when invoice data are received in an EDP system an accounts payble clerk determines the account numbers to be charged and enters them at a terminal. if purchase orders include these account numbers the system performs this step automatically by retrieving the account numbers from the computer file of purchase orders. the data are compared to the purchase order and receiving report. the common matching criterion on all documents is the purchase order number. quantities dollar amounts due dates terms and unit prices are compared and reconciled. when in agreement the cost data are entered into the accounts payable file (and listings in journal from are produced as needed). alternatively payment can be made immediately by means of EDI or a computer-generated check. the receiving datary records. these postings and those for materials issuances are processed electronically to eliminate manual posting.