from buildingSMART: An IfcObjectDefinition
is the generalization of any semantically treated thing or process,
either being a type or an occurrences. Object defintions can be named,
using the inherited Name
attribute, which should be a user recognizable label for the object
occurrance. Further explanations to the object can be given using the
Objects are independent pieces
of information that might contain or reference other pieces of
information. There are three essential kinds of relationships in which
object definitons (by their instantiable subtypes) can be involved:
of other objects - an assignment
relationship (IfcRelAssigns) that
refers to other types of objects and creates a bi-directional
association. The semantic of the assignment is established at the level
of the subtypes of the general IfcRelAssigns
relationship. There is no dependency implied a priori by the assignment.
to external resources - an
association relationship (IfcRelAssociates)
that refers to external sources of information (most notably a
or document) and creates a uni-directional association. There is no
dependency implied by the association.
of other objects - an
aggregation relationship (IfcRelDecomposes)
that establishes a whole/part relation and creates a bi-directional
relation. There is an implied dependency established.
New abstract entity in Release IFC2x Edition 3.
IFC2x Edition 3
abstract entity IfcObjectDefinition has
been added. Upward compatibility for file
based exchange is guaranteed.
|| Reference to the relationship objects, that assign (by an association relationship) other subtypes of
IfcObject to this object instance. Examples are the association to products, processes, controls, resources
|| Reference to the decomposition relationship, that allows this object to be the composition of other objects.
An object can be decomposed by several other objects.
|| References to the decomposition relationship, that allows this object to be a part of the decomposition.
An object can only be part of a single decomposition (to allow hierarchical strutures only).
|| Reference to the relationship objects, that associates external references or other resource definitions
to the object.. Examples are the association to library, documentation or classification.