PDF417 is a stacked linear barcode symbol format used in a variety of applications such as transportation, identification cards, and inventory management. PDF stands for Portable Data File. The PDF417 symbology was invented by Dr. Ynjiun P. Wang at Symbol Technologies in 1991. (Wang 1993) It is represented by ISO standard 15438. Additionally, PDF417 Codes are playing a prominent role in Apple’s new electronic wallet iOS app, Passbook.

Aztec Code is a very efficient two-dimensional (2D) symbology that use square modules with a unique finder pattern in the middle of the symbol. Characters, numbers, text and bytes of data may be encoded in an Aztec barcode. Aztec code has the potential to use less space than other matrix barcodes because it does not require a surrounding blank “quiet zone”.

The symbol is built on a square grid with a bulls-eye pattern at its center for locating the code. Data is encoded in concentric square rings around the bulls-eye pattern. Aztec barcodes are some of the smallest and most dependable symbologies in use today. Additionally, Aztec Codes are playing a prominent role in Apple’s new electronic wallet iOS app, Passbook.

Data Matrix is a 2D (matrix) barcode format available as open standard. Data Matrix was designed in 1989, and standardized by many organizations including NASA, US DoD and major industries such as electronics, pharmaceutical and postal marking. The information to be encoded can be text or raw data. Typical data size is from a few bytes up to 2 kilobytes. The length of the encoded data depends on the symbol dimension that is used. Error correction codes are added to increase symbol strength: even if they are partially damaged, they can still be read. A Datamatrix symbol can store up to 2,335 alphanumeric characters.

QR Code is a 2D (matrix) barcode format initially developed, patented and owned by Toyota subsidiary Denso Wave for car parts management; it is now in the public domain. The “QR” is derived from “Quick Response”, as the creator intended the barcode to allow its contents to be decoded rapidly. The QR Code can store up to 2,335 ASCII characters in one barcode symbol, and includes Error Correction Code (ECC) which allows error-free reading even when a symbol has been partially lost or destroyed. Additionally, QR Codes are playing a prominent role in Apple’s new electronic wallet iOS app, Passbook.

GS1 DataBar™ symbols can carry more information and identify small items than the current EAN/UPC bar code. GS1 DataBar enables GTIN identification for fresh variable measure and hard-to-mark products like loose produce, jewelry and cosmetics. Additionally, GS1 DataBar can carry GS1 Application Identifiers such as serial numbers, lot numbers, and expiration dates, creating solutions to support product authentication and traceability for fresh food products and couponing.

Code 39 (also called “3 of 9 Code”) was developed by Dr. David Allais and Ray Stevens in 1974. Code 39 is a discrete, variable length symbology and was the first alphanumeric bar code to be developed. It is designed to encode twenty-six uppercase letters (A-Z), numeric digits (0-9), and seven special characters: space, minus (-), plus (+), period(.), dollar sign ($), slash(/), and percent (%). It can be extended to encode the ASCII character set by using a two character coding scheme. Each character is composed of nine elements: five bars and four spaces. Three of the elements are wide (binary value 1) and six elements are narrow (binary value 0), the width ratio can be chosen between 1:2 and 1:3.

Code 39 is one of the only type of barcodes in common use that does not require a checksum. An inadequately interpreted bar cannot generate another valid character. The template must then add a fixed asterisk (*) before and after the data and print the field using a Code 39 barcode font. This “self-checking” makes it especially attractive for applications where it is inconvenient to perform calculations each time a barcode is printed. 

Code 128 is a very high density barcode symbology only used for alphanumeric bar codes. The symbol can be as long as necessary to store the encoded data and is designed to encode all 128 ASCII characters; it will use the least amount of space for data of 6 characters or more of any one-dimensional symbology.

Code 128 is made up of six sections: the quiet zone, start character, encoded character, check character, stop character, and another quiet zone. Each data character is made up of eleven black or white modules with the exception of the stop character, which has 13 modules. Three bars and three spaces are formed out of these eleven modules; bars and spaces can vary between one and four modules wide.

Code 128 includes a checksum digit for verification. The bar code may also be verified character-by-character affirming the parity of each data byte. Its specific structure also allows numeric data to be encoded at double-density.

UPC was the first bar code symbology widely adopted. The UPC symbology was designed to make it ideal for coding products. UPC can be printed on packages using a variety of printing processes. The format allows the symbol to be scanned with any package orientation. Omnidirectional scanning allows any package orientation provided the symbol faces the scanner. The UPC format can be scanned by hand-held wands and can be printed by equipment in the store.

The EAN barcode is primarily used in supermarkets to identify products at the point of sale. In 1977 the EAN code was used by 12 countries (all the countries of the European Community). Today, use of the EAN code has spread to all west European countries, USA, Canada, Australia and Japan.