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GS1 Application Identifier (AI)

A GS1 Application Identifier is a prefix of two to four digits that tells a scanner what the data following it means. The AI 01 marks a GTIN, 10 a batch number, 17 an expiration date. Only with an AI can a single barcode carry several fields at once, which is what GS1-128, GS1 DataMatrix, and GS1 DataBar are built for.

The table below lists every AI defined by GS1, with its official short title and its data format. Identifiers, titles, and format codes are part of the GS1 standard and are therefore given in their original notation, not translated.

How to read the data format: N stands for digits, X for the alphanumeric character set of the standard. A plain number is a fixed length, so N14 means exactly fourteen digits. Two dots mean a variable length up to that maximum, so X..20 is up to twenty characters. A plus joins the parts of a composite field, and square brackets mark an optional part. An identifier written as a range, such as 3100-3105, uses its last digit to indicate the number of decimal places.

Two identifiers carry no short title in the source, which is why their name column is empty.

Source: GS1 Barcode Syntax Dictionary, retrieved 2026-09-20. In case of doubt, the GS1 General Specifications, published by GS1 at gs1.org, are binding.