Article 23 of the Model Law in International Commercial Arbitration specifically refers to statements of claim and defence. As regards the statement of claim the Article provides that， within the period of time agreed by the parties or decided on by the arbitral tribunal， the claimant has to state the facts supporting their claim， the points at issue and the relief or remedy sought. In response the respondent should state his defence in respect of these particulars， unless the parties have otherwise agreed as to the required elements of such statements. In addition the parties may submit with their statements all documents they consider to be relevant or may add a reference to the documents or other evidence they will submit.

　　However， unless otherwise agreed by the parties， either party may amend or supplement their claim or defence during the course of the arbitral proceedings， unless the arbitral tribunal considers it inappropriate to allow such amendment having regard to the delay in making it.

　　Article 24 makes it clear that all statements， documents or other information supplied to the arbitral tribunal by one party shall be communicated to the other party. Also any expert report or evidentiary document on which the arbitral tribunal may rely in making its decision also has to be communicated to the parties.

　　Article 25 makes clear the different consequences for the parties if they fail to submit their statements of claim or defence. Thus unless otherwise agreed by the parties， if， without showing sufficient cause， the claimant fails to communicate his statement of claim in accordance with article 23(1)， then not surprisingly as there will be no claim to determine， the arbitral tribunal shall terminate the proceedings. However， where the respondent fails to communicate their statement of defence in accordance with article 23(1)， the arbitral tribunal shall continue the proceedings， but it will not treat such failure in itself as an admission of the claimant‘s allegations.

　　Article 25 provides further that where either party fails to appear at a hearing or to produce documentary evidence， the arbitral tribunal may continue the proceedings and make the award on the evidence before it. These provisions， which empower the arbitral tribunal to carry out its task even if one of the parties does not participate are of considerable practical importance since they allow the tribunal to perform its function even where one of the parties has little interest in co-operating or expediting its operation.

　　3 Compared to the obligations of the seller， the general obligations of the buyer under the UN Convention on the International Sale of Goods are less extensive and relatively simple; they are to pay the price for the goods and take delivery of them as required by the contract (Article 53)。 However， the convention does go on to detail how such action is to be conducted.

　　As regards payment the following provisions apply.

　　Firstly， the buyer‘s obligation to pay the price includes taking such steps and complying with such formalities as may be required under the contract or any laws and regulations to enable payment to be made (Article 54)。

　　Where a contract has been validly concluded but does not expressly or implicitly fix or make provision for determining the price， the parties are considered， in the absence of any indication to the contrary， to have impliedly made reference to the price generally charged at the time of the conclusion of the contract for such goods sold under comparable circumstances in the trade concerned (Article 55)。 If the price is fixed according to the weight of the goods， in case of doubt it is to be determined by the net weight (Article 56)。

　　If the buyer is not bound to pay the price at any other particular place， he must pay it to the seller： at the seller‘s place of business. However， if the payment is to be made when the goods or documents are handed over， payment should be made at the place where the handing over takes place. If the seller changes his place of business after the contract has been entered into， he will be liable for any additional expenses that arise as a consequence of that change (Article 57)。