Recommendation B.31)
USE OF THE INTERNATIONAL SYSTEM OF UNITS (SI)
	The CCITT,
recommends
	that the various ITU organs, as well as Administrations and recognized private operating agencies should use in their mutual relations:
–	the units of the international system of units (SI) adopted by the General Conference of Weights and Measures (CGPM) and supported by the International Organization for Standardization (ISO); this system is based on the rationalized form of electromagnetic and electrotechnical relations;
–	the letter symbols adopted in the SI system;
–	rules similar to those of the SI system when it is necessary to form names of other units and their symbols in the field of telecommunications.
	Note – References of relevant publications (updated in 1988).
	BIPM publications: “BIPM Publication: Le système international d'unités” (SI).2)
	International Standard ISO 31: “General principles concerning quantities, units and symbols”
	Parts of International Standard ISO 31 of greatest interest for the telecommunications:
	0		(General principles)
	I		(Quantities and units of space and time)
	II		(Quantities and units of periodic and related phenomena)
	V		(Quantities and units of electricity and magnetism)
	VI		(Quantities and units of light and related electromagnetic radiations)
	VII		(Quantities and units acoustics)
	XI		(Mathematical signs and symbols)
	International Standard ISO 1000: “SI units and recommendations for the use of their multiples and of certain other units”
	IEC Publication 27: see Recommendation B.1
	See also ISO Standards Handbook 2 (1982) “Units of measurement”.