The term "disclaimer" is used in the decisions G 1/03 (identical to G 2/03) (OJ 2004, 413, 448), G 2/10 (OJ 2012, 376) and G 1/16 (OJ 2018, A70) as meaning an amendment to a claim resulting in the incorporation therein of a "negative" technical feature, typically excluding from a general feature specific embodiments or areas.

Furthermore G 1/16 concurred with decision T 1870/08, that a disclaimer is only a proper disclaimer if the remaining legal subject-matter is less than that of the unamended claim. If any subject-matter can be identified which falls within the scope of the claim after amendment by the proposed disclaimer, but which did not do so before the amendment, the disclaimer is improper and, as a consequence of this, unallowable under Art. 123(2) EPC.

The board in T 1870/08 provided the example of a negative formulation removing a restricting feature: While this formulation may look like a disclaimer, it may in fact extend the legal scope of protection.

The term "undisclosed disclaimer" relates to the situation in which neither the disclaimer itself nor the subject-matter excluded by it have been disclosed in the application as filed. The term "disclosed disclaimer" relates to the situation in which the disclaimer itself might not have been disclosed in the application as filed, but the subject-matter excluded by it has a basis in the application as filed, e.g. in an embodiment. Thus, undisclosed disclaimers and disclosed disclaimers can be distinguished according to whether the subject-matter on which the respective disclaimer is based is explicitly or implicitly, directly and unambiguously, disclosed to the skilled person using common general knowledge, in the application as filed (G 1/16).