IEC 60027 (formerlyIEC 27) is atechnicalinternational standard forletter symbols published by theInternational Electrotechnical Commission (IEC), comprising the following parts:
A closely related international standard onquantities andunits isISO 31. The ISO 31 and IEC 60027 Standards are being revised by the two standardization organizations in collaboration. The revised harmonized standard is known asISO/IEC 80000, Quantities and units. It supersedes both ISO 31 and part of IEC 60027.
IEC 60027-2 Amendment 2, as published in January 1999, was the first international standard defining thebinary prefixes, as proposed byInternational Electrotechnical Commission (IEC) since 1996 (kibi- (Ki),mebi- (Mi),gibi- (Gi) andtebi- (Ti))[1] but extended them up topebi (Pi) andexbi- (Ei).[2][3] This didn't change in the second edition of the standard, published in 2000,[4][5] but the third edition in 2005 added prefixeszebi- (Zi) andyobi- (Yi).[6] The harmonizedISO/IECIEC 80000-13:2008 standard supersedes subclauses 3.8 and 3.9 of IEC 60027-2:2005. The only significant change is the addition of explicit definitions for some quantities.[7]
IEC 60027-3, as published in 2002, defines the logarithmic unitsdecibel andneper.