SAE AS15531A contains requirements for a digital time division command/response, multiplex data bus, for use in systems integration, that is functionally equivalent to MIL-STD-1553B with Notice 2. Even with the use of this document, differences may exist between multipex data buses in different system applications due to particular application requirements and the options allowed in this document. The system designer must recognize this fact and design the multiplex bus controller (BC) hardware and software to accommodate such differences. These designer selected options must exist to allow the necessary flexibility in the design of specific multiplex systems in order to provide for the control mechanism, architectural redundancy, degradation concept, and traffic patterns peculiar to the specific application requirements.