Definition from IAI: An IfcReferencesCostDocument is a
means of referencing many costs and/or cost modifiers to a single document
where the document is a price list or quotation or other source of cost
information.
HISTORY: New class in IFC
Release 2x.
ISSUES: See issue and change
log for changes made in IFC Release 2x.
Use Definitions
The purpose of this class is to be able to identify a reference source
from which costs are obtained. Since many objects may be costed from the same
referenced document, use of a relationship class allows the document to be
identified once only when information is exchanged or shared rather than many
times. If there is no need to identify a costing source, then by not asserting
the IfcReferencesCostDocument class, there is no additional information load on
the IfcCostValue class.