a) Waiting for the preliminary opinion not compatible with convergent approach 

(i) Preliminary opinion not an invitation to make further submissions 

In T 1756/16 the board refused under Art. 13(2) RPBA to admit an inventive-step objection raised only after the summons to oral proceedings. It did not accept the appellant's argument that it had to be taken into account because it had been submitted within the period set in the board's communication under Art. 15(1) RPBA. It pointed out that – even if, as in this case, a communication under Art. 15(1) RPBA often set the parties a time limit for filing any submissions, which would then be subject to the admission criteria in Art. 114(2) EPC and Art. 13 RPBA – it was not a communication under R. 100(2) EPC inviting them to file observations within a specified period. The appellant had therefore not been entitled to presume that any new objections would be admitted simply because they had been filed before that time limit. See also T 884/18.

In T 1767/18 the board pointed out that a communication sent by a board in preparation for oral proceedings was not binding. It was intended solely as an aid to preparing for the oral proceedings and was precisely not to be understood as an invitation to make new submissions.

(ii) Requirement to respond to the case made by the opposing party 

In T 1108/16 the board found as follows: a party's omitting to carefully analyse the opposing party's written pleadings and preferring to wait for the board's preliminary opinion before responding to an objection (here: objection of extended scope of protection) was at odds with the function of appeal proceedings, which were aimed at reviewing the contested decision, and with the rule designed to ensure the necessary procedural economy that parties had to present their complete cases at an early stage (Art. 106(1) EPC, R. 99(2) EPC and Art. 12(2) RPBA). The respondent's conduct ran counter to procedural economy and so the board refused to admit the arguments it had submitted only in response to the board's communication.

See also chapter V.A.4.5.5f) "Board's opinion based exclusively on earlier party submissions or reasoning of the first-instance division" and chapter V.A.4.5.5g) "Importance of a direct response to the other party's written submissions".