This standard defines a method for incorporating more than one source of control into a CAMAC crate. The standard fully conforms to the mechanical and signal standards of the CAMAC system as described in ANSI/IEEE Std 583-1975, Modular Instrumentation and Digital Interface System (CAMAC), or EUR 4100e. In order to allow more than one Controller to access the Dataway of a CAMAC Criite, an Auxiliary Controller Bus (ACE) and priority arbitration protocol are fully defined. This permits the use of Auxiliary Controllers (ACs) in normal stations in the crate. The ACB carries encoded address information from an AC to the Crate Controller (CC) in the control station of a CAMAC crate, and carries Look-at- Me signals from the CC to the ACs. The ACB, connected between controllers, may also be used to establish priority for control of the CAMAC Dataway. This standard is fully compatible with ANSI/ IEEE Std 595-1976, Serial Highway Interface System (CAMAC), or EUR 6100e, and the ANSIAEEE Std 596-1976, Parallel Highway Interface System (CAMAC) or EUR 4600e. It may also be used in autonomous systems (systems with no external highways) or in systems with Type U Crate Controllers (such as systems with a computer I/O bus as the highway).