The role class “ProductionUnit” should be used for sub units/sub production steps of units/production lines, station, processes single component, cycle, location in which the production step takes place. It is used for hierarchization. The definition of a “ProductionUnit” is given in IEC 62264-1:2013, 5.3.6: “Production units are the lowest level of equipment for continuous manufacturing processes. Production units are composed of lower level elements, such as equipment modules, sensors, and actuators, but definitions of these are outside the scope of the IEC 62714 series. A production unit generally encompasses all of the equipment required for a segment of continuous production that operates in a relatively autonomous manner. It generally converts, separates, or reacts to one or more feedstocks to produce intermediate or final products. The major processing activity or product generated often identifies the production unit. Examples of production unit identifications are ‘Catalytic Cracker #1’ and ‘Alkylation Unit 2’. Production units have well-defined processing capabilities and throughput capacities.”