This part of ISO 13399 specifies a reference dictionary for adaptive items, together with their descriptive properties and domains of values.This part of ISO 13399 specifies a reference dictionary containing:— definitions and identifications of the classes of adaptive items, with an associated classification scheme;— definitions and identifications of the data element types that represents the properties of adaptive items;— definitions and identifications of domains of values for describing the above-mentioned 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 13399. It is associated with a computer-sensible and human-readable definition and with a computer-sensible identification. Identification of a dictionary entry allows unambiguous reference to it from any application that implements the information model defined in ISO 13399-1.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, resulting from a joint effort between ISO/TC 184/SC 4 and IEC SC 3D, and in its extensions defined in ISO 13584-24 and ISO 13584-25.The following are within the scope of this part of ISO 13399:— standard data that represent the various classes of adaptive items;— standard data that represent the various properties of adaptive items;— standard data that represent domains of values used for properties of adaptive items;— one implementation method by which the standard data defined in this part of ISO 13399 can be exchanged.