processing the message, a negative ACK message is sent to the sending system. The message that caused the error will be diagnosed, fixed, and then resent by the sending system. A negative ACK is indicated by using an AE (Application Error) value in the first field of the MSA segment. This code indicates that there was a problem processing the message. This could be related to the message structure, or the message itself.