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# Product Identifier

> A unique code that distinguishes a product model, batch or individual item, and that anchors the identity of a Digital Product Passport over its entire lifetime.

## Definition

A unique string that identifies a product at a defined level of granularity, model, batch or
individual item, and that remains stable for the life of what it identifies. In passport work it
is the key that links the physical object to its data record.

## Expanded Explanation

Identity operates at three levels and they are not interchangeable. A model level identifier, such
as a Global Trade Item Number, identifies a product type and is shared by every unit of it. A batch
or lot identifier narrows this to a production run, which is the level at which most material,
sourcing and compliance evidence actually differs. A serial identifier addresses a single physical
item, which is what repair history, ownership and end of life records require.

The applicable legislation sets the level that must be supported. The battery passport under
Regulation (EU) 2023/1542 requires passports at the level of the individual battery. Other product
groups may permit model or batch level passports. Because the required level can only increase in
practice, designing an identifier scheme that can carry serialisation later is cheaper than
retrofitting it.

Identifiers should also be issued from a scheme that third parties can interpret. ISO/IEC 15459
defines the principles of unique identification, and issuing agencies such as GS1 provide globally
unique keys that avoid collisions between companies.

## Why It Matters

The identifier is the one element of a passport that cannot be corrected quietly later. Data fields
can be edited and carriers reprinted, but if two different products share an identifier, or the same
product is issued two identifiers by different systems, the resulting records cannot be reconciled
and the traceability chain breaks.

## Common Misconceptions

#### The internal SKU is enough

An internal stock keeping unit is a commercial code that is reused, retired and changed for
merchandising reasons. Passport identity must be unique, stable and resolvable outside the
organisation, which an SKU generally is not.

## Related Terms

* [GS1](/docs/knowledge-base/glossary/gs1)
* [GS1 Digital Link](/docs/knowledge-base/glossary/gs1-digital-link)
* [Data Carrier](/docs/knowledge-base/glossary/data-carrier)
* [Product Traceability](/docs/knowledge-base/glossary/product-traceability)
* [Digital Product Passport](/docs/knowledge-base/glossary/digital-product-passport)
* [GTIN](/docs/knowledge-base/glossary/gtin)
* [Resolver](/docs/knowledge-base/glossary/resolver)

## Related Knowledge Base Articles

* [What Is a Digital Product Passport?](/docs/knowledge-base/digital-product-passports/what-is-a-digital-product-passport)
* [Who Needs a Digital Product Passport?](/docs/knowledge-base/digital-product-passports/who-needs-a-digital-product-passport)

## Related Articles

* [EPCIS](/docs/knowledge-base/glossary/epcis)
* [GS1](/docs/knowledge-base/glossary/gs1)
* [GTIN](/docs/knowledge-base/glossary/gtin)
* [GS1 Digital Link](/docs/knowledge-base/glossary/gs1-digital-link)
* [Product Traceability](/docs/knowledge-base/glossary/product-traceability)
* [Resolver](/docs/knowledge-base/glossary/resolver)
* [Data Carrier](/docs/knowledge-base/glossary/data-carrier)
* [Harmonised Standard](/docs/knowledge-base/glossary/harmonised-standard)

## See Also

* [Standards & Technology](/docs/knowledge-base/standards-and-technology/overview)
* [Implementation](/docs/knowledge-base/implementation/overview)

## References

* ISO/IEC 15459, unique identification: [https://www.iso.org/standard/54779.html](https://www.iso.org/standard/54779.html)
* Regulation (EU) 2023/1542 concerning batteries and waste batteries:
  [https://eur-lex.europa.eu/eli/reg/2023/1542/oj](https://eur-lex.europa.eu/eli/reg/2023/1542/oj)
* GS1 General Specifications: [https://www.gs1.org/standards/barcodes-epcrfid-id-keys/gs1-general-specifications](https://www.gs1.org/standards/barcodes-epcrfid-id-keys/gs1-general-specifications)

## About This Article

About This Article

<dl>
  <dt>
    Last Reviewed
  </dt>

  <dd>
    2026-08-07
  </dd>

  <dt>
    Next Scheduled Review
  </dt>

  <dd>
    2027-08-07
  </dd>

  <dt>
    Article Version
  </dt>

  <dd>
    1.0
  </dd>
</dl>

tieback Knowledge is a continuously maintained reference library covering Digital Product
Passports, product traceability, product compliance and related regulations. Articles are
reviewed regularly as legislation, standards and implementation guidance evolve.

## Related Docs

* [Standards & Technology](/docs/knowledge-base/standards-and-technology/overview)
* [Implementation](/docs/knowledge-base/implementation/overview)
* [Digital Product Passports](/docs/knowledge-base/digital-product-passports/overview)
* [Glossary](/docs/knowledge-base/glossary/overview)