The boards have been called upon several times to discuss the question whether a correction under R. 88, second sentence, EPC 1973 (now R. 139 EPC) could be allowed even if the requested amendment would constitute an extension of protection within the meaning of Art. 123(2) EPC 1973 over the disclosure made on the date of filing. In decisions T 401/88 (OJ 1990, 297) and T 514/88 (OJ 1992, 570) the answer was negative. In T 200/89 (OJ 1992, 46) the board took a similar view with regard to Art. 123(3) EPC 1973 and concluded that requests for correction under R. 88 EPC 1973 and requests for amendment under Art. 123 EPC 1973 had to be considered separately.
A further question was whether, for the purposes of correction under R. 88, second sentence, EPC 1973 (now R. 139 EPC), the evidence that nothing else would have been intended than what was offered as the correction could take the form of documents filed only after the application. On this point a different conclusion was reached in T 401/88 (OJ 1990, 297) than in J 4/85 (OJ 1986, 205).
As a result of referrals by the President of the EPO (G 3/89, OJ 1993, 117) and by a board of appeal (G 11/91, OJ 1993, 125) both questions came to be decided by the Enlarged Board. The Enlarged Board's conclusion was that the parts of a European application or patent relating to the disclosure (description, claims and drawings) could be corrected only within the limits of what the skilled person would derive directly and unambiguously, using common knowledge and seen objectively and relative to the date of filing, from the whole of these documents as originally filed. Such a correction was of a strictly declaratory nature and thus did not infringe the prohibition of extension under Art. 123(2) EPC 1973. Other documents - notably priority documents and the abstract - could not be used for correction purposes even if filed together with the application, but could, however, be adduced as evidence of common general knowledge on the date of filing. Evidence of what constituted such knowledge on that date could be furnished in any suitable form. And documents not relating to the disclosure could, under certain circumstances, be included partially or wholly in the disclosure by means of reference.
No correction was possible if there was any doubt as to whether a mistake existed, or whether nothing else could have been intended other than what was offered as the correction.
In T 1008/99, the request for correction of errors concerned a European divisional application which had been filed with a wrong description not related to the earlier (parent) application. The wrongly filed description should therefore be replaced by the description of the parent application. The board held that for the purposes of R. 88 EPC 1973, the error had to be apparent from the divisional application itself, and the parent application could not be used to demonstrate that the error was obvious.
Moreover, according to decision G 2/95 (OJ 1996, 555, point 2 of the Reasons), the interpretation of R. 88, second sentence, EPC 1973 had to be in accord with Art. 123(2) EPC 1973, which meant that a correction under R. 88 EPC 1973 was bound by Art. 123(2) EPC 1973, in so far as it related to the content of the European patent application as filed. A correction could therefore be made only within the limits of the content of the parts of the application which determined the disclosure of the invention, namely the description, claims and drawings. Other documents could only be used for proving what was common general knowledge on the date of filing. As far as a divisional application pursuant to Art. 76 EPC 1973 was concerned, the content of the application which determined the disclosure was that of the divisional application as filed, rather than that of the earlier (parent) application.
In T 195/09 the invention related to mechanical warewashing compositions containing scale inhibiting polymers. With regard to Art. 123(3) EPC, the appellant/patent proprietor submitted, inter alia, that, by considering the description, the skilled person would have understood that the granted claim 1 referred erroneously to copolymerizable sulfonated polymers instead of copolymerizable sulfonated monomers and that the amended claim 1 according to the auxiliary request, by reporting the truly intended technical features of the invention, would not extend the scope of the granted patent. However, the finding of the decision under appeal on the question of common general knowledge and the board's reasoning in respect of the application of Art. 69(1) EPC led it to conclude that claim 1 as granted would have been understood by the skilled person as it stood. Therefore, this argument of the appellant/patent proprietor could also not justify the allowability under Art. 123(3) EPC of the auxiliary request. The board also noted that the decisions G 3/89 and G 11/91, cited by the appellant/patent proprietor during oral proceedings, concern only the allowability of a request for correction of an error and the relationship between R. 88 EPC 1973 and Art. 123(2) EPC. Therefore, these decisions could not apply to the case at issue where the allowability of the amended patent under Art. 123(3) EPC had to be decided on.