Examination of an opposition is limited to the extent to which the patent is opposed in the notice of opposition. If the opponent limits the notice of opposition to certain matters, the remaining matters are not opposed within the meaning of Art. 101 and 102 EPC 1973 or the subject of any proceedings within the meaning of Art. 114 and 115 EPC 1973 (G 9/91 and G 10/91, OJ 1993, 408 and 420). The opponent thereby deliberately refrains from exercising his right under the EPC to oppose the other matters covered by the patent and, consequently, the EPO has no competence to deal with them at all. (T 737/92, T 653/02, T 31/08).
Following G 9/91 and G 10/91 (OJ 1993, 408 und 420), the board in T 580/89 of 28 April 1993 concluded that it had no power to examine the patentability of the subject-matter of claims which had not been opposed in the notice of opposition but were the subject of observations by the third party under Art. 115 EPC 1973 which had not reached the EPO until after the decision of the opposition division had been taken.