Article 568. Project design and contract costs

1. Unless otherwise provided in the contract, the goods to be exchanged shall be presumed to be of equal value and the costs of their transfer and acceptance shall be borne in each case by the party responsible for the exchange. 2. Where, under the contract, changes in the goods exchanged are deemed to be unequal, the party obliged to deliver the goods whose price is lower than the price of the goods by providing in exchange must pay the price difference immediately before or after the performance of its duty to deliver the goods, unless otherwise provided for in the contract.