IfcReference

IfcReference

实体定义

此实体用于引用实例上属性的值。它可以指标量属性的值，也可以指基于集合的属性中的值。引用的属性可以是直接值、对象引用、集合、反向对象引用和反向集合。引用可以被链接以形成对象属性引用的路径。

 

Attribute definitions

#	Attribute	Type	Cardinality	Description	C
1	TypeIdentifier	IfcIdentifier	[0:1]	Optional identifier of the entity or type such as 'IfcMaterialLayerSet'. For entity, type, or select-based references within a collection, this resolves the reference to such type. If omitted, the type is assumed to be the same as the declared referencing attribute. EXAMPLE  IfcRelAssociatesMaterial.RelatingMaterial may be resolved to IfcMaterialLayerSet.	X
2	AttributeIdentifier	IfcIdentifier	[0:1]	Optionally identifies a direct or inverse attribute within an entity such as 'MaterialLayers'. If TypeIdentifier is specified and refers to an entity, the attribute must exist within the referenced entity. A null value indicates a reference to the type or entity itself, such as for indicating that the type of a value must match a specified constraint.	X
3	InstanceName	IfcLabel	[0:1]	Optionally identifies an instance within a collection according to name. If the instance has an attribute called 'Name', such attribute is used for comparison; otherwise the first STRING-based attribute of the entity is used. EXAMPLE  IfcRoot-based entities such as IfcPropertySet use the Name attribute; IfcRepresentation entities use the RepresentationIdentifier attribute.	X
4	ListPositions	IfcInteger	L[1:?]	Optionally identifies an instance within a collection according to position starting at 1. For referencing single-level collections, this attribute contains a single member; for referencing multi-level collections, then this LIST attribute contains multiple members starting from the outer-most index.	X
5	InnerReference	IfcReference	[0:1]	Optional reference to an inner value for ENTITY, SELECT, SET, or LIST attributes. A path may be formed by linking IfcReference instances together. EXAMPLE  A material layer thickness may be referenced using several instances: #1=IFCREFERENCE($,'IfcSlab','HasAssociations',#2); #2=IFCREFERENCE($,'IfcMaterialLayerSet','MaterialLayers',#3); #3=IFCREFERENCE('Core','IfcMaterialLayer','LayerThickness',$);	X

 

 

 

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcReference
1	TypeIdentifier	IfcIdentifier	[0:1]	Optional identifier of the entity or type such as 'IfcMaterialLayerSet'. For entity, type, or select-based references within a collection, this resolves the reference to such type. If omitted, the type is assumed to be the same as the declared referencing attribute. EXAMPLE  IfcRelAssociatesMaterial.RelatingMaterial may be resolved to IfcMaterialLayerSet.	X
2	AttributeIdentifier	IfcIdentifier	[0:1]	Optionally identifies a direct or inverse attribute within an entity such as 'MaterialLayers'. If TypeIdentifier is specified and refers to an entity, the attribute must exist within the referenced entity. A null value indicates a reference to the type or entity itself, such as for indicating that the type of a value must match a specified constraint.	X
3	InstanceName	IfcLabel	[0:1]	Optionally identifies an instance within a collection according to name. If the instance has an attribute called 'Name', such attribute is used for comparison; otherwise the first STRING-based attribute of the entity is used. EXAMPLE  IfcRoot-based entities such as IfcPropertySet use the Name attribute; IfcRepresentation entities use the RepresentationIdentifier attribute.	X
4	ListPositions	IfcInteger	L[1:?]	Optionally identifies an instance within a collection according to position starting at 1. For referencing single-level collections, this attribute contains a single member; for referencing multi-level collections, then this LIST attribute contains multiple members starting from the outer-most index.	X
5	InnerReference	IfcReference	[0:1]	Optional reference to an inner value for ENTITY, SELECT, SET, or LIST attributes. A path may be formed by linking IfcReference instances together. EXAMPLE  A material layer thickness may be referenced using several instances: #1=IFCREFERENCE($,'IfcSlab','HasAssociations',#2); #2=IFCREFERENCE($,'IfcMaterialLayerSet','MaterialLayers',#3); #3=IFCREFERENCE('Core','IfcMaterialLayer','LayerThickness',$);	X

 

EXPRESS Specification

ENTITY IfcReference;
  TypeIdentifier : OPTIONAL IfcIdentifier;
  AttributeIdentifier : OPTIONAL IfcIdentifier;
  InstanceName : OPTIONAL IfcLabel;
  ListPositions : OPTIONAL LIST [1:?] OF IfcInteger;
  InnerReference : OPTIONAL IfcReference;
END_ENTITY;

 

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