This part of ISO 81346 contains sector-specific stipulations for structuring principles and reference designation rules on technical products and technical product documentation of power plants.It applies in combination with IEC 81346-2, ISO/TS 81346-3, VGB-B 101 and VGB-B 102 for the classification of systems and objects, and for function-, product- and location-specific designation of technical products and their documentation for power plants.It specifies the designation blocks for the clear identification and localization of the technical products, which are used for their labelling in the plant, for their designation in technical documents and for the designation of the technical documents as well.This part of ISO 81346 encompasses the process of energy conversion. The specifications in this document apply for the power plant process, for the primary energy supply and final products distribution, as well as for auxiliary media and auxiliary energy supply, waste materials and waste energy disposal.This part of ISO 81346 is not applicable to recovery of the primary energy and the media for supplying the process, nor to the processing of residues from process disposal (e.g. gypsum, slag products, waste water, etc.).