This part of this European Standard specifies the requirements for the hardware to perform the tasks within a BACS. This part of this European Standard provides the terms, definitions and abbreviations for understanding of Part 2 and Part 3. Part 2 relates only to physical items/devices, i.e.: - operator stations and other human system interface devices; - devices for management functions; - control devices, automation stations and application specific controllers; - field devices and their interfaces; - cabling and interconnection of devices; - engineering and commissioning tools. This part of this European Standard shows a generic system model to which all-different types of BACS and their interconnections (BACS-network) can fit. A graphical concept of the BACS network in terms of LAN and inter-network topology will be provided in Part 5 of this standard. National annexes: National annexes may specify the local requirements of physical and electrical characteristics, the verifications for BACS devices and equipment, and the code of practice for the physical installation of systems. The annexes shall refer to the regional implementations of the relevant IEC standards.