Standard Letter Symbols for Units of Measurement (SI Units, Customary Inch-Pound Units, and Certain Other Units)
|Publication Date:||25 March 2004|
This standard supersedes ANSI/IEEE Std 260.1-1993 in accordance with IEEE's policy of periodic standards review and update. Since the 1993 standard was approved, significant changes have occurred in the International System of Units (SI). Corresponding updates have been issued for some of the documents referred to by this standard. Significant, newly revised references are IEEE/ASTM SI 10-2002 (superseding ANSI/IEEE Std 268-1992 and ASTM E 380) and the seventh edition of Le Système international d'unités (The International System of Units, 1998, BIPM).
Since IEEE Std 260.1-1993 was issued, the IEEE has adopted Policy 9.19, Metric Policy, which calls upon all IEEE organizational units to support the use of the SI. The IEEE-SA Standards Board Implementation Plan for this policy, approved in 1995, states in part:
Stage III-After January 1, 2000: Proposed new standards and revised standards submitted for approval shall use metric units exclusively in the normative portions of the standard. Inchpound data may be included, if necessary, in footnotes or annexes that are informative only.
Standards Coordinating Committee 14 (SCC14) shall work with the committees responsible for generating IEEE standards to help them carry out this implementation plan. Policy 9.19 recognizes the need for some exceptions and contains the following statement: "Necessary exceptions to this policy, such as where a conflicting world industry practice exists, must be evaluated on an individual basis and approved by the responsible major board of the Institute for a specific period of time." SCC14, as part of the coordination process, shall review requests for individual exceptions and shall report its recommendations to the IEEE-SA Standards Board.
This standard covers letter symbols for units of measurement. It does not include abbreviations for technical terms, nor does it cover symbols for physical quantities.
The symbols given in this standard are intended for all applications, including use in text and equations; in graphs and diagrams; and on panels, labels, and nameplates. Provision is made for modifications to be used when only character sets of limited capability are available.