Notes · 30 September 2026

Basic UDI-DI vs UDI-DI

The UDI-DI identifies one device model. The basic UDI-DI groups models for one intended purpose, and EUDAMED hangs certificates on that group.

People mix these up because both are called a UDI and both appear in EUDAMED. They answer different questions.

The UDI-DI identifies one device model as it is labelled and sold. That is the code you type when a buyer asks “is this exact code still on the EU market?” The basic UDI-DI identifies a group of device models that share the same intended purpose, risk class, and essential design. The manufacturer assigns it, and it is the key EUDAMED uses when a notified body registers a certificate that covers that group.

Where each one shows up

• On the unit label and in a purchase order: the UDI-DI, plus a UDI-PI for the lot or serial.
• In the declaration of conformity and in the certificate scope: the basic UDI-DI.
• In the public device record: both, when the manufacturer submitted both. The device payload includes a basicUdi field. It is often filled. It is not always filled in the rows a public search returns.

A certificate search that only sends the UDI-DI from the label will miss certificates that were registered against the basic UDI-DI. That is a property of the public certificate module, not a quirk of one website. UdiWatch reads the basic UDI-DI off the device and queries certificates with it. When that query returns nothing, the device page shows no expiry. We do not copy a date from a brochure to fill the gap.

A practical split

Covered CP Stent, UDI-DI 10887714028257, has a certificate date in the public record, which means the basic-UDI path returned one. UDI-DI 16977660098955 does not. Both are real public records. One is not “more registered” than the other because a date is present. Class I devices often have no notified-body certificate to find. Class III devices often do. Absence is information only after you know which kind of device you are looking at.

If you are writing a watchlist, store the UDI-DI you buy or sell. Keep the basic UDI-DI beside it when the register gives you one, because that is the identifier a certificate expiry will move under. Watching only the basic UDI-DI will not tell you that one labelled model left the market while its siblings stayed.

More notes

• EUDAMED: “no longer on the market”
• EUDAMED certificate expiry dates
• How to search a device in public EUDAMED

Not an official European Commission page. Public device and actor pages on this site repeat fields the register already publishes.