A technically valid symbol does not create ownership of a GTIN, GLN, or SSCC.
GS1 workflow
Turn business identifiers into correctly structured GS1 data.
Learn how GTINs, SSCCs, GLNs, Application Identifiers, fixed and variable fields, separators, symbol choices, and Digital Link fit together.
They tell software whether the next field is a GTIN, date, batch, serial, weight, or other attribute.
GS1-128, DataBar, DataMatrix, and QR have different capacities and operational roles.
GS1 data is a shared language between companies and systems.
The barcode is only the carrier. The business meaning comes from assigned identifiers and Application Identifiers that let receiving software interpret every field consistently.
1. The three layers of a GS1 barcode
Identifier
A GTIN, SSCC, GLN, or another assigned key identifies the trade item, logistics unit, location, asset, document, or relationship.
Attributes
Batch, serial, dates, weight, count, price, and other fields add context to the identified object.
Data carrier
GS1-128, GS1 DataBar, GS1 DataMatrix, GS1 QR Code, and other carriers encode the element string so scanners can send it to business software.
Syntax is not assignment
The builder can calculate check digits and assemble a valid element string, but it cannot confirm that an identifier has been licensed, allocated, or accepted by a trading partner.
2. Core GS1 identifiers
GTIN
Global Trade Item Number. Identifies products and services at a specific packaging level. Common lengths are 8, 12, 13, and 14 digits.
SSCC
Serial Shipping Container Code. An 18-digit identifier for logistics units such as pallets, cases, or parcels.
GLN
Global Location Number. Identifies legal entities, functions, physical locations, or digital locations.
Serial and lot data
Attributes such as serial number and batch/lot distinguish individual items or production groups after the primary identifier is known.
Packaging levels matter
A consumer unit, inner pack, case, and pallet may require different identifiers. Do not reuse a retail-unit GTIN for a higher packaging level unless the relevant rules and trading partners explicitly allow that workflow.
3. Application Identifiers
An Application Identifier, often abbreviated AI, is a short numeric prefix that defines the meaning and format of the data immediately following it. Parentheses are used in human-readable representations to make the fields understandable, but the parentheses are generally not encoded as data.
| AI | Meaning | Data format | Use |
|---|---|---|---|
| (00) | SSCC | 18 digits | Identifies a logistics unit such as a pallet or case. |
| (01) | GTIN | 14 digits | Identifies a trade item. Shorter GTINs are zero-padded to 14 digits in the element string. |
| (10) | Batch / lot | Variable, up to 20 characters | Identifies a production batch or lot. Requires a separator when followed by another field. |
| (11) | Production date | 6 digits | Date represented in YYMMDD form. |
| (15) | Best-before date | 6 digits | Date represented in YYMMDD form. |
| (17) | Expiration date | 6 digits | Date represented in YYMMDD form. |
| (21) | Serial number | Variable, up to 20 characters | Identifies an individual instance of a trade item. |
| (30) | Variable count | Variable, up to 8 digits | Count of items contained in a variable-measure trade item. |
| (37) | Count of trade items | Variable, up to 8 digits | Count of trade items contained in a logistics unit. |
| (310n) | Net weight in kilograms | 6 digits | The final AI digit defines decimal precision. |
| (392n) | Price | Variable | Price with decimal precision defined by the final AI digit. Currency is not included. |
| (414) | Physical-location GLN | 13 digits | Identifies a physical location. |
Use the current GS1 Application Identifier specification
The table above covers common fields, not every AI or every business rule. Confirm the exact field, length, character set, and sector requirement for production use.
4. Fixed-length fields, variable-length fields, and FNC1
Fixed-length fields end automatically because the receiving software knows their exact length. Variable-length fields need an explicit separator when another field follows, unless the variable field is last in the symbol.
Human-readable element string
(01)09506000134352(17)280531(10)LOT2048(21)SN000184Conceptual machine sequence
FNC1 + 01 + GTIN + 17 + YYMMDD + 10 + LOT2048 + separator + 21 + SN000184In the example, AI (10) is variable length. A separator is needed before AI (21). The builder inserts the appropriate control character for compatible symbols; you should not replace it with a visible space, hyphen, or parenthesis.
Put fixed-length fields first when practical.
Place a variable field last to avoid an unnecessary separator.
Do not encode human-readable parentheses as data.
Confirm scanner and software handling of FNC1.
5. Dates, weights, prices, and implied decimals
Dates
Common date AIs use six digits in YYMMDD order. The business meaning depends on the AI: production, packaging, best-before, sell-by, or expiration are not interchangeable.
Implied decimal positions
Some AI families use the final AI digit to define decimal precision. For example, a weight field may contain six digits with the decimal position implied rather than printed in the encoded value.
| Illustrative AI | Encoded value | Interpreted value |
|---|---|---|
| (3100) | 000125 | 125 kg |
| (3102) | 000125 | 1.25 kg |
| (3103) | 000125 | 0.125 kg |
These examples illustrate the decimal mechanism. Select the correct AI for unit of measure and precision required by the actual application.
6. Choosing the GS1 data carrier
| Carrier | Strengths | Typical consideration |
|---|---|---|
| GS1-128 | Widely used in logistics and supports multiple AIs. | Linear and often wide; requires enough horizontal label space. |
| GS1 DataBar | Compact family for retail and some expanded data applications. | Choose the exact DataBar variant required by the scanning environment. |
| GS1 DataMatrix | High data capacity in a compact 2D area; common in healthcare and direct marking. | Requires compatible 2D imaging scanners and correct symbol construction. |
| GS1 QR Code | Can carry GS1 element strings and can support broader consumer interaction workflows. | Confirm point-of-sale and application support before replacing an established linear symbol. |
| EAN / UPC | Efficient retail point-of-sale identification for a GTIN. | Does not carry batch, serial, dates, or other attributes in the main symbol. |
Scanner capability is part of the decision
A 2D symbol may carry more data, but the workflow must include imaging scanners, compatible software, and agreed parsing rules. Do not assume every point-of-sale or warehouse device supports every carrier.
7. GS1 Digital Link
GS1 Digital Link expresses GS1 identifiers in a web-compatible URI structure. The same identity can connect a scan to product information, traceability, instructions, authentication, recalls, sustainability information, or other digital services.
Illustrative structure
https://example.com/01/09506000134352/21/SN000184The domain, resolver behavior, path structure, and linked content should be planned as a maintained web service. A URI that merely looks correct is not enough; it must resolve reliably and expose the intended information to users and systems.
Element string
Optimized for scanner-to-system processing using AIs and control characters.
Digital Link URI
Represents identifiers in a web-address form that can resolve to digital resources.
8. Recommended production workflow
1
Confirm the business requirement.
Identify the trading partner, process, carrier, data fields, scanner environment, and applicable sector rules.
2
Confirm identifier assignment.
Use the correct GTIN, SSCC, GLN, or other GS1 key for the exact object or level being identified.
3
Select Application Identifiers.
Choose only the fields required by the use case and enter them in a logical order.
4
Build and inspect both representations.
Review the human-readable element string and the raw machine data, including separators.
5
Choose and size the carrier.
Use the symbol required by the operational environment and preserve quiet zones and dimensions.
6
Test parsing, not only scanning.
Confirm that the receiving application splits AIs and values correctly after the scanner sends the data.
7
Verify final production output.
Use the actual substrate, print method, label position, finishing, and representative scanners.
9. What the builder validates, and what it cannot
The app can help with
Field formatting, supported lengths, check-digit calculation, AI assembly, separators, readable output, symbol generation, and export.
You must still confirm
Identifier ownership, allocation rules, trading-partner acceptance, legal requirements, sector rules, production dimensions, and formal verification.
Test the data through the whole system
A scanner may decode the symbol correctly while an ERP, WMS, POS, or healthcare system rejects or misinterprets the string. End-to-end testing is essential.
10. Troubleshooting GS1 data
| Symptom | Likely cause | Correction |
|---|---|---|
| All fields appear as one long value | Missing FNC1 separator after a variable-length field. | Reorder fields or insert the correct separator. |
| Parentheses appear in scanned data | Human-readable parentheses were encoded literally. | Encode AI digits without parentheses; keep parentheses only for display. |
| GTIN rejected | Wrong length, bad check digit, wrong packaging level, or unassigned identifier. | Validate the GTIN and confirm its intended item level. |
| Date interpreted incorrectly | Wrong AI, wrong YYMMDD order, or invalid business date. | Confirm the date AI and source data. |
| Symbol scans but system ignores attributes | Receiving software does not parse the selected AIs or carrier. | Confirm scanner configuration and application mapping. |
| 2D symbol not read at point of sale | Legacy laser scanner or software not enabled for the carrier. | Validate device and POS support before deployment. |