Credit sale bill entry in retail POS

Credit Sale is sale in which the bill amount is paid later, not in the time of purchase.

Business rules

Credit sales allowed only for the credit allowed customer.
After the credit bill customer outstanding will be increased.
Customer outstanding will be received later in Accounts in receipt entry.
It should have both time and amount limit.
Credit sale will be one of the tender type in POS payment screen.
Customer outstanding should be displayed in POS Bill screen when the customer is selected for next sales.