Supplementary unit

The supplementary unit was an old classification used by the International System of Units. It was created in 1960 by the General Conference on Weights and Measures. It was used to describe units that were neither base units nor derived units. Only two units were ever called supplementary units: the radian and steradian.^[1]

In 1995, the supplementary unit classification was eliminated. The radian and steradian were re-classified as derived units.