Dear Raghuraman,
Thank you for your response.
I cant predict the PO number, it will change depends upon third party system, i.e every time i will receive new PO numbers so by using multi mapping how can we achieve this. it may be 5 or 10 or 2 different types of PO numbers with multiple records in one file.
Note: PO number is Alphanumaric with special character "-"