In the Futurebus+? series of standards, tools with which high-performance bus-based systems may be developed are provided. This architecture provides a wide range of performance scalability over both cost and time for multiple generations of single- and multiple-bus multiprocessor systems. This document, a companion standard to the ISO/IEC 10857: 1994 (ANSI/IEEE Std 896.1, 1994 Edition) Futurebus+(R) Logical Layer Specification, builds on the logical layer by adding requirements for a spaceborne profile. It is to this profile that products will claim conformance. Other specifications may be required in conjunction with this standard.