Disclaimers play an important role in the drafting of claims and amendments. The principles concerning the allowability of disclaimers are set out in chapter II.E.1.7.3 e) "Drafting of disclaimers – clarity".

CLR II A 3.7 Principles in connection with categories of claim

In T 688/91 the board found that the fact that claims of different categories were deemed to be independent claims did not preclude reference to other independent claims. In the board's view, however, any such reference had to make perfectly clear whether or not the reference was intended to replace features. In the former case, it had for reasons of clarity to replace all the features, and in the latter case none.

CLR II A 3.6 Unspecified features and relative qualities

Unspecified features are permitted as follows:

(a) To avoid an undue limitation of the scope of the claim where the person skilled in the art can verify the result by tests involving nothing more than trial and error (T 88/87).

(b) To render the meaning of the feature intelligible from the actual claim.