**Total** – Calculates the total for an order form.
**SubTotal** – Calculates the total of all shipments in an order form.
**HandlingTotal** – Calculates the handling total for an order form.
**ShippingSubtotal** – Calculates the shipping subtotal for an order form.
**OrderDiscountTotal** – Calculates the order form discount amount. It is the total of all order-level discounts of all line items in all shipments in an order form.
**DiscountTotal** – Calculates the order form discount total. It is the total of
order-level discount amounts
line item discount amounts for all line items in all shipments
shipment discount amounts of all shipments in an order form
**OrderFormTotals** – Calculates the order form total.
**TaxTotal** – Calculates an order form's tax total.

## Change the default calculation
## Change the default validation
The default implementation validates that the total is not negative after the calculation. To change the behavior, override the appropriate method: ValidateTotal, ValidateSubtotal, ValidateHandlingTotal, ValidateShippingSubtotal, or ValidateTaxTotal.