Code 128

Code 128
User Mike1024 · Public domain · source
Name	Code 128
Type	Linear barcode
Introduced	1981
Inventor	Computer Identics?
Capacity	High density
Charset	128 ASCII
Symbology	1D

Code 128 is a high-density one-dimensional barcode symbology widely used for alphanumeric or numeric-only data. It was introduced in 1981 to encode the full 128-character ASCII set and quickly gained adoption across supply chains, logistics, retail, and manufacturing. Implementations of Code 128 interoperate with an ecosystem of standards, scanners, label printers, and data systems developed by organizations and companies worldwide.

History

Code 128 emerged during a period of rapid development in automatic identification and data capture technologies alongside standards and organizations such as EAN-13, Universal Product Code, International Organization for Standardization, GS1, and companies like IBM, Intermec, Honeywell International, and Zebra Technologies. The symbology’s creation paralleled innovations in devices from manufacturers such as Symbol Technologies and Datalogic. Adoption was driven by logistics networks including United Parcel Service, DHL, FedEx, and retail chains like Walmart and Target Corporation seeking compact, high-density linear codes. Regulatory and industry frameworks from bodies such as U.S. Department of Transportation, European Commission, and International Air Transport Association influenced labeling practices that integrated Code 128 into tracking, pallet labeling, and document management systems used by entities like Amazon (company), Maersk, and Toyota.

Symbology and encoding

The symbology uses bars and spaces grouped in patterns of six elements forming 11 modules per symbol, with start, data, check, and stop symbols. It was designed to represent the full ASCII set and includes special function codes to switch between encodings. Hardware and software implementations rely on principles similar to optical recognition systems developed by laboratories and firms such as MIT Lincoln Laboratory, Bell Labs, Hewlett-Packard, and Canon Inc.. Barcode generation and verification are integrated into enterprise software platforms from vendors such as SAP SE, Oracle Corporation, Microsoft, and IBM for inventory and transaction processing.

Character sets (Code Set A, B, C)

Code 128 provides three code sets to optimize density for different data types. Code Set A encodes uppercase letters, control codes, and punctuation, aligning with character ranges used in systems from Digital Equipment Corporation and DEC, while Code Set B encodes upper- and lowercase letters and punctuation, fitting common text streams handled by applications from Adobe Inc. and Mozilla Foundation. Code Set C encodes numeric data in double-density pairs, favored in financial and shipping contexts used by institutions like JPMorgan Chase, Citigroup, and Bank of America for check and remittance processing. Switching among code sets is accomplished via designated shift codes analogous to mode switches in protocols standardized by groups such as IETF and hardware conventions from Intel Corporation and Motorola Solutions.

Start, stop, and control codes

Start codes select the initial code set and are followed by data symbols; a stop pattern signals the end of the symbol. Control functions include shifts, code set changes, and special function codes used for application identifiers defined by GS1 in implementations for product identification in collaborations with UN/CEFACT and logistics providers like FedEx. Printer firmware from companies like SATO Holdings and Brother Industries implements these codes alongside scanner firmware from Cognex Corporation and Honeywell to ensure reliable decoding in point-of-sale systems deployed by McDonald’s, Starbucks, and Subway.

Checksum calculation

The checksum is a weighted modular sum calculated over the start code and data symbols; the result ensures data integrity and is included before the stop symbol. This verification method echoes error-detection techniques used in standards from ISO/IEC committees and cryptographic checksum concepts referenced in work by researchers from RAND Corporation and NIST for data validation. Implementations in embedded systems by ARM Holdings and microcontroller toolchains from Microchip Technology often include optimized routines for this calculation to meet performance requirements in automated sorting systems at facilities operated by UPS and Royal Mail.

Variants and subsets (GS1-128, EAN-128)

GS1-128 and the label EAN-128 represent application-layer conventions that use Code 128 to encode GS1 Application Identifiers for supply chain semantics. GS1-128 was developed by GS1 in collaboration with trading partners such as Walmart, Tesco, Carrefour, and Metro AG to carry information like serial shipping container codes used by ISO-registered logistics frameworks. EAN-128 historically referenced similar overlays adopted in Europe alongside standards from European Article Numbering Association and retailers including Marks & Spencer and Schwarz Gruppe.

Applications and usage

Code 128 is widely used for shipping labels, order tracking, asset tagging, healthcare specimen labeling, and manufacturing work-in-progress tracking. It is deployed in logistics operations by FedEx, UPS, DHL, and maritime operators like Maersk Line; in retail by Walmart, Amazon, and IKEA; and in healthcare systems at institutions such as Mayo Clinic, Johns Hopkins Hospital, and Cleveland Clinic. Integration spans enterprise resource planning from SAP, point-of-sale hardware from NCR Corporation, warehouse management systems used by XPO Logistics, and mobile data terminals produced by Apple Inc. and Samsung Electronics.

Category:Barcodes