Composite symbologies are a class of bar code symbology, the principal distinguishing feature of which is that they comprise two or more components, each of which is a distinct symbol, but which contain a set of related data. Typically one component is a linear symbol containing primary data, which may be read on its own in some areas of the application, and the other component(s) is a two-dimensional symbol containing supplementary data which qualifies the primary message, and requiring all components to be read to extract the complete message. The EAN.UCC Composite symbology, which is one such symbology. The use of the symbology is intended to comply with the GS1 General Specifications.

An EAN.UCC Composite symbol consists of a linear component (encoding the item's primary identification) associated with an adjacent two-dimensional component (encoding supplementary data, such as a batch number or expiration date). The EAN.UCC Composite symbol always includes a linear component so that the primary identification is readable by all scanning technologies, and so that two-dimensional imagers can use the linear component as a finder pattern for the adjacent two-dimensional component. The EAN.UCC Composite symbol always includes a multi-row two-dimensional component, for compatibility with linear and two-dimensional imagers, and with linear and rastering laser scanners.

EAN.UCC Composite symbols are intended for encoding identification numbers and data supplementary to the identification in accordance with GS1 General Specifications. The administration of the numbering system by EAN and UCC ensures that identification codes assigned to particular items are unique world-wide and that they and the associated supplementary data are defined in a consistent way.

ISO/IEC 24723:2006 specifies the requirements for the EAN.UCC Composite symbology. It specifies the EAN.UCC Composite symbology characteristics; data character encodation, symbol formats, dimensions and print quality requirements, error correction rules, and reference decoding algorithms. For those linear and two-dimensional components of EAN.UCC Composite symbols with published symbology specifications, those published specifications apply, except as specifically noted in ISO/IEC 24723:2006.