Common GLN Mistakes (and How to Avoid Them)

Global Location Numbers (GLNs) play a critical role in DSCSA compliance and EPCIS data exchange. Yet pharmacies often encounter issues with incorrect or inconsistent GLN usage, leading to rejected files, shipment delays, and confusion across trading partners. Understanding these common mistakes—and how to prevent them—helps ensure clean, reliable serialized data.

1. Using the Wrong GLN in EPCIS

Each EPCIS event requires the correct GLN for the location where the serialized activity occurred. Confusing a corporate GLN with a store location GLN, or using a functional GLN in place of a physical one, can cause trading partners to misinterpret the event or reject the file entirely.

Avoid it by:

• Maintaining an internal reference list of GLNs and their specific purposes.

• Ensuring systems are configured to use the correct GLN for receiving, shipping, and business functions.

2. Not Distinguishing Between Shipping and Billing GLNs

Some pharmacies maintain centralized billing or returns departments separate from their physical receiving locations. Using a billing GLN for a shipping or receiving event can misroute shipments or misclassify transactions.

Avoid it by:

• Clearly documenting functional GLNs and training staff on where each applies.

3. Reusing GLNs Improperly

A GLN is meant to be persistent. Once assigned, it should not be reused for a new location, a new purpose, or a different address. Reuse creates ambiguity and undermines traceability.

Avoid it by:

• Retiring GLNs permanently when stores close, relocate, or undergo major operational changes.

4. Misalignment With Trading Partners

If wholesalers, manufacturers, or 3PLs have outdated GLNs on file, they may send data to incorrect identifiers or reject EPCIS events referencing unfamiliar GLNs.

Avoid it by:

• Verifying GLN alignment during onboarding and updating trading partners promptly when changes occur.

5. Missing GLNs in Outbound Data

Some pharmacies forget to include GLNs in outbound EPCIS files, TI/TS records, or operational messages—especially when new locations or functions are added.

Avoid it by:

• Ensuring every system generating DSCSA data is configured with an up-to-date GLN list.

How to Deal With Multiple GLNs

Pharmacies sometimes discover that trading partners—such as wholesalers, manufacturers, or 3PLs—have assigned their own GLNs to represent the pharmacy’s locations. These partner-created identifiers often originate from legacy EDI systems or pre-DSCSA practices, resulting in multiple GLNs circulating for the same store.

Managing these external GLNs is essential to maintaining accuracy in EPCIS events and ensuring consistent DSCSA compliance.

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1. Identify All GLNs Trading Partners Have on File

Request a list of GLNs from major trading partners and compare them to your official GS1-assigned GLNs.

Any GLN that did not come from your GS1 Company Prefix should be considered unofficial.

This provides visibility into conflicting or duplicate location identifiers.

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2. Confirm the Official GLN for Each Location

Your GS1-generated GLN is always the authoritative identifier.

Externally assigned GLNs should not be used in EPCIS or TI/TS data and should be flagged for cleanup.

Share the official list internally so teams do not inadvertently rely on outdated identifiers.

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3. Communicate Correct GLNs to Trading Partners

Provide trading partners with:

• Your legal entity GLN

• Location/store GLNs

• Functional GLNs (if used)

Request that they update their systems and retire any GLNs previously created on your behalf.

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4. Monitor and Map During the Transition

As trading partners update their records:

• Maintain a temporary crosswalk between unofficial and official GLNs.

• Review EPCIS files for references to incorrect identifiers.

• Notify partners immediately if legacy GLNs reappear.

Early detection prevents inconsistent DSCSA event data.

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5. Establish an Official GLN Policy for Future Onboarding

Set expectations to avoid future duplication:

• Partners should use your GLNs—not create new ones.

• All GLN questions should route to a designated compliance or supply chain contact.

• Updates to store addresses, functions, or ownership will be communicated proactively.

This ensures long-term GLN consistency across all trading relationships.

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Want to learn more about GLNs? Explore the related articles in our blog series to dive deeper into how GLNs work, why they matter, and how they’re used across the supply chain.

• Introduction to GLNs: The Foundation of Global Track-and-Trace, DSCSA Compliance, and EPCIS Data Exchange
• How GLNs Are Used in DSCSA & EPCIS: Why Every Pharmacy Needs Accurate Location Data
• GLN Structure Explained: How the 13-Digit Identifier Powers DSCSA Compliance and EPCIS Traceability
• ‍How to Obtain a GLN and Best Practices for Pharmacies

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