5.3.3.6 IfcTask

RV ⓘ

AbV ⓘ

5.3.3.6.1 Semantic definition

An IfcTask is an identifiable unit of work to be carried out in a construction project.

A task is typically used to describe an activity for the construction or installation of products, but is not limited to these types. For example it might be used to describe design processes, move operations and other design, construction and operation related activities as well.

Quantities of resources consumed by the task are dealt with by defining the IfcElementQuantity for the resource and not at the instance of IfcTask.

5.3.3.6.1.1 Attribute use definition

Each occurrence of IfcTask is given a name that is indicative of its content (IfcRoot.Name). A textual description of the task may be provided and this may be further elaborated by a narrative long description (IfcProcess.LongDescription). A work method may be declared for the method of work used in carrying out a task. A task is identified as being either a milestone task or not. A milestone task is defined by the marker IsMilestone. and has no duration. A status and priority for each task may also be set.

5.3.3.6.1.2 Time and duration use definition

Compared to previous IFC releases, basic task time information (scheduled start time, scheduled finish time, duration) is now directly attached to IfcTask through the TaskTime attribute. Regular tasks are defined through IfcTaskTime. Recurring tasks are defined through IfcTaskTimeRecurring. In case a regular task is derived from a recurring task both tasks should be linked together through a IfcRelNests relationship, where IfcRelNests.IsNestedBy points to the recurring task and IfcRelNests.Nests points to all regular tasks that have been derived from the recurring task.

5.3.3.6.1.3 Representation of other activities

The use definitions for IfcTask have been generalised to represent other activities as well, including activities that had been defined by own entities in previous IFC releases. This includes

Order actions
Move operations

IfcTask represents an order that might be carried out by a Helpdesk acting the role of interface for the organization between the facility user and the functional requirement of fulfilling their needs. The actual task represented by the IfcTask entity is turning a request into an order and initiating the action that will enable the order to be completed. The IfcProjectOrder or one of its subtypes including maintenance work order, is related to the IfcTask using IfcRelAssignsToControl.

IfcTask can also be used to describe an activity that moves people, groups within an organization or complete organizations together with their associated furniture and equipment from one place to another. It thus replaces the previous IFC entity IfcMove. The functionality is represented in IfcTask as follows:

Move from: The place from which actors and their associated equipment are moving. Use IfcRelAssignsToProcess where RelatingProcess points to the task and RelatedObjects holds the location(s) from which to move.
Move to: The place to which actors and their associated equipment are moving. Use IfcRelAssignsToProduct where RelatedObjects points to the task(s) and RelatingProduct points to the location to which to move.
Punch list: A list of points concerning a move that require attention. Use LongDescription or else identify sub-tasks to track punch list items individually via IfcRelNests.

5.3.3.6.2 Entity inheritance

- IfcRoot

5.3.3.6.3 Attributes

#	Attribute	Type	Description
IfcRoot (4)
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 is 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 (7)
	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 structures 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 definition 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 definition can only be part of a single decomposition (to allow hierarchical structures 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)
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 or when the concrete entity instantiated does not have a PredefinedType attribute. The latter is the case in some exceptional leaf classes and when instantiating IfcBuiltElement directly.
	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 was previously 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.
IfcProcess (5)
6	Identification	OPTIONAL IfcIdentifier	An identifying designation given to a process or activity. It is the identifier at the occurrence level. IFC4-CHANGE Attribute promoted from subtypes.
7	LongDescription	OPTIONAL IfcText	An extended description or narrative that may be provided. IFC4-CHANGE New attribute.
	IsPredecessorTo	SET [0:?] OF IfcRelSequence FOR RelatingProcess	Dependency between two activities, it refers to the subsequent activity for which this activity is the predecessor. The link between two activities can include a link type and a lag time.
	IsSuccessorFrom	SET [0:?] OF IfcRelSequence FOR RelatedProcess	Dependency between two activities, it refers to the previous activity for which this activity is the successor. The link between two activities can include a link type and a lag time.
	OperatesOn	SET [0:?] OF IfcRelAssignsToProcess FOR RelatingProcess	Set of relationships to other objects, e.g. products, processes, controls, resources or actors, that are operated on by the process.
Click to show 21 hidden inherited attributes
IfcTask (6)
8	Status	OPTIONAL IfcLabel	Current status of the task. NOTE Particular values for status are not specified, these should be determined and agreed by local usage. Examples of possible status values include 'NOTSTARTED', 'STARTED', 'COMPLETED'.
9	WorkMethod	OPTIONAL IfcLabel	The method of work used in carrying out a task. NOTE This attribute should not be used if the work method is specified for the IfcTaskType
10	IsMilestone	IfcBoolean	Identifies whether a task is a milestone task (= TRUE) or not (= FALSE). NOTE In small project planning applications, a milestone task may be understood to be a task having no duration. As such, it represents a singular point in time.
11	Priority	OPTIONAL IfcInteger	A value that indicates the relative priority of the task (in comparison to the priorities of other tasks).
12	TaskTime	OPTIONAL IfcTaskTime	Time related information for the task. IFC4-CHANGE Attribute added
13	PredefinedType	OPTIONAL IfcTaskTypeEnum	Identifies the predefined types of a task from which the type required may be set. IFC4-CHANGE Attribute added

Table 5.3.3.6.1.3.G

5.3.3.6.4 Formal propositions

Name	Description
CorrectPredefinedType	The attribute ObjectType must be asserted when the value of PredefinedType is set to USERDEFINED.
`NOT(EXISTS(PredefinedType)) OR (PredefinedType <> IfcTaskTypeEnum.USERDEFINED) OR ((PredefinedType = IfcTaskTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcObject.ObjectType))`
HasName	The Name attribute should be inserted to describe the task name.
`EXISTS(SELF\IfcRoot.Name)`

Table 5.3.3.6.1.3.H

5.3.3.6.5 Property sets

Pset_PackingInstructions MOVE
- PackingCareType
- WrappingMaterial
- ContainerMaterial
- SpecialInstructions
Pset_Risk
- RiskName
- RiskType
- NatureOfRisk
- RiskAssessmentMethodology
- UnmitigatedRiskLikelihood
- UnmitigatedRiskConsequence
- UnmitigatedRiskSignificance
- MitigationPlanned
- MitigatedRiskLikelihood
- MitigatedRiskConsequence
- MitigatedRiskSignificance
- MitigationProposed
- AssociatedProduct
- AssociatedActivity
- AssociatedLocation

5.3.3.6.6 Concept usage

task example — Figure 5.3.3.6.1.3.A — Constraining the task duration

task instantiation diagram — Figure 5.3.3.6.1.3.A — Constraining the task duration

5.3.3.6.7 Examples

Figure 5.3.3.6.1.3.F

Construction Scheduling Task

5.3.3.6.8 Formal representation

 ENTITY IfcTask
 SUBTYPE OF (IfcProcess);
	Status : OPTIONAL IfcLabel;
	WorkMethod : OPTIONAL IfcLabel;
	IsMilestone : IfcBoolean;
	Priority : OPTIONAL IfcInteger;
	TaskTime : OPTIONAL IfcTaskTime;
	PredefinedType : OPTIONAL IfcTaskTypeEnum;
 WHERE
	CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR (PredefinedType <> IfcTaskTypeEnum.USERDEFINED) OR ((PredefinedType = IfcTaskTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcObject.ObjectType));
	HasName : EXISTS(SELF\IfcRoot.Name);
END_ENTITY;

5.3.3.6.9 References

IfcProcess