j) Basis of the appeal proceedings unchanged and amendment not detrimental to procedural economy 

On the interpretation of the term "exceptional circumstances" in Art. 13(2) RPBA, the board in T 988/17 observed that neither Art. 13(2) RPBA nor the related explanatory remarks in CA/3/19 (see also Supplementary publication 2, OJ 2020, 60) explained how to determine in general whether circumstances are "exceptional". However, the remarks did mention, as an example of such circumstances, situations where the board raised an objection for the first time in a communication. According to these remarks, the changed basis of the appeal proceedings in such a situation justified amending submissions. The board concluded that the question of whether, conversely, amended submissions also changed the basis of the appeal proceedings was thus a possible criterion to be applied when assessing whether the circumstances were exceptional. In addition, the board had to consider the criteria under Art. 13(1) RPBA when exercising its discretion under Art. 13(2) RPBA. In the case before it, the board concluded that the amended submissions (on whether there was an inventive step), which were based on facts and evidence already submitted earlier on in the appeal proceedings, did not change the basis of the proceedings, helped to resolve the issue raised and were therefore not detrimental to procedural economy. It therefore exercised its discretion to admit the new submissions into the proceedings.