This recommeded practice provides a single source of component function identifiers which, along with related recommended practices concerning unique identification principles and definitions, implementation instructions, and system descriptions, makes up a concept, entitled the Energy Industry Identification System (EIIS), for uniquely identifying systems, structures, and components of nuclear and fossil fueld power plant projects (electric power generating stations) and realted facilities. Hydro and other types of power plant projects are not included in this issue.