请教商务英语翻译，英翻中

Within 2 months before the goods goes to the site,Owner shall open one irrevocable stand-by L/C covering 80% of the goods price vaild till the completion of acceptance of the goods.The price for goods in the contract shall be paid in following manner as per milestone stipulated in appendix .

热心网友

Within 2 months before the goods goes to the site,Owner shall open one irrevocable stand-by L/C covering 80% of the goods price vaild till the completion of acceptance of the goods.The price for goods in the contract shall be paid in following manner as per milestone stipulated in appendix . 在货物到达目的地前两个月内，买方开立不可撤消的备用信用证，其金额为货物总价的80%，有次期至交货完成。货款按照附件规定通过以下方式支付以。as per milestone 我也不知道该怎么译，不好意思。

热心网友

Within 2 months before the goods goes to the site,Owner shall open one irrevocable stand-by L/C covering 80% of the goods price vaild till the completion of acceptance of the goods.The price for goods in the contract shall be paid in following manner as per milestone stipulated in appendix.在货物运送到指定地点前两个月，所有人开具面额为货物价值80%的不可撤消的备用信用证，有效期至完成交货止。合同货价按附件中每航行里程计价通过以下方式支付。