IEC 81714-3:2004 Specifies requirements concerning the classification of connect nodes assigned to graphical symbols, being a representation of functional and product concepts. Due to the strong interrelation between the product and its corresponding graphical representation, identical classification principles are applied for both the classification of connect nodes of products as well as for the classification of networks and their representation by graphical symbols in computer-aided systems. It has the status of a horizontal standard in accordance with IEC Guide 108.