Developed by HDA’s eCommerce Task Force, this electronic data interchange (EDI) set is intended for use within the chargeback process (i.e., reconciliation). The 2020 revision includes updated reject reason codes in the AAA segment; follow-up action coding in AAA04 was added. Business use case examples have been updated from prior versions to illustrate these enhancements. These guidelines were developed with the application of the Accredited Standards Committee (ASC) X12 standards, version 4010.