Definition from IAI: An IfcCostModifierValue is the value
of a cost modifier that can be added to or subtracted from a cost.
HISTORY: New class in IFC
Release 2x.
ISSUES: See issue and change
log for additions and changes made in IFC Release 2x.
Use Definition
The currency in which a modifier value is expressed may be the same as
or different to the currency of the cost that is being modified if, AND ONLY
IF, the modifier value is not added to or subtracted from that cost. For
instance, it might be possible to buy something in (say) Polish Zloty but to
have a delivery cost from the landing point in US$. However, this is not an
appropriate use of the IfcCostModifier.ModifierAssignments concept; such
a circumstance should be dealt with by treating the modifier as a cost in its
own right. Usage of the IfcCostModifierValue should be restricted to
circumstances where the value of the IfcCostModifierValue.Currency
attribute is the same as the value of the IfcCost.Currency attribute of
the cost being modified.