Appropriate for shipping scales. ( (The charge is determined from the
"shipping weight", and spread back to the OrderItems in proportion to their
The "lookup number" is the sum of the "shipping weights" of the OrderItems,
converted to the QuantityUnit specified by the quantityUnit attribute of the
CalculationScale. The "base monetary value" is the sum of the "net prices" of
the OrderItems. The "result multiplier" is one. The mathematical weights are
the "shipping weights" of the OrderItems.