This British Standard specifies the symbols to be used on railway signalling circuit diagrams but does not provide guidance on their application. It also gives a standard system of nomenclature and labelling of wires such that each wire can be readily identified with that shown on the circuit diagram. This British Standard does not cover symbols for high voltage power distribution, telecommunications or electronic products. These are covered in IEC60617 or an appropriate British Standard. This British Standard does not include proprietary systems and specialized applications. NOTE1 The symbols in this British Standard provide for apparatus in general use. Wiring symbols have been designed so that they can be combined together where one does not represent the complete device. In this British Standard, where certain elements are added for illustrative purposes, they are shown by dashed lines. If additional information is required to support the symbol, a “#?? may be used to reference a note on the diagram. NOTE2 The size of symbols as drawn are in proportion but are not necessarily relative to one another; nor do they give the specific size to be used. The relative thickness of lines may also be varied, e.g. for contact elements.