ISO 31

ISO 31 (Quantities and units, International Organization for Standardization, 1992) is a superseded international standard concerning physical quantities, units of measurement, their interrelationships and their presentation. It was revised and replaced by ISO/IEC 80000.

Parts
The standard comes in 14 parts:


 * ISO 31-0: General principles (replaced by ISO/IEC 80000-1:2009)
 * ISO 31-1: Space and time (replaced by ISO/IEC 80000-3:2007)
 * ISO 31-2: Periodic and related phenomena (replaced by ISO/IEC 80000-3:2007)
 * ISO 31-3: Mechanics (replaced by ISO/IEC 80000-4:2006)
 * ISO 31-4: Heat (replaced by ISO/IEC 80000-5)
 * ISO 31-5: Electricity and magnetism (replaced by ISO/IEC 80000-6)
 * ISO 31-6: Light and related electromagnetic radiations (replaced by ISO/IEC 80000-7)
 * ISO 31-7: Acoustics (replaced by ISO/IEC 80000-8:2007)
 * ISO 31-8: Physical chemistry and molecular physics (replaced by ISO/IEC 80000-9)
 * ISO 31-9: Atomic and nuclear physics  (replaced by ISO/IEC 80000-10)
 * ISO 31-10: Nuclear reactions and ionizing radiations (replaced by ISO/IEC 80000-10)
 * ISO 31-11: Mathematical signs and symbols for use in the physical sciences and technology (replaced by ISO 80000-2:2009)
 * ISO 31-12: Characteristic numbers (replaced by ISO/IEC 80000-11)
 * ISO 31-13: Solid state physics (replaced by ISO/IEC 80000-12)

A second international standard on quantities and units was IEC 60027. The ISO 31 and IEC 60027 Standards were revised by the two standardization organizations in collaboration to integrate both standards into a joint standard ISO/IEC 80000 - Quantities and Units in which the quantities and equations used with SI are to be referred as the International System of Quantities (ISQ). ISO/IEC 80000 supersedes both ISO 31 and part of IEC 60027.

Coined words
ISO 31-0 introduced several new words into the English language that are direct spelling-calques from the French. Some of these words have been used in scientific literature.

Related national standards

 * Canada: CAN/CSA-Z234-1-89 Canadian Metric Practice Guide (covers some aspects of ISO 31-0, but is not a comprehensive list of physical quantities comparable to ISO 31)
 * United States: There are several national SI guidance documents, such as NIST SP 811, NIST SP 330, NIST SP 814, IEEE/ASTM SI 10, SAE J916. These cover many aspects of the ISO 31-0 standard, but lack the comprehensive list of quantities and units defined in the remaining parts of ISO 31.