This document is the avionics standards for GPS/Galileo/SBAS equipment supporting Required Navigation Performance (RNP) en route and terminal operations, departure operations, RNP APCH (approach) down to Localizer Performance with vertical guidance (LPV) minima and Automatic Dependent Surveillance – Broadcast (ADS-B). This document does not provide specifications for a production approval. A future release of the document will provide requirements supporting production approval, typically through a new Technical Standard Order (TSO) or European Technical Standard Order (ETSO). This document has a Zipped supplement (ED-259A DO-401 Supplement) that contains six files.