Resolution 7 of the 9th CGPM (1948)
 
Writing and printing of unit symbols and of numbers

Principles

Roman (upright) type, in general lower case, is used for symbols of units; if, however, the symbols are derived from proper names, capital roman type is used. These symbols are not followed by a full stop.

In numbers, the comma (French practice) or the dot (British practice) is used only to separate the integral part of numbers from the decimal part. Numbers may be divided in groups of three in order to facilitate reading; neither dots nor commas are ever inserted in the spaces between groups.

    Unit Symbol Unit Symbol

    ·metre

    m

    ampere

    A

    ·square metre

    m2

    volt

    V

    ·cubic metre

    m3

    watt

    W

    ·micron

    µ

    ohm

    capital omega

    ·litre

    l

    coulomb

    C

    ·gram

    g

    farad

    F

    ·tonne

    t

    henry

    H

    second

    s

    hertz

    Hz

    erg

    erg

    poise

    P

    dyne

    dyn

    newton

    N

    degree Celsius

    °C

    ·candela

     
       

    (new candela)

    cd

    ·degree absolute

    °K

    lux

    lx

    calorie

    cal

    lumen

    lm

    bar

    bar

    stilb

    sb

    hour

    h

       

Notes

  1. The symbols whose unit names are preceded by dots are those which had already been adopted by a decision of the CIPM.
  2. The symbol for the stere, the unit of volume for firewood, shall be "st" and not "s", which had been previously assigned to it by the CIPM.
  3. To indicate a temperature interval or difference, rather than a temperature, the word "degree" in full, or the abbreviation "deg" must be used.

Reference:
Comptes rendus de la 9e CGPM (1948), 1949, 70

Note:

The CGPM abrogated certain decisions on units and terminology, in particular: micron, degree absolute, and the terms "degree", and "deg", 13th CGPM, 1967 (Resolutions 7 and 3), and the litre; 16th CGPM, 1979 (Resolution 6).



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