5.4.3.55 IfcRelPositions
5.4.3.55.1 Semantic definition
An IfcRelPositions relationship informs on the positioning dependency between a product and a positioning element.
This relationship does not affect the geometric representation of a product nor its geometrical placement, which is done through subtypes of IfcObjectPlacement.
To geometrically place an IfcReferent along an alignment curve, the IfcReferent.ObjectPlacement is used. To inform that an IfcReferent is positioned along an alignment curve, maybe referring to a certain stationing value, IfcRelPositions is used. This is independent from the actual geometrical placement of the referent. For this reason, the semantics of IfcRelPositions shall not be used to calculate the geometry of the placement, but just to inform on the position of the referent on the alignment curve.5.4.3.55.2 Entity inheritance
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- IfcRelPositions
- IfcRelConnectsElements
- IfcRelConnectsPortToElement
- IfcRelConnectsPorts
- IfcRelConnectsStructuralActivity
- IfcRelConnectsStructuralMember
- IfcRelContainedInSpatialStructure
- IfcRelCoversBldgElements
- IfcRelCoversSpaces
- IfcRelFillsElement
- IfcRelFlowControlElements
- IfcRelInterferesElements
- IfcRelReferencedInSpatialStructure
- IfcRelSequence
- IfcRelServicesBuildings
- IfcRelSpaceBoundary
5.4.3.55.3 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, Only the last modification is stored - either as addition, deletion or modification. The attribute has been changed to be OPTIONAL. |
| 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. |
| Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes | |||
| IfcRelPositions (2) | |||
| 5 | RelatingPositioningElement | IfcPositioningElement |
Positioning element defining the source of the relative position. |
| 6 | RelatedProducts | SET [1:?] OF IfcProduct |
Relatively positioned product. |
5.4.3.55.4 Formal propositions
| Name | Description |
|---|---|
| NoSelfReference |
The instance of the PositionedElement shall not be the same instance as the Product. |
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5.4.3.55.5 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. |
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| Click to show 2 hidden inherited concepts Click to hide 2 inherited concepts | |||
5.4.3.55.6 Examples
5.4.3.55.7 Formal representation
ENTITY IfcRelPositions
SUBTYPE OF (IfcRelConnects);
RelatingPositioningElement : IfcPositioningElement;
RelatedProducts : SET [1:?] OF IfcProduct;
WHERE
NoSelfReference : SIZEOF(QUERY(temp <* RelatedProducts | RelatingPositioningElement :=: temp)) = 0;
END_ENTITY;