EU UDI Three Codes Breakdown: What Are the Differences Between Basic UDI-DI, UDI-DI and UDI-PI? - Wiselink Group-A More Controllable, Stable, and Future-Oriented Material Direction

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EU UDI Three Codes Breakdown: What Are the Differences Between Basic UDI-DI, UDI-DI and UDI-PI?

Time：2026-09-22 11:12:08

When undertaking EU MDR registration for medical devices, the UDI code is an indispensable core component. Many practitioners frequently encounter Basic UDI-DI, UDI-DI and UDI-PI in documents, certificates and the Eudamed database, yet often confuse their definitions. This may lead to pitfalls during documentation preparation, label design and database submission. This article clarifies the definitions, applications and placement requirements of the three identifiers.

一、Three UDI Codes

（一）Basic UDI-DI, abbreviated as bUDI

Positioning：Top-level identifier for the product regulatory family

Key point：It will NOT be printed on product labels or barcodes. It only appears in technical documentation, the Eudamed database, CE certificates and DoC (Declaration of Conformity) documents.

All models under one Basic UDI-DI must share the same intended purpose, risk classification and core design principles.

Simple explanation：The bUDI acts as a master number for a product family, grouping a series of similar product models.

（二）UDI-DI：Device Identifier

Positioning：Static identifier for a specific model and packaging level

It is a fixed code, independent of batch numbers or expiry dates.
A new UDI-DI is required once the model or packaging specification is modified.

Simple explanation：The UDI-DI corresponds to one specific model and packaging specification, serving as the static base segment within label barcodes.

（三）UDI-PI：Production Identifier

Positioning：Dynamic identifier for product production traceability

Components (selectable as applicable)：Batch number (Lot), Serial Number (SN), manufacturing date, expiry date, etc.

Printed on label 2D codes / barcodes as the variable dynamic segment.
The UDI-PI varies for every batch under the same UDI-DI.
Function: Trace down to specific batches or individual units to achieve full product lifecycle traceability.

（四）Quick Comparison of the Three Codes

Code Name	Printed on Label Barcode	Attribute	Core Function
Basic UDI-DI (bUDI)	No	Top-level family identifier	Groups product regulatory families; used in Eudamed, CE certificates and technical documentation
UDI-DI	Yes	Static fixed identifier	Identifies specific model + packaging specification; code change required for model/packaging revisions
UDI-PI	Yes	Dynamic variable identifier	Carries batch, serial number and other production data for unit / batch traceability

二、Practical Reminders

Basic UDI-DI must be filled out for CE certificates, DoCs and technical documentation. UDI will not appear on outer packaging barcodes, a common pitfall for new practitioners.
The 2D barcode on product labels consists of two parts: fixed UDI-DI + dynamic UDI-PI.
Multiple models within the same product family share one Basic UDI-DI, yet each model and packaging level is assigned an independent UDI-DI. The UDI-PI differs for every production batch.

三、Conclusion

The UDI system is a core compliance requirement under the EU MDR regulation. Clear differentiation between these three identifiers helps enterprises avoid common compliance errors in Eudamed registration, label design and certificate review, reducing supplementary submissions and shortening project timelines.For further enquiries, please contact Wiselink.

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