IEC TR 60668:1980

Serves as a guide for selection of panel cut-out sizes and instrument front dimensions so that users may plan installations with the assurance that equipment purchased will fit, and manufacturers can design to ensure conformance to users' needs. Recognizes three known modular elements: 12 mm and 20 mm, both from established European practice, and 12.5 mm, the module established in IEC 60473. Has the status of a technical report.