【正文】 ules applicable to their contract would however be well advised to bine the reference to the Principles with an arbitration agreement. The reason for this is that the freedom of choice of the parties in designating the law governing their contract is traditionally limited to national laws. Therefore, a reference by the parties to the Principles will normally be considered to be a mere agreement to incorporate them in the contract, while the law governing the contract will still have to be determined on the basis of the private international law rules of the forum. As a result, the Principles will bind the parties only to the extent that they do not affect the rules of the applicable law from which the parties may not derogate. The situation may be different if the parties agree to submit disputes arising from their contract to arbitration. Arbitrators are not necessarily bound by a particular domestic law. This is selfevident if they are authorised by the parties to act as amiable positeurs or ex aequo et bono. But even in the absence of such an authorisation there is a growing tendency to permit the parties to choose rules of law other than national laws on which the arbitrators are to base their decisions. See in particular Art. 28(1) of the 1985 UNCITRAL Model Law on International Commercial Arbitration。 where a party has more than one place of business the relevant place of business is that which has the closest relationship to the contract and its performance, having regard to the circumstances known to or contemplated by the parties at any time before or at the conclusion of the contract。 (b) lack of authority。 or (b) if it was reasonable for the offeree to rely on the offer as being irrevocable and the offeree has acted in reliance on the offer. ARTICLE (Rejection of offer) An offer is terminated when a rejection reaches the offeror. ARTICLE (Mode of acceptance) (1) A statement made by or other conduct of the offeree indicating assent to an offer is an acceptance. Silence or inactivity does not in itself amount to acceptance. (2) An acceptance of an offer bees effective when the indication of assent reaches the offeror. (3) However, if, by virtue of the offer or as a result of practices which the parties have established between themselves or of usage, the offeree may indicate assent by performing an act without notice to the offeror, the acceptance is effective when the act is performed. ARTICLE (Time of acceptance) An offer must be accepted within the time the offeror has fixed or, if no time is fixed, within a reasonable time having regard to the circumstances, including the rapidity of the means of munication employed by the offeror. An oral offer must be accepted immediately unless the circumstances indicate otherwise. ARTICLE (Acceptance within a fixed period of time) (1) A period of time for acceptance fixed by the offeror in a telegram or a letter begins to run from the moment the telegram is handed in for dispatch or from the date shown on the letter or, if no such date is shown, from the date shown on the envelope. A period of time for acceptance fixed by the offeror by means of instantaneous munication begins to run from the moment that the offer reaches the offeree. (2) Official holidays or nonbusiness days occurring during the period for acceptance are included in calculating the period. However, if a notice of acceptance cannot be delivered at the address of the offeror on the last day of the period because that day falls on an official holiday or a nonbusiness day at the place of business of the offeror, the period is extended until the first business day which follows. ARTICLE (Late acceptance. Delay in transmission) (1) A late acceptance is nevertheless effective as an acceptance if without undue delay the offeror so informs the offeree or gives notice to that effect. (2) If a letter or other writing containing a late acceptance shows that it has been sent in such circumstances that if its transmission had been normal it would have reached the offeror in due time, the late acceptance is effective as an acceptance unless, without undue delay, the offeror informs the offeree that it considers the offer as having lapsed. ARTICLE (Withdrawal of acceptance) An acceptance may be withdrawn if the withdrawal reaches the offeror before or at the same time as the acceptance would have bee effective. ARTICLE (Modified acceptance) (1) A reply to an offer which purports to be an acceptance but contains additions, limitations or other modifications is a rejection of the offer and constitutes a counteroffer. (2) However, a reply to an offer which purports to be an acceptance but contains additional or different terms which do not materially alter the terms of the offer constitutes an acceptance, unless the offeror, without undue delay, objects to the discrepancy. If the offeror does not object, the terms of the contract are the terms of the offer with the modifications contained in the acceptance. ARTICLE (Writings in confirmation) If a writing which is sent within a reasonable time after the conclusion of the contract and which purports to be a confirmation of the contract contains additional or different terms, such terms bee part of the contract, unless they materially alter the contract or the recipient, without undue delay, objects to the discrepancy. ARTICLE (Conclusion of contract dependent on agreement on specific matters or in a specific form) Where in the course of negotiations one of the parties insists that the contract is not concluded until there is agreement on specific matters or in a specific form, no contract is concluded before agreement is reached on those matters or in that form. ARTICLE (Contract with terms deliberately left open) (1) If the parties