Introduction to GLNs: The Foundation of Global Track-and-Trace, DSCSA Compliance, and EPCIS Data Exchange

The Drug Supply Chain Security Act (DSCSA) has transformed how the pharmaceutical supply chain tracks, verifies, and exchanges data about prescription products. While terms like serialization, EPCIS, and traceability are now widely discussed, one critical element still causes confusion for many: the GLN, or Global Location Number.

GLNs are more than just identifiers—they are the backbone of supply chain visibility. Understanding how GLNs work, how they fit into GS1 standards, and how they support DSCSA compliance is essential for pharmacies, distributors, manufacturers, and any trading partner exchanging Electronic Product Code Information Services (EPCIS) data.

What Is a GLN?

A Global Location Number (GLN) is a 13-digit, globally unique identifier used to identify a business entity, physical location, or function within an organization. GLNs ensure that supply chain partners know who they are transacting with and where events occur, a necessity for DSCSA’s interoperable electronic tracing requirements.

Unlike a GTIN (global trade identification number), which identifies a product, a GLN identifies a location, such as a pharmacy, warehouse, shipping dock, receiving department, or corporate headquarters.

Why GLNs Matter in the Modern Supply Chain

Today’s pharmaceutical supply chain depends on accurate, standardized data exchange. GLNs play a crucial role because they:

1. Enable precise traceability‍

Under DSCSA, every serialized event captured in EPCIS must include the correct exact physical location (the readPoint) in the facility (the bizLocation) where the event occurs. Both the readPoint and the bizLocation rely on GLNs; without these identifiers, trading partners cannot accurately trace product movement.  ‍

2. Support interoperability

‍GLNs ensure that every trading partner speaks the same language. Whether two companies use different internal systems, ERP platforms, or inventory tools, a GLN provides a shared reference point—a requirement for seamless EPCIS transmission.  ‍

3. Reduce errors and mismatches

‍Incorrect or missing GLNs are among the most common reasons EPCIS files are rejected. Accurate GLN usage prevents failed shipments, compliance delays, and costly investigations.  ‍

4. Strengthen DSCSA compliance

‍DSCSA mandates the use of standardized identifiers across the supply chain. GLNs are a central part of GS1’s global system for location identity, supporting the reliability and auditability regulators expect.

How GLNs Fit into GS1 Standards

GLNs are one component of the overarching GS1 system, which develops and maintains standards to improve the efficiency, safety, and visibility of supply chains across industries. GS1 is best known for barcodes and product identifiers, but the system also includes:

• GTINs for product identification

• SSCCs (Serial Shipping Container Codes) for shipping container tracking

• EPCIS for sharing serialized event data

• GLNs for identifying where events occur

Together, these identifiers create a unified, globally recognized structure for exchanging supply chain information. In EPCIS events, GLNs are used to specify:

• where a product was commissioned

• where it was packed or shipped

• where it was received

• which business unit performed the action

GS1 requires GLNs to be unique and accurately maintained to ensure clean, interoperable DSCSA data exchange.

Types of GLNs

Not all GLNs serve the same purpose. GLNs can identify different layers of a business, and choosing the right type is crucial for DSCSA compliance and EPCIS accuracy.

1. Legal Entity GLNs‍

A legal entity GLN identifies a corporation, company, or other legally recognized business. Examples include:

• A pharmacy corporation

• A wholesale distributor

• A manufacturer

These GLNs specify who owns the product at each step, which is essential for defining the chain of custody under DSCSA.

2. Location GLNs‍

A location GLN identifies a specific physical or digital place where supply chain activities occur, such as:

• A retail pharmacy

• A distribution center

• A shipping dock

• A receiving bay

• An EPCIS repository

In EPCIS events, these GLNs are used in fields like readPoint and bizLocation, allowing trading partners to pinpoint where a serialized event took place.

3. Functional Location GLNs

Functional location GLNs identify departments or internal units within a business. Examples include:

• Billing departments

• Quality assurance departments

• Customer service or returns processing units

These GLNs help differentiate operational functions, especially in complex organizations or pharmacy networks.

GLN Hierarchies and How They Work

GLNs are not isolated identifiers; they function within a hierarchy. A single company may have:

• 1 legal entity GLN

• 50 store location GLNs

• 150 functional department GLNs

This layered structure allows for precise EPCIS reporting and eliminates ambiguity. For example:

• A legal entity GLN identifies the corporation

• A physical location GLN identifies Store #123

• A functional GLN identifies its receiving department

When EPCIS data includes the correct GLNs at each level, trading partners can trace product flow without confusion and maintain full DSCSA compliance.

Summary

GLNs are essential identifiers for DSCSA compliance and EPCIS data exchange, ensuring every trading partner knows exactly where serialized events occur. This guide explains what GLNs are, why they matter in today’s pharmaceutical supply chain, and how different types of GLNs support accurate, interoperable traceability.

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