Définition d'un type d'objet type
Objekt (allgemein) - Typ

The object type defines the specific information about a type, being common to all occurrences of this type. It refers to the specific level of the well recognized generic - specific - occurrance modeling paradigm. The IfcTypeObject gets assigned to the individual object instances (the occurrences) via the IfcRelDefinesByType relationship.

NOTE  The terms 'Type' and 'Style' are often used interchangeably.

The object type is represented by a set of property set definitions. The attached property sets describe the available alpha-numeric information about the object type. and are used to define all common properties that apply to all object occurrences of that type.

NOTE  If a property having having the same name is used within the IfcPropertySet assigned to an IfcTypeObject (and subtypes) and to an occurrence of that type, then the occurrence property overrides the type property. See IfcRelDefinesByType for an explanatory figure.

Object types may be exchanged without being already assigned to objects. An object type may have an indication of the library (or catalogue) from which its definition originates. This association is handled by the inherited HasAssociations relationship pointing to IfcRelAssociatesLibrary.

HISTORY  New entity in IFC2x
IFC2x3 CHANGE  The IfcTypeObject is now subtyped from the new supertype IfcObjectDefinition, and the attribute HasPropertySets has been changed from a LIST into a SET.
IFC4 CHANGE  (1) The entity IfcTypeObject shall not be instantiated from IFC4 onwards. It will be changed into an ABSTRACT supertype in future releases of IFC. (2) The inverse attribute Types has been renamed from ObjectTypeOf.

XSD Specification:

 <xs:element name="IfcTypeObject" type="ifc:IfcTypeObject" substitutionGroup="ifc:IfcObjectDefinition" nillable="true"/>
 <xs:complexType name="IfcTypeObject">
   <xs:extension base="ifc:IfcObjectDefinition">
     <xs:element name="HasPropertySets" nillable="true" minOccurs="0">
        <xs:element ref="ifc:IfcPropertySetDefinition" maxOccurs="unbounded"/>
       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcPropertySetDefinition"/>
       <xs:attribute ref="ifc:cType" fixed="set"/>
       <xs:attribute ref="ifc:arraySize" use="optional"/>
    <xs:attribute name="ApplicableOccurrence" type="ifc:IfcIdentifier" use="optional"/>

EXPRESS Specification:

ENTITY IfcTypeObject
SUPERTYPE OF(ONEOF(IfcTypeProcess, IfcTypeProduct, IfcTypeResource))
SUBTYPE OF IfcObjectDefinition;
ApplicableOccurrence : OPTIONAL IfcIdentifier;
HasPropertySets : OPTIONAL SET [1:?] OF IfcPropertySetDefinition;
Types : SET [0:1] OF IfcRelDefinesByType FOR RelatingType;
WR1 : EXISTS(SELF\IfcRoot.Name);

Link to EXPRESS-G diagram EXPRESS-G diagram

Attribute Definitions:

ApplicableOccurrence : The attribute optionally defines the data type of the occurrence object, to which the assigned type object can relate. If not present, no instruction is given to which occurrence object the type object is applicable. The following conventions are used:
  • The IFC entity name of the applicable occurrence using the IFC naming convention, CamelCase with IFC prefix
  • It can be optionally followed by the predefined type after the separator "/" (forward slash), using Uupper case
  • If one type object is applicable to many occurrence objects, then those occurrence object names should be separate by comma "," forming a comma separated string.
EXAMPLE Refering to a furniture as applicable occurrence entity would be expressed as 'IfcFurnishingElement', refering to a brace as applicable entity would be expressed as 'IfcMember/BRACE', refering to a wall and wall standard case would be expressed as 'IfcWall, IfcWallStandardCase'.
HasPropertySets : Set list of unique property sets, that are associated with the object type and are common to all object occurrences referring to this object type.
IFC2x3 CHANGE  The attribute aggregate type has been changed from LIST to SET.
Types : Reference to the relationship IfcRelDefinedByType and thus to those occurrence objects, which are defined by this type.

Formal Propositions:

WR1 : A Name attribute has to be provided. The name can be declared within the IFC specification as part of the property set agreements.

Inheritance Graph:

ENTITY IfcTypeObject
GlobalId : IfcGloballyUniqueId;
OwnerHistory : OPTIONAL IfcOwnerHistory;
Name : OPTIONAL IfcLabel;
Description : OPTIONAL IfcText;
ENTITY IfcObjectDefinition
HasAssignments : SET OF IfcRelAssigns FOR RelatedObjects;
Nests : SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy : SET OF IfcRelNests FOR RelatingObject;
HasContext : SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy : SET OF IfcRelAggregates FOR RelatingObject;
Decomposes : SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations : SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcTypeObject
ApplicableOccurrence : OPTIONAL IfcIdentifier;
HasPropertySets : OPTIONAL SET [1:?] OF IfcPropertySetDefinition;
Types : SET [0:1] OF IfcRelDefinesByType FOR RelatingType;

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