ISO_31-0 SI Units

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Review of Content Standard

Quantities and Units(ISO 31:1992)

September, 2005

This review is intended to assess the potential utility of content standards for use andpotentially for inclusion in an ISO 11179-based metadata registry. The review is directedprimarily toward the utility of the standard itself rather than to matching the standardwith specific agency programs. The review covers issues such as the sub!ect areacurrency "uality authority and acceptance of the standards. These are factors that needto be ta#en into account no matter what the programmatic application of the standard maybe.

1. Smmar!

Internationa" Standard ISO 31$%uantitiesand units International Organi&ation forStandardi&ation199'( is the most widely respected style guide for the use of units ofmeasurement and formulas involving them in scientific and educational documentsworldwide. In most countries the notations used in mathematics and science te)tboo#s atschools and universities follow e)actly the guidelines given by ISO *1.

This standard gives general information about principles concerning physical "uantitiese"uations "uantity and unit symbols and coherent unit systems especially theInternational System of +nits SI including recommendations for printing symbols andnumbers. ,nne) , includes a guide to terms used in names for physical "uantities ,nne) a guide to the rounding of numbers ,nne) international organi&ations in the field of

"uantities and units.

2. Identifi#ation of Standard

2.1. $it"e

Quantities and units

2.2. %#ron!m

ISO *1/199'

2.3. &eb pa'e(), Identifier, or Conta#t Information:

2.3.1 &eb pa'e()

http://www.iso.ch/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER!"#$%&CS$$%&CS#"'%&CS!%scopelist

2.3.2 Identifier

&S( !$:$))#
http://en.wikipedia.org/wiki/Physical_quantityhttp://en.wikipedia.org/wiki/Physical_unithttp://en.wikipedia.org/wiki/International_Organization_for_Standardizationhttp://en.wikipedia.org/wiki/International_Organization_for_Standardizationhttp://en.wikipedia.org/wiki/International_Organization_for_Standardizationhttp://en.wikipedia.org/wiki/Measurementhttp://en.wikipedia.org/wiki/Physical_quantityhttp://en.wikipedia.org/wiki/Physical_unithttp://en.wikipedia.org/wiki/International_Organization_for_Standardizationhttp://en.wikipedia.org/wiki/International_Organization_for_Standardizationhttp://en.wikipedia.org/wiki/Measurement

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2.3.3 Conta#t Information

&nte*national (*gani+ation ,o* Standa*di+ation -&S(

http://www.iso.o*g/iso/en/&S((nline.,*ontpage

2. %t*orit!

2..1 Creator


C $#0 Quantities0 units0 s123ols0 con4e*sion ,acto*s

Sec*eta*iat: S&S

Sec*eta*1: M*. 5nde*s 6. ho*

Chai*: M*. 7unna* Pete*sson -Sweden until end #''"

2..2. %##eptan#e a at*oritative

The Internationa" S!tem of +nit$abbreviated SIfrom the 0renchphrase SystmeInternational d'Units( is the most widely used system of units. It is the most commonsystem for everyday commercein the world and is almost universally used in the realmof science.

In 192 SI was selected as a specific subset of the e)isting 3etre-4ilogram-Second

systems of units $34S( rather than the older entimetre-5ram-Secondsystem $5S(.6arious new units were added with the introduction of the SI and at later times. SI issometimes referred to as the metri# !temespecially in the +nited States which hasnot widely adopted it and in the +nited 4ingdom where conversion is only partial. SI isa specific canon of measurements derived and e)tended from theMetric system howevernot all metric units of measurement are accepted as SI units.

2.5 b"i*er


Much o, the 2ate*ial in &S( !$ co2es o*iginall1 ,*o2 Docu2ent&UP5P8#9 o, the Commission for Symbols, Units and Nomenclature-SUN Co22ission !;o, theInternational Union of Pure and AppliedPhysics

So2e o, the 2ate*ial in &S( !$ o*iginates ,*o2 theInterdivisionalCommittee on Terminology, Nomenclature and Symbols

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2.- an'a'e()

This standard is available in both 0rench and 8nglish.

3. Content de#ription

3.1 Sb/e#t area of #ontent and area of app"i#ation

ISO *1 covers onlyphysical "uantitiesused for the "uantitative description of physicalphenomena. It does not cover conventional scales $e.g.eaufort scaleichter scalecolour intensity scales( results of conventional tests currencies or information content.The presentation here is only a brief summary of some of the detailed guidelines and

e)amples given in the standard.

:hysical "uantities can be grouped into mutually comparable categories. 0or e)amplelength width diameter and wavelength are all in the same category which is they are allquantities of the same kind. One particular e)ample of such a "uantity can be chosen as areference "uantity called the unit and then all other "uantities in the same category canbe e)pressed in terms of this unit multiplied by a number called the numerical value. 0ore)ample if we write

the wavelength is; .97? is the numerical value of the wavelength in metres.

3ore generally we can writeA; @AA B CADwhereAis the symbol for the "uantity and @AA symboli&es the numerical value ofAif itis e)pressed using the unit CAD. oth the numerical value and the unit symbol are factorsand their product is the "uantity.The value of a "uantity is independent of the unit chosen to represent it. It must bedistinguished from the numerical value of the "uantity that occurs when the "uantity ise)pressed in a particular unit. The above curly-brac#et notation could be e)tended with aunit-symbol inde) to clarify this dependency as in @Am; .9

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$!po'rap*i# #onvention

S!mbo" for antitie

%uantities are generally represented by a symbol formed from single letters of theFatin or 5ree# alphabet.

Symbols for "uantities are set in italic type independent of the type used in therest of the te)t.

If in a te)t different "uantities use the same letter symbol they can bedistinguished via subscripts.

, subscript is only set in italic type if it consists of a symbol for a "uantity or avariable. Other subscripts are set in upright $roman( type. 0or e)ample write Vnfor a ?nominal volume? $where ?n? is !ust an abbreviation for the word

?nominal?( but write Vnif nis a running inde) number.

ame and !mbo" for nit

If an internationally standardi&ed symbol e)ists for a unit then only that symbolshould be used. See the SIarticle for the list of standard symbols defined by theInternational System of +nits. Gote that the distinction between uppercase andlowercase letters is significant for SI unit symbols. 0or e)ample ?#? is the prefi)#ilo and ?4? stands for the unit #elvin. The symbols of all SI units named after aperson start with an uppercase letter as do the symbols of all prefi)es from mega

on upwards. ,ll other symbols are lowercase the only e)ception islitre whereboth l and F are allowed.

Symbols for units should be printed in an upright $roman( typeface.

mber

Gumbers should be printed in upright $roman( type.

Gumbers consisting of long se"uences of digits can be made more readable by

separating them into groups preferably groups of three separated by a smallspace. ISO *1-2 specifies that such groups of digits should never be separated bya comma or point as these are reserved for use as the decimal sign.

ISO *1-2 specifies that the decimal sign is the comma on the baseline butrecogni&es that in 8nglish documents a dot on the line is also commonly used.

0or numbers whose magnitude is less than 1 the decimal sign should be precededby a &ero.
http://en.wikipedia.org/wiki/Italic_typehttp://en.wikipedia.org/wiki/Roman_typehttp://en.wikipedia.org/wiki/SIhttp://en.wikipedia.org/wiki/Litrehttp://en.wikipedia.org/wiki/Litrehttp://en.wikipedia.org/wiki/Roman_typehttp://en.wikipedia.org/wiki/Roman_typehttp://en.wikipedia.org/wiki/Italic_typehttp://en.wikipedia.org/wiki/Roman_typehttp://en.wikipedia.org/wiki/SIhttp://en.wikipedia.org/wiki/Litrehttp://en.wikipedia.org/wiki/Roman_typehttp://en.wikipedia.org/wiki/Roman_type

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4preion

+nit symbols follow the numerical value in the e)pression of a "uantity.

Gumerical value and unit symbol are separated by a space. This rule also appliesto the symbol ?H? for degrees elsius as in ?' H?. The only e)ceptions are thesymbols for the units of plane angle degree minute and second which follow thenumerical value without a space in between $for e)ample ?*2H?(.

Jhere "uantities are added or subtracted parenthesis can be used to distribute aunit symbol over several numerical values as in

T; ' H > * H ; $' > *( H; 122 #J K #J ; $122 K ( #J$but not/ 122 K #J(d; 1' = $1 K 12>L( m

:roducts can be written as a! a ! a=! or a=!. The sign for multiplying numbersis a cross $=( or a half-heigh dot $ (. The cross should be used ad!acent to numbers=if a dot on the line is used as the decimal separator to avoid confusion between adecimal dot and a multiplication dot.

Mivision can be written as aE! or by writing the product of aand !>1 fore)ample a=!>1. Gumerator or denominator can themselves be products or"uotients but in this case a solidus $E( should not be followed by a multiplicationsign or division sign on the same line unless parentheses are used to avoidambiguity.

Mathe2atical signs and s123ols

, comprehensive list of internationally standardi&ed mathematical symbols and notationscan be found in ISO *1-11.

3.3 %dien#e()

Scientists and researchers worldwide. In most countries the notations used inmathematics and science te)tboo#s at schools and universities follow e)actly theguidelines given by ISO *1.

3. Re"ated Standard3.5 Standard 6ependen#ie

See 3,: Nelationships of Standards and 5uidance Mocuments for SI +nits

3.- Content 7a"it!
http://en.wikipedia.org/w/index.php?title=ISO_31-11&action=edithttp://en.wikipedia.org/w/index.php?title=ISO_31-11&action=edithttp://en.wikipedia.org/w/index.php?title=ISO_31-11&action=edit

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Pigh.

. Crren#! of Content

.1 6ate

199'

.2 8erion, +pdate

he last pu3lished 4e*sion was pu3lished in $))#. he cu**ent*e4ision has *eached the decision *e4iew stage -)'.)# as o, $)))8$#8##.

.3 Crren#!

The wi#ipedia states/ N, second older and today less widely #nown internationalstandard on "uantities and units is I8 '7.There are plans to merge these two standardsin the ne)t edition of ISO *1. ref/ http/EEen.wi#ipedia.orgEwi#iEISOQ*1

5. %##eptan#e

Internationa" Standard ISO 31$%uantitiesand units International Organi&ation forStandardi&ation199'( is the most widely respected style guide for the use of units ofmeasurement and formulas involving them in scientific and educational documentsworldwide. In most countries the notations used in mathematics and science te)tboo#s atschools and universities follow e)actly the guidelines given by ISO *1.

-. Content detai"

-.1 Sie tatiti# (etimated)

The standard comes in 1L parts/ISO *1-2/ 5eneral principlesISO *1-1/ Spaceand timeISO *1-'/ :eriodic and relatedphenomena

ISO *1-*/ 3echanicsISO *1-L/ PeatISO *1-/ 8lectricityand magnetismISO *1-/ Fightand related electromagnetic radiationsISO *1-7/ ,cousticsISO *1-

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ISO *1-11/ 3athematical signs and symbolsfor use in the physical sciences andtechnologyISO *1-1'/ haracteristic numbersISO *1-1*/ Solid state physics

Nu23e*s o, pages 4a*ies.

-.2 ormat S#*ema()

Pape* and pd, 4e*sions a*e a4aila3le.

-.3 ;edia 6own"oad

54aila3le as a pd, >le ,*o2http://www.iso.ch/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER!"#$%&CS$$%&CS#"'%&CS!%scopelist

-. i#enin' Ie-.5 6o#mentation

ISO standards are available for purchase online. ISO 1222 along with all parts of ISO *1are available in boo# form as

&S( Standa*ds and3oo@: Quantities and units. !*d ed.0&nte*national (*gani+ation ,o* Standa*di+ation0 7ene4a0 $))!0!

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Si+e P*ice

&S( !$8':$))# PD 4e*sion-en

Documents

ISO_31-0 SI Units