Petition for review proceedings consist of two stages. In the first stage, a panel of the Enlarged Board composed of three members (two legally qualified, one technically qualified) examines all petitions for review and rejects those which are clearly inadmissible or clearly unallowable (unanimity is required; R. 109(2)(a) EPC). Those not rejected are considered by a panel composed of five members (four legally qualified, one technically qualified; R. 109(2)(b) EPC). In these cases, the three-member panel under R. 109(2)(a) EPC is supplemented by two further legally qualified members (Art. 2(3) RPEBA). The chairman of the board against whose decision the petition was filed may not take part in the proceedings (Art. 2(6) RPEBA).