IfcConstraint

标签：定义 IfcLabel constraint ConstraintGrade 约束 IfcConstraint

IfcConstraint

实体定义

IfcConstraint用于定义可应用于对象或特性值的约束或限制值或边界条件。

 

约束可以细分为用户定义的约束和系统定义的约束。用户定义的约束由用户应用，并且仅限于对象特性等高级定义。系统定义的约束可以应用于任何对象属性，通常由应用程序定义以强制执行数据验证或参数行为，并且旨在由应用程序强制执行，但不可由最终用户直接编辑。

 

IfcConstraint可以通过IfcRelAssociatesConstraint关系与IfcObjectDefinition或IfcPropertyDefinition的任何子类型相关联以指示系统定义的约束，或者可以通过IfcResourceConstraintRelationship与IfcResourceObjectSelect（例如IfcPropertySingleValue）相关联以指示用户定义的约束。

 

约束必须具有通过IfcConstraint.name属性应用的名称，也可以具有通过IfConstraint.description应用的描述。约束的级别（硬、软、咨询）必须通过IfcConstraint.ConstraintGrade或IfcConstraint.UserDefinedGrade指定，而源，创建actor和创建约束的时间可以选择性地通过IfcConstraint.Source、IfcConstraint.CreateActor和IfcConstraint_CreateonTime断言。

 

约束还可能具有通过IfcExternalReferenceRelationship关联的附加外部信息（如分类或文档信息），可通过反向属性IfcConstraint.HasExternalReferences访问

 

IFC2.0中的新实体

IFC4 CHANGE CreationTime更改为ISO 8601表示的IfcDateTime，HasExternalReferences新的反向属性。

 

Formal Propositions

Rule	Description
WR11	The attribute UserDefinedGrade must be asserted when the value of the IfcConstraintGradeEnum is set to USERDEFINED.

 

 

 

 

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcConstraint
1	Name	IfcLabel	[1:1]	A human-readable name to be used for the constraint.	X
2	Description	IfcText	[0:1]	A human-readable description that may apply additional information about a constraint.	X
3	ConstraintGrade	IfcConstraintEnum	[1:1]	Enumeration that qualifies the type of constraint.	X
4	ConstraintSource	IfcLabel	[0:1]	Any source material, such as a code or standard, from which the constraint originated.	X
5	CreatingActor	IfcActorSelect	[0:1]	Person and/or organization that has created the constraint.	X
6	CreationTime	IfcDateTime	[0:1]	Time when information specifying the constraint instance was created.	X
7	UserDefinedGrade	IfcLabel	[0:1]	允许指定用户定义的约束等级，超出IfcConstraintNum类型的ConstraintGrade属性提供的枚举值（硬、软、咨询）。当为属性UserDefinedGrade并行提供值时，属性ConstraintGrade应具有枚举值USERDEFINED。	X
	HasExternalReferences	IfcExternalReferenceRelationship @RelatedResourceObjects	S[0:?]	Reference to an external references, e.g. library, classification, or document information, that are associated to the constraint.	X
	PropertiesForConstraint	IfcResourceConstraintRelationship @RelatingConstraint	S[0:?]	Reference to the properties to which the constraint is applied.	X

 

EXPRESS Specification

ENTITY IfcConstraint
 ABSTRACT SUPERTYPE OF(ONEOF(IfcMetric, IfcObjective));
  Name : IfcLabel;
  Description : OPTIONAL IfcText;
  ConstraintGrade : IfcConstraintEnum;
  ConstraintSource : OPTIONAL IfcLabel;
  CreatingActor : OPTIONAL IfcActorSelect;
  CreationTime : OPTIONAL IfcDateTime;
  UserDefinedGrade : OPTIONAL IfcLabel;
 INVERSE
  HasExternalReferences : SET OF IfcExternalReferenceRelationship FOR RelatedResourceObjects;
  PropertiesForConstraint : SET OF IfcResourceConstraintRelationship FOR RelatingConstraint;
 WHERE
  WR11 : (ConstraintGrade <> IfcConstraintEnum.USERDEFINED) OR ((ConstraintGrade = IfcConstraintEnum.USERDEFINED) AND EXISTS(SELF\IfcConstraint.UserDefinedGrade));
END_ENTITY;

 

 

 

 

 

 

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标签：定义,IfcLabel,constraint,ConstraintGrade,约束,IfcConstraint
From： https://www.cnblogs.com/herd/p/17559476.html