Application Identifier (AI)
An Application Identifier is a GS1 numeric prefix — such as (01) for GTIN or (10) for batch number — that defines the meaning and format of the data field that follows it in a GS1 barcode.
What You Need to Know
GS1 element strings are self-describing: a GS1-128 or GS1 DataBar symbol can carry many fields in one barcode, each tagged with its AI. AI (01) declares the next 14 digits are a GTIN, AI (17) an expiry date, AI (10) a variable-length lot number, AI (21) a serial number. The scanner parses the identifiers — not position — to route each value correctly, which is why field order follows GS1 logic rather than free arrangement.
AIs dictate data type and length: some are fixed (dates are always YYMMDD, GTIN always 14), some variable and terminated by FNC1 or the symbol end. Trading partners mandate which AIs a label must carry — pharmaceutical serialization requires GTIN + serial + lot + expiry together, which is why GS1-128 and DataMatrix dominate regulated supply chains. When generating, always encode the AI itself in the barcode data.
Where Application Identifier (AI) Applies
Code 128 carrying GS1 Application Identifier element strings — the standard barcode of global logistics.
Generate GS1-128 →The variable-length DataBar carrying GTIN plus extra AI data — weights, dates, lot numbers — on fresh food.
Generate GS1 DataBar Expanded →A compact 2D matrix code with fixed Reed-Solomon error correction — the standard for pharma serialization and tiny parts.
Generate Data Matrix →The 14-digit Global Trade Item Number for cases and inner packs, carried by GS1-128 or ITF-14 symbols.
Generate GS1-14 (GTIN-14) →