Decisions relating to the base units of the SI

SI Brochure, from Appendix 1

Electrical units:

	CIPM, 1946	definition of mechanical and electrical units in the SI
	10th CGPM, 1954	ampere adopted as a base unit
	14th CGPM, 1971	adopts the name siemens, synmbol S, for electrical conductance
	18th CGPM, 1987	forthcoming adjustment to the representation of the volt and of the ohm
	CIPM, 1988	Josephson effect
	CIPM, 1988	quantum Hall effect
	CIPM, 2000	realization of the ohm using the value of the von Klitzing constant
	23rd CGPM, 2007	possible redefinition of certain base units of the International System of Units (SI)
	24th CGPM, 2011	possible future revision of the International System of Units, the SI
	25th CGPM, 2014	future revision of the International System of Units, the SI
	26th CGPM, 2018	revision of the International System of Units, the SI

We are pleased to present the 9th edition of the SI Brochure (2019), which defines and presents the Système International d'Unités, the SI (known in English as the International System of Units).