The following provisions shall apply to any person employed as a member of the travelling personnel of an undertaking engaged in the transport of passengers or goods whether for another undertaking or on its own account:
(a)subject to the provisions of sub-paragraphs (b) and (c), where a person is employed by an undertaking which has its principal place of business in the territory of one Party, the legislation of that Party concerning liability for contributions shall apply to him as if he were employed in its territory even if he is employed in the territory of the other Party;
(b)subject to the provisions of sub-paragraph (c), where the undertaking has a branch or agency in the territory of one Party and a person is employed by that branch or agency, the legislation of that Party concerning liability for contributions shall apply to him;
(c)where a person is ordinarily resident in the territory of one Party and is employed wholly or mainly in that territory, the legislation of that Party concerning liability for contributions shall apply to him, even if the undertaking which employs him does not have a place of business or branch or any agency in that territory.