In G 3/89 (OJ 1993, 117) and 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 application or patent had to contain such an obvious error that a skilled person was in no doubt that the information was not correct and could not be meant to read as such. The skilled person must be in a position objectively and unambiguously to recognise the incorrect information using common general knowledge. If, on the other hand, it was doubtful whether any information at all was incorrect, then a correction was ruled out. The same applies if incorrect information only becomes apparent in the light of the proposed correction.

In T 664/03 the board held that, even if it considered an interpretation of granted claim 1 in the broader context of the description, it was at least doubtful that the skilled person would come to the conclusion that the feature in question was incorrectly defined in that claim. Therefore, the precondition for correction under R. 88, second sentence, EPC 1973 had not been met.

In T 829/05 the board held that, even if the skilled person were aware of an inconsistency between the claim and the drawing, he would have no cause to believe that the claim was incorrect. The drawing was stated to be diagrammatic and, in the absence of any evident technical reason to suspect that the claim was incorrect, the skilled person would simply accept the inconsistency as being characteristic of a schematic drawing.

In T 2230/08 the board considered that the definition of the range of temperature for the incoming stream of regenerating gas in claim 1 did not appear to the skilled person as an error, even less as an obvious one. Furthermore there was no evidence that an error of transcription occurred in the case at issue. Consequently, the request for correction under R. 139 EPC was rejected.

In T 1436/12 the applicant sought the correction of a reference to a document (a US patent application identified by its docket number) incorporated by reference in the European application. Given that the incorporation by reference of features from a cross-referenced document fell under a different regime before the EPO than before the USPTO, the board deemed it to be conceivable that the incorporation of the reference was meant only for the prosecution before the USPTO and was, therefore, deliberately not amended when the International application was filed at the EPO. Thus the board was not convinced that the reference to a docket number in an application filed at the EPO must generally be considered to have been made in error.

In T 1702/12 the board held that the skilled person had no reason to doubt the value of 500 when reading granted claim 1 at face value, since this value made technical sense. Even when taking the description and dependent claims of the granted patent into account, the skilled person could not be sure that the value of 500 was erroneous, or whether an error occurred in the description or said dependent claims. The board rejected the argument that any relevant evidence must be taken into account. Rather, if it was necessary to study the prosecution history of the case in order to determine whether an error had been made and what the correction should be, then the criterion of immediacy in R. 139 EPC was not met.

In T 2523/11 the appellant sought to correct a value of a range in claim 1. The board held that while the range in claim 1 was not necessarily what the appellant wished to pursue, and even if this might indeed have been unintentional, the error itself was not obvious, since the wording of claim 1 was clear and understandable, no inconsistency with regard to the description existed, the range fell within the range as originally disclosed and it made perfect technical sense. Hence, the skilled person would not have any reason to doubt that it was anything but the limited range which was intended to be pursued.