The scope of this guideline covers process control systems used by the energy utility industry for controlling and monitoring the generation, transmission, storage and distribution of electric power, gas and heat in combination with the control of supporting processes. This includes in particular the following systems, applications and components: — the overall IT-supported central and distributed process control, monitoring and automation technology as well as IT systems used for their operation, such as programming and parameterization devices; — digital controllers and automation components such as control and field devices or PLCs, including digital sensor and actuator elements; — all further supporting IT systems used in the process control domain, e.g. for supplementary data visualization tasks and for controlling, monitoring, data archiving and documentation purposes; — the overall communications technology used in the process control domain, e.g. networks, telemetry, telecontrol applications and remote control technology; — digital metering and measurement devices, e.g. for measuring energy consumption, generation or emission values; — digital protection and safety systems, e.g. protection relays or safety PLCs; — distributed components of future smart grid environments; — all software, firmware and applications installed on above mentioned systems. Outside the scope of this guideline is the conventional or classic control equipment that is non-digital, i.e. purely electro-mechanical or electronic monitoring and process control systems. Furthermore, energy process control systems in private households and other, comparable residential building installations are outside the scope of this guideline. Telecommunication systems and components used in the process control environment are also not directly part of the scope of this guideline. These are covered by the standard “ISO/IEC 27011:2008Information technology — Security techniques — Information security management guidelines for telecommunications organizations based on ISO/IEC 27002”. It is recommended that users of this guideline should implement the measures defined in that standard for the telecommunication systems and components used in the process control environment.