This document has been declared "Stabilized" and will no longer be subjected to periodic reviews for currency. Users are responsible for verifying references and continued suitability or technical requirements. New technology may exist. This standard defines a bus and module interface to the Pi-Bus. This standard specifies the requirements/functions for the Pi-Bus side of a bus interface unit (BIU) needed to facilitate the interoperability of modules on a Pi-Bus for avionics systems. The corresponding software/device side interface requirements are not specified in this standard.