IEC 61360-1:2009 provides a firm basis for the clear and unambiguous definition of characteristic properties (data element types) of all elements of electrotechnical systems from basic components to sub-assemblies and full systems. The principles and methods of this standard may be used in areas outside the original conception such as assemblies of components and electrotechnical systems and subsystems. In addition, this standard provides for establishing a classification hierarchy and the allocation of applicable and relevant properties to each of the classes so established in order to describe fully the characteristics of objects belonging to that class. This edition includes the following significant technical changes with respect to the previous edition: - extended administrative data for status and source of content; - support of multiple language variants for data element types and classes; - support for multiple alternative units for data element types; - improved conventions for definition writing based on ISO 704 and ISO/IEC 11179-4; - enhanced definitions and descriptions.