The GS1 Composite Symbology is the specification for a 2D barcode symbol included above a DataBar, UPC, EAN, or Code 128 barcode to encode additional data. Composite symbols are not supported by all barcode scanners and implementation can be more difficult than other options. IDAutomation recommends using DataBar Expanded to encode Application Identifiers (AIs) with additional data when possible because DataBar is approved for use in all POS systems after January 1, 2010, all data is encoded in a single symbol and implementation is much easier.
The GS1 Composite Symbology consists of a linear component, which encodes the item’s primary data, and an adjacent 2D composite component, which encodes supplementary data to the linear component. DataBar Composite components are rarely used and IDAutomation no longer recommends using composite data in GS1 symbols. When more information needs to be encoded in GS1 data, IDAutomation recommends DataBar Expanded, GS1 Data Matrix, or GS1 QR Code instead of composite components.
The linear component will be GS1-128, EAN-8, EAN-13, UPC-A, UPC-E, or any barcode in the GS1 DataBar family. The supplementary, 2D composite component will be one of the following:
- Composite Code A barcode, which derives from the MicroPDF417 specification, for EAN-8, EAN-13, UPC-A, UPC-E, GS1 DataBar barcodes, or
- Composite Code C barcode, which derives from the PDF417 specification, for GS1-128 (UCC/EAN-128) barcodes.
MicroPDF417 barcodes are assigned a specific matrix of row/column combinations. This matrix limits the amount of data that may be encoded in 2D composites. The 2D composites can encode up to 56 numeric characters. Alpha characters and certain punctuation characters may also be encoded in the composite, but the maximum number of characters that can be encoded will be reduced significantly.
Composite Code C barcodes, used as composites for GS1-128 and based on PDF417 standards, can encode approximately 800 characters.