It was established in decision T 238/88 (OJ 1992, 709) that the clarity of a claim is not diminished by the mere breadth of a term of art (e.g. "alkyl") contained in it, if the meaning of such term - either per se or in the light of the description - is unambiguous for a person skilled in the art (see also T 950/97, T 103/00, T 1173/03 and T 2068/10; on the problem of the interpretation of claims in general, see point 6 below).
In T 523/91 the board held that the wording "plastics in combination with inserts" and "this insert is combined with the plastics granules in a wound or folded manner" did not cause the subject-matter of the claim to be unclear within the meaning of Art. 84 EPC 1973. Although the nature of the combination covered many possibilities, the resulting subject-matter of the claim was broad rather than unclear. The broadness of a claim could not be contested on its own but only in conjunction with other criteria such as novelty, inventive step or reproducibility.
Likewise in T 688/91 the board stated that a broad claim was not to be equated with one lacking clarity. In this instance the claim was worded as follows: "Integrated microprogrammed apparatus [...] with apparatus to generate the T-states T0 [...], T1 [...], [...] characterised in that [...] the generation both of the T-states T0, T1 [...] and of the further T-states [...] is in each case effected as a function of preceding T-states and of state parameters such as the instantaneous values of state and/or mode signals and [...]". The board held that, even if the words "such as" were understood to mean "for example", with the result that the subsequent information was not to be interpreted in a restrictive sense, the words "state parameters" were clear in as much as they conveyed the fact that T-state generation was to be effected as a function of any parameters representing one of the states of the apparatus. Although the claim was to be regarded as broad, since the terms used were open to general interpretation, breadth was not to be equated with an absence of clarity.
In T 630/93 the board noted that Art. 84, first sentence, EPC 1973 implied that it was not always necessary for a claim to identify technical features or steps in full detail. The function of the essential features, although normally expressed in technical terms, was often to define the borders of an invention rather than details of the invention within those borders. Thus, essential features could often be of a very general character and in extreme cases indicate only principles or a new idea (see also Chapter II.C, sufficiency of disclosure).
In T 29/05 it was held that the existence of unrelated subject matter in the claims at issue was merely hypothetical, and no evidence had been provided by the examining division to support its possible presence in the prior art. In the absence of such evidence, each and every nucleic acid molecule (as specified) had to be assumed to be related to the subject matter disclosed in the application. The fact that a large number of possible nucleic acid sequences might fall within the scope of the claim was not a reason for raising a lack of clarity objection.