IfcObject

IfcObject

Defintion from IAI: An IfcObject is the generalization of any semantically treated thing or process within IFC. Objects are things as they appear - i.e. occurences.

NOTE Examples of IfcObject include physically tangible items, such as wall, beam or covering, physically existing items, such as spaces, or conceptual items, such as grids or virtual boundaries. It also stands for processes, such as work tasks, for controls, such as cost items, for actors, such as persons involved in the design process, etc.

Objects are independent pieces of information that might contain or reference other pieces of information. There are four essential kind of relationships in which objects can be involved:

Assignment of other objects - an assignment relationship (IfcRelAssigns) 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.
Association to external resources - an association relationship (IfcRelAssociates) refer to external sources of information (most notably a classification or document) and creates a uni-directional association. There is no dependency implied by the association.
Aggregation 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.
Refinement by type and properties - a refinement relationship (IfcRelDefines) that uses a type definition or (partial) property set definition 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).

HISTORY New Entity in IFC Release 1.0
ISSUES See issue and change log for changes made in IFC Release 2x.

EXPRESS specification:

ENTITY IfcObject

ABSTRACT SUPERTYPE OF

(ONEOF(IfcActor, IfcControl, IfcGroup, IfcProcess, IfcProduct, IfcProject, IfcResource))

SUBTYPE OF (

IfcRoot);

ObjectType

OPTIONAL IfcLabel;

INVERSE

IsDefinedBy

SET OF IfcRelDefines FOR RelatedObjects;

HasAssociations

SET OF IfcRelAssociates FOR RelatedObjects;

HasAssignments

SET OF IfcRelAssigns FOR RelatedObjects;

Decomposes

SET OF IfcRelDecomposes FOR RelatedObjects;

IsDecomposedBy

SET [0:1] OF IfcRelDecomposes FOR RelatingObject;

WHERE

WR1

SIZEOF(QUERY(temp <* IsDefinedBy | 'IFCKERNEL.IFCRELDEFINESBYTYPE' IN TYPEOF(temp))) <= 1;

END_ENTITY;

Attribute definitions:

ObjectType	:	The type denotes a particular type that indicated the object futher. The use has to be established at the level of instantiable subtypes of IfcObject.
IsDefinedBy	:	Set of Relationships to type or property (statically or dynamically defined) information that further define the object. In case of type information, the associated IfcObjectType contains the specific information (or type, or style), that is common to all instances of IfcObject refering to the same type.
HasAssignments	:	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 or groups.
Decomposes	:	References to the decomposition relationship, that allows this object to be a part of the decomposition.
IsDecomposedBy	:	Reference to the decomposition relationship, that allows this object to be the composition of other objects.