Historical
IEC 81714-3 Ed. 1.0 b:1998
Design of graphical symbols for use in the technical documentation of products - Part 3: Classification of connect nodes, networks and their encodin
Specifies primarily requirements concerning the classification of connect nodes assigned to graphical symbols, being a representation of functional and product concepts. Basic rules are given in ISO/IEC 11714-1
International Electrotechnical Commission [iec]