IFC 4.3.x development

5.3.3.7 IfcTaskType

Change log

IFC4

added

5.3.3.7.1 Semantic definitions at the entity

An IfcTaskType defines a particular type of task that may be specified for use within a work control.

HISTORY  New entity in IFC4

An IfcTaskType provides for all forms of types of task that may be specified. It is a reference definition for a unit of work that may be broken down into (a sequence of) subtasks. Please note that a reference definition can not be part of a workflow definition, i.e. IfcTaskType instances define the most abstract level of a reference process without dependencies to other reference processes.

Usage of IfcTaskType defines the parameters for one or more occurrences of IfcTask. Parameters may be specified through property sets that may be enumerated in the IfcTaskTypeEnum data type or through explict attributes of IfcTaskType. Task occurrences (IfcTask entities) are linked to the task type through the IfcRelDefinesByType relationship.

Figure 1 shows the definition of a task type that is part of a task template library. Please note that in this example the task type is further subdivided into tasks that define task times (for example, duration) and/or a task sequence.

"task type instantiation diagram"

5.3.3.7.1 Attributes

# 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.
IfcTypeObject
5 ApplicableOccurrenceOPTIONAL IfcIdentifier The attribute optionally defines the data type of the occurrence object, to which the assigned type object can relate. If not present, no instruction is given to which occurrence object the type object is applicable. The following conventions are used:

* The IFC entity name of the applicable occurrence using the IFC naming convention, CamelCase with IFC prefix

* It can be optionally followed by the predefined type after the separator "/" (forward slash), using uppercase

* If one type object is applicable to many occurrence objects, then those occurrence object names should be separate by comma "," forming a comma separated string.

> EXAMPLE Refering to a furniture as applicable occurrence entity would be expressed as 'IfcFurnishingElement', refering to a brace as applicable entity would be expressed as 'IfcMember/BRACE', refering to a wall and wall standard case would be expressed as 'IfcWall, IfcWallStandardCase'.
6 HasPropertySets OPTIONAL SET [1:?] OF IfcPropertySetDefinition Set ~~list~~ of unique property sets, that are associated with the object type and are common to all object occurrences referring to this object type.

> IFC2x3 CHANGE  The attribute aggregate type has been changed from LIST to SET.
Types SET [0:1] OF IfcRelDefinesByType FOR RelatingType Reference to the relationship IfcRelDefinedByType and thus to those occurrence objects, which are defined by this type.
IfcTypeProcess
7 Identification OPTIONAL IfcIdentifier An identifying designation given to a process type.
8 LongDescription OPTIONAL IfcText An long description, or text, describing the activity in detail.

> NOTE  The inherited _SELF\IfcRoot.Description_ attribute is used as the short description.
9 ProcessType OPTIONAL IfcLabel The type denotes a particular type that indicates the process 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.
OperatesOn SET [0:?] OF IfcRelAssignsToProcess FOR RelatingProcessSet of relationships to other objects, e.g. products, processes, controls, resources or actors that are operated on by the process type.

> HISTORY New inverse relationship in IFC4.
IfcTaskType
10 PredefinedType IfcTaskTypeEnum Identifies the predefined types of a task type from which

the type required may be set.
11 WorkMethod OPTIONAL IfcLabel The method of work used in carrying out a task.

5.3.3.7.2 Entity inheritance

dot_inheritance IfcTaskType IfcTaskType IfcTypeProcess IfcTypeProcess IfcTaskType->IfcTypeProcess IfcEventType IfcEventType IfcEventType->IfcTypeProcess IfcTypeObject IfcTypeObject IfcTypeProcess->IfcTypeObject IfcProcedureType IfcProcedureType IfcProcedureType->IfcTypeProcess IfcTypeProduct IfcTypeProduct IfcTypeProduct->IfcTypeObject IfcObjectDefinition IfcObjectDefinition IfcTypeObject->IfcObjectDefinition IfcTypeResource IfcTypeResource IfcTypeResource->IfcTypeObject IfcContext IfcContext IfcContext->IfcObjectDefinition IfcRoot IfcRoot IfcObjectDefinition->IfcRoot IfcObject IfcObject IfcObject->IfcObjectDefinition IfcPropertyDefinition IfcPropertyDefinition IfcPropertyDefinition->IfcRoot IfcRelationship IfcRelationship IfcRelationship->IfcRoot

5.3.3.7.3 Definitions applying to General Usage

5.3.3.7.3.1 Classification Association

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.

5.3.3.7.3.2 Identity

IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.

5.3.3.7.3.3 Nesting

IfcTaskType may nest other IfcTaskType or IfcTask entities using the IfcRelNests relationship. Such nesting indicates decomposed level of detail. Nesting of IfcTask entities is used if a task type shall be detailed by a sequence of tasks or if there is a need to include additional time information such as the duration of subtasks. Please note that IfcTask entities being contained within an IfcTaskType are linked with their task occurrences via IfcRelDefinesByObject relationships. It is also possible to define a task type for these IfcTask entities via IfcRelDefinesByType relationships. For further information please see the documentation of IfcRelDefinesByObject.

5.3.3.7.3.4 Revision Control

Ownership, history, and merge state is captured using IfcOwnerHistory.

5.3.3.7.4 Formal representations

ENTITY IfcTaskType
 SUBTYPE OF (IfcTypeProcess);
	PredefinedType : IfcTaskTypeEnum;
	WorkMethod : OPTIONAL IfcLabel;
 WHERE
	CorrectPredefinedType : (PredefinedType <> IfcTaskTypeEnum.USERDEFINED) OR ((PredefinedType = IfcTaskTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcTypeProcess.ProcessType)) ;
END_ENTITY;