IEC 81346-2:2019 establishes classification schemes with defined object classes and their associated letter codes, and is primarily intended for use in reference designations and for designation of generic types. The classification schemes are applicable for objects in all technical disciplines and all branches of industry. IEC 81346-2:2019 is a horizontal publication also intended for for use by technical committees in preparation of publications related to reference designations in accordance with the principles laid down in IEC Guide 108. IEC 81346-2:2019 cancels and replaces the first edition published in 2009. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) The entry classes of the classification scheme have been defined to reflect the �inherent function� of the object classified; b) The classes are defined to align with the principles of ISO 22274 and ISO 704; c) A three-level classification scheme has been defined, which provides a greater flexibility for the designer in some technical fields; d) Classes are defined by their definition and provided with a preferred term. Examples are provided if needed; e) A separate classification scheme for spaces has been provided.