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.
When generating GS1 symbols, IDAutomation recommends testing the result with the Barcode Data Decoder App which parses out the AIs and Element Strings as shown in the graphic below. The app also verifies MOD10 check digits when required by highlighting them in green.
The following chart provides examples of common GS1 element strings as defined by the GS1 Application Identifier Specification.
Chart 1. Popular GS1 AIs.
| Purpose | AI | Data Field Format (Fixed or Variable) |
| SSCC-18 | 00 | 18 numbers: 17 digits + MOD10 check digit |
| GTIN-14 | 01 | 14 numbers: 13 digits + MOD10 check digit |
| GTIN-14 of contained items | 02 | 14 numbers: 13 digits + MOD10 check digit |
| Future assignment | 03 | 14 digits |
| Future assignment | 04 | 16 digits |
| Batch or Lot Number | 10 | Variable, up to 20 digits |
| Production Date | 11 | 6 numbers: YYMMDD |
| Due Date | 12 | 6 numbers: YYMMDD |
| Packaging Date | 13 | 6 numbers: YYMMDD |
| Future assignment | 14 | 6 digits |
| Best before Date | 15 | 6 numbers: YYMMDD |
| Sell By Date | 16 | 6 numbers: YYMMDD |
| Expiration Date | 17 | 6 numbers: YYMMDD |
| Future assignment | 18 | 6 digits |
| Future assignment | 19 | 6 digits |
| Variant | 20 | 2 number digits |
| Serial Number | 21 | Variable, up to 20 characters |
| Count of items | 30 | Variable, up to 8 numbers |
| Trade Item Count | 37 | Variable, up to 8 numbers |
| USPS | 91 | 20 numbers: 19 digits + MOD10 check digit USPS Delivery Confirmation Service |
| Intra Company Internal | 90-99 | Variable, alpha numeric internal use data up to 30 characters |
| USPS | 99 | USPS Intelligent Mail Container Barcode |
| GDTI | 253 | Global Document Type Identifier – up to 30 characters |
| GCN | 255 | Global Coupon Number – 12 digits + MOD10 check digit |
| Weight or dimensions | 310-369 | 7 numbers (First number indicates the decimal point position) |
| PO Number | 400 | Variable, up to 30 characters |
| GINC | 401 | Variable, Global Identification Number for Consignment – up to 30 characters |
| GSIN | 402 | Variable, Global Shipment Identification Number – up to 17 numbers |
| Routing Code | 403 | Variable, up to 30 characters |
| Shipping related | 410-415 | 13 numbers: 12 digits + MOD10 check digit (GLN) |
| Ship to | 420 | Variable, up to 20 digits |
| Origin | 422 | 3 digit ISO country code |
| Net Weight in Kilograms | 3103 | 6 numbers: AI is 310(n), where (n) indicates the decimal position |
| Net Weight in Pounds | 3202 | 6 numbers: AI is 320(n), where (n) indicates the decimal position |
| Price | 3922 | Variable, up to 15 numbers: AI is 392(n), where (n) indicates the decimal position |
| Price in ISO Currency | 3932 | Variable, up to 15 numbers: AI is 393(n), where (n) indicates the decimal position |
| GRAI | 8003 | Variable, Global Returnable Asset Identifier – up to 30 characters |
| GIAI | 8004 | Global Individual Asset Identifier, often used in DOD UID Labels. |
| CPID | 8010 | Variable, Component/Part Identifier – up to 30 characters. |
| GSRN | 8018 | Variable, Global Service Relation Number – up to 18 characters. |
| Coupon Extended Code | 8100 | 6 numbers |
| USA Coupon Codes | 8110 | Variable, 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 URL | 8200 | Variable, up to 70 characters. |
Below are a few examples of GS1 barcodes encoding element strings.
- Element strings may be checked with the IDAutomation Element String Testing Tool.
- The examples below were generated with the ASPX Barcode Generator Script.
- Barcodes may be generated and tested from links provided at the ASPX Script Download page. For example, https://www.bcgen.com/aspxscripts/idautomation-code128.aspx?PT=T&D=(01)3456789012345717991231.
Chart 2. Element string example encoding two defined length element strings.
| Element String | Element String | ||
| AI | GTIN Field | AI | Expiration Date Field (YYMMDD) |
| 01 | 234567890123457 | 17 | 991231 |
| Data To Encode: (01)3456789012345717991231 | |||
GS1-128:
GS1 DataBar Expanded:
(01)34567890123457
(17)991231
GS1 Data Matrix:
(01)34567890123457
(17)991231
GS1 QR Code:
(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 String | Variable Element String | ||
| AI | Batch Field | AI | Serial Number Field |
| 10 | 3456789 | 21 | 3456789012 |
| Data To Encode: (01)34567890123457103456789(21)3456789012 | |||
GS1-128:
GS1 Data Matrix:
(01)34567890123457
(10)3456789
(21)3456789012
GS1 QR Code:
(01)34567890123457
(10)3456789
(21)3456789012
GS1 DataBar Expanded:
(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.