IfcClassificationReference

IfcClassificationReference

实体定义

IfcClassificationReference是对特定分类键（或符号）的分类系统或源（请参见IfcClassification）的引用。

继承属性具有以下含义：

标识：持有为分类项目（或表格）的特定参考提供的密钥。

名称：允许对分类符号进行人类可解释的指定。

位置：可选地保持到分类系统（或源）的直接URI链接，以超链接分类键。

IfcClassificationReference可以直接分配给IfcClassification，例如，如果不必包括任何分类层次，或者如果数据集中包括完整的分类层次，则它引用父分类符号。第一种称为“轻量级分类”，第二种称为完全分类。然后，属性ReferencedSource保存以下信息（由IfcClassificationReferenceSelect选择）：

属于IFCC分类类型：直接参考分类系统（提供元信息）；

IfcClassificationReference类型：对分类层次结构中父分类符号的引用。

示例：IfcClassificationReference可以通过从抽象IfcExternalReference类继承的“Identification”属性用作“轻量级”分类的一种形式。在这种情况下，“标识”可以采用（例如）单类符号“L6814”，如果各方都很好地理解该分类，并且已知该分类来自特定分类源，则该符号就足够了。名称属性可以是标题“坦克”。这将消除模型更完整分类结构的开销需求。

IFC2x中的新实体。

IFC4更改属性描述，并添加反向属性引用。属性标识已从ItemReference重命名。

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcExternalReference
1	Location	IfcURIReference	[0:1]	Location, where the external source (classification, document or library) can be accessed by electronic means. The electronic location is provided as an URI, and would normally be given as an URL location string.	X
2	Identification	IfcIdentifier	[0:1]	The Identification provides a unique identifier of the referenced item within the external source (classification, document or library). It may be provided as a key, e.g. a classification notation, like NF2.3 a handle a uuid or guid It may be human readable (such as a key) or not (such as a handle or uuid) depending on the context of its usage (which has to be determined by local agreement).	X
3	Name	IfcLabel	[0:1]	Optional name to further specify the reference. It can provide a human readable identifier (which does not necessarily need to have a counterpart in the internal structure of the document).	X
	ExternalReferenceForResources	IfcExternalReferenceRelationship @RelatingReference	S[0:?]	Reference to all associations between this external reference and objects within the IfcResourceObjectSelect that are tagged by the external reference.	X
IfcClassificationReference
4	ReferencedSource	IfcClassificationReferenceSelect	[0:1]	The classification system or source that is referenced.	X
5	Description	IfcText	[0:1]	Description of the classification reference for informational purposes.	X
6	Sort	IfcIdentifier	[0:1]	Optional identifier to sort the set of classification references within the referenced source (either a classification facet of higher level, or the classification system itself).	X
	ClassificationRefForObjects	IfcRelAssociatesClassification @RelatingClassification	S[0:?]	The classification reference with which objects are associated.	X
	HasReferences	IfcClassificationReference @ReferencedSource	S[0:?]	The parent classification references to which this child classification reference applies. It can either be the final classification item leaf node, or an intermediate classification item.	X

 

EXPRESS Specification

ENTITY IfcClassificationReference
 SUBTYPE OF (IfcExternalReference);
  ReferencedSource : OPTIONAL IfcClassificationReferenceSelect;
  Description : OPTIONAL IfcText;
  Sort : OPTIONAL IfcIdentifier;
 INVERSE
  ClassificationRefForObjects : SET [0:?] OF IfcRelAssociatesClassification FOR RelatingClassification;
  HasReferences : SET [0:?] OF IfcClassificationReference FOR ReferencedSource;
END_ENTITY;

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