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The parties to a contract of sale shall be free to exclude the application thereto of the present Law either entirely or partially. Such exclusion may be express or implied.
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1. The parties shall be bound by any usage which they have expressly or impliedly made applicable to their contract and by any practices which they have established between themselves.
2. They shall also be bound by usages which reasonable persons in the same situation as the parties usually consider to be applicable to their contract. In the event of conflict with the present Law, the usages shall prevail unless otherwise agreed by the parties.
3. Where expressions, provisions or forms of contract commonly used in commercial practice are employed, they shall be interpreted according to the meaning usually given to them in the trade concerned.
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A contract of sale need not be evidenced by writing and shall not be subject to any other requirements as to form. In particular, it may be proved by means of witnesses
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1. The buyer shall lose the right to rely on a lack of conformity of the goods if he has not given the seller notice thereof promptly after he discovered the lack of conformity or ought to have discovered it. If a defect which could not have been revealed by the examination of the goods provided for in Article 38 is found later, the buyer may nonetheless rely on that defect, provided that he gives the seller notice thereof promptly after its discovery. In any event, the buyer shall lose the right to rely on a lack of conformity of the goods if he has not given notice thereof to the seller within a period of two years from the date on which the goods were handed over, unless the lack of conformity constituted a breach of a guarantee covering a longer period.
2. In giving notice to the seller of any lack of conformity, the buyer shall specify its nature and invite the seller to examine the goods or to cause them to be examined by his agent.
3. Where any notice referred to in paragraph 1 of this Article has been sent by letter, telegram or other appropriate means, the fact that such notice is delayed or fails to arrive at its destination shall not deprive the buyer of the right to rely thereon.
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Where the parties have agreed upon a date for the payment of the price or where such date is fixed by usage, the buyer shall, without the need for any other formality, pay the price at that date.
Where the contract is not avoided, damages for a breach of contract by one party shall consist of a sum equal to the loss, including loss of profit, suffered by the other party. Such damages shall not exceed the loss which the party in breach ought to have foreseen at the time of the conclusion of the contract, in the light of the facts and matters which then were known or ought to have been known to him, as a possible consequence of the breach of the contract.
Where the breach of contract consists of delay in the payment of the price, the seller shall in any event be entitled to interest on such sum as is in arrears at a rate equal to the official discount rate in the country where he has his place of business or, if he has no place of business, his habitual residence, plus 1%.
http://www.unidroit.org/english/conventions/c-main.htm