IfcDiscreteElement

IfcDiscreteElement

Definition from IAI: This class defines elements in a building services system that do not participate as either devices or distribution elements, such as insulation or attaching elements. This class will be more fully elaborated in future IFC releases.

HISTORY: New entity in IFC R2.0.
ISSUES: See issues and change log for changes made in IFC R2x.

Geometry Use Definitions

The geometric representation of IfcDiscreteElement is given by the IfcProductDefinitionShape, allowing multiple geometric representations. Included are:

Local Placement

The local placement is defined in the supertype IfcProduct. It is defined by a subtype of IfcObjectPlacement which can define an absolute placement, relative placement, or grid reference, with each defining the local coordinate system referenced by all geometric representations. The PlacementRelTo relationship of IfcLocalPlacement, if given, shall point to the same IfcSpatialStructureElement which is used in the ContainedInStructure inverse attribute, or to a referenced spatial structure element at a higher level. If the relative placement is not used, the absolute placement is defined within the world coordinate system.

Informal propositions for local placement:

If the LocalPlacement is specified, then all aggregated components should use this placement as their relative placement.

Standard Geometric Representation

Currently, the use of attribute driven geometry for this class is not supported. The standard geometric representation is defined using explicit geometry.

B-Rep Representation

The faceted B-Rep capabilities (with or without voids) shall be supported for B-Rep representation.

EXPRESS specification:

ENTITY IfcDiscreteElement

SUBTYPE OF (

IfcEquipmentElement);

PredefinedType

IfcDiscreteElementTypeEnum;

WHERE

WR1

(PredefinedType <> IfcDiscreteElementTypeEnum.USERDEFINED) OR ((PredefinedType = IfcDiscreteElementTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcObject.ObjectType));

END_ENTITY;

Attribute definitions:

PredefinedType

Predefined generic types are specified in an Enumeration. A TypeDefinition is available for each generic type (as the required attributes differ). Use Type Definition corresponding to this generic type.

Type Definitions
Type driven PropertySets
PreDefined Type Associated PropertySet
Insulation Pset_Insulation
UserDefined
NotDefined

Formal Propositions:

WR1

References (1):

Name

Type

Referred through

Express-G

IfcEquipmentElement

Entity

Subtype

Diagram 2

Inheritance graph

ENTITY IfcDiscreteElement;

ENTITY IfcRoot;

GlobalId

IfcGloballyUniqueId;

OwnerHistory

IfcOwnerHistory;

Name

OPTIONAL IfcLabel;

Description

OPTIONAL IfcText;

ENTITY IfcObject;

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;

ENTITY IfcProduct;

ObjectPlacement

OPTIONAL IfcObjectPlacement;

Representation

OPTIONAL IfcProductRepresentation;

INVERSE

ReferencedBy

SET OF IfcRelAssignsToProduct FOR RelatingProduct;

ENTITY IfcElement;

Tag

OPTIONAL IfcIdentifier;

INVERSE

ConnectedTo

SET OF IfcRelConnectsElements FOR RelatingElement;

ConnectedFrom

SET OF IfcRelConnectsElements FOR RelatedElement;

ContainedInStructure

SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;

ENTITY IfcDiscreteElement;

PredefinedType

IfcDiscreteElementTypeEnum;

END_ENTITY;