This part of ISO 13584 specifies a reference dictionary for all the parts described in the various ISO mechanical fastener standards, together with their descriptive properties and domains of values. This part of ISO 13584 specifies a reference dictionary that contains: — definitions and identifications of the classes of fasteners as they are described in the various ISO mechanical fastener standards, with associated classification schemes; — definitions and identifications of data element types that represents properties of fasteners, and — definitions and identifications of domains of values that help to describe the above data element types. Each class, property or domain of values of this application domain constitutes an entry of the reference dictionary defined in this part of ISO 13584. It is associated with a computer sensible and human-readable definition, and with a computer sensible identification. Identification of a dictionary entry allows for unambiguous reference from any application. Definitions and identifications of dictionary entries are defined by means of standard data that consist of instances of the EXPRESS entity data types defined in the common dictionary schema, and in its extensions defined in ISO 13584-24 and ISO 13584-25. The following are within the scope of this part of ISO 13584: — standard data that represents the classes of fasteners; — standard data that represents the properties of fasteners; — standard data that represents domains of values used for properties of fasteners. The following are outside the scope of this part of ISO 13584: — methodology for structuring parts families used for specifying standard data defined in this part of ISO 13584; — implementation method by which the standard data defined in this part of ISO 13584 may be exchanged.