To use this module, when some customer returns some refundable products
to you after you created an invoice, you need to:

For a sale order:

1.  Go to *Sales \> Sales Orders \> Create*.
2.  Choose a customer and add a product whose *Invoicing Policy* is
    *Delivered quantities*, and input some quantity to sell.
3.  Confirm the sale.
4.  Go to *Delivery \> Validate \> Apply*.
5.  Return to the sale order.
6.  Press *Create Invoice \> Invoiceable lines \> Create and View
    Invoices*.
7.  The created invoice's amount is the same you sold.
8.  Return to the sale order.
9.  Go to *Delivery \> Return*.
10. Set *Quantity* to a lower quantity than the sold one, and enable *To
    Refund*.
11. Press *Return \> Validate \> Apply*.
12. Return to the sale order.
13. Press *Create Invoice \> Invoiceable lines (deduct down payments) \>
    Create and View Invoices*.
14. A refund is created for the quantity you returned before.

For allowing to refund quantities after the picking has been confirmed
if you did not check 'to refund' in wizard, you can change the value of
'Refund Options' field.

To use this module, when you return some refundable products to your
supplier after you created an invoice, you need to:

1.  Go to *Purchase \> Purchase Orders \> Create*.
2.  Choose a supplier and add a product whose *Invoicing Policy* is
    *Delivered quantities*, and input some quantity to buy.
3.  Confirm the order.
4.  Go to *Delivery \> Validate \> Apply*.
5.  Return to the purchase order.
6.  Press on smart button "Invoices" and create one.
7.  The created invoice's amount is the same you sold.
8.  Return to the purchase order.
9.  Go to *Delivery \> Return*.
10. Set *Quantity* to a lower quantity than you bought, and enable *To
    Refund*.
11. Press *Return \> Validate \> Apply*.
12. Return to the purchase order.

For allowing to refund quantities after the picking has been confirmed
if you did not check 'to refund' in wizard, you can change the value of
'Refund Options' field.
