For the purposes of this Directive:

(a) "vehicle" means a vehicle as defined in Article 1(1) of Directive 72/166/EEC;

(b) "bureau" means a national insurers' bureau as defined in Article 1(3) of Directive 72/166/EEC;

(c) "guarantee fund" means the body referred to in Article 1(4) of Directive 84/5/EEC;

(d) "parent undertaking" means a parent undertaking as defined in Articles 1 and 2 of Directive 83/349/EEC [0J No L 193, 18. 7. 1983, p. 1];

(e) "subsidiary" means a subsidiary undertaking as defined in Articles 1 and 2 of Directive 83/349/EEC; any subsidiary undertaking of a subsidiary undertaking shall also be regarded as a subsidiary of the parent undertaking which is at the head of those undertakings.