See also IV.E.7.7 "Binding effect of decision remitting case to department of first instance" below.
It was established by the Enlarged Board in G 1/97 (OJ 2000, 322) that:
1. In the context of the EPC 1973, the jurisdictional measure to be taken in response to requests based on the alleged violation of a fundamental procedural principle and aimed at the revision of a final decision of a board of appeal having the force of res judicata should be the refusal of the requests as inadmissible.
2. The decision on inadmissibility is to be issued by the board of appeal which took the decision forming the subject of the request for revision. The decision may be issued immediately and without further procedural formalities.
3. This jurisdictional measure applies only to requests directed against a decision of a board of appeal bearing a date after that of the present decision.
4. If the Legal Division of the EPO is asked to decide on the entry in the Register of European Patents of a request directed against a decision of a board of appeal, it must refrain from ordering that the entry be made if the request, in whatever form, is based on the alleged violation of a fundamental procedural principle and aimed at the revision of a final decision of a board of appeal.
This situation has not been changed by the introduction of a petition for review in Art. 112a EPC (T 365/09). According to the board, a first difference between appeal and petition evidently lay in the fact that, unlike Art. 106(1) EPC, Art. 112a(3) EPC clearly excludes a suspensive effect of the petition. Moreover, a petition for review can, according to Art. 112a EPC, only be based on fundamental procedural violations or defects during the appeal proceedings, which do not include questions relating to patentability. This can be derived from the exhaustive list of fundamental procedural violations and defects in Art. 112a(2) EPC and R. 104 and 105 EPC. This view has, in the meantime, been confirmed in G 3/08 (OJ 2011, 10).
In T 846/01 it was clear that the appellants were not contesting the substance of the opposition division's interlocutory decision, which dealt with the renumbering of the claims and the adaptation of the description, but were actually trying to reopen the issue of validity which had already been decided in an earlier decision of a board of appeal. Under Art. 106 EPC 1973 and in view of the principle of res judicata, this finding in the decision was not open to challenge, even though the opposition division decision was accompanied by a form stating the decision was appealable.