題組內容

四：下列為信用狀中關於受益人應行提示單據之敘述：       "2/3 SET OF CLEAN ON BOARD BILLS OF LADING MADE OUT TO THE ORDER OF UNIONCON LTD., MARKED "FREIGHT PREPAID", AND NOTIFY APPLICANT."
 請依上列敘述，回答下列問題：

（一）"2/3 SET"意義為何？試解釋之。【7 分】