【正文】 Principles socalled “consumer transactions” which are within the various legal systems being increasingly subjected to special rules, mostly of a mandatory character, aimed at protecting the consumer, . a party who enters into the contract otherwise than in the course of its trade or profession. The criteria adopted at both national and international level also vary with respect to the distinction between consumer and nonconsumer contracts. The Principles do not provide any express definition, but the assumption is that the concept of “mercial” contracts should be understood in the broadest possible sense, so as to include not only trade transactions for the supply or exchange of goods or services, but also other types of economic transactions, such as investment and/or concession agreements, contracts for professional services, etc. 3. The Principles and domestic contracts between private persons Notwithstanding the fact that the Principles are conceived for international mercial contracts, there is nothing to prevent private persons from agreeing to apply the Principles to a purely domestic contract. Any such agreement would however be subject to the mandatory rules of the domestic law governing the contract. 4. The Principles as rules of law governing the contract a. Express choice by the parties As the Principles represent a system of principles and rules of contract law which are mon to existing national legal systems or best adapted to the special requirements of international mercial transactions, there might be good reasons for the parties to choose them expressly as the rules of law governing their contract. In so doing the parties may refer to the Principles exclusively or in conjunction with a particular domestic law which should apply to issues not covered by the Principles (see the Model Clause in the footnote to the second paragraph of the Preamble). Parties who wish to choose the Principles as the rules of law governing their contract are well advised to bine such a choice of law clause 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 (see Comment 3 on Article ). The situation is 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 parties are generally permitted to choose “rules of law” other than national laws on which the arbitrators are to base their decisions (see in particular Article 28(1) of the 1985 UNCITRAL Model Law on International Commercial Arbitration。 Article 24(1) of the Rules of the Arbitration Institute of the Stockholm Chamber of Commerce). Normally arbitral tribunals will apply a particular domestic law as the proper law of the contract, yet exceptionally they may resort to anational or supranational rules such as the Principles. This may occur when it can be inferred from the circumstances that the parties intended to exclude the application of any domestic law (. where one of the parties is a State or a government agency and both parties have made it clear that neither would accept the application of the other’s domestic law or that of a third country), or when the contract presents connecting factors with many countries none of which is predominant enough to justify the application of one domestic law to the exclusion of all the others. 5. The Principles as a means of interpreting and supplementing international uniform law instruments International uniform law instruments may give rise to questions concerning the precise meaning of their individual provisions and may present gaps. Traditionally international uniform law has been interpreted on the basis of, and supplemented by, principles and criteria of domestic law, be it the law of the forum or that which would, according to the relevant rules of private international law, be applicable in the absence of an international uniform law. Recently, both courts and arbitral tribunals have increasingly abandoned such a “conflictual” approach, seeking instead to interpret and supplement international uniform law by reference to autonomous and internationally uniform principles and criteria. This approach, expressly sanctioned in recent conventions (see, ., Art. 7 of the 1980 UN Convention on Contracts for the International Sale of Goods (CISG)), is based on the assumption that international uniform law, even after its incorporation into the various national legal systems, only formally bees an integrated part of the latter, whereas from a substantive point of view it does not lose its original character of a special body of law autonomously developed at international level and intended to be applied in a uniform manner throughout the world. Until now, such autonomous principles and criteria for the interpretation and supplementing of international uniform law instruments have had to be found in each single case by the judges and arbitrators themselves on the basis of a parative survey of the solutions adopted in the different national legal systems. The Principles could considerably facilitate their t