In T 1554/16 the appellant (opponent) had attached a translation of a Japanese patent specification to its grounds of appeal. Later, after receiving the summons to oral proceedings, it also filed a translation of the related patent application. For the board, the later translation was not an amendment to the appeal case within the meaning of Art. 13(1) RPBA 2020, because a Japanese patent specification usually did not contain any teaching going beyond the original disclosure in the application and so the opponent's line of argument had already been clear from the translation of the specification. The disclosure in the translated application did not add anything new to the substance of that line of argument.