This recommendation applies to circuit diagrams used in electrotechnology and the general recommendations given in IEC Publication 113-3, Part 3, are also applicable. Does not deal with rules for markings of apparatus terminals. The markings shown in certain figures are only examples. Includes in detail: purpose of a circuit diagram, contents of a circuit diagram, general guiding principles (layout, functional grouping), arrangement of symbols on diagrams (methods for indicating symbol location, methods of circuit representation, separation of symbols in detached representation, methods of referencing parts in the case of detached representation, representation of unused elements, representation of contacts), representation of circuits (supply, main circuits, delaited recommendations, simplifications, recommended layout for some fundamental circuits), markings and desgnations. Last clause shows examples of complete circuit diagrams.