지불방법에서요, 잘이해가 안되서요. 전문가의 조언을 좀 구합니다.

Terms of Payment：By Confirmed, Irrevocable, Transferable and Divisible L/C to be available by sight draft to reach the Seller before August 15, 2004 and to remain valid for negotiation in China until 21 days after the Time of Shipment. The L/C must specify that transshipment and partial shipments are allowed and that 15% more or less in quantity and value is allowed for the first shipment. After the first shipment, the quantity and value will be confirmed in written by both sides and 5% more or less in quantity is allowed. <이하생략>