IEC 60027 (formerly IEC 27) is a technical international standard for letter symbols published by the International Electrotechnical Commission (IEC), comprising the following 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.