International Law — Sources of — Practice of the Parties to the Dispute as Determining the Law Applicable by the Arbitrator.

Acquiescence — Absence of Protest — Relevance of.

Arbitration — Award — How far Based on Available Sources of Evidence.

State Territory — Cession — Requirement of Formal Delivery of Possession — Whether Forming Part of International Law — Formal Delivery in regard to Territories Awarded by the Arbitrator — Declarative or Constitutive Effect of the Arbitral Award — The Principle uti possidetis juris — Application to Cession and to Arbitral Awards — Effectiveness of the Latter — Admissibility of Partial Executions — Tacit Consent of the Parties — Absence of Protest — Legal Nature of Boundary Commissions.