A system is an organized combination of related parts within an AEC product, composed for a common purpose or function or to provide a service. A system is essentially a functionally related aggregation of products. The grouping relationship to one or several instances of IfcProduct (the system members) is handled by IfcRelAssignsToGroup.
NOTE The use of IfcSystem often applies to the representation of building services related systems, such as the piping system, cold water system, etc. Members within such a system may or may not be connected using the connectivity related entities (through IfcDistributionPort).
HISTORY New entity in IFC1.0
| # | Attribute | Type | Description |
|---|---|---|---|
| IfcRoot | |||
| 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, > NOTE only the last modification in stored - either as addition, deletion or modification. > IFC4 CHANGE 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. |
| IfcObjectDefinition | |||
| HasAssignments | SET [0:?] OF IfcRelAssigns FOR RelatedObjects | 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. | |
| Nests | SET [0:1] OF IfcRelNests FOR RelatedObjects | 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). > IFC4 CHANGE The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition. | |
| IsNestedBy | SET [0:?] OF IfcRelNests FOR RelatingObject | 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). > IFC4 CHANGE The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition. | |
| HasContext | SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions | 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. > IFC4 CHANGE The inverse attribute datatype has been added. | |
| IsDecomposedBy | SET [0:?] OF IfcRelAggregates FOR RelatingObject | 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). > IFC4 CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates. | |
| Decomposes | SET [0:1] OF IfcRelAggregates FOR RelatedObjects | 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). > IFC4 CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates. | |
| HasAssociations | SET [0:?] OF IfcRelAssociates FOR RelatedObjects | 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. | |
| IfcObject | |||
| 5 | ObjectType | OPTIONAL IfcLabel | The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED. |
| IsDeclaredBy | SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects | Link to the relationship object pointing to the declaring object that provides the object definitions for this object occurrence. The declaring object has to be part of an object type decomposition. The associated IfcObject, or its subtypes, contains the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes. > IFC4 CHANGE New inverse relationship, change made with upward compatibility for file based exchange. | |
| Declares | SET [0:?] OF IfcRelDefinesByObject FOR RelatingObject | Link to the relationship object pointing to the reflected object(s) that receives the object definitions. The reflected object has to be part of an object occurrence decomposition. The associated IfcObject, or its subtypes, provides the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes. > IFC4 CHANGE New inverse relationship, change made with upward compatibility for file based exchange. | |
| IsTypedBy | SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects | Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type. > IFC4 CHANGE New inverse relationship, the link to IfcRelDefinesByType had previously be included in the inverse relationship IfcRelDefines. Change made with upward compatibility for file based exchange. | |
| IsDefinedBy | SET [0:?] OF IfcRelDefinesByProperties FOR RelatedObjects | Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object. > IFC4 CHANGE The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange. | |
| IfcGroup | |||
| IsGroupedBy | SET [0:?] OF IfcRelAssignsToGroup FOR RelatingGroup | Reference to the relationship IfcRelAssignsToGroup that assigns the one to many group members to the IfcGroup object. > IFC4 CHANGE The cardinality has been changed from 1..1 to 0..? in order to allow the exchange of a group concept without having already group members assigned. It now also allows the use of many instances of IfcRelAssignsToGroup to assign the group members. The change has been done with upward compatibility for file based exchange. | |
| IfcSystem | |||
| ServicesBuildings | SET [0:1] OF IfcRelServicesBuildings FOR RelatingSystem | Reference to the ~~building~~ spatial structure via the objectified relationship IfcRelServicesBuildings, which is serviced by the system. | |
| ServicesFacilities | SET [0:?] OF IfcRelReferencedInSpatialStructure FOR RelatedElements | ||
Any object occurrence or object type can have a reference to a specific classification reference, i.e. to a particular facet within a classification system.
The IfcGroup establishes an arbitrary collection of objects through utilizing this concept.
IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.
Any object occurrence can be typed by being assigned to a common object type utilizing this concept. A particular rule, restricting the applicable subtypes of IfcTypeObject that can be assigned, is introduced by overriding this concept at the level of subtypes of IfcObject.
An attribute Name and optionally Description can be used for all subypes of IfcObject. For those subtypes, that have an object type definition, such as ifcBeam - IfcBeamType, the common Name and optionally Description is associated with the object type.
| PsetName |
|---|
| 'Pset_ServiceLifeFactors' |
Any object occurrence can hold property sets, each being a set of individual properties having name, description, value(s) and unit(s). A reference to applicable property sets, being part of this specification, is introduced at the level of sub types of IfcObject.
Any object occurrence can hold property sets, either directly at the object occurrence as element specific property sets, or at the object type, as type property sets. In this case, the properties that are provided to the object occurrence are the combinations of element specific and type properties. In case, that the same property (within the same property set, is defined both, in occurrence and type properties, the property value of the occurrence property overrides the property value of the type property.
Ownership, history, and merge state is captured using IfcOwnerHistory.
ENTITY IfcSystem SUPERTYPE OF (ONEOF (IfcBuildingSystem ,IfcBuiltSystem ,IfcDistributionSystem ,IfcStructuralAnalysisModel ,IfcZone)) SUBTYPE OF (IfcGroup); INVERSE ServicesBuildings : SET [0:1] OF IfcRelServicesBuildings FOR RelatingSystem; ServicesFacilities : SET [0:?] OF IfcRelReferencedInSpatialStructure FOR RelatedElements; END_ENTITY;