GS1 Composite symbols consist of a linear component associated with an adjacent 2D component which is used for encoding supplmentary data – such as a batch number or expiration date. The linear component should be scannable by normal 1D scanners even though such scanner may ignore the 2D component.
The linear component may be one of the following: EAN-13, UPC-A, EAN-8, GS1-128 or a Databar symbol.
The 2D component may be a CC-A or CC-B component (a variant of Micro PDF417) or, in the case of GS1-128 linear components, may be a CC-C component (a variant of PDF417). The choice between CC-A and CC-B components is made on the basis of the amount of data to be encoded in the 2D component. CC-A can accommodate up to 56 digits (excluing any control characters), while CC-B can hold up to 338 digits. A CC-C component may be used only with a GS1-128 linear component, but can hold up to 2360 digits.
The 2D component includes a linkage flag to distinguish the component from a stand-alone 2D barcode and to ensure that the 2D component does not scan without the linear component.
The following examples illustrate the range of combinations available.
EAN-13
with CC-A and 5 digit supplementary

EAN-8 with CC-A

GS1-128 with CC-A/B composite

GS1-128 with CC-C composite
Databar
Omnidirectional with CC-A/B

Databar Stacked with CC-A/B

Databar Expanded-Stacked with CC-A/B
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