You can inquire the p/o history record which have beeen closed  The p/o status is ˇ§Order completeˇ¨  by ˇ§Order Recordˇ¨ . Similiarly, you catch the same information as ˇ§Order Tracking ˇ¨.  

You can track your purchase order status which havenˇ¦t been closed, you can catch the information as belows by Order Tracking 

You can pay your purchase order by credit card  when the purchase order status is ˇ§Order under negotitationˇ¨

You can cancel your purchase order when the purchase order status is ˇ§Order under negotitationˇ¨.