Definition from buildingSMART: A definition relationship
(IfcRelDefines) that uses a type definition or property set definition
(seens as partial type information) to define the properties of the object
instance. It is a specific - occurrence relationship with implied dependencies
(as the occurrence properties depend on the specific properties).
The IfcRelDefines relationship establishes the link between one
type (specific) information and several objects (occurrences). Those
occurrences then share the same type (or partial type) information.
EXAMPLE: Several instances of windows within
the IFC project model may be of the same (catalogue or manufacturer) type.
Thereby they share the same properties. This relationship is established by a
subtype of the IfcRelDefines relationship assigning an
IfcProductType (or subtype thereof) to the
HISTORY: New entity in IFC
|| Reference to the objects (or single object) to which the property definition applies.