IfcTask

Natural language names
Aufgabe
Task
Tâche
Change log
ItemSPFXMLChangeDescription
IFC2x3 to IFC4
    IfcTask
      OwnerHistoryMODIFIEDInstantiation changed to OPTIONAL.
      IdentificationXMODIFIEDName changed from TaskId to Identification.
Instantiation changed to OPTIONAL.
      LongDescriptionMODIFIEDName changed from Status to LongDescription.
Type changed from IfcLabel to IfcText.
      StatusXMODIFIEDName changed from WorkMethod to Status.
      WorkMethodXXMODIFIEDName changed from IsMilestone to WorkMethod.
Type changed from BOOLEAN to IfcLabel.
Instantiation changed to OPTIONAL.
      IsMilestoneXXMODIFIEDName changed from Priority to IsMilestone.
Type changed from INTEGER to BOOLEAN.
Instantiation changed from OPTIONAL.
      PriorityADDED
      TaskTimeADDED
      PredefinedTypeADDED
IFC4 Addendum 1
    IfcTask
      IsMilestoneMODIFIEDType changed from BOOLEAN to IfcBoolean.
      PriorityMODIFIEDType changed from INTEGER to IfcInteger.
Semantic definitions at the entity
Entity 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.

HISTORY  New entity in IFC1.0. Renamed from IfcWorkTask in IFC2x.
IFC4 CHANGE  Attributes TaskTime and PredefinedType added. IfcMove and IfcOrderRequest has been removed in IFC4 and are now represented by IfcTask. IfcRelAssignsTasks relationship has been removed as well.

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.

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.

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

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:

Attribute definitions
#AttributeTypeCardinalityDescription G
8StatusIfcLabel? 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 'Not Yet Started', 'Started', 'Completed'.
X
9WorkMethodIfcLabel? 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
X
10IsMilestoneIfcBoolean 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.
X
11PriorityIfcInteger? A value that indicates the relative priority of the task (in comparison to the priorities of other tasks).X
12TaskTimeIfcTaskTime? Time related information for the task.
IFC4 CHANGE Attribute added
X
13PredefinedTypeIfcTaskTypeEnum? Identifies the predefined types of a task from which the type required may be set.
IFC4 CHANGE Attribute added
X
Formal Propositions
RuleDescription
HasNameThe Name attribute should be inserted to describe the task name.
CorrectPredefinedTypeThe attribute ObjectType must be asserted when the value of PredefinedType is set to USERDEFINED.
Inherited definitions from supertypes
Entity inheritance IfcProcess IfcObject IfcObjectDefinition IfcRoot
Attribute inheritance
#AttributeTypeCardinalityDescriptionG
IfcRoot
1GlobalIdIfcGloballyUniqueId Assignment of a globally unique identifier within the entire software world. X
2OwnerHistoryIfcOwnerHistory? 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.
X
3NameIfcLabel? 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
4DescriptionIfcText? Optional description, provided for exchanging informative comments.X
IfcObjectDefinition
HasAssignmentsIfcRelAssigns
@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
NestsIfcRelNests
@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).
IFC4 CHANGE  The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition.
X
IsNestedByIfcRelNests
@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).
IFC4 CHANGE  The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition.
X
HasContextIfcRelDeclares
@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.
IFC4 CHANGE  The inverse attribute datatype has been added.
X
IsDecomposedByIfcRelAggregates
@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).
IFC4 CHANGE  The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
X
DecomposesIfcRelAggregates
@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).
IFC4 CHANGE  The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
X
HasAssociationsIfcRelAssociates
@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
IfcObject
5ObjectTypeIfcLabel? 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.
X
IsDeclaredByIfcRelDefinesByObject
@RelatedObjects
S[0:1]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.
X
DeclaresIfcRelDefinesByObject
@RelatingObject
S[0:?]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.
X
IsTypedByIfcRelDefinesByType
@RelatedObjects
S[0:1]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.
X
IsDefinedByIfcRelDefinesByProperties
@RelatedObjects
S[0:?]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.
X
IfcProcess
6IdentificationIfcIdentifier? An identifying designation given to a process or activity. It is the identifier at the occurrence level.
IFC4 CHANGE Attribute promoted from subtypes.
X
7LongDescriptionIfcText? An extended description or narrative that may be provided.
IFC4 CHANGE  New attribute.
X
IsPredecessorToIfcRelSequence
@RelatingProcess
S[0:?]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. X
IsSuccessorFromIfcRelSequence
@RelatedProcess
S[0:?]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. X
OperatesOnIfcRelAssignsToProcess
@RelatingProcess
S[0:?]Set of relationships to other objects, e.g. products, processes, controls, resources or actors, that are operated on by the process.X
IfcTask
8StatusIfcLabel? 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 'Not Yet Started', 'Started', 'Completed'.
X
9WorkMethodIfcLabel? 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
X
10IsMilestoneIfcBoolean 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.
X
11PriorityIfcInteger? A value that indicates the relative priority of the task (in comparison to the priorities of other tasks).X
12TaskTimeIfcTaskTime? Time related information for the task.
IFC4 CHANGE Attribute added
X
13PredefinedTypeIfcTaskTypeEnum? Identifies the predefined types of a task from which the type required may be set.
IFC4 CHANGE Attribute added
X
Definitions applying to General Usage

 Instance diagram


Concept usage

Object Typing

The Object Typing concept template applies to this entity as shown in Table 14.

HasTypeRelatingType
IfcTaskType

Table 14 — IfcTask Object Typing

The IfcTask defines the anticipated or actual occurrence of any task; common information about task types is handled by IfcTaskType.

EXAMPLE  It includes fixed duration, fixed unit or fixed work. An IfcTask can be aggregated to a task type in order to specify a task sequence or any time related information, e.g. the duration of a task. Please see the documentation of IfcTaskType for further information.


Property Sets

The Property Sets for Objects concept template applies to this entity as shown in Table 15.

PredefinedTypePsetNameProperties
MOVEPset_PackingInstructions

Table 15 — IfcTask Property Sets for Objects



Nesting

The Object Nesting concept applies to this entity.

IfcTask may be contained within an IfcTask using the IfcRelNests relationship. An IfcTask may in turn nest other IfcTask, IfcProcedure or IfcEvent entities. Such nesting indicates decomposed level of detail. From IFC4 onwards it is required to have a summary task (root of all tasks), which is used to define a link to the work plan or work schedule. All subtasks of the summary tasks are then implicitly linked to this work plan or work schedule. Please note that the summary task is used for data organization and not meant to store typical task information as defined by the user. It is therefore recommended that the summary task is hidden from the user to avoid confusion. Please also note that IfcRelNests is used to show the dependency between regular tasks and recurring task definitions (please see the section about time and duration use definitions).

As shown in Figure 144, the installation of a number of items of equipment within a particular space may be the subject of a single task which is identified as 'fix equipment in space 123'. IfcTask represents the occurrence of a work performance of a type of process in a construction plan.

task example

Figure 144 — Task visualization

A task may nest other tasks as sub-items; the nesting relationship is modeled by IfcRelNests as shown in Figure 145. For example, the construction of a stud wall may be designated as a nesting task named 'install wall #1' including other tasks such as 'install dry wall', 'install studs', 'wall taping', and 'erect wall' as sub-processes. A value that indicates the relative tree view position of the task (in comparison to the tree view position of other tasks and the task hierarchy defined by IfcRelNests).

The task order information that is used for viewing purposes is derived from the order defined by the IfcRelNests relationship and thus is independent of the logical task order defined through IfcRelSequence. The hierarchy and order defined through IfcRelNests enables to order the tasks in a tree view or list view structure.

task instantiation diagram

Figure 145 — Task nesting relationships

A top-level task is declared within the IfcProject using the IfcRelDeclares relationship.



Sequential Connectivity

The Sequential Connectivity concept applies to this entity.

The relationship IfcRelSequence is used to indicate control flow. An IfcTask as a successor to an IfcTask indicates logical sequence how these tasks should be performed. IfcTask's can be triggered or can trigger IfcEvent's, which is also defined through the relationship IfcRelSequence.



Control Assignment

The Control Assignment concept applies to this entity.

Occurrences of IfcTask may be assigned to an IfcWorkControl (either a work plan or a work schedule) through IfcRelAssignsToControl. Please note that the IfcRelAssignsTasks relationship class has been removed in IFC4 and is no longer available.



Process Assignment

The Process Assignment concept applies to this entity.

It is suggested to use the 'summary task' (root element of the task hierarchy that is required for task management purposes) to assign all subtask to a work plan or work schedule. Resources used by tasks are assigned by IfcRelAssignsToProcess.



Product Assignment

The Product Assignment concept applies to this entity.



Classification

The Classification Association concept applies to this entity.

An IfcTask may be assigned a Work Breakdown Structure (WBS) code. A WBS code is dealt with as a classification of task and is associated to a task occurrence using the IfcRelAssociatesClassification relationship class. As well as being to designate the code, the classification structure also enables the source of the work breakdown structure classification to be identified.



Constraint

The Constraint Association concept template applies to this entity as shown in Table 16.

Description
Indicate fixed duration of task with ConstraintGrade=HARD and Benchmark=EQUALTO such that changes to an assigned IfcConstructionResource.ResourceTime.ScheduleWork should impact IfcConstructionResource.ResourceTime.ScheduleUsage, and vice-versa.

Table 16 — IfcTask Constraint Association

Constraints may be applied to a task to indicate fixed task duration, fixed start or fixed finish, where IfcMetric.ReferencePath is set to the corresponding attribute on the IfcTaskTime entity.



mvdXML Specification
<?xml version="1.0"?>
<ConceptRoot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" uuid="21853f8a-16d3-49f2-b896-17d1682b4d49" name="IfcTask" status="sample" applicableRootEntity="IfcTask">
  <Applicability uuid="00000000-0000-0000-0000-000000000000" status="sample">
    <Template ref="12dcc939-4507-4491-b675-d677656aa7ac" />
    <TemplateRules operator="and" />
  </Applicability>
  <Concepts>
    <Concept uuid="34452f8b-af1c-4ae0-bcb4-db8735a50f22" name="Object Typing" status="sample" override="false">
      <Template ref="35a2e10e-20df-40f4-ab2f-dacf0a6744f4" />
      <TemplateRules operator="and">
        <TemplateRule Parameters="RelatingType[Type]='IfcTaskType'" />
      </TemplateRules>
    </Concept>
    <Concept uuid="9d37e4e0-b3ba-4419-aa74-234234155370" name="Property Sets" status="sample" override="false">
      <Template ref="f74255a6-0c0e-4f31-84ad-24981db62461" />
      <TemplateRules operator="and">
        <TemplateRule Parameters="PredefinedType[Value]='MOVE' AND PsetName[Value]='Pset_PackingInstructions'" />
      </TemplateRules>
    </Concept>
    <Concept uuid="72ca9e97-eded-4e6d-a1f0-3d2436d9d4f5" name="Nesting" status="sample" override="false">
      <Template ref="38ca8788-5e47-411c-8294-d56f9e9a5691" />
    </Concept>
    <Concept uuid="21bda0ee-ffb5-4b65-a177-d7c12dbb8473" name="Sequential Connectivity" status="sample" override="false">
      <Template ref="c9f11880-8cf6-47fe-abac-05c73b4041b1" />
    </Concept>
    <Concept uuid="e534dc2e-f002-42f8-9e8b-4b660a9344fc" name="Control Assignment" status="sample" override="false">
      <Template ref="813e73fe-5641-4648-a680-8887cf4359f1" />
    </Concept>
    <Concept uuid="1c5f7dc6-eaff-4524-b809-185ed4679b32" name="Process Assignment" status="sample" override="false">
      <Template ref="e841d02b-ccfd-4d1f-9433-da4084658468" />
    </Concept>
    <Concept uuid="a5dbb564-e023-4ec6-9730-06c2a2450fd0" name="Product Assignment" status="sample" override="false">
      <Template ref="ec9cfb04-adfe-4868-8168-d78fe995a913" />
    </Concept>
    <Concept uuid="79db4b23-5b43-4ea1-9068-d96f6b374cd4" name="Classification" status="sample" override="false">
      <Template ref="4a224609-6578-4c75-afcf-8affa86e5ef2" />
    </Concept>
    <Concept uuid="216de181-6d09-4242-8fd5-42b11dfa2c15" name="Constraint" status="sample" override="false">
      <Template ref="c08b264c-f7c6-479f-af7f-5d645c130ea8" />
      <TemplateRules operator="and">
        <TemplateRule Description="Indicate fixed duration of task with ConstraintGrade=HARD and Benchmark=EQUALTO such that changes to an assigned &lt;i&gt;IfcConstructionResource.ResourceTime.ScheduleWork&lt;/i&gt; should impact &lt;i&gt;IfcConstructionResource.ResourceTime.ScheduleUsage&lt;/i&gt;, and vice-versa. " Parameters="" />
        <TemplateRule Description="Indicate constrained start date with ConstraintGrade=HARD and Benchmark of EQUALTO, GREATERTHANOREQUALTO, or LESSTHANOREQUALTO to indicate &quot;must start on&quot;, &quot;start no earlier than&quot; or &quot;start no later than&quot; respectively where &lt;i&gt;IfcMetric.DataValue&lt;/i&gt; indicates the specific &lt;i&gt;IfcDateTime&lt;/i&gt;. Use SOFT constraint having LESSTHAN benchmark to indicate &quot;start as soon as possible&quot;. " Parameters="" />
        <TemplateRule Description="Indicate constrained finish date with ConstraintGrade=HARD and Benchmark of EQUALTO, GREATERTHANOREQUALTO, or LESSTHANOREQUALTO to indicate &quot;must finish on&quot;, &quot;finish no earlier than&quot; or &quot;finish no later than&quot; respectively where &lt;i&gt;IfcMetric.DateValue&lt;/i&gt; indicates the specific &lt;i&gt;IfcDateTime&lt;/i&gt;. Use SOFT constraint having GREATERTHAN benchmark to indicate &quot;finish as late as possible&quot;. " Parameters="" />
      </TemplateRules>
    </Concept>
  </Concepts>
</ConceptRoot>
Concept inheritance

#ConceptTemplateModel View
IfcRoot
IdentitySoftware IdentityGeneral Usage
Revision ControlRevision ControlGeneral Usage
IfcObject
Object User IdentityObject User IdentityGeneral Usage
Object Predefined TypeObject Predefined TypeGeneral Usage
Property Sets with OverrideProperty Sets with OverrideGeneral Usage
IfcTask
Object TypingObject TypingGeneral Usage
Property SetsProperty Sets for ObjectsGeneral Usage
NestingObject NestingGeneral Usage
Sequential ConnectivitySequential ConnectivityGeneral Usage
Control AssignmentControl AssignmentGeneral Usage
Process AssignmentProcess AssignmentGeneral Usage
Product AssignmentProduct AssignmentGeneral Usage
ClassificationClassification AssociationGeneral Usage
ConstraintConstraint AssociationGeneral Usage
Formal representations
XML Specification
 <xs:element name="IfcTask" type="ifc:IfcTask" substitutionGroup="ifc:IfcProcess" nillable="true"/>
 <xs:complexType name="IfcTask">
  <xs:complexContent>
   <xs:extension base="ifc:IfcProcess">
    <xs:sequence>
     <xs:element name="TaskTime" type="ifc:IfcTaskTime" nillable="true" minOccurs="0"/>
    </xs:sequence>
    <xs:attribute name="Status" type="ifc:IfcLabel" use="optional"/>
    <xs:attribute name="WorkMethod" type="ifc:IfcLabel" use="optional"/>
    <xs:attribute name="IsMilestone" type="ifc:IfcBoolean" use="optional"/>
    <xs:attribute name="Priority" type="ifc:IfcInteger" use="optional"/>
    <xs:attribute name="PredefinedType" type="ifc:IfcTaskTypeEnum" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcTask
 SUBTYPE OF (IfcProcess);
  Status : OPTIONAL IfcLabel;
  WorkMethod : OPTIONAL IfcLabel;
  IsMilestone : IfcBoolean;
  Priority : OPTIONAL IfcInteger;
  TaskTime : OPTIONAL IfcTaskTime;
  PredefinedType : OPTIONAL IfcTaskTypeEnum;
 WHERE
  HasName : EXISTS(SELF\IfcRoot.Name);
  CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR (PredefinedType <> IfcTaskTypeEnum.USERDEFINED) OR ((PredefinedType = IfcTaskTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcObject.ObjectType));
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

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