IEC 60027-7:2010适用于电能的产生、传输和分配。它给出了数量和单位的名称和字母符号。此外，还给出了多个下标及其继承的规则。它是对IEC 60027-1的补充。因此，IEC 60027-1中已经给出的字母符号只有在其在发电、输电和配电领域具有特殊意义，或者在该领域使用特殊下标时，才会重复。

IEC 60027-7:2010 is applicable to generation, transmission, and distribution of electric energy. It gives names and letter symbols for quantities and units. In addition, rules for multiple subscripts and their succession are given. It is an addition to IEC 60027-1. Therefore letter symbols already given in IEC 60027-1 are repeated only if they have a special meaning in the field of power generation, transmission, and distribution or if they are used in this field with special subscripts.