3.2.3 Use of the description and/or drawings to establish definitions of unclear terms not defined in the claims 

Some technical features of the claims may be defined by unclear terms so that the scope of the claims cannot be determined unambiguously. In such cases, the description and/or drawings is/are used to interpret the meaning of the terms in question (see F‑IV, 4.2).

For example: 

Claim 1: Pneumatic tyre comprising a wide groove disposed in a tread portion, characterised in that the wide groove is provided on the groove bottom with at least one longitudinal rib extending in the longitudinal direction of the wide groove. 

Description: The term "wide", as used in the context of the present invention, means not less than 20mm wide. 

The term "wide" in claim 1 is unclear, since it is a relative term with no well-defined meaning in this technical field. Consequently the scope of the claim is unclear (F‑IV, 4.6, Art. 84). However, the description gives an unambiguous definition of this term. The definition of "wide" as being "not less than 20mm wide" is taken into account when the search is carried out (subsequently, an objection to the clarity of the term "wide" is raised in the search opinion according to Art. 84, second sentence). The definition of "wide" in the description is also a fallback position (see B‑III, 3.2.5).