BARCODE
Barcode symbologies can be divided into three groups: linear, 2D and stacked.
Linear (one-dimensional) barcode
Bar codes in their most familiar format have been with us for over decades. These linear, or 1D (one dimensional as opposed to two dimensional) symbologies continue to be the most widely used optical recognition technology. Well over 200 encodation schemes or symbologies have been invented over the years, but the most common 1D symbologies are EAN, Code 39, Interleaved 2-of-5 (ITF), and Code 128.
Standardization within and across industries has been, and continues to be, essential to the impressive growth and widespread implementation of barcode technology. Barcode standards apply to printing, scanning, and verification of bar code symbologies.
Two dimensional (2D) barcode
The need to encode more information in a smaller space has driven the development, standardization, and growing use of 2D barcodes.
There are two types of 2D barcodes in current use: stacked codes and matrix codes.
Stacked Symbologies
Stacked symbologies evolved as 1D codes — Code 39 and Code 128 — stacked in horizontal layers to create the multirow symbologies, Code 49 and Code 16K, respectively. PDF417 followed in 1990 with added features that increased data capacity, improved data density, and strengthened reading reliability by a scanner.
Uniform Symbol Specifications for Code 49, Code16K, and PDF417 are available from AIM. SuperCode, a stacked code that can break data into small packets and create various shaped symbols, is also available.
Matrix symbologies
Matrix symbologies offer higher data densities than stacked codes in most cases, as well as orientation-independent scanning. A matrix code is made up of a pattern of cells that can be square, hexagonal, or circular in shape. Data is encoded via the relative positions of these light and dark areas, and encoding schemes use error detection and correction techniques to improve reading reliability and enable reading of partially damaged symbols. Matrix codes are scaleable and well-suited both as small ID marks on products and as conveyor-scannable symbols on shipped packages.
Composite barcode
This is a newly-emerging class of symbology in which two symbols are printed in close proximity (fixed relative positions) to each other and contain linked data. Typically, one component is a linear symbol and the other either a multi-row or a matrix symbol.
These are intended for applications where different parts of the information may be required at different points of the item's life, and in cases where there are restrictions on the amount of space available in which, for example, a second linear bar code could be placed.
The major application will be that of the UCC.EAN composite symbol, which was originated to meet the needs of industries like pharmaceuticals where both product identification and supplementary information such as batch number and expiration date need to be encoded in a small space on a package. These symbols comprise one of the standard UCC.EAN family of linear codes such as EAN-13 or UPC-A, or a UCC.EAN 128 symbol, or the new RSS family of 'reduced space' symbologies together with an associated two-dimensional multi-row symbol.
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