---
metadata:
  title: CIPM, 1980
  date: '1980-01-01'
  source: BIPM - Pavillon de Breteuil
resolutions:
- dates:
  - '1980-01-01'
  title: SI supplementary units (radian and steradian)
  identifier: 1
  url: https://www.bipm.org/en/CIPM/db/1980/1/
  approvals:
  - type: affirmative
    degree: unanimous
    message: |-
      +

      The Comité International des Poids et Mesures (CIPM),
  considerations:
  - type: taking into account
    date_effective: '1980-01-01'
    message: taking into consideration Resolution 3 adopted by ISO/stem:["TC" 12]
      in 1978 and Recommendation U 1 (1980) adopted by the Comité Consultatif des
      Unités at its 7th meeting,
  - type: considering
    date_effective: '1980-01-01'
    message: considering that the units radian and steradian are usually introduced
      into expressions for units when there is need for clarification, especially
      in photometry where the steradian plays an important role in distinguishing
      between units corresponding to different quantities,
  - type: considering
    date_effective: '1980-01-01'
    message: considering that in the equations used one generally expresses plane
      angle as the ratio of two lengths and solid angle as the ratio between an area
      and the square of a length, and consequently that these quantities are treated
      as dimensionless quantities,
  - type: considering
    date_effective: '1980-01-01'
    message: considering that the study of the formalisms in use in the scientific
      field shows that none exists which is at the same time coherent and convenient
      and in which the quantities plane angle and solid angle might be considered
      as base quantities,
  - type: considering
    date_effective: '1980-01-01'
    message: |-
      considering also

       that the interpretation given by the CIPM in 1969 for the class of supplementary units introduced in cgpm-resolution:en/11/12[Resolution 12] of the 11th Conférence Générale des Poids et mesures (CGPM) in 1960 allows the freedom of treating the radian and the steradian as SI base units,
       that such a possibility compromises the internal coherence of the SI based on only seven base units,
  actions:
  - type: decides
    date_effective: '1980-01-01'
    message: decides to interpret the class of supplementary units in the International
      System as a class of dimensionless derived units for which the CGPM allows the
      freedom of using or not using tem in expressions for SI derived units.