EU MDR UDI Identifiers-Part II

EU MDR UDI Identifiers and Structure Explained

Summary: Part II – Continuing our series on EU MDR UDI, this article explains the key components of the EU MDR Unique Device Identification (UDI) system—Basic UDI-DI, Master UDI-DI, UDI-DI, and UDI-PI—along with when each is required, how they differ, and which issuing entities support UDI creation.

What is EU Basic UDI-DI?

The Basic UDI-DI serves as a regulatory anchor for grouping devices that share the same intended purpose, risk classification, and core design/manufacturing features. Unlike the UDI-DI, it does not appear on product packaging or labeling and it does not appear on any trade item. Instead, it:

• Uniquely identifies the product model throughout the entire life cycle of the product
• Appears in documentation and regulatory filings
• Serves as the main key within the EUDAMED database

Key Functions of Basic UDI-DI:

1. Primary model identifier – connects devices with similar characteristics and intended use.
2. Database key – links all related UDI-Dis within the UDI database and across EUDAMED modules.
3. Regulatory reference – used in technical documentation, conformity declarations, certificates, and post-market surveillance reports
4. Label-independent – not printed on the device or packaging, but possibly included in the instructions for use.

This identifier streamlines regulatory processes and supports efficient oversight of device families throughout their lifecycle.

What is the Additional Identifier EU Master UDI-DI?

The Master UDI-DI is an alphanumeric identifier under Regulation 2017/745 for medical devices. However, in contrast to the Basic UDI-DI, this identifier appears directly on the product label or packaging as part of the UDI barcode. Furthermore, its primary purpose is to provide an extra layer of identification for highly individualized products, such as contact lenses and spectacle frames, streamlining data entry in the EUDAMED database and enabling more detailed clinical specifications.

To ensure accuracy and prevent duplication, the system validates the format of each Master UDI-DI upon registration, particularly for GS1 issuing entities. While it may seem like an added complexity, the Master UDI-DI plays a vital role in enhancing traceability and safety across the medical device landscape.

When is a Master UDI-DI required for medical devices?

• They are in the same generic product group
• A device has individual specifications (e.g. curvature, cylinder, visual acuity)
• They are classified under the same MDR rules
• They have similar risk profiles and clinical assessments

Specifically, device types that require Master UDI-DI registration include: standard soft contact lenses, rigid gas permeable (RGP) contact lenses, spectacle frames and lenses, ready-made reading spectacles.

When to Assign a New UDI-DI vs. UDI-PI

A new UDI-DI must be assigned when changes could lead to misidentification or ambiguity in device traceability.

These changes may include, for example:

• An updated device name or trade name, reflecting branding or product line adjustments.
• Version or model updates, which indicate design or performance modifications.
• Changes to single-use labeling, clarifying whether the device is intended for one-time or repeated use.
• Revisions to sterile packaging or sterilization requirements, ensuring product safety and compliance.
• Adjustments to the quantity per package, which can impact labeling and supply chain documentation.
• New or revised critical warnings or contraindications, supporting accurate and safe device use.
• Disclosure of CMR or endocrine-disrupting substances, as required for transparency and patient safety.

Consequently, each UDI-DI is linked to one—and only one—Basic UDI-DI, which maintains consistent traceability across all product variations.

In contrast, a new UDI-PI is sufficient for minor updates such as:

• Bug fixes
• Security patches
• Usability-related interface changes

Manufacturers often use versioning logic—such as updating the third digit of a version number—to determine when a new UDI-PI is needed. It’s important to note that there is no requirement to assign a unique UDI for each installation.

Issuing Entities for UDI Codes

To ensure consistency and reliability in device identification, EU MDR UDI codes must be assigned through one of four officially designated issuing entities. These organizations operate systems for generating both UDI-DIs and Basic UDI-DIs, as required under MDR Article 27(2) and IVDR Article 24(2). The designated entities are:

1. GS1
2. HIBCC
3. ICCBBA
4. IFA GmbH

Specifically, these entities are appointed by the European Commission and are required to operate for a minimum of ten years. Moreover, their designation has recently been extended through 2029, reinforcing their role in supporting the EU’s medical device regulatory framework.

GS1-Specific Format

When GS1 is the issuing entity:

• The Master UDI-DI follows the format of the GMN code
• The UDI-DI corresponds to the GTIN code

As a result, this standardized approach simplifies integration with global supply chain systems and supports seamless traceability.

Key Dates for UDI Implementation

Class III & Implantable Devices:

• May 26, 2021 – UDI marking
• May 26, 2023 – reusable devices

Class IIa & IIb Devices:

• May 26, 2023 – UDI marking
• May 26, 2025 – reusable devices

Class I Devices:

• May 26, 2025 – UDI marking
• May 26, 2027 – reusable devices

Additionally, these markings must appear on the device packaging and, for reusable devices, often directly on the device itself.

In conclusion, understanding the roles of UDI-DI, UDI-PI, Basic UDI-DI, and Master UDI-DI is fundamental for MDR compliance. Each plays a distinct governance role in device identification and traceability—from high-level product grouping to individualized labeling. As a result, these identifiers form the foundation of accurate EUDAMED registration, post-market surveillance, and regulatory documentation.

Read Part 1 our EU MDR UDI Series: EU MDR UDI Overview

Read Part 3 of our EU MDR UDI Series: EU MDR UDI Implementation

Additional Resources:

1. European Commission – Unique Device  Identification (UDI) System  under the EU medical devices Regulations 2017/745 and 2017/746 – https://health.ec.europa.eu/document/download/add107c5-0ca8-45d3-b049-63bb84c4ce31_en?filename=md_faq_udi_en.pdf
2. Public Health – Unique Device Identifier – UDI – European Commission – https://health.ec.europa.eu/medical-devices-topics-interest/unique-device-identifier-udi_en
3. BSI – Overview of the EU Basic UDI-DI  – https://compliancenavigator.bsigroup.com/en/medicaldeviceblog/overview-of-the-eu-basic-udi-di/
4. European Commission – Identifiers – https://webgate.ec.europa.eu/udi-helpdesk/en/udi-assignment/identifiers.html
5. European Commission – MDCG 2018-6 Clarifications of UDI related responsibilities in relation to Article 16 of the Medical Device Regulation 2017/745 and the In-Vitro Diagnostic Medical Devices Regulation 2017/746 https://ec.europa.eu/docsroom/documents/31927
6. Public Health – UDI/Device registration – European Commission – https://health.ec.europa.eu/medical-devices-eudamed/udidevice-registration_en
7. VDE Health – UDI for medical devices according to MDR – https://www.vde.com/topics-en/health/consulting/udi-for-medical-devices-according-mdr
8. ISPE -Medical Device UDI Components Management in the European Union – https://ispe.org/pharmaceutical-engineering/july-august-2021/medical-device-udi-components-management-european-union
9. TUV Article 27 (MDR): Unique Device Identification system – https://de-mdr-ivdr.tuvsud.com/Article-27-Unique-Device-Identification-system.html
10. MAVEN – Unique Device Identification (UDI) Requirements in EU MDR – https://mavenprofserv.com/blog/udi-requirements-new-requirement-in-eu-mdr/
11. Johner Institute – Unique Device Identification (UDI) in the EU – https://blog.johner-institute.com/regulatory-affairs/unique-device-identification-udi/
12. DDismart – UDI & EUDAMED Explained under EU MDR – https://www.ddismart.com/blog/udi-eudamed-explained-under-eu-mdr