A fault tolerant,real time high speed data communication standard is defined based on a ring topology and the use of a Token passing access method with distrbuted control.The requirements for the HSRB standard have been driven predominantly,but not exclusively,by military applications .Particular attention has been given to the need for low message latency,deterministic message priority and comprehensive reconfiguration capabilities.This document contains a definition ofthe semantics and protocol including delimfters ,tokens,message priority,addressing ,error detection and media.Parameters related to particullar media and bit rates are define in the Appendix.