IFC 4.3.0.1 (IFC4X3) development

5.4.3.42 IfcPositioningElement

ABSTRACT This definition may not be instantiated

5.4.3.42.1 Semantic definition

New and abstract entity definition for positioning and annotating elements that are used to position other elements relatively.

5.4.3.42.2 Entity inheritance

5.4.3.42.3 Attributes

# Attribute Type Description
IfcRoot (4)
1 GlobalId IfcGloballyUniqueId

Assignment of a globally unique identifier within the entire software world.

2 OwnerHistory OPTIONAL IfcOwnerHistory

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,

3 Name OPTIONAL IfcLabel

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.

4 Description OPTIONAL IfcText

Optional description, provided for exchanging informative comments.

IfcObjectDefinition (7)
HasAssignments SET [0:?] OF IfcRelAssigns FOR RelatedObjects

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.

Nests SET [0:1] OF IfcRelNests FOR RelatedObjects

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).

IsNestedBy SET [0:?] OF IfcRelNests FOR RelatingObject

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).

HasContext SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions

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.

IsDecomposedBy SET [0:?] OF IfcRelAggregates FOR RelatingObject

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).

Decomposes SET [0:1] OF IfcRelAggregates FOR RelatedObjects

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).

HasAssociations SET [0:?] OF IfcRelAssociates FOR RelatedObjects

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.

IfcObject (5)
5 ObjectType OPTIONAL IfcLabel

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.

IsDeclaredBy SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects

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.

Declares SET [0:?] OF IfcRelDefinesByObject FOR RelatingObject

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.

IsTypedBy SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects

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.

IsDefinedBy SET [0:?] OF IfcRelDefinesByProperties FOR RelatedObjects

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.

IfcProduct (5)
6 ObjectPlacement OPTIONAL IfcObjectPlacement

This establishes the object coordinate system and placement of the product in space. The placement can either be absolute (relative to the world coordinate system), relative (relative to the object placement of another product), or constrained (e.g. relative to grid axes, or to a linear positioning element). The type of placement is determined by the various subtypes of IfcObjectPlacement. An object placement must be provided if a representation is present.

7 Representation OPTIONAL IfcProductRepresentation

Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case a shape representations (IfcProductDefinitionShape). The product definition shape provides for multiple geometric representations of the shape property of the object within the same object coordinate system, defined by the object placement.

ReferencedBy SET [0:?] OF IfcRelAssignsToProduct FOR RelatingProduct

Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product.

PositionedRelativeTo SET [0:?] OF IfcRelPositions FOR RelatedProducts

No description available.

ReferencedInStructures SET [0:?] OF IfcRelReferencedInSpatialStructure FOR RelatedElements

No description available.

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IfcPositioningElement (2)
ContainedInStructure SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements

Relationship to a spatial structure element, to which the positioning element is primarily associated.

Positions SET [0:?] OF IfcRelPositions FOR RelatingPositioningElement

No description available.

Table 5.4.3.42.C

5.4.3.42.4 Formal propositions

Name Description
HasPlacement

The placement for the grid has to be given.

EXISTS(SELF\IfcProduct.ObjectPlacement)
Table 5.4.3.42.D

5.4.3.42.5 Property sets

  • Pset_Risk
    • RiskName
    • RiskType
    • NatureOfRisk
    • RiskAssessmentMethodology
    • UnmitigatedRiskLikelihood
    • UnmitigatedRiskConsequence
    • UnmitigatedRiskSignificance
    • MitigationPlanned
    • MitigatedRiskLikelihood
    • MitigatedRiskConsequence
    • MitigatedRiskSignificance
    • MitigationProposed
    • AssociatedProduct
    • AssociatedActivity
    • AssociatedLocation
  • Pset_Tolerance
    • ToleranceDescription
    • ToleranceBasis
    • OverallTolerance
    • HorizontalTolerance
    • OrthogonalTolerance
    • VerticalTolerance
    • PlanarFlatness
    • HorizontalFlatness
    • ElevationalFlatness
    • SideFlatness
    • OverallOrthogonality
    • HorizontalOrthogonality
    • OrthogonalOrthogonality
    • VerticalOrthogonality
    • OverallStraightness
    • HorizontalStraightness
    • OrthogonalStraightness
    • VerticalStraightness
  • Pset_Uncertainty
    • UncertaintyBasis
    • UncertaintyDescription
    • HorizontalUncertainty
    • LinearUncertainty
    • OrthogonalUncertainty
    • VerticalUncertainty
  • Qto_BodyGeometryValidation
    • GrossSurfaceArea
    • NetSurfaceArea
    • GrossVolume
    • NetVolume
    • SurfaceGenusBeforeFeatures
    • SurfaceGenusAfterFeatures

5.4.3.42.6 Concept usage

Concept Usage Description
IfcRoot (2)
Revision Control General

Ownership, history, and merge state is captured using IfcOwnerHistory.

Software Identity General

IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.

IfcObjectDefinition (9)
Aggregation General

No description available.

Approval Association General

No description available.

Classification Association General

Any object occurrence or object type can have a reference to a specific classification reference, i.e. to a particular facet within a classification system.

Constraint Association General

No description available.

Document Association General

No description available.

Library Association General

No description available.

Material Association General

No description available.

Material Single General

No description available.

Nesting General

No description available.

IfcObject (5)
Assignment to Group General

No description available.

Object Predefined Type General

No description available.

Object Typing General

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.

This concept can be applied to the following resources:

Object User Identity General

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.

Property Sets with Override General

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.

IfcProduct (18)
Body Geometry General

The body or solid model geometric representation of an IfcProduct is typically defined using a Tessellation or Brep. Subtypes may provide recommendations on other representation types that may be used. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

Box Geometry General

No description available.

CoG Geometry General

No description available.

Mapped Geometry General

No description available.

Object Typing General

This concept can be applied to the following resources:

Product Geometric Representation General

The geometric representation of any IfcProduct is provided by the IfcProductDefinitionShape allowing multiple geometric representations. It uses the Product Placement concept utilizing IfcLocalPlacement to establish an object coordinate system, within all geometric representations are founded.

Product Geometry Colour General

No description available.

Product Geometry Layer General

No description available.

Product Local Placement General

No description available.

Product Relative Positioning General

If the IfcProduct Product Placement is placed relative to an IfcPositioningElement this relationship covers the information on which IfcPositioningElement positions the IfcProduct.

Product Span Positioning General

No description available.

Product Topology Representation General

No description available.

Property Sets for Objects General

This concept can be applied to the following resources:

Quantity Sets General

This concept can be applied to the following resources:

Reference Geometry General

No description available.

Reference SweptSolid Geometry General

No description available.

Reference SweptSolid PolyCurve Geometry General

No description available.

Reference Tessellation Geometry General

No description available.

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IfcPositioningElement (3)
FootPrint Geometry General

The 2D geometric representation of IfcGrid is defined using the 'GeometricCurveSet' geometry. The following attribute values should be inserted

The following constraints apply to the 2D representation:

design grid
Figure 5.4.3.42.A — Grid layout

As shown in Figure 5.4.3.42.A, the IfcGrid defines a placement coordinate system using the ObjectPlacement. The XY plane of the coordinate system is used to place the 2D grid axes. The Representation of IfcGrid is defined using IfcProductRepresentation, referencing an IfcShapeRepresentation, that includes IfcGeometricCurveSet as Items. All grid axes are added as IfcPolyline to the IfcGeometricCurveSet.

representation of a design grid
Figure 5.4.3.42.B — Grid representation

As shown in Figure 5.4.3.42.B, the attributes UAxes and VAxes define lists of IfcGridAxis within the context of the grid. Each instance of IfcGridAxis refers to the same instance of IfcCurve (here the subtype IfcPolyline) that is contained within the IfcGeometricCurveSet that represents the IfcGrid.

Product Local Placement General

The local placement for IfcGrid is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric representations.

  • The PlacementRelTo relationship of IfcLocalPlacement shall point (if given) to the local placement of the same IfcSpatialStructureElement, which is used in the ContainedInStructure inverse attribute, or to a spatial structure element at a higher level, referenced by that.
  • If the relative placement is not used, the absolute placement is defined within the world coordinate system.
Spatial Containment General

This concept can be applied to the following resources:

Table 5.4.3.42.E

5.4.3.42.7 Formal representation

ENTITY IfcPositioningElement
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcGrid
	,IfcLinearPositioningElement
	,IfcReferent))
 SUBTYPE OF (IfcProduct);
 INVERSE
	ContainedInStructure : SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;
	Positions : SET [0:?] OF IfcRelPositions FOR RelatingPositioningElement;
 WHERE
	HasPlacement : EXISTS(SELF\IfcProduct.ObjectPlacement);
END_ENTITY;

5.4.3.42.8 References

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5.4.3.42.9 Changelog

  • New resource
  • inverse attribute, Positions