A claim's subject-matter is normally defined in terms of positive features indicating that certain technical elements are present. Exceptionally, however, the subject-matter may be restricted using a negative limitation expressly stating that particular features are absent. This may be done e.g. to remove non-patentable embodiments disclosed in the application as filed (see T 4/80, OJ 4/1982, 149) or if the absence of a feature can be deduced from the application as filed (see T 278/88, not published in OJ).

Negative limitations such as disclaimers may be used only if adding positive features to the claim either would not define more clearly and concisely the subject-matter still protectable (see T 4/80, OJ 4/1982, 149) or would unduly limit the scope of the claim (see T 1050/93, not published in OJ).

With respect to the allowability of a disclaimer not disclosed in the application as filed, see VI, 5.3.11.