Identifiers & GS1
DPP Kit uses GS1 identifiers to make credentials resolvable — meaning anyone can look up a product or facility by its identifier.
Quick Reference
| Credential Type | Identifier | Format | Example |
|---|---|---|---|
| DFR, DIA | GLN-13 | 13 digits | 9347823000012 |
| DPP, DTE, DCC | GTIN-14 | 14 digits | 09347823000029 |
Your Organization Prefix
Every organization gets a unique 7-digit prefix at registration. This prefix is the foundation for all identifiers your organization generates. You can find your prefix on the Organization page.
GS1 Application Identifiers
GS1 uses Application Identifiers (AIs) to structure data. DPP Kit uses these AIs in resolver paths:
| AI | Name | Usage |
|---|---|---|
01 | GTIN | Product identification |
10 | Batch/Lot | Batch-level tracking |
21 | Serial Number | Unit-level tracking |
414 | GLN | Location/facility identification |
Resolver Path Examples
# Facility (GLN)
/414/9347823000012
# Product (GTIN)
/01/09347823000029
# Product with batch
/01/09347823000029/10/LOT-2024-001
# Product with batch and serial
/01/09347823000029/10/LOT-2024-001/21/UNIT-042
Check Digit Calculation
The last digit of every GLN-13 and GTIN-14 is a check digit calculated using the GS1 mod-10 algorithm. DPP Kit calculates this automatically — you don't need to compute it yourself.
For reference, the algorithm:
- Starting from the right (excluding the check digit position), multiply alternating digits by 3 and 1
- Sum all results
- The check digit is
(10 - (sum mod 10)) mod 10
Bringing Your Own Identifiers
If your organization has GS1-assigned identifiers (from a GS1 Member Organization), you can enter them directly when issuing credentials. DPP Kit validates the check digit to ensure correctness.
For pilots, auto-generated identifiers are recommended. They're valid GS1-format identifiers that work fully within DPP Kit. When transitioning to production with real GS1 membership, you can switch to your assigned identifiers.
Future: External ID Scheme Owners
The identifier system is designed to be extensible. In future releases, organizations will be able to bring identifiers from external ID Scheme Owners:
- OS Hub for facility identifiers
- GS1 Member Organizations for GTIN/GLN
This will be an additive change — no restructuring required.