GS1 AI (Application Identifier) & Element String Specification Reference

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The GS1 Application Identifier (AI) appears after the Function Code 1 (FNC1) in GS1-128, DataBar Expanded, GS1-DataMatrix and GS1-QRCode barcode symbols to encode certain types of information. Multiple AIs may be encoded in a single symbol to allow, for example, serial numbers, sell-by dates and other information to be automatically evaluated at the point of sale.

When generating GS1 Symbols, the following rules apply:

  • The FNC1 character is not visible and is only available within certain barcode types.
  • The AI is defined by the digits after the FNC1 character, which must be the first character in a GS1 barcode.
  • The Element String is the combination of the AI and its data field.
  • Multiple fixed length element strings may be included in a single barcode symbol without additional FNC1 characters, if variable length element strings (such as those with AIs 10, 21 or 92 as defined below) are included last. This is because the reading device understands the length of each fixed length element string. IDAutomation offers an Element String Testing Tool that may be used to check multiple fixed length element strings.
  • If additional element strings are encoded after a variable length element string, an additional FNC1 is required between them to define the end of the variable length element string.

The following chart provides examples of common GS1 element strings as defined by the GS1 Application Identifier Specification (v16 2016) and should be verified by a GS1 Member Organization before implementation.

Chart 1. Popular GS1 AIs.

 PurposeAIData Field Format (Fixed or Variable)
 SSCC-180018 numbers: 17 digits + MOD10 check digit
 GTIN-140114 numbers: 13 digits + MOD10 check digit
 GTIN-14 of contained items0214 numbers: 13 digits + MOD10 check digit
 Future assignment0314 digits
 Future assignment0416 digits
 Batch or Lot Number10Variable, up to 20 digits
 Production Date116 numbers: YYMMDD
 Due Date126 numbers: YYMMDD
 Packaging Date136 numbers: YYMMDD
 Future assignment146 digits
 Best before Date156 numbers: YYMMDD
 Sell By Date166 numbers: YYMMDD
 Expiration Date176 numbers: YYMMDD
 Future assignment186 digits
 Future assignment196 digits
 Variant202 number digits
 Serial Number21Variable, up to 20 characters
 Count of items30Variable, up to 8 numbers
 Trade Item Count37Variable, up to 8 numbers
 USPS9120 numbers: 19 digits + MOD10 check digit USPS Delivery Confirmation Service
 Intra Company Internal90-99Variable, alpha numeric internal use data up to 30 characters
 USPS99USPS Intelligent Mail Container Barcode
 GDTI253Global Document Type Identifier – up to 30 characters
 GCN255Global Coupon Number – 12 digits + MOD10 check digit
 Weight or dimensions310-3697 numbers (First number indicates the decimal point position)
 PO Number400Variable, up to 30 characters
 GINC401Variable, Global Identification Number for Consignment – up to 30 characters
 GSIN402Variable, Global Shipment Identification Number – up to 17 numbers
 Routing Code403Variable, up to 30 characters
 Shipping related410-41513 numbers: 12 digits + MOD10 check digit (GLN)
 Ship to420Variable, up to 20 digits
 Origin4223 digit ISO country code
 Net Weight in Kilograms31036 numbers: AI is 310(n), where (n) indicates the decimal position
 Net Weight in Pounds32026 numbers: AI is 320(n), where (n) indicates the decimal position
 Price3922Variable, up to 15 numbers: AI is 392(n), where (n) indicates the decimal position
 Price in ISO Currency3932Variable, up to 15 numbers: AI is 393(n), where (n) indicates the decimal position
 GRAI8003Variable, Global Returnable Asset Identifier – up to 30 characters
 GIAI8004Global Individual Asset Identifier, often used in DOD UID Labels.
 CPID8010Variable, Component/Part Identifier – up to 30 characters.
 GSRN8018Variable, Global Service Relation Number – up to 18 characters.
 Coupon Extended Code81006 numbers
 USA Coupon Codes8110Variable, up to 70 characters. The DataBar Coupon Symbol consists of the company prefix, offer code and other data as defined by the Joint Industry Coupon Committee and GS1.
 Extended Packaging URL8200Variable, up to 70 characters.

Below are a few examples of GS1 barcodes encoding element strings.

Chart 2. Element string example encoding two defined length element strings.

 Element StringElement String
 AIGTIN FieldAIExpiration Date Field (YYMMDD)
 0123456789012345717991231
 Data To Encode: (01)3456789012345717991231

GS1-128:

GS1-128 AI Example 1
GS1 DataBar Expanded:

GS1 DataBar Expanded
(01)34567890123457
(17)991231

GS1 Data Matrix:

GS1-DataMatrix AI Example 1
(01)34567890123457
(17)991231

GS1 QR Code:

GS1-QRCode Example 1
(01)34567890123457
(17)991231

Chart 3. Element string example encoding one defined length element string and two variable length element strings. The addition of parentheses around the AI of 21 will insert an additional FNC1 within the barcode symbol with the exception of GS1 DataBar, which requires the ASCII 202 character (Ê) to be inserted as a delimiter after the data of a variable length element string.

 Variable Element StringVariable Element String
 AIBatch FieldAISerial Number Field
 103456789213456789012
 Data To Encode: (01)34567890123457103456789(21)3456789012

GS1-128:

GS1-128 Variable Length Element String Example

GS1 Data Matrix:

GS1-DataMatrix Variable Length Element String Example
(01)34567890123457
(10)3456789
(21)3456789012

 GS1 QR Code:

GS1-QRCode Example 1
(01)34567890123457
(10)3456789
(21)3456789012

GS1 DataBar Expanded:

GS1 DataBar Element String Example
(01)34567890123457
(10)3456789
(21)3456789012

NOTE: When using DataBar Expanded, the ASCII 202 character (Ê) must be inserted as a delimiter after the data of a variable length element string. For example: (01)34567890123457103456789Ê(21)3456789012

Additional information regarding GS1 Identification Keys.