Following the entry into force of the EPC 2000, the second sentence of R. 139 EPC reads: "if the request for such correction concerns the description, claims or drawings, the correction must be obvious in the sense that it is immediately evident that nothing else would have been intended than what is offered as the correction". This wording does not differ in substance from the former R. 88 EPC 1973; only some editorial changes have been made in the three languages.
In G 3/89 (OJ 1993, 117; see also G 11/91, OJ 1993, 125) the Enlarged Board of Appeal specified that, for a correction under R. 88, second sentence, EPC 1973 to be allowed, the respective part of the European patent had to contain such an obvious error that a skilled person was in no doubt that the feature concerned could not be meant to read as such. If, on the other hand, it was doubtful whether that feature was incorrectly defined, then a correction was ruled out (see T 664/03, T 580/05; see also T 382/07 where G 11/91 did not apply).
In J 42/92 the board had to decide whether a request under R. 88, second sentence, EPC 1973 could be made after grant. It came to the conclusion that a request under R. 88 EPC 1973 for amendments to the description or claims could only be filed during the pendency of application or opposition proceedings. Under Art. 97(4) EPC 1973, the decision to grant a European patent took effect on the date on which the European Patent Bulletin mentioned the grant. After this date, R. 88 EPC 1973 could only be applied while opposition proceedings were pending. In the case at issue, the decision to grant the patent had already taken effect, and no opposition had been filed. The appeal had therefore been dismissed, since the EPO had ceased to have jurisdiction to consider a request under R. 88 EPC 1973 at the time when the request was filed. The board also pointed out that there is no reason why, once no application or opposition proceedings are pending before the EPO, decisions on the question of corrections (bearing in mind the requirement of obviousness to a skilled person) should not fall within the sole jurisdiction of the national courts or other authorities responsible for proceedings in which this question may arise (quoting J 42/92, see also J 23/03 and T 493/08).
Readers should note that G 1/10 (OJ 2013, 194) deals with the different fields of application of various provisions as compared with R. 140 EPC (formerly R. 89 EPC 1973), in particular R. 139 EPC (points 9 and 11 of the Reasons) and Art. 123 EPC (see point 13 of the Reasons).