Applies to stabilized supplies designed to supply d.c. power from an a.c. or d.c. source for applications such as, but not restricted to, computers, telecommunication, laboratories and industrial equipment. It is in four parts: Part 1, Introduction and definitions, Part 2, Marking, performance ratings and physical characteristics, Part 3, Electromagnetic interference emanation tests, and Part 4, Methods of test. Based on and technically similar to IEC 478, Parts 1 to 4.