The data model consists of the following:
The IfcPropertyResource defines a basic set of property types
that can be associated with occurrence objects (subtypes of IfcObject)
and type objects (subtypes of IfcTypeObject) through the
IfcPropertySet (defined in the Kernel). These properties are used to
assign property definitions that are semantically defined by a name string and
are extensible in terms of their definitions.
NOTE: Frequently, there is a need to extend the
attributes that are attached to an individual object or group of objects. Yet
it may not be necessary to extend the attributes for every object within the
same class. Using the same capabilities as for types of an element, it is
possible to define such sets of attributes and associate them with individual
The association of attributes to objects can be defined by two different
- by defining a type object (IfcTypeObject) which defines a
specific object information (including the relevant properties) which are
attached to all instances (or occurrences) of the type object (via the
- by defining a property set (IfcPropertySet, a logical grouping
of related properties) which defines the common property information for a
group of instances (or occurrences), this is done via the
The semantic information of what an individual property denotes has to
be given by the Name attribute. The Name is human interpretable
and can also be computer interpretable by convention. This convention has to be
established by implementers' agreements.
NOTE: The IFC specification defines a set of property
sets, which provides a recommended usage of property sets for objects in the
IFC model. In addition to the IFC property set specification also regional or
project specific definitions of property sets are possible. Thereby property
sets provide an mechanism to localize IFC definitions.
All subtypes of IfcProperty are referenced later by the
IfcPropertySet. Thereby the IfcPropertySet establishes a tree of
property definitions through the IfcSimpleProperty (and its subtypes)
and IfcComplexProperty. It should be noted, that any instance of
IfcSimpleProperty (and its subtypes) shall only be referenced once (by
either IfcPropertySet or IfcComplexProperty).
NOTE: The property set attached to an object shall
have a tree structure, therefore all properties (either
IfcSimpleProperty -and subtypes- or IfcComplexProperty) shall be
used only once within that structure.
Interfaced schemas (8):
Select types (1):