---
title: "Tag: check-digit | OpenEPCIS | OpenEPCIS - an open-core, GS1-conformant EPCIS implementation."
canonical_url: "https://openepcis.io/tags/check-digit"
last_updated: "2026-09-02T11:48:50.428Z"
meta:
  "og:title": "Tag: check-digit | OpenEPCIS | OpenEPCIS - an open-core, GS1-conformant EPCIS implementation."
---

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# **Tag: check-digit**

- [<h2>**Identifiers: GTIN, SKU and What Identifies What**</h2>

  One product needs exactly one GS1 identifier — the GTIN. Where the connector finds it, why your SKU is a different thing, and how batch, serial and logistics-unit levels build on top.#connectors#gtin#sku#lgtin#sgtin#sscc#check-digit](https://openepcis.io/docs/connectors/identifiers-gtin-and-sku)