This standard applies to the definition and application of function numbers for devices used in electrical substations and generating plants and in installations of power utilization and conversion apparatus. A device function number, with an appropriate prefix and suffix where necessary, is used to identify the function of each device in all types of switchgear. These numbers are to be used in drawings, elementary and connection diagrams, instruction books, publications, and specfications. In addition, the number may be placed on, or adjacent to, each device on the assembled equipment so the device may be readily identified. This PAR is proposed to revise C37.2-1991 to reflect current technology and usage. Revision Standard - Superseded. The definition and application of function numbers for devices used in electrical substations and generating plants and in installations of power utilization and conversion apparatus are covered. The purpose of the numbers is discussed, and 94 numbers are assigned. The use of prefixes and suffixes to provide a more specific definition of the function is considered. Device contact designation is also covered.