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Decisions
Returns the list of SI-related decisions.
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Decisions relating to the establishment of the SI
Establishment of the SI
Decision to establish the SI
Decision on the first six base units
Decision to adopt the name "Systeme international d'Unites"
Confirms the name and the abbreviation "SI"; names prefixes from tera to pico; establishes the supplementary units rad and sr; lists some derived units
Declarations concerning base, supplementary, derived and coherent units, and the use of prefixes
"SI units" and "units of the SI"
Possible redefinition of certain base units of the SI
Possible future revision of the SI
Future revision of the SI
On progress towards the redefinition of the SI
Revision of the SI (to enter into force on 20 May 2019)
Decisions relating to the base units of the SI
Length
Sanction of the prototype metre
Definition and use of the prototype metre
Adoption of the metre as a base unit
Redefinition of the metre in terms of krypton-86 radiation
Recommendation of the value for the speed of light
Redefinition of the metre using the speed of light, realization of the definition of the metre
Specification of the rules for the practical realization of the definition of the metre
Revision of the list of recommended radiations [92nd CIPM]
Revision of the list of recommended radiationsi [94th CIPM]
Revision of the list of recommended radiations [96th CIPM]
Revision of the mise en pratique of the definition of the metre and development of new optical frequency standards
On updates to the list of standard frequencies
On the possible future revision of the SI
Revision of the mise en pratique of the definition of the metre and development of new optical frequency standards
Updates to the list of standard frequencies
Revision of the SI (to enter into force on 20 May 2019)
Mass
Sanction of the prototype kilogram
Declaration on distinguishing mass and weight, and on the conventional value of gₙ
Adoption of the kilogram as a base unit
Declaration on applying prefixes to the gram
On the future redefinition of the kilogram
Possible redefinition of certain base units of the SI
On the possible future revision of the SI
On the future revision of the SI
Revision of the SI (to enter into force on 20 May 2019)
Time
Adoption of the second as a base unit
Definition of the second as a fraction of the tropical year 1900
Ratification of the CIPM 1956 definition of the second
Declaration of the caesium-133 hyperfine transition to be the recommended standard
Request to the CIPM to investigate atomic and molecular frequency standards
Definition of the second in terms of the caesium transition
Definition of International Atomic Time (TAI)
Request to the CIPM to define and establish International Atomic Time (TAI)
Endorsement of the use of Coordinated Universal Time (UTC)
On secondary representations of the second
On the revision of the mise en pratique of the definition of the metre and the development of new optical frequency standards
Updates to the list of standard frequencies [98th CIPM]
Possible future revision of the SI
Updates to the list of standard frequencies [102nd CIPM]
Updates to the list of standard frequencies [104th CIPM]
Revision of the SI (to enter into force on 20 May 2019)
Electrical units
Definition of coherent electrical units in the metre-kilogram-second (MKS) system of units (to enter into force on 1 January 1948)
Adoption of the ampere as a base unit
Adoption of the siemens, symbol S, for electical conductance
On the forthcoming adjustment to the representations of the volt and of the ohm
Definition of the conventional value of the Josephson constant (to enter into force on 1 January 1990)
Definition of the conventional value of the von Klitzing constant (to enter into force on 1 January 1990)
Possible redefinition of certain base units of the SI
Possible future revision of the SI
Future revision of the SI
Revision of the SI (to enter into force on 20 May 2019)
Thermodynamic temperature
Adoption of the triple point of water as the thermodynamic reference point; adoption of the zero of Celsius temperature to be 0.01 degrees below the triple point
Adoption of the name degree Celsius for the Celsius temperature scale
Definition of thermodynamic temperature such that the triple point of water is 273.16 degrees Kelvin exactly; definition of standard atmosphere
Adoption of degree Kelvin as a base unit
Formal definition of the kelvin, symbol K
Definition of the International Temperature Scale of 1990 (ITS-90)
Addition of a note to the definition of the kelvin
Clarification of the definition of the kelvin
Possible redefinition of certain base units of the SI
Possible future revision of the SI
Future revision of the SI
Revision of the SI (to enter into force on 20 May 2019)
Amount of substance
Definition of the mole, symbol mol, as a seventh base unit, and rules for its use
Adoption of the special name katal, kat
On the possible future redefinition of certain base units of the SI
Possible future revision of the SI
Future revision of the SI
Revision of the SI (to enter into force on 20 May 2019)
Luminous intensity
Definition of photometric units: new candle and new lumen (to enter into force on 1 January 1948)
Adoption of the candela as a base unit
Definition of the candela, symbol cd, in terms of a black body radiator
Redefinition of the candela in terms of monochromatic radiation
Possible future revision of the SI
Revision of the SI (to enter into force on 20 May 2019)
Decisions relating to SI derived and supplementary units
SI derived units
Acceptance of the continued use of the curie as a non-SI unit
Presentation of a list of examples of SI derived units and adoption of special names for 14 of them
Lists some examples of derived units
Adoption of the special name becquerel (Bq)
Adoption of the special name gray (Gy)
Adoption of the special name sievert (Sv)
Clarification of the relationship between absorbed dose (SI unit gray) and dose equivalent (SI unit sievert)
Adoption of the special name katal, kat
Modification of the relationship between absorbed dose and dose equivalent
Supplementary units
Adoption of the term supplementary unit to describe the radian and steradian
Decision to interpret supplementary units as dimensionless derived unit
Decision to abrogate the class of supplementary units; confirmation of the CIPM interpretation that they are dimensionless derived units
Decisions concerning terminology and the acceptance of units for use with the SI
SI prefixes
Adoption of the SI prefixes from tera to pico
Decision to add femto and atto to the list of prefixes
Decision to add peta and exa to the list of prefixes
Decision to add zetta, zepto, yotta and yocto to the list of prefixes
Decision to add ronna, ronto, quetta and quecto to the list of prefixes
Unit symbols and numbers
Adoption of rules for printing unit symbols and numbers
Unit names
Abrogation of the use of the micron and new candle as units accepted for use with the SI
The decimal marker
Decision to allow the use of the point or the comma as the decimal marker
Units accepted for use with the SI: an example, the litre
Definition of the litre as the volume of 1 kg of water
Request to the CIPM to report on the difference between the litre and the cubic decimetre
Recommendation that volume be expressed in SI units and not in litres
Abrogation of the former definition of the litre; recommendation that litre may be used as a special name for the cubic decimetre
Decision, as an exception, to allow both l and L as symbols for the litre
