Under R. 76(2)(b) EPC (former R. 55(b) EPC 1973), the notice of opposition must contain, inter alia, the number of the patent, the name of the proprietor and the title of the invention. If the identification of the patent against which the opposition has been filed is insufficient, the opposition must be rejected as inadmissible under R. 77(1) EPC (former R. 56(1) EPC 1973), unless the deficiency has been remedied before expiry of the opposition period.
In T 317/86 (OJ 1989, 378) the opponent had not indicated the title of the invention within the period specified under R. 77(2) EPC (former R. 56(2) EPC 1973). The board decided that omission from the notice of opposition of the title of the invention - merely an item of bibliographical data identifying the contested patent - did not constitute a deficiency within the meaning of R. 77(2) EPC (former R. 56(2) EPC 1973), provided that the other particulars available to the EPO were together sufficient to identify easily and beyond doubt the patent being contested by means of an opposition.
In T 344/88 the board of appeal considered whether the citing by the opponent of the wrong number for a patent specification contravened R. 76(2)(c) EPC (former R. 55(c) EPC 1973), if the mistake was not corrected until after expiry of the opposition period. The first patent specification cited by the opponent bore no relation at all to the invention. However, the notice of opposition contained enough detailed information for it to have been possible to identify the actual patent specification intended. The board of appeal allowed the number to be corrected. Given such a detailed submission of facts, it would have been taking formal requirements too far to reject the opposition simply because the wrong number had been given for a cited patent specification. Whether or not the EPO actually effected a correction between receipt of the notice of opposition and expiry of the period of opposition was irrelevant. The sole decisive factor was that the error was recognisable within the period for opposition and that the opposition division was able, on the basis of the description of the citation, to establish the latter's identity beyond all doubt.
In T 335/00 and T 336/00, the R. 76(2)(b) EPC (former R. 55(b) EPC 1973) requirements were not strictly fulfilled. Among other things, the title of the invention was missing, and the opposition was directed to the application. The board nonetheless deemed the opposition admissible because the contested patent was identifiable uniquely and fairly easily on the basis of the specified publication number. Even the mistake of opposing an application and the omission of the title did not seem serious enough to the board to render the opposition inadmissible.