Respected Suryanarayana Sir,
Let us assume that a person from INDIA receive purchase order from USA.
Now, INDIAN do not want to purchase goods from India, He planned to purchase goods from CHINA & Sell it to USA.
Now, if INDIAN tell to CHINA party that he is going to send goods to USA, there is full possibility that CHINA & USA will come together in future.
Now to avoid this INDIAN exporter import goods from china but does not file bill of entry for imports in India., he contacts shipping line for Switch B/L so now shipper & consignee is changed and now USA party becomes importer and INDIAN party becomes exporter (in new bill of lading). So CHINA party will feel that his importer is from INDIA, & USA party will feel that he is importing from INDIA. CHINA & USA will never come in contact with each other as INDIAN is middle man.
Such kind of transaction is widely used in INDIA & shipping line call it Switch B/L