ISO/IEC 15459-4:2014 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 automatic identification and data capture (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 ISO 17367 and ISO 17366, respectively, are defined and supported by examples.