IEC 60027 (formerly IEC 27) is the International Electrotechnical Commission's standard on Letter symbols to be used in electrical technology. It consists of several parts:
A closely related international standard on quantities and units is ISO 31. The ISO 31 and IEC 60027 Standards are being revised by the two standardization organizations in collaboration. The revised harmonized standard is known as ISO/IEC 80000, Quantities and units. It supersedes both ISO 31 and part of IEC 60027.
A 1999 addendum to IEC 60027-2 on binary prefixes has resulted in some public interest in the standard and is still being widely discussed in the computer community, as it firmly deprecates the use of kilobit to mean kibibit, and kilobyte to mean kibibyte, just as earlier IEC standards deprecated the use of cycles per second to mean hertz.
The harmonized ISO/IEC IEC 80000-13:2008 standard cancels and replaces subclauses 3.8 and 3.9 of IEC 60027-2:2005 (those defining prefixes for binary multiples). The only significant change is the addition of explicit definitions for some quantities.