This part of IEC61069 : specifies the detailed method of the assessment of system safety of a basic control system (BCS) based on the basic concepts of IEC61069‑1 and methodology of IEC61069‑2 , defines basic categorization of system safety properties, describes the factors that influence system safety and which need to be taken into account when evaluating system safety, and provides guidance in selecting techniques from a set of options (with references) for evaluating the system safety. The treatment of safety in this standard is confined to hazards that can be present within the BCS itself. That is, the BCS itself as a physical entity will not impose a hazard. Considerations of hazards that can be introduced by the process or equipment under control, of the BCS to be assessed, are excluded.