Provides guidelines for suppliers to meet evolving requirements for digital process control systems through which users can be assured of the compatibility, the interworkability, the interconnectability, the interoperability and the interchange-ability of the devices they choose.It gives the overall requirements. For better understanding, this part gives background information and examples in annexes. It defines the requirements for FBs to provide control and to facilitate maintenance and technical management as applications which interact with actuators and measurement devices.