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Understanding Barcode Symbologies

A barcode symbology is the encoding scheme used to express numerical and character data with a pattern of bars and spaces in a barcode. The bars and spaces are the most basic elements of a barcode, and their arrangement defines the type of symbology that is used.

Symbologies can be divided into four categories:

ClosedLinear Symbologies

A linear symbology is a single row of bars and spaces. The elements can vary either by width (such as UPC-8, illustrated below) or by height (such as Royal Mail 4-State, illustrated below):


UPC-8

 



Royal Mail 4-State

Closed2-D Stacked Symbologies

A 2-D stacked symbology contains multiple rows of bars and spaces. In some 2-D stacked symbologies, separator areas exist between multiple data rows (such as GS1 Databar Expanded Stacked, illustrated below). Other 2-D stacked symbologies contain no separator areas (such as PDF417, illustrated below).


GS1 DataBar Expanded Stacked

 



PDF417

Closed2-D Matrix Symbologies

A 2-D matrix symbology has a two-dimensional pattern of elements that doesn't necessarily have a row-by-row structure. Typically, the elements are squares or dots rather than bars. In Aztec Code, the data is written in a spiral outward.


Aztec Code

ClosedComposite Symbologies

A composite symbology defines barcodes with two different components: a 2-D stacked symbology followed by either a linear or 2-D stacked component. A separator row always exists between the two components.


GS1 DataBar Expanded Stacked linear
with CC-A 2-D







GS1 DataBar Limited linear
with CC-B 2-D

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