Pursuant to § 2.26(a), subject to reservations in § 2.26(b), and subject to policy guidance and direction by the Under Secretary, the following delegation of authority is made to the Deputy Under Secretary for Trade and Foreign Agricultural Affairs, if appointed, to be exercised only during the absence or unavailability of the Under Secretary: Perform all the duties and exercise all the powers which are now or which may hereafter be delegated to the Under Secretary for Trade and Foreign Agricultural Affairs: Provided, that this authority shall be exercised by the respective Deputy Under Secretary in the order in which he or she has taken office as a Deputy Under Secretary.