IEC 60027 is a technical international standard for letter symbols published by the International Electrotechnical Commission (IEC), comprising the following parts:IEC 60027-1: General IEC 60027-2: Telecommunications and electronics IEC 60027-3: Logarithmic and related quantities, and their units IEC 60027-4: Symbols for quantities to be used for rotating electrical machines IEC 60027-6: Control technology IEC 60027-7: Physiological quantities and units