This Change 1 correct errors that have arisen since the publication of ED-73F reported by manufacturers and by ICAO, and to have consistent content between revised transponder MOPS (ED-73) and 1090 ADS-B MOPS (ED-102). The largest of the changes is a revision to the Basic Dataflash function, which reduced the list of supported registers. The updated version will be used by manufactures to obtain EASA European Technical Standard Order (ETSO-C112) and facilitate demonstration to Acceptable Means of Compliance (AMC) proposed in CS-ACNS. The document is technically identical to RTCA DO-181F Change 1. Final Editing of the document will be performed during Council Approval.