If it is necessary to use the same purchase order number is made to cancel a document has already been posted. The Purchasing Department should be specified in the document notes that it is original. "A new update or Revise" all the time.
If necessary, Require the cancellation of the original purchase order number to the document. Note the purchasing department should know that the original document. "Renovation or Revise" every time.
In case of necessity. To use the order number, the cancellation of original documents. Purchasing department should enter a note note in a document that is original. "New improved or Revise." every time.