This standard specifies a set of codes and formats to be used by devices connected via the IEEE 488.1 bus. This standard also defines communication protocols necessary to effect application independent device-dependent message exchanges and further defines common commands and characteristics useful in instrument system applications. This standard is intended to directly apply to small to medium-scale instrument systems. It applies to systems comprised mainly of measurement, stimulus, and interconnect devices with an instrumentation controller. The standard may also apply to certain devices outside the scope of the instrument system environment. As well as defdefining a variety of device-dependent messages, this standard extends and further interprets certain interface functions contained in ANSI/IEEE Std 488.1-1987 [2] while remaining compatible with that standard. This standard covers the following topics: (1) IEEE 488.1 subsets (2) Standard message handling protocols including error handling (3) Unambiguous program and response message syntactic structures (4) Common commands useful in a wide range of instrument system applications ( 5 ) Standard status reporting structures (6) System configuration and synchronization protocols Use of this standard does not relieve the user from the burden of responsibility for system compatibility at the application level. The user must be familiar with the characteristics of all the system components in order to configure an optimum system. The intended readers of this standard include both controller and device designers.