Overview
ISO/IEC 16388:2023 is the international standard that specifies the Code 39 bar code symbology for automatic identification and data capture (AIDC). It defines the symbology characteristics, character encodation, symbol structure, dimensional rules, tolerances, a reference decoding algorithm, symbol quality criteria and the symbology identifier prefix strings used to tag Code 39 symbols. This third edition updates and consolidates technical requirements to ensure interoperable production, reading and testing of Code 39 bar codes.
Key topics and technical requirements
- Encodable character set: Full uppercase alphanumeric A–Z and 0–9 plus space and special characters
$ % + - . / and a dedicated start/stop character (usually represented as *).
- Symbol structure: Leading quiet zone, start character, data characters (optional check character), stop character, trailing quiet zone, with an intercharacter gap between characters.
- Element format: Each character uses 9 elements (5 bars, 4 spaces) with 3 wide and 6 narrow elements (parity enables self-checking).
- Dimensions and tolerances:
- Narrow element width X is application-defined.
- Wide/narrow ratio: 2.0:1 to 3.0:1.
- Intercharacter gap (I): minimum = X; maximum rules depend on X (specified in the standard).
- Quiet zone: minimum = 10X.
- Recommended minimum bar code height for manual scanning: 5.0 mm or 15% of symbol width, whichever is greater.
- Decoding algorithm (reference): Verify quiet zones; for each character measure total element width S, compute threshold T = S/8, classify elements as wide/narrow against T, match patterns to allowed characters, start reading at start/stop character and continue until a valid stop is found.
- Symbol quality and testing: Test procedures and parameters are defined (referencing print quality testing and application-defined parameters in clauses 4.6–4.7).
- Symbology identifier: Prefix strings for Code 39 are specified (Annex C) for use in data carriers and interchange.
Practical applications
Code 39 is widely used for:
- Inventory and asset tracking
- Logistics and warehouse labeling
- Manufacturing and part identification
- Healthcare and laboratory sample tagging
- Legacy systems requiring human-readable alphanumeric labels
Use ISO/IEC 16388:2023 when designing, printing, decoding or certifying Code 39 bar codes to ensure interoperability, correct decodability and compliance with international AIDC practices.
Who should use this standard
- Barcode hardware manufacturers (printers, scanners)
- AIDC software developers and integrators
- QA and test laboratories assessing barcode quality
- Procurement and standards teams specifying barcode requirements for applications
Related standards
Keywords: ISO/IEC 16388:2023, Code 39 bar code, Code 39 symbology specification, barcode standards, AIDC, decoding algorithm, symbol quality, wide/narrow ratio, intercharacter gap.
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