The Enlarged Board of Appeal remarked in G 9/91 (OJ 1993, 408) that in practice it is rather unusual that the opposition is limited to only a certain part (subject-matter) of the patent. Normally, the whole of the patent is opposed. Addressing the situation where it was clear from the statement under R. 55(c) EPC 1973 (R. 76(2)(c) EPC) that the patent was opposed only to a certain extent, the Enlarged Board held that by limiting the extent to which the patent is opposed to only certain subject-matters, the opponent deliberately refrains from making use of his right under the EPC to oppose remaining subject-matters covered by the patent. Such subject-matters are therefore, strictly speaking, not subject to any "opposition" in the sense of Art. 101 and 102 EPC, nor are there any "proceedings" in the sense of Art. 114 and 115 EPC concerning such non-opposed subject-matters.

The statements in the notice of opposition relevant to the extent to which the European patent is opposed should be interpreted in such a way that an addressee would understand them, taking into account the surrounding circumstances (T 376/90, OJ 1994, 906; see also T 1/88, in which the board based its interpretation of equivocal procedural acts on the "objective value of the declaration", German: "objektiver Erklärungswert"). However, the general practice of interpreting the absence of such statements as an indication of the opponent's intention to oppose the patent concerned in its entirety, has been subject to scrutiny in the light of G 9/91. In T 376/90 the board doubted that this "liberal" practice could be continued. In the extreme, where the extent to which a patent is opposed is in serious doubt, this reviewed approach may lead to a rejection of the opposition as inadmissible (T 376/90). However, in T 764/06 the board concluded from the absence of a statement under R. 55(c) EPC 1973 that the patent was opposed only to a certain extent that the patent in suit was opposed in its entirety.