The system layer issues associated with bus-based computer systems are described. It is intended to be a tool for Futurebus+ board and system designers. As such, the intent of this recommended practice is to characterize a variety of systems topics as they relate to Futurebus+. When used in conjunction with other IEEE standards, the details to develop modular, open-architecture-based systems fulfillling user needs across a wide computing spectrum are available. The specifications that may be required in conjunction with this recommended practice are: ISO/IEC 10857:1994, IEEE Std 896.2-1991, IEEE Std 896.4-1993, IEEE Std 896.5-1993, IEEE Std 1149.1-1990, IEEE Std 1156.1-1993, IEEE Std 1194.1-1991, IEEE Std 1212-1991, IEEE Std 1212.1-1993, IEEE Std 1301.1-1991, and IEEE P1394/D6.8, March 1994.