This part of IEC 61360 series provides a formal model for data according to the scope as given in IEC 61360-1 and ISO 13584-42, and thus provides a means for the computersensible representation and exchange of such data. The intention is to provide a common information model for the work of IEC SC3D and ISO TC184/SC4, thus allowing for the implementation of dictionary systems dealing with data delivered according to either of the standards elaborated by both committees. The scope of this part of IEC 61360 is the common ISO/IEC dictionary schema based on the intersection of the scopes of the two base standards IEC 61360-1 and ISO 13584-42. The presented EXPRESS model represents a common formal model for the two standards and facilitates a harmonization of both. The IEC 61360-2 forms the master document. ISO 13584-42 contains a copy of the IEC 61360-2 EXPRESS model in an informative annex In a number of clauses, where the common EXPRESS model allows more freedom, IEC has defined more restrictions which are found in the methodology part of IEC 61360-1. Two schemas are provided in this part of IEC 61360 defining the two options that may be selected for an implementation. Each of these options is referred to as a conformance class. – The ISO13584_IEC61360_dictionary_schema2 provides for modelling and exchanging technical data element types with associated classification scheme used in the data element type definitions. It constitutes conformance class 1 of this part of IEC 61360. – The ISO13584_IEC61360_language_resource_schema provides resources for permitting strings in various languages. It has been extracted from the dictionary schema, since it could be used in other schemata. It is largely based on the support_resource_schema from ISO 10303-41:2000, and can be seen as an extension to that. It allows for the usage of one specific language throughout an exchange context (physical file) without the overhead introduced when multiple languages are used. When used together with ISO 10303-21, each schema defines one single exchange format. The exchange format defined by conformance class 1 is fully compatible with the ISO 13584 series.