Disputes — Arbitration — Procedure — Competence — Iran-United States Claims Settlement Declaration — Forum selection clause — Contracts containing provisions for settlement of disputes by Iranian courts — Cases arising therefrom outside the jurisdiction of the Iran-United States Claims Tribunal — Interpretation — Clause conferring jurisdiction over some contractual disputes upon the courts of Iran — Whether sufficient to exclude jurisdiction of the Tribunal — Ambiguity in clause — The law and practice of the Iran-United States Claims Tribunal