This part of ISO/IEC 15459 specifies a unique string of characters for the identification of individual products and product packages. The character string is intended to be represented in a linear bar code symbol or two-dimensional symbol or other AIDC media attached to the entity to meet management needs. To address management needs different classes of identities are recognized in the various parts of ISO/IEC 15459, which allows different requirements to be met by the identities associated with each class. The rules for the identification of an individual occurrence of a product or product package, understood to mean the layers zero and one defined in the International Standards ISO 17367 and ISO 17366, respectively, are defined and supported by examples.