((a)) ** .—** To facilitate the administration of the System, the Secretary, under such terms and conditions as the Secretary may consider advisable, may appoint and establish advisory committees in regard to the functions of the Service as the Secretary considers advisable.

((b)) ** .—** is waived with respect to any advisory commission or advisory committee established by law in connection with any System unit during the period for which the commission or committee is authorized by law.

((c)) ** .—** Any member of any advisory commission or advisory committee established in connection with any System unit may serve after the expiration of the member’s term until a successor is appointed.

((d)) ** .—** Members of an advisory committee established under subsection (a) shall receive no compensation for their services as such but shall be allowed necessary travel expenses as authorized by .