#### 5.3.3.1 IfcTask

| Tâche
| Aufgabe

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

- 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.

## Plumbing System Design

Instance diagram

Identity

The Identity concept applies to this entity.

Exchange |  |  |  |  |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Import |  |  |  |  |  |  |  |  |  |  |  |  |
Export | R |  |  |  |  |  |  |  |  |  |  |  |

Process Assignment

The Process Assignment concept applies to this entity as shown in Table 10.

Type | Description
--- | ---
IfcSubContractResource | Indicates cost of a contracted service or product procurement.
IfcConstructionProductResource | Indicates provisioned product resource corresponding to an arbitrary quantity of products needed for a building in early design, such as plumbing fixtures.
Table 10 — IfcTask Process Assignment

Exchange |  |  |  |  |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Import |  |  |  |  |  |  |  |  |  |  |  |  |
Export | R |  |  |  |  |  |  |  |  |  |  |  |

XSD 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:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcTask

| SUBTYPE OF (IfcProcess);

Status | : | OPTIONAL IfcStrippedOptional;
WorkMethod | : | OPTIONAL IfcStrippedOptional;
IsMilestone | : | IfcStrippedOptional;
Priority | : | OPTIONAL IfcStrippedOptional;
TaskTime | : | OPTIONAL IfcStrippedOptional;
PredefinedType | : | OPTIONAL IfcStrippedOptional;

| 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;

Attribute Definitions:

Status | : | 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'.
WorkMethod | : | 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
IsMilestone | : | 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.
Priority | : | A value that indicates the relative priority of the task (in comparison to the priorities of other tasks).

Formal Propositions:

HasName | : | The Name attribute should be inserted to describe the task name.
CorrectPredefinedType | : | The attribute ObjectType must be asserted when the value of PredefinedType is set to USERDEFINED.

Inheritance Graph:

ENTITY IfcTask

| ENTITY IfcRoot

GlobalId | : | IfcGloballyUniqueId;
OwnerHistory | : | OPTIONAL IfcOwnerHistory;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;

| ENTITY IfcObjectDefinition

| INVERSE

HasAssignments | : | SET OF IfcRelAssigns FOR RelatedObjects;
Nests | : | SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy | : | SET OF IfcRelNests FOR RelatingObject;
HasContext | : | SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy | : | SET OF IfcRelAggregates FOR RelatingObject;
Decomposes | : | SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations | : | SET OF IfcRelAssociates FOR RelatedObjects;

| ENTITY IfcObject

ObjectType | : | OPTIONAL IfcStrippedOptional;

| INVERSE

IsDeclaredBy | : | SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
Declares | : | SET OF IfcRelDefinesByObject FOR RelatingObject;
IsTypedBy | : | SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
IsDefinedBy | : | SET OF IfcRelDefinesByProperties FOR RelatedObjects;

| ENTITY IfcProcess

Identification | : | OPTIONAL IfcStrippedOptional;
LongDescription | : | OPTIONAL IfcStrippedOptional;

| INVERSE

OperatesOn | : | SET OF IfcRelAssignsToProcess FOR RelatingProcess;

| ENTITY IfcTask

Status | : | OPTIONAL IfcStrippedOptional;
WorkMethod | : | OPTIONAL IfcStrippedOptional;
IsMilestone | : | IfcStrippedOptional;
Priority | : | OPTIONAL IfcStrippedOptional;
TaskTime | : | OPTIONAL IfcStrippedOptional;
PredefinedType | : | OPTIONAL IfcStrippedOptional;

END_ENTITY;

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