Linguistic errors, errors of transcription and mistakes in any document filed with the EPO may be corrected on request. Requests for such amendments may be made at any time. However, if the error to be corrected concerns items which third parties might expect to be able to take at face value, so that their rights would be jeopardised by correction (e.g. priority claims), the request for correction must be filed as soon as possible, and at least in time that it could be incorporated in the publication of the European patent application. An exception to this rule may be allowed if it is apparent on the face of the published application that a mistake has been made (see J 4/82, OJ 10/1982, 385 as well as J 2/92, J 3/91 and J 6/91, OJ 6/1994, 375, 365 and 349, respectively, as well as J 11/92, OJ 1-2/1995, 25, and J 7/94, OJ 12/1995, 817). Regarding correction of the date indicated for the previous filing, see also III, 6.6.

If the error is in the description, claims or drawings, the correction must be obvious in the sense that it is immediately evident that nothing else could have been intended than what is offered as the correction. Such a correction may be effected only within the limits of what a skilled person would derive directly and unambiguously, using common general knowledge, and seen objectively and relative to the date of filing, from the whole of the documents as filed (see G 3/89 and G 11/91, OJ 3/1993, 117, 125; see also C-VI, 5.4).

In the case of electronic filing of European patent applications, the technical documents (description, claims, abstract and drawings) may be attached in their original format, provided this format is one listed in the Notice dated 29 October 2002 (OJ 11/2002, 545). Pursuant to this Notice, these technical documents may also be attached in a format other than those listed, provided that the applicant informs the EPO, when filing the application, where the EPO can reasonably acquire the corresponding software. If, on the date of filing, the documents making up the European patent application are available both in the format provided by the epoline^® Online Filing software and in another admissible format in accordance with the above-mentioned Notice, the documents in the latter format can also be used in order to determine whether a request for correction of the description, claims, or drawings is allowable.

It is in particular not allowable to replace the complete application documents (i.e. description, claims and drawings) by other documents which the applicant had intended to file with his request for grant (see G 2/95, OJ 10/1996, 555). The Examining Division decides on the request for correction. If a request for correction is pending before termination of the technical preparations for publication, a reference to the request is published on the front page.