API for decoding the content of structured barcodes GS1-128/Datamatrix

GS1-128 (formerly known as UCC-128, EAN 128 or UCC/EAN-128), and GS1-Datamatrix are standards for encoding item identification and logistics data. Physically, GS1-128 is represented as a 1-dimension Code-128 barcode and GS1-Datamtrix is represented as a 2-dimensions Datamatrix barcode.

When those barcodes are read, their content can be decode into multiple values using a set of standard "Application Identifiers". For example, most pharmacy items have a GS1-Datamatrix barcode containg their GTIN, lot number and expiry date.

This module does not directly allow you to print or scan barcodes. Instead, the focus of this module is on decoding the data contained in barcodes. To this end, it provides objects to fine-tune the Application Identifiers and the associated data types.

Caveat Emptor: when an "Application Identifiers" has variable-length data, the barcodes must contain a special character (<GS>, group separator) but as this is not an ASCII character. Some barcdode readers will not include this character: decoding the structured data will then be impossible. Other readers will translate GS1 to ASCII character 29, but this character is not printable, and some applications may not record it. Yet other readers will let you configure how to map <GS>, which may help improve compatibility.