n) Editorial amendments to remove inconsistencies and typographical errors 

In T 131/18 the main request at issue (filed after notification of the summons to oral proceedings) was, save for two amendments, identical in wording and content to auxiliary request 3, which had already been filed in response to the reply and which the board considered to meet the conditions for admission under Art. 13(1) RPBA. The two amendments in the main request served to clear up inconsistencies remaining in auxiliary request 3 (wording incompatible with Art. 123(2) EPC removed from claim 1 but left in dependent claim 2, and an unclear expression replaced in claim 1 but not in claim 6). The board concurred with the appellant that the amendments were merely editorial changes occasioned chiefly by its communication under Art. 15(1) RPBA, and classed this as an exceptional circumstance within the meaning of Art. 13(2) RPBA. Art. 13(2) RPBA had not been intended to rule out entirely the possibility of making minor amendments such as ones correcting obvious discrepancies or grammatical errors, which were admissible under R. 139 EPC for instance, once the summons to oral proceedings had been issued. See also T 911/20, in which a linguistic mistake was corrected that had first been objected to at the oral proceedings before the board.

Similarly, in T 676/21, the board admitted a new auxiliary request 1, filed during the oral proceedings before the board, in which a typographical error had been corrected. This typographical error was already contained in the claims as maintained by the opposition division and contravened Art. 123(3) EPC. It had been overlooked by all up to the oral proceedings.

In T 1558/22, by contrast, the board refused to admit an amendment filed at the oral proceedings that went beyond correcting obvious inconsistencies or grammatical errors. The correction took the form of deleting method claims 12 and 13, which, according to the patent proprietor, contained an obvious error in that certain – clearly intended – features had been left out by mistake. The board, however, could not see any obvious error; nor did it consider it obvious what had originally been intended. It held that the proprietor was obliged, as part of its procedural duty to act diligently, to go through its own requests again ahead of the oral proceedings, and to correct them if necessary.