Developed by HDMA’s eCommerce Task Force, these three electronic data interchange (EDI) sets are used to administer contract and chargeback transactions. The sets provide additional codes to identify third-party pharmacy billing and eligible customers. This 2013 revision includes updates to the 844 and 849 transaction sets to accommodate a situation in which the bill-to and ship-to parties are not the same. Business use case examples have been updated from prior versions. These guidelines were developed with the application of the Accredited Standards Committee (ASC) X12 standards, version 4010. Note: HDA's 845, 849 and 844 EDI guidelines were updated in 2019, 2020 and 2021, respectively. Visit the main Resources page to download the latest versions.