Under Art. 13(1) RPBA, it is at the board's discretion to admit any amendment to a party's case after it has filed its grounds of appeal or reply. Art. 13(1) RPBA merely lists examples of factors to be considered by the board in exercising its discretion (complexity of the new subjectmatter, current state of proceedings and procedural economy) and not an exhaustive set of criteria which must be cumulatively met for subsequently amended submissions to be disregarded (R 16/09, T 253/10). As a rule, the boards' decisions should be based on the issues in dispute at first instance, which does not rule out the admission of new submissions, but does subject it to the fulfilment of certain criteria, given that no entirely "fresh case" should be created on appeal (on this and other points, see also T 356/08, T 1685/07, T 162/09).
Although the belated filing of claim request is inherently fraught with the risk that they be disregarded, the situation is, nonetheless, rather frequently encountered. Accordingly, there are many decisions by the boards of appeal which define the circumstances which may arise, and the criteria which should be fulfilled, to justify the admission of these requests (T 516/06).
Thus, in addition to the factors referred to in Art. 13(1) RPBA, the following criteria may, according to settled case law, likewise be decisive: there must be sound reasons for filing a request at a late stage in the proceedings, as may be the case where amendments are occasioned by developments during the proceedings. The amendments must be prima facie clearly allowable, and their introduction must not constitute an abuse of procedure. They must not extend the scope of discussion determined by the grounds of appeal and the respondent's reply or introduce new facts on which the other party has had no opportunity to comment. Nor may they lead to an excessive delay in the proceedings. The time at which requests comprising amended claims were filed and the number of amended claim sets are also factors to be considered. Besides the timing of the request, an important factor is whether the various claim versions "converge" or "diverge", in other words whether they develop and increasingly limit the subject-matter of the independent claim of a main request in the same direction and/or in the direction of a single inventive idea, or whether they entail different lines of development because, for instance, they each incorporate different features. The scope of the amendment and the degree of difficulty or complexity involved in examining it are relevant, while the request's chances of success may also be important (see, on the last point, T 951/91, OJ 1995, 202; T 81/03, T 942/05, T 1474/06, T 162/09, T 1634/09, T 376/10, T 683/10).