This part of the series DIN EN 60027 is applicable to generation, transmission and distribution of electrical energy. It gives names and letter symbols for quantities and units in this sector. In addition, rules for multiple subscripts and their succession are given. DIN EN 60027-7 supplements DIN EN 60027-1. Therefore, letter symbols already given in DIN EN 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. The responsible Committee is GK 112 "Größen, Einheiten und Formelzeichen" ("Quantities and units, and their letter units") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.