Foreword?In the IEEE@ as in engineering and the sciences in general@ graphic and alphabetic symbols and designations are an important factor in effective communication. The rapid technological expansion in the electrical and electronics fields results in proposals for new symbols and designations being generated in many areas. In order to eliminate confusion@ it is necessary to establish and use a coordinated set of symbols and designations@ thus providing a common language that is formed according to carefully established principles. As a result of discussions in the Symbols Committee and later in the Standards Committee@ this Recommended Practice for the Preparation and Use of Symbols was developed. The purpose of the recommendations is to provide guidance to the Technical Committees and others within the IEEE who may be engaged either in developing Standards Publications or in preparing publications. It is believed that by following the guidelines laid down herein@ it will be possible for such committees and individuals to develop Standards Publications which employ fully coordinated and universally understood symbology. In addition@ there is much information in this Recommended Practice that can be of considerable aid to persons and organizations who are users of symbols. The Standards Coordinating Committee for Letter and Graphic Symbols feels that the availability of this document to such users will provide answers to many questions and solutions to many problems frequently encountered in the application of symbology. Questions to which the answers cannot be found in this Recommended Practice may be directed to IEEE Standards Coordinating Committee for Letter and Graphic Symbols Institute of Electrical and Electronics Engineers 345 East 47th Street New York@ N.Y. 10017 ScopeThe IEEE Standards Coordinating Committee for Letter and Graphic Symbols recognizes the need for guidelines to be used in developing and applying those symbols that are employed in the electrical and electronics fields. These include: abbreviations@ functional designations@ graphic symbols@ letter combinations@ mathematical symbols@ reference designations@ symbols for quantities@ and symbols for units. Such guidelines are useful not only to members of the Standards Coordinating Committee@ but are especially helpful to any other committee engaged in developing Standards Publications in the areas mentioned. Accordingly@ these guidelines have been formulated and are given in detail herein. There is considerable confusion as to what is meant by the terms "abbreviation"@ "designation"@ and "symbol". The first step@ then@ is to define the terms involved. This has been done and@ for additional guidance@ examples have been included to show how such terms are used. Applicable reference Standards Publications are listed at the end of each section. The basic Standards Publication number is given for each document; it is assumed that the user will obtain the latest issue and amendment in each case. Committees@ Subcommittees@ and Task Forces of the IEEE and its Groups that find it necessary to engage in the development of symbols are required to advise the IEEE Standards Coordinating Committee for Letter and Graphic Symbols of the intended action before beginning work. Other bodies (outside of IEEE) are urged to do so. The Standards Coordinating Committee for Letter and Graphic Symbols is continuously reviewing and coordinating in the above-mentioned areas. This committee also is constantly engaged in developing new symbols to take care of advances in the state of the electrical and electronics arts. A considerable background in symbology has been built up by this committee over the years@ and its aid and counsel are available to any individual or group.