Invalid parsing of trade measures: AIs (31nn, 32nn, 35nn, 36nn) in GS1-128

[zipus]

The GS1-128 parser currently accepts (310) as a valid Application Identifier (AI), which is non-conformant with the GS1 General Specifications. The correct AI is of the form (310n) where n is a digit from 0 to 9 indicating the number of decimal places in the net weight (in kilograms). For example, (3103) indicates 3 decimal places.

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Expected Behavior

According to the GS1 Application Identifiers definitions, the AI must be exactly 4 digits long, in the format:

(310n) → Net weight in kilograms with `n` decimal places

Examples:

• ✅ (3103) with value 000035 means 0.035 kg → valid
• ❌ (310) with value 3000035 → invalid (no such AI defined)

The parser should reject (310) and raise a ValidationError.

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Actual Behavior

Currently, the parser accepts this invalid format:

(01)98456789014533(310)3000035

...even though (310) is not defined in the GS1 standard as a valid AI. This could cause misinterpretation of data and undermine compliance with barcode validation in regulated supply chains.

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Relevant GS1 Specification

• GS1 General Specifications – Release 25.0 (2025)
• Section 3.6.2: Trade Measures – AIs (31nn, 32nn, 35nn, 36nn), page 166
  • Quote: “Application Identifiers of the form 31nn specify trade item weight in kilograms.”
  • There is no AI (310), only AI (310n) with a fourth digit for precision.

[arthurdejong]

Hi @zipus,

Thanks for pointing this out and providing the pull request I went for a different kind of solution than you provided. It turns out that the hack that was done in the update script to generate the dat file for these kind of application identifiers was actually wrong.

If we ensure that e.g. the 3100-3105 range is considered as range in the dat file the change is a bit less hacky and will be applied to other, similar numbers as well.

I fixed this in 210b9ce and included a bit of refactoring to take the number of decimal places from the AI instead of the value.

This does mean that the handling of these numbers change a bit. To construct a number with anything in the 3100-3105 range you have to supply an AI in that range (supplying 310 no longer works) but the last digit of the AI is now ignored.