Q631-97 (R2002)

1. Scope 1.1 This Standard lists terms and definitions, primarily intended for the description of reliability, availability, maintainability, and maintenance support aspects of items. It is a document relating to Chapter 191 of the International Electrotechnical Vocabulary (IEV), IEC 50 (191). Extra notes are used in this Standard to clarify certain definitions taken from IEV. The terminology is based on an engineering approach, but it is also adapted to mathematical modelling techniques which are fundamental to the application of the terms. Appendix A contains definitions of modifiers (see Clause 2.3.7) and related terms. Related subjects, such as probabilistic and statistical concepts, are treated only when they are needed to facilitate the reading and understanding of this Standard. Other international standards should be consulted when necessary. In particular, IEC 50 (191) should be consulted for a more complete list of terms and definitions. Note: Where more than one term is specified in the title of a definition, the first term is preferred; the other(s) may be used as synonyms.