IfcObject

Natural language names
Objekt
Object
Objet
Semantic definitions at the entity
Entity definition

An IfcObject is the generalization of any semantically treated thing or process. Objects are things as they appear - i.e. occurrences.

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, or for actors such as persons involved in the design process.

Objects 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 inherited Description attribute. The ObjectType attribute is used:

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

NOTE  See IfcRelDefinesByType for an explanatory figure. Also see there for how to override type properties by occurrence properties. See IfcRelDefinesByObject for an explanatory figure for the assignment of a partial type.
HISTORY  New entity in IFC1.0
IFC4 CHANGE  The inverse relationships Declares, IsDeclaredBy, and IsTypedBy have been added, types are not longer included in the IsDefinesBy relationship. IfcProject has been promoted to be a subtype of IfcObjectDefinition -> IfcContext.

Informal Propositions:

  1. A partial type assignment, i.e. the inverse attribute IsDeclaredBy, or Declares shall only be used, if the object is part of a decomposition, i.e. if either IsDecomposedBy, or Decomposes is exerted.
Attribute definitions
#AttributeTypeCardinalityDescription G
5ObjectTypeIfcLabel? The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED.
X
IsDeclaredByIfcRelDefinesByObject
@RelatedObjects
S[0:1]Link to the relationship object pointing to the declaring object that provides the object definitions for this object occurrence. The declaring object has to be part of an object type decomposition. The associated IfcObject, or its subtypes, contains the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes.
IFC4 CHANGE  New inverse relationship, change made with upward compatibility for file based exchange.
X
DeclaresIfcRelDefinesByObject
@RelatingObject
S[0:?]Link to the relationship object pointing to the reflected object(s) that receives the object definitions. The reflected object has to be part of an object occurrence decomposition. The associated IfcObject, or its subtypes, provides the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes.
IFC4 CHANGE  New inverse relationship, change made with upward compatibility for file based exchange.
X
IsTypedByIfcRelDefinesByType
@RelatedObjects
S[0:1]Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type.
IFC4 CHANGE  New inverse relationship, the link to IfcRelDefinesByType had previously be included in the inverse relationship IfcRelDefines. Change made with upward compatibility for file based exchange.
X
IsDefinedByIfcRelDefinesByProperties
@RelatedObjects
S[0:?]Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object.
IFC4 CHANGE  The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange.
X
Inherited definitions from supertypes
Entity inheritance IfcActor IfcControl IfcGroup IfcProcess IfcProduct IfcResource IfcObjectDefinition IfcRoot
Attribute inheritance
#AttributeTypeCardinalityDescriptionG
IfcRoot
1GlobalIdIfcGloballyUniqueId Assignment of a globally unique identifier within the entire software world. X
2OwnerHistoryIfcOwnerHistory? Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object,
NOTE  only the last modification in stored - either as addition, deletion or modification.
IFC4 CHANGE  The attribute has been changed to be OPTIONAL.
X
3NameIfcLabel? Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule. X
4DescriptionIfcText? Optional description, provided for exchanging informative comments.X
IfcObjectDefinition
HasAssignmentsIfcRelAssigns
@RelatedObjects
S[0:?]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.X
NestsIfcRelNests
@RelatedObjects
S[0:1]References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical strutures only).
IFC4 CHANGE  The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition.
X
IsNestedByIfcRelNests
@RelatingObject
S[0:?]References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types).
IFC4 CHANGE  The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition.
X
HasContextIfcRelDeclares
@RelatedDefinitions
S[0:1]References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object.
IFC4 CHANGE  The inverse attribute datatype has been added.
X
IsDecomposedByIfcRelAggregates
@RelatingObject
S[0:?]References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definitions can be aggregated by several other objects (occurrences or parts).
IFC4 CHANGE  The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
X
DecomposesIfcRelAggregates
@RelatedObjects
S[0:1]References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definitions can only be part of a single decomposition (to allow hierarchical strutures only).
IFC4 CHANGE  The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
X
HasAssociationsIfcRelAssociates
@RelatedObjects
S[0:?]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.X
IfcObject
5ObjectTypeIfcLabel? The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED.
X
IsDeclaredByIfcRelDefinesByObject
@RelatedObjects
S[0:1]Link to the relationship object pointing to the declaring object that provides the object definitions for this object occurrence. The declaring object has to be part of an object type decomposition. The associated IfcObject, or its subtypes, contains the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes.
IFC4 CHANGE  New inverse relationship, change made with upward compatibility for file based exchange.
X
DeclaresIfcRelDefinesByObject
@RelatingObject
S[0:?]Link to the relationship object pointing to the reflected object(s) that receives the object definitions. The reflected object has to be part of an object occurrence decomposition. The associated IfcObject, or its subtypes, provides the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes.
IFC4 CHANGE  New inverse relationship, change made with upward compatibility for file based exchange.
X
IsTypedByIfcRelDefinesByType
@RelatedObjects
S[0:1]Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type.
IFC4 CHANGE  New inverse relationship, the link to IfcRelDefinesByType had previously be included in the inverse relationship IfcRelDefines. Change made with upward compatibility for file based exchange.
X
IsDefinedByIfcRelDefinesByProperties
@RelatedObjects
S[0:?]Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object.
IFC4 CHANGE  The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange.
X
Definitions applying to General Usage

 Instance diagram


Concept usage

Object User Identity

The Object User Identity concept applies to this entity.

An attribute Name and optionally Description can be used for all subypes of IfcObject. For those subtypes, that have an object type definition, such as ifcBeam - IfcBeamType, the common Name and optionally Description is associated with the object type.



Object Predefined Type

The Object Predefined Type concept applies to this entity.



Object Typing

The Object Typing concept applies to this entity.

Any object occurrence can be typed by being assigned to a common object type utilizing this concept. A particular rule, restricting the applicable subtypes of IfcTypeObject that can be assigned, is introduced by overriding this concept at the level of subtypes of IfcObject.



Property Sets for Objects

The Property Sets for Objects concept applies to this entity.

Any object occurrence can hold property sets, each being a set of individual properties having name, description, value(s) and unit(s). A reference to applicable property sets, being part of this specification, is introduced at the level of sub types of IfcObject.



Property Sets with Override

The Property Sets with Override concept applies to this entity.

Any object occurrence can hold property sets, either directly at the object occurrence as element specific property sets, or at the object type, as type property sets. In this case, the properties that are provided to the object occurrence are the combinations of element specific and type properties. In case, that the same property (within the same property set, is defined both, in occurrence and type properties, the property value of the occurrence property overrides the property value of the type property.



mvdXML Specification
<?xml version="1.0"?>
<ConceptRoot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" uuid="e60ba889-b830-457c-8551-1f5bb04e7377" name="IfcObject" status="sample" applicableRootEntity="IfcObject">
  <Applicability uuid="00000000-0000-0000-0000-000000000000" status="sample">
    <Template ref="c7ad266e-1918-4f78-b6a7-7c889a92e44f" />
    <TemplateRules operator="and" />
  </Applicability>
  <Concepts>
    <Concept uuid="b6683294-9b20-4230-be6f-66be3c6e6f94" name="Object User Identity" status="sample" override="false">
      <Template ref="c19ec186-9cfd-47fc-a4d4-9fb35008d04a" />
    </Concept>
    <Concept uuid="db7acf12-3ad4-4476-8e64-803b35fe8431" name="Object Predefined Type" status="sample" override="false">
      <Template ref="25248261-98df-4d0a-9364-5653575ca421" />
    </Concept>
    <Concept uuid="41d988ad-131f-4e38-b736-1e9cc28c26bf" name="Object Typing" status="sample" override="false">
      <Template ref="35a2e10e-20df-40f4-ab2f-dacf0a6744f4" />
    </Concept>
    <Concept uuid="fd52471d-aa2d-4a82-9ac0-967908c78fa1" name="Property Sets for Objects" status="sample" override="false">
      <Template ref="f74255a6-0c0e-4f31-84ad-24981db62461" />
    </Concept>
    <Concept uuid="559f82ae-5587-4811-9c4a-375db1c19c2a" name="Property Sets with Override" status="sample" override="false">
      <Template ref="e26040e8-82e2-4f6a-bc63-ac8e6da2d0ae" />
    </Concept>
  </Concepts>
</ConceptRoot>
Concept inheritance

#ConceptTemplateModel View
IfcRoot
IdentitySoftware IdentityGeneral Usage
Revision ControlRevision ControlGeneral Usage
IfcObjectDefinition
Classification AssociationClassification AssociationGeneral Usage
IfcObject
Object User IdentityObject User IdentityGeneral Usage
Object Predefined TypeObject Predefined TypeGeneral Usage
Object TypingObject TypingGeneral Usage
Property Sets for ObjectsProperty Sets for ObjectsGeneral Usage
Property Sets with OverrideProperty Sets with OverrideGeneral Usage
Formal representations
XML Specification
 <xs:element name="IfcObject" type="ifc:IfcObject" abstract="true" substitutionGroup="ifc:IfcObjectDefinition" nillable="true"/>
 <xs:complexType name="IfcObject" abstract="true">
  <xs:complexContent>
   <xs:extension base="ifc:IfcObjectDefinition">
    <xs:sequence>
     <xs:element name="IsDeclaredBy" type="ifc:IfcRelDefinesByObject" nillable="true" minOccurs="0" maxOccurs="1"/>
     <xs:element name="IsTypedBy" type="ifc:IfcRelDefinesByType" nillable="true" minOccurs="0" maxOccurs="1"/>
     <xs:element name="IsDefinedBy" nillable="true" minOccurs="0">
      <xs:complexType>
       <xs:sequence>
        <xs:element ref="ifc:IfcRelDefinesByProperties" minOccurs="0" maxOccurs="unbounded"/>
       </xs:sequence>
       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcRelDefinesByProperties"/>
       <xs:attribute ref="ifc:cType" fixed="set"/>
       <xs:attribute ref="ifc:arraySize" use="optional"/>
      </xs:complexType>
     </xs:element>
    </xs:sequence>
    <xs:attribute name="ObjectType" type="ifc:IfcLabel" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcObject
 ABSTRACT SUPERTYPE OF(ONEOF(IfcActor, IfcControl, IfcGroup, IfcProcess, IfcProduct, IfcResource))
 SUBTYPE OF (IfcObjectDefinition);
  ObjectType : OPTIONAL IfcLabel;
 INVERSE
  IsDeclaredBy : SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
  Declares : SET [0:?] OF IfcRelDefinesByObject FOR RelatingObject;
  IsTypedBy : SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
  IsDefinedBy : SET [0:?] OF IfcRelDefinesByProperties FOR RelatedObjects;
 WHERE
  UniquePropertySetNames : ((SIZEOF(IsDefinedBy) = 0) OR IfcUniqueDefinitionNames(IsDefinedBy));
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

References  References: IfcRelDefinesByObject IfcRelDefinesByType

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