If the facts and grounds essential to a decision have been submitted by one party and if the party whose case is to be rejected has been afforded sufficient time to comment, the principle concerning the right to a hearing set out in Art. 113(1) will have been respected. If the decision in opposition proceedings is to be based on grounds which were raised in the examination proceedings but not in the notice of opposition, the observations by the parties or the communications of the Opposition Division, these must be introduced (i.e. raised for discussion) by the Opposition Division in the opposition proceedings before the decision is given so as to afford the parties an opportunity to comment. If the opposition is based on lack of inventive step, the proprietor of the patent must expect that the prior art newly designated in the opposition proceedings will be considered in conjunction with the prior art described in the introductory part of an independent claim. However, if new facts and grounds are introduced during the proceedings or if the facts and grounds on which the envisaged decision is to be based were not stated so unambiguously and clearly in the written submissions of the parties as to give a party occasion to comment, the party concerned must be given an opportunity to submit an opinion and to produce evidence before the decision is given.