IfcContext

IfcContext是项目上下文的泛化，其中定义了对象、类型对象、属性集和属性。IfcProject作为IfcContext的子类型提供了有关施工项目的所有信息的上下文，它可以包含一个或多个IfcProjectLibrary作为IfcContext的子类型，以便为项目注册包含的库。引用的产品库在IfcProjectLibrary中声明为该库的上下文。
可以使用继承的Name属性命名上下文定义，该属性应该是用户可识别的键或上下文编号。长名称可以添加全名。可以使用继承的Description属性进一步解释上下文。
上下文由引用上下文中相应对象的关系对象IfcRelDeclares声明。在子类型级别引入了更具体的关系。

 

 

#	Attribute	Type	Cardinality	Description	C
IfcRoot
1	GlobalId	IfcGloballyUniqueId	[1:1]	Assignment of a globally unique identifier within the entire software world.	X
2	OwnerHistory	IfcOwnerHistory	[0:1]	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, NOTE  only the last modification in stored - either as addition, deletion or modification.	X
3	Name	IfcLabel	[0:1]	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.	X
4	Description	IfcText	[0:1]	Optional description, provided for exchanging informative comments.	X
IfcObjectDefinition
	HasAssignments	IfcRelAssigns @RelatedObjects	S[0:?]	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.	X
	Nests	IfcRelNests @RelatedObjects	S[0:1]	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).	X
	IsNestedBy	IfcRelNests @RelatingObject	S[0:?]	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).	X
	HasContext	IfcRelDeclares @RelatedDefinitions	S[0:1]	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.	X
	IsDecomposedBy	IfcRelAggregates @RelatingObject	S[0:?]	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).	X
	Decomposes	IfcRelAggregates @RelatedObjects	S[0:1]	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).	X
	HasAssociations	IfcRelAssociates @RelatedObjects	S[0:?]	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.	X
IfcContext
5	ObjectType	IfcLabel	[0:1]	The object type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. NOTE  Subtypes of IfcContext do not introduce a PredefinedType attribute, therefore the usage of ObjectType is not bound to the selection of USERDEFINED within the PredefinedType enumaration.	X
6	LongName	IfcLabel	[0:1]	Long name for the context as used for reference purposes.	X
7	Phase	IfcLabel	[0:1]	Current project phase, or life-cycle phase of this project. Applicable values have to be agreed upon by view definitions or implementer agreements.	X
8	RepresentationContexts	IfcRepresentationContext	S[1:?]	Context of the representations used within the context. When the context is a project and it includes shape representations for its components, one or several geometric representation contexts need to be included that define e.g. the world coordinate system, the coordinate space dimensions, and/or the precision factor.	X
9	UnitsInContext	IfcUnitAssignment	[0:1]	Units globally assigned to measure types used within the context.	X
	IsDefinedBy	IfcRelDefinesByProperties @RelatedObjects	S[0:?]	Set of relationships to property set definitions attached to this context. Those statically or dynamically defined properties contain alphanumeric information content that further defines the context.	X
	Declares	IfcRelDeclares @RelatingContext	S[0:?]	Reference to the IfcRelDeclares relationship that assigns the uppermost entities of includes hierarchies to this context instance. NOTE  The spatial hiearchy is assigned to IfcProject using the IfcRelAggregates relationship. This is a single exception due to compatibility reasons with earlier releases.	X