As far as I can see, there is no clear answer in the case law to the question whether a patent proprietor can revert to the patent as granted in opposition appeal proceedings if it has not requested maintenance as granted before the Opposition Division (OD).
In decisions such as T 105/09 and T 755/00 the patent proprietor has been allowed to do so, provided that this behaviour was not the expression of an abuse of procedure.
However, nowadays, some (perhaps most) Boards see things differently, as the present decision in a revocation appeal case illustrates.
*** Translation of the German original ***
[2.2] It is true that pursuant to Article 12(1) RPBA appeal proceedings shall be based on the notice of appeal and the statement of grounds of appeal, but pursuant to paragraph (4) of the same article the Board has the power to hold inadmissible requests which could have been presented in the first instance proceedings, although they comply with the requirements of paragraph (1).
There is no doubt that in the present case the claims as granted could have been part of the first instance proceedings. However, the patent proprietor has limited itself during the opposition proceedings and has not pursued the granted version, so that the first instance could not decide on the granted version.
[2.3] The factual situation underlying decision T 933/04 cited by the [opponent] is essentially the same as in the present case: the appellant (patent proprietor) also abandoned the granted version during the opposition proceedings and pursued a limited version in order to circumvent an objection of the OD, but during the appeal proceedings it wanted to revert to the granted version. The Board was of the opinion that the patent proprietor had abandoned its right to have a reasoned decision of the OD on the patent as granted. As a consequence, it did not admit the request to maintain the patent as granted.
[2.4] Even if the Board would not asses the corresponding behaviour of the [patent proprietor] in the present case as an abandonment of the granted version, the admission of this request that has only been filed during the appeal proceedings contravenes procedural economy. As a matter of fact, if it admitted the request, the Board would have to decide on this request for the first time, which is not in line with its role as a reviewing body (Überprüfungsinstanz), or to remit the case, which would considerably delay the proceedings and increase the costs incurred by the adverse party.
As Article 12(4) RPBA has precisely the purpose of avoiding such situations, the Board has not admitted the sole request of the [patent proprietor].
[2.5] The [patent proprietor] has explained that its procedural behaviour during the first instance proceedings had the purpose of accelerating the proceedings because, in view of the opinion of the OD expressed in the summons it thought that it was not appropriate to defend the granted version.
However, the Board cannot see how this behavior could accelerate the proceedings. Quite to the contrary, the fact that there is no decision on this request delays the entire first and second instance proceedings.
This argument, therefore, cannot prompt the Board to exercise its discretion in another way.
 As there is no request that is both admissible and agreed upon by the [patent proprietor] (A 113(2)), the appeal has to be dismissed.
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The file wrapper can be found here.