• **Total** – Calculates the total of all return order forms in a purchase order.

  Text

  

• **SubTotal** – Calculates the subtotal of all return order forms in a purchase order.

  Text

  

• **ShippingSubTotal** – Calculates the shipping subtotal of all return order forms in a purchase order.

  Text

  

## Change the default calculation

By inheriting from the default implementation of the interface, DefaultReturnPurchaseOrderCalculator, you can override the calculations. Just override one or more methods in DefaultReturnPurchaseOrderCalculator.

## Change the default validation

The default implementation validates that the totals are not negative after the calculation. To change the behavior, override the ValidateTotal, ValidateSubTotal and ValidateShippingSubTotal methods.