(1) For the purposes of this Part -

"college of supervisors" means a permanent but flexible structure for co-operation, coordination and facilitation of decision-making concerning the supervision of a group;

"group" means a group of undertakings that - (a) consists of a participating undertaking, its subsidiaries and the entities in which the participating undertaking or its subsidiaries hold a participation, as well as undertakings linked to each other by a relationship as set out in Article 12(1) of Directive 83/349/EEC, or (b) is based on the establishment, contractually or otherwise, of strong and sustainable financial relationships among the undertakings;

"group supervisor" means the supervisory authority responsible for group supervision, determined in accordance with Regulation 248;