This part of IEC 605 provides a general procedure for design of test cycles, where no applicable preferred test cycles can be found in IEC 605-3. It applies to the design of operating and environmental test cycles referred to in 8.1 and 8.2 of IEC 605-1. The resulting test cycle should be included in the detailed reliability test specification. Tests which include cycles designed according to this standard are not intended to replace ordinary tests such as qualification tests, functional pe rformance tests and environmental tests. Pre-exposure tests may in some cases be necessary before commencing the test cycles designed by the methods of this standard. The basis of the decision as to whether to include pre-exposure tests is outside the scope of this standard.