I need help doing a Logical DFD for the Textbook Chapter 4 problem SP 4-4 on Cornick, Inc. from Accounting Information Systems by Gelinas/Dull/Wheeler/Hill 11e: Use the narrative to prepare a logical DFD. Use visio or any other diagramming software to create the diagram for the problem.

The narrative is : Cornick Inc sells office products to businesses in the eastern region fo the US. Each month, the IT division at Cornick prints monthly statements and sends them to accounts receivable department where a clerk mails them to customers. Cornick's customers mail their payments back to cornick, where a clerk in AR batches the checks and sends them to the cashier. The AR Clerk then uses the payment stub to enter the payments into the computer, where the AR master data are updated to record the payment.

The answer has to be in 4 column format with 16 diagram elements. I know the 4 columns are IT/AR/Customer/Cashier. I am confuses on the 16 elements