Application identifier
The two, three or four digit number that specifies the data that immediately follows it in a GS1-128 barcode.

Bearer bars
Horizontal bars printed above any of the barcodes. These can be used  when a barcode is printed on-demand to highlight damaged printhead elements. Also used above and below ITF-14 barcodes to prevent short scans.

Bearer box
The bars that surround an ITF-14 symbol to equalise the pressure exerted by the flexographic printing process.

Check digit
The last digit of an identifier that is calculated from all the preceding digits to check that the data has been correctly composed.

Consumer unit
An item that may be sold at a retail point of sale. Also referred to as a trade item.

The eight digit barcode that represents a GTIN-8.

The thirteen digit barcode that represents a GTIN-13.

The name of the symbology used by EAN-8, EAN-13, UPC-A and UPC-E barcodes.

GTIN Global trade item number
The unique number for a product line. This number identifies items or services that are priced, ordered or invoiced at any point in the supply chain.

The name given to the eight digit GTIN that may be shown in an EAN-8 barcode.

The name given to the twelve digit global trade item number formed from a UPC company prefix number. This may be shown in UPC-E, UPC-A, ITF-14 and GS1-128 barcodes.

The name given to the thirteen digit GTIN that may be shown in EAN-13, ITF-14 or GS1-128 barcodes.

The name given to the fourteen digit GTIN that may be shown in either ITF-14 or GS1-128 barcodes on traded units.

The global body for GS1 member organisations which administers the GS1 system.

Item number – See GTIN

A 14-digit interleaved two of five barcode. The barcode may be used to show GTIN-12, GTIN-13 and GTIN-14 numbers on trade items not crossing a retail point of sale.

Ladder format
Printing barcodes perpendicular to the printhead i.e they will appear as rungs of a ladder when printed. The opposite to picket fence orientation.

Light Margins – See Quiet zones

Logistics unit
A unit, for example a pallet load, which is constructed for moving goods from one place to another.

The factor used to vary the nominal size of each barcode to ensure it is scannable. See X-dimension

The smallest element (i.e. thinnest bar or space) of a barcode. See X-dimension

Outer case
A kind of traded unit.

Pallet label
The GS1 logistics label that is used to track and identify pallets loads or any other transport units.

Picket fence orientation
Printing a barcode so that the bars parallel to the printhead. The opposite of ladder format.

Quiet zone
The clear space required to the left and right of any barcode formerly known as light margins.

Quiet zone indicators
Marks to indicate the Quiet zones required.

Serial shipping container code. The unique eighteen digit identifier for a transport unit.

Specular reflectance
The reflectance of light from highly polished surfaces.

The material on to which a barcode is printed.

A type of barcode symbol.

Trade item
Any item that is identified for pricing, ordering and invoicing purposes. This includes both consumer units and traded units.

Traded unit
An item that is priced, ordered and invoiced between manufacturers, retailers and wholesalers. Also known as an outer case.

The reduction in height of a barcode.

Universal Product Code, version A. The name for the 12 digit barcode that represents a GTIN-12.

Universal Product Code, version E. The name for the eight digit barcode that represents a GTIN-12 with zero suppression.

The nominal width of the narrowest bars or spaces of a barcode.