Under Art. 13(1) RPBA 2007, the board must exercise its discretion in view of the need for procedural economy, that is, the need to conclude proceedings swiftly and to create legal certainty. It also follows from the inter-relationship between Art. 12 and 13 RPBA 2007 that amendments made to a party's case after filing of the grounds of appeal do not form part of the subject of the appeal and so must be admitted in order to be considered (T 253/10).