The patent claims must clearly define the subject-matter for which protection is sought under Art. 84 EPC. In T 94/82 (OJ 1984, 75) it was held that this requirement was fulfilled in a claim to a product when the characteristics of the product were specified by parameters relating to the physical structure of the product, provided that those parameters could be clearly and reliably determined by objective procedures which were usual in the art. In such a product claim, it sufficed to state the physical properties of the product in terms of parameters, since it was not mandatory to give instructions in the claim itself as to how the product was to be obtained. The description, however, had to fulfil the requirements of Art. 83 EPC 1973 and thus enable the person skilled in the art to obtain the claimed product described in it (see also T 487/89, T 297/90, T 541/97). Nor should this be understood as also referring to those variants falling under the literal wording of the claim but which the skilled person would immediately exclude as being clearly outside the scope of practical application of the claimed subject matter, for example, claims including an open ended range for a parameter where it was clear for a skilled person that the open-ended range was limited in practice. Values of the parameter not obtainable in practice would not be regarded by the skilled person as being covered by the claims and thus could not justify an objection of insufficiency of disclosure (T 1018/05).

It is of relevance whether a problem falls within Art. 83 or Art. 84 EPC when taking into consideration that examination in respect of the requirements of Art. 83 EPC is still permitted during opposition proceedings, whereas in respect of Art. 84 EPC it is limited during opposition proceedings to those cases where there has been an amendment (see T 127/85, OJ 1989, 271; see also T 301/87, OJ 1990, 335; T 1055/98; T 5/99). With regard to the examination in respect of Art. 84 EPC during opposition proceedings see also chapter II.A.1.4.; and recent decision G 3/14, confirming the jurisprudence exemplified by T 301/87).

In T 292/85 (OJ 1989, 275) the stated grounds for the refusal were that the disclosure was not sufficient under Art. 83 EPC 1973 and there was consequently a lack of proper support under Art. 84 EPC 1973. The board pointed out that in appropriate cases it is only possible to define the invention (the matter for which protection was sought, Art. 84 EPC 1973), in a way which gives fair protection having regard to the nature of the invention which had been described by using functional terminology in the claims. The need for fair protection governs both the considerations concerning the scope of claims and the requirements for sufficient disclosure. The board found that an invention is sufficiently disclosed if at least one way is clearly indicated enabling the skilled person to carry out the invention.

In T 409/91 (OJ 1994, 653; ex parte) and T 435/91 (OJ 1995, 188; inter partes) it was pointed out that the protection conferred by a patent should correspond to the technical contribution to the art made by the disclosure of the invention described therein, which excludes the patent monopoly being extended to subject-matter which, after reading the patent specification, would still not be at the disposal of the skilled person. The available information must enable the skilled person to achieve the envisaged result within the whole ambit of the claim containing the respective functional definition without undue difficulty, and the description with or without the relevant common general knowledge must provide a fully self-sufficient technical concept as to how this result is to be achieved. T 409/91 was followed up in T 713/98, where the board stated that the requirement of understanding a claim characterised by a functional feature defining a result to be achieved was one of clarity and the requirement of implementing it was one of support, both within the meaning of Art. 84 EPC 1973. Implementation, viewed in relation to the disclosure as a whole, was highly relevant to the question of sufficiency under Art. 83 EPC 1973. See also T 1225/07.

In the inter partes case T 435/91 (OJ 1995, 188), one of the essential technical features was defined only by its function. It was not possible to identify, on the basis of the information contained in the patent specification or of common general knowledge, compounds other than those specifically mentioned as bringing about the desired effect. The board held that the compositions must all be available to the skilled person if the definition was to meet the requirements of Art. 83 EPC 1973.

However, as long as there are no concrete grounds for believing that the invention cannot be carried out within the whole range claimed, there is no reason for not allowing more broadly based claims in an application (T 242/92, T 484/92). In opposition proceedings the opponent bears the burden of proving that the invention cannot be carried out within the whole range claimed (T 418/91, T 456/91, T 548/91). See in this chapter II.C.9.

In T 1404/05 the board found that where a claim is vaguely formulated and leaves several constructions open as possibilities, and on one of these constructions part of the subject-matter claimed is not sufficiently described to be carried out, the claim is open to objection under Art. 100(b) EPC 1973. To avoid this objection the claim needs to be explicitly restricted to a construction which is also possible on the vague formulation of the claim, but which construction is not open to an Art. 100(b) EPC 1973 objection. The mere fact that the description makes clear that this latter construction is the one intended does not mean that the claim can be treated as being confined to this latter construction. Art. 69 EPC 1973 and its protocol were intended to assist a patent proprietor in contending for a broader interpretation of a claim than perhaps its wording warranted, not for cutting down the scope of a claim.

In T 553/11 the board pointed out that if the proprietor wishes to argue for a narrow scope of a claim, this should be on the basis of the ordinary wording of the claim, and not on the basis of something appearing only in the description (following T 1404/05). The board also referred to T 681/01, where it was emphasised that the normal rule of claim construction is that the terms used in a claim should be given their ordinary meaning in the context of the claim in which they appear. The description may not be used to rewrite the claim and redefine the technical features required by the claim in a way not warranted by the wording of the claim itself. In particular the description cannot be relied on to exclude subject-matter from the claim which the ordinary meaning of the terms used would include as part of what is claimed. See also chapter II.A.6.3. "Using description and drawings to interpret the claims".

In T 1188/15 the skilled person had no requirement to interpret the claim in a more limited sense in the light of a specific embodiment of the description to which the claim was not limited, the claim itself imparting a clear and credible technical teaching to the skilled reader.

In T 1691/11 claim 1 of all requests included the features of "at least two independent programmable motors" and "at least one of the transferring devices being coupled to each of the programmable motors". These features were clear and unambiguous. The clear linguistic structure of the claim did not allow for any different interpretation. Additionally, a discrepancy between the claims and the description was not a valid reason to ignore the clear linguistic structure of a claim and thus to interpret the claim differently (see also T 431/03). When the wording of a claim is perfectly clear it needs to be considered under Art. 83 EPC, rather than undertaking another speculative interpretation of the claim.

T 2182/11 concerned the second aspect of the appellant's (opponent's) objection relating to the alleged impossibility of carrying out the claimed invention over the whole range claimed because of the vague claim language. The board had in particular stated in its preliminary opinion that the expression "register with" was very broad. The board stated that breadth of an expression was really a matter concerning the clarity requirement of Art. 84 EPC rather than a ground for opposition. In as far as the objection was to be considered under Art. 83 EPC, the mere fact that a term is broad does not prevent a skilled person from carrying out the invention.