This part of ISO 23584 provides the basis for the preparation of a reference dictionary of standardized product properties for the area of optics and photonics, and for the provision of this reference dictionary and its entire contents in electronic form. This part of ISO 23584, on the basis of the rules set forth in ISO 13584-42, IEC 61360-1 and in the ISO/IEC Guide 77-2 for specification of product properties and families, specifies a reference dictionary of standardized product properties for the area of optics and photonics. The properties are determined on the basis of standardized attributes. To ensure optimum unambiguity the standardized properties are classified into definition classes forming a so-called standardized “reference hierarchy”.