This generic standard may be applied in all fields of electronics where equipment and installations are required to conform to the 19" Equipment Practice based on IEEE 1101.1, IEC 297-3, and IEC 297-4. The purpose of this standard is to specify dimensions which will ensure mechanically interchangeability of Subracks and Plug-in Units based on IEEE 1101.1, IEC 297-3, and IEC 297-4. New IEEE Standard - Inactive-Reserved. A generic standard that may be applied in all fields of electronics where equipment and installations are required to conform to the 482.6 mm (19 in) equipment practice based on IEEE Std 1101.1-1991, IEC 297-3 (1984), and IEC 297-4 (1995). Dimensions are provided that will ensure mechanical interchangeability of subracks and plug-in units.