(139)The college of supervisors should be a permanent platform for coordination among supervisory authorities, fostering a common understanding of the risk profile of the group and of its related undertakings and aiming at a more efficient and effective risk based supervision at both group and individual levels. In this context, in order to ensure a proper functioning of the college it is necessary to set out criteria for considering a branch to be significant for the purpose of the participation of supervisory authorities of significant branches in the college. It is also essential to harmonise the requirements applicable to the coordination of supervision of insurance and reinsurance groups, in order to foster the convergence of supervisory practices.