1、IEEE Std 260.1-2004(Revision ofIEEE Std 260.1-1993)IEEE Standards260.1TMIEEE Standard Letter Symbols for Units of Measurement(SI Units, Customary Inch-Pound Units,and Certain Other Units)3 Park Avenue, New York, NY 10016-5997, USAIEEE Standards Coordinating Committee 14Sponsored by theStandards Coor
2、dinating Committee on Quantities, Units, and Letter Symbols(SCC14)IEEE Standards24 September 2004Print: SH95220PDF: SS95220Recognized as anAmerican National Standard (ANSI)The Institute of Electrical and Electronics Engineers, Inc.3 Park Avenue, New York, NY 10016-5997, USACopyright 2004 by the Inst
3、itute of Electrical and Electronics Engineers, Inc.All rights reserved. Published 24 September 2004. Printed in the United States of America.IEEE is a registered trademark in the U.S. Patent (978) 750-8400. Permission to photocopy portions of any individual standard for educationalclassroom use can
4、also be obtained through the Copyright Clearance Center.Note: Attention is called to the possibility that implementation of this standard may require use of subject mat-ter covered by patent rights. By publication of this standard, no position is taken with respect to the existence orvalidity of any
5、 patent rights in connection therewith. The IEEE shall not be responsible for identifying patentsfor which a license may be required by an IEEE standard or for conducting inquiries into the legal validity orscope of those patents that are brought to its attention.Copyright2004 IEEE. All rights reser
6、ved.iiiIntroductionThis standard supersedes ANSI/IEEE Std 260.1-1993 in accordance with IEEEs policy of periodic stan-dards review and update. Since the 1993 standard was approved, significant changes have occurred in theInternational System of Units (SI). Corresponding updates have been issued for
7、some of the documentsreferred to by this standard. Significant, newly revised references are IEEE/ASTM SI 10-2002 (supersedingANSI/IEEE Std 268-1992 and ASTM E 380) and the seventh edition of Le Systme international dunits(The International System of Units, 1998, BIPM).Since IEEE Std 260.1-1993 was
8、issued, the IEEE has adopted Policy 9.19, Metric Policy, which calls uponall IEEE organizational units to support the use of the SI. The IEEE-SA Standards Board ImplementationPlan for this policy, approved in 1995, states in part:Stage IIIAfter January 1, 2000: Proposed new standards and revised sta
9、ndards submittedfor approval shall use metric units exclusively in the normative portions of the standard. Inch-pound 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 gene
10、ratingIEEE standards to help them carry out this implementation plan. Policy 9.19 recognizes the need for someexceptions and contains the following statement: “Necessary exceptions to this policy, such as where aconflicting world industry practice exists, must be evaluated on an individual basis and
11、 approved by theresponsible major board of the Institute for a specific period of time.” SCC14, as part of the coordinationprocess, shall review requests for individual exceptions and shall report its recommendations to the IEEE-SA Standards Board. Notice to usersErrataErrata, if any, for this and a
12、ll other standards can be accessed at the following URL: http:/standards.ieee.org/reading/ieee/updates/errata/index.html.Users are encouraged to check this URL forerrata periodically.InterpretationsCurrent interpretations can be accessed at the following URL: http:/standards.ieee.org/reading/ieee/in
13、terp/index.html.PatentsAttention is called to the possibility that implementation of this standard may require use of subject mattercovered by patent rights. By publication of this standard, no position is taken with respect to the existence orvalidity of any patent rights in connection therewith. T
14、he IEEE shall not be responsible for identifyingpatents or patent applications for which a license may be required to implement an IEEE standard or forconducting inquiries into the legal validity or scope of those patents that are brought to its attention.This introduction is not part of IEEE Std 26
15、0.1-2004, IEEE Standard Letter Symbols for Units of Measurement(SI Units, Customary Inch-Pound Units, and Certain Other Units.)ivCopyright 2004 IEEE. All rights reserved.ParticipantsAt the time this standard was completed, the working group had the following membership: James R. Frysinger,ChairThe f
16、ollowing members of the individual balloting committee voted on this standard. Balloters may havevoted for approval, disapproval, or abstention. When the IEEE-SA Standards Board approved this standard on 25 March 2004, it had the followingmembership:Don Wright,ChairSteve M. Mills, Vice ChairJudith G
17、orman,Secretary*Member EmeritusAlso included are the following nonvoting IEEE-SA Standards Board liaisons:Satish K. Aggarwal, NRC RepresentativeRichard DeBlasio, DOE RepresentativeAlan Cookson, NIST RepresentativeDon MessinaIEEE Standards Project EditorGordon J. AubrechtBruce B. BarrowStanley L. Ehr
18、lichStan I. JakubaJoseph G. LangensteinJohn T. ScottRalph M. ShowersBarry N. TaylorLorelle YoungAllan J. ZuckerwarO. C. AmrhynGordon J. AubrechtBruce B. BarrowDavid BartonJohn BenedictAnne BosmaWilliam BrennerDennis BrownridgeStephen P. ConradGary DonnerStanley L. EhrlichJim ElwellHoward FrazierJame
19、s R. FrysingerDudley GallowayRandall GrovesRobert GrowBal GuptaDonald W. HillgerJohn HorchStan I. JakubaTony JeffreeGeza JoosThomas M. KuriharaDee S. LongJack LoudonRoger MarksFrank MayleArthur O. McCoubreyNigel McQuinGary MichelJames W. MooreJohn NicholsT. W. OlsenLorraine PaddenRonald PetersenPerc
20、y PoolBill PottsJohn RossettiMohindar S. SachdevAnne-Marie SahazizianRobert SchaafJohn T. ScottJohn SheppardRalph M. ShowersJohn St. ClairThomas StaraiJames StonerEva TarasiewiczBarry N. TaylorJames WilsonLorelle YoungAllen J. ZuckerwarTheodore WildiChuck AdamsH. Stephen BergerMark D. BowmanJoseph A
21、. BruderBob DavisRoberto de BoissonJulian Forster*Arnold M. GreenspanMark S. HalpinRaymond HapemanRichard J. HollemanRichard H. HulettLowell G. JohnsonJoseph L. Koepfinger*Hermann KochThomas J. McGeanDaleep C. MohlaPaul NikolichT. W. OlsenRonald C. PetersenGary S. RobinsonFrank StoneMalcolm V. Thade
22、nDoug ToppingJoe D. WatsonCopyright2004 IEEE. All rights reserved.vContents1. Overview 11.1 Organization. 11.2 Scope 12. References 23. Abbreviations. 24. General principles of letter symbol standardization 24.1 Letter symbols 24.2 Alphabets and typography . 34.3 Remarks concerning quantity symbols
23、44.4 Remarks concerning unit symbols. 44.5 The International System of Units (SI) 54.6 Usage 75. Unit symbols 76. Unit symbols to be used with limited character sets 176.1 Limitations arising from the use of ASCII 0000-0127 186.2 Limitations arising from the use of HTML-coded web pages and electroni
24、c mail . 196.3 Examples of symbols for limited character sets 206.4 Limitations arising from importing and exporting documents between computer programs 21Annex A (normative) Notation for expressing the reference of a level. 22Annex B (informative) Bibliography. 23Copyright 2004 IEEE. All rights res
25、erved.1IEEE Standard Letter Symbols for Units of Measurement (SI Units, Customary Inch-Pound Units, and Certain Other Units) 1. Overview1.1 OrganizationThis standard is divided into six clauses. Clause 1 provides the organization and scope of this standard.Clause 2 gives the reference to the IEEE/AS
26、TM standard on metric practice. Clause 3 provides a list ofabbreviations used throughout this standard. Clause 4 establishes the general principles of letter symbolstandardization and includes a list of SI prefixes and their symbols. Clause 5 provides a list of units and theirsymbols. Clause 6 makes
27、 provisions for adaptation of this standard in cases where only a character set lim-ited in capability is available.This standard also contains two annexes. Annex A provides information about the identification of referencelevels when using logarithmic scaling units. Annex B provides a bibliography.
28、1.2 ScopeThis standard covers letter symbols1for units of measurement. It does not include abbreviations for techni-cal terms, nor does it cover symbols for physical quantities.2The symbols given in this standard are intended for all applications, including use in text and equations; ingraphs and di
29、agrams; and on panels, labels, and nameplates. Provision is made for modifications to be usedwhen only character sets of limited capability are available.1“Letter symbol” as a technical term does not have the same meaning as either “name” or “abbreviation.” An abbreviation is a letter ora combinatio
30、n of letters that by convention represents a word or a name in a particular language. For example, the symbol for electro-motive force is E, whereas the abbreviation is emf in English, fem in French, and EMK in German. The unit names ampere and secondhave sometimes been abbreviated amp and sec, resp
31、ectively, but this usage is now deprecated. The standard unit symbols for ampereand second are A and s, respectively.2As used in this standard, the term physical quantitymeans a measurable attribute of phenomena or matter. Examples are length, mass,and time.IEEEStd 260.1-2004 IEEE STANDARD LETTER SY
32、MBOLS2Copyright 2004 IEEE. All rights reserved.2. ReferencesThis standard shall be used in conjunction with the latest version of the following publication:IEEE/ASTM SI 10-2002, American National Standard for Use of the International System of Units (SI):The Modern Metric System.33. AbbreviationsANS
33、I American National Standards InstituteCGPM Confrence Gnrale des Poids et Mesures (General Conference on Weights and Measures)cgs centimeter-gram-secondCIPM Comit International des Poids et Mesures (International Committee for Weights and Measures)IEC International Electrotechnical CommissionIEEE In
34、stitute of Electrical and Electronics EngineersISO International Organization for StandardizationSI Systme International dUnits (International System of Units)4. General principles of letter symbol standardization4.1 Letter symbolsLetter symbols include symbols for physical quantities (quantity symb
35、ols) and symbols for the units inwhich these quantities are measured (unit symbols).A quantity symbol is, in general, a single letter4(for example, Ifor electric current) specified as to generalform of type and modified when appropriate by one or more subscripts or superscripts. In a given work, the
36、same letter symbol should appear throughout for the same physical quantity, regardless of the unitsemployed or of special values assigned.A unit symbol5is a letter or group of letters (for example, mm for millimeter), or in a few cases a specialsign, that may be used in place of the name of a unit.
37、It may include numbers to indicate exponents (forexample, m2for square meter) and multiplication or division operators (for example, m/s for meter persecond).3IEEE publications are available from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, P.O. Box 1331, Piscataway,NJ 08855
38、-1331, USA (http:/standards.ieee.org/).4Symbols composed of two letters are sometimes used for numerical transport parameters, such as Refor Reynolds number.5Unit symbols have sometimes been treated in the same manner as general abbreviations, but the recommendations of the InternationalCommittee fo
39、r Weights and Measures (CIPM), and of many other international and national bodies concerned with standardization,emphasize the symbolic character of these designations and rigidly prescribe the manner in which they shall be treated. This concept ofthe unit symbol is therefore adopted in this standa
40、rd.IEEEFOR UNITS OF MEASUREMENT Std 260.1-2004Copyright 2004 IEEE. All rights reserved.34.2 Alphabets and typographyLetter symbols are mainly restricted to the English and Greek alphabets. Those Greek letters that are easilyconfused with English letters shall be avoided. The type families that are u
41、sed for text in modern book andjournal publishing all include sloping (italic) type faces and related upright (roman) type faces. The formerare used for quantity symbols; the latter, for unit symbols. The distinctions are discussed more fully in thefollowing paragraphs. (In the context of this stand
42、ard, upright is used simply in contrast with sloping andcarries no connotation regarding serifs, line widths, or the like.) In situations where upright and sloping arenot both available, care shall be taken to avoid confusion between quantities and units.Unconventional typefaces should generally not
43、 be used for letter symbols. Script and Old English faces, forexample, are not appropriate for unit symbols. Such special faces have seen limited use for quantity sym-bols, but good modern practice avoids them.Symbols for physical quantities, mathematical variables, indexes, and general functions6ar
44、e printed in slop-ing type. For example:Aareaeelementary electric chargex, y, zCartesian coordinatesi, j, k, nindexesf(x)function of xSymbols for units of measurement, mathematical constants, specific mathematical functions, operators, andnumerals are printed in upright type. For example: cmcentimet
45、er e base of natural logarithms sin xsine ofxJ2(z), Jn(z) Bessel functionsdxdifferential of x formula for kinetic energySubscripts and superscripts are governed by the above principles. Those that are letter symbols for quantitiesor for indexes are printed in sloping type, while all others are print
46、ed in upright type. For example:Cpheat capacity at constant pressure paij, a45matrix elementsIi, Ioinput current, output currentxavaverage value of xFor indicating the vector character of a quantity, boldface sloping type is used. For example:FforceHmagnetic field strengthOrdinary sloping type is us
47、ed to represent the magnitude of a vector quantity. It is also commonly used for avector quantity when there is no need to draw attention to the vector character of the quantity.When tensor quantities of second or higher order are to be represented by a single letter, sans serif typeshould be used (
48、for example, A, B).6The term general functionsis here used to contrast with specific mathematical functions, for which upright type is to be used.E12-mv2=IEEEStd 260.1-2004 IEEE STANDARD LETTER SYMBOLS4Copyright 2004 IEEE. All rights reserved.4.3 Remarks concerning quantity symbolsQuantity symbols m
49、ay be used in mathematical expressions in any way consistent with good mathematicalusage. The product of two quantities, aand b,is indicated by writing ab. The quotient may be indicated bywritingor If more than one slash (/) is used in any algebraic term, parentheses shall be inserted to remove any ambigu-ity. Thus, one may write (a/b)/c, or a/(b/c), but not a/b/c.Subscripts and superscripts are widely used with quantity symbols. Several subscripts or superscripts,sometimes separated by commas, may be attached to a single letter. But, so far as
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