Terms of payment:The buyer shall open though a bank accepable to the seller an Irrevocable Letter of Credit at sight to reach the Seller 30 days before the month of shipment and remained valid for negotiation in China until the 15th day after the day of shipment.麻烦帮我翻译一下,
问题描述：
Terms of payment:The buyer shall open though a bank accepable to the seller an Irrevocable Letter of Credit at sight to reach the Seller 30 days before the month of shipment and remained valid for negotiation in China until the 15th day after the day of shipment.麻烦帮我翻译一下,
答
关于付款：尽管在装运货物月30天之前，银行便同意提供给购买者一份不可变更的信用状，并且在装运货物15天之后在中国仍具有协商法律效应，购买者也应保持坦诚的态度。
答
这是最基本的外贸术语：
付款条件：买方须通过一家卖方认可的银行开立即期不可撤销信用证,不迟于装运月份前30天到达卖方,装运日后15日内在中国境内议付有效.