Develop a functional decomposition model based on the "AS IS" process described in PART II. Note that a business function concerns what is being done and not concerned about the how, when and where aspects of the activities. Decompose starting with the top function (1st level) and ending up to the 3rd level

for the following example

The purchasing department of Company X completes a paper purchase order and sends it to Supplier A via fax, with a copy going to the accounts payable department of X. Supplier A ships the goods and they arrive at company X's receiving dock. A clerk at X's receiving dock completes a paper receiving document describing the goods and sends it to X's accounts payable department. Supplier A meanwhile sends a paper invoice to X's accounts payable department. A clerk in X's accounts payable department would match three documents: the original purchase order, the receiving document, and the invoice. If all three documents match, an accounts payable clerk issues a paper check to supplier A. If they don't match, an accounts payable clerk calls supplier A by phone to reconcile any shipment errors.