(c) Notwithstanding paragraph (b), where three arbitrators are to be appointed as a result of the exercise of the discretion of the Center under Article 14(b), the Claimant shall, by notice to the Center and to the Respondent, nominate an arbitrator within 15 days after the receipt by it of notification by the Center that the Tribunal is to be composed of three arbitrators. The Respondent shall nominate an arbitrator within 30 days after the receipt by it of the said notification. The two arbitrators shall, within 20 days after the appointment of the second arbitrator, nominate a third arbitrator, who shall be the presiding arbitrator.
(d) If the nomination of any arbitrator is not made within the applicable period of time referred to in the preceding paragraphs, that arbitrator shall be appointed in accordance with Article 19.
Appointment of Three Arbitrators in Case of Multiple Claimants or Respondents