b) Board's preliminary opinion based exclusively on earlier submissions 

In T 908/19 the appellant (opponent) justified the late submission of a further document and new lines of attack only at the oral proceedings by arguing that neither the document nor the objections could have been raised earlier since they were filed in response to the board's preliminary opinion expressed in the annex to the summons. The board could not accept this argument, as its preliminary opinion had been based exclusively on the submissions made by the parties in the grounds of appeal and the reply. Nor had the appellant identified any particular aspect that might be new or surprising to it, but rather appeared motivated by the fact that the board had pronounced itself provisionally in favour of the respondent. Thus, the board saw no exceptional circumstances, let alone ones that had been reasoned, which could justify the late filing of these submissions.

See also T 276/17 (D 23 not admitted, because the board's communication had merely addressed an issue already raised by the opposition division and made the connection with one of the appellant's arguments).