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Category Codes

Examiners for European (EP) and Patent Cooperation Treaty (WO) patents may assign relevance indicators to the references that they cite. These indicators are called category codes and tell you how relevant the Examiner considers the citation to be in relation to the patent claims.

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Code

Definition

X

EP - Particularly relevant if taken alone

WO - Document of particular relevance, the claimed invention cannot be considered novel or cannot be considered to involve an inventive step

Y

EP - Particularly relevant if combined with another document of the same category

WO - Document of particular relevance, the claimed invention cannot be considered to involve an inventive step when the document is combined with one or more such documents, such combination being obvious to a person skilled in the art

A

Technology background

O

Non-written disclosure

P

EP - intermediate document

WO - Published prior to the international filing date but later than the priority date claimed

T

Theory or principle underlying the invention

E

Earlier patent document but published on, or after, the filing date

D

Document cited in the application

L

Document cited for other reasons

&

Member of the same patent family, corresponding document

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Did You Know ...

The definition of the codes may vary by patent-issuing authority.