#### 5.3.3.5 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.

## Building Automation

The following concepts are inherited at supertypes:

- IfcRoot: Revision Control

Instance diagram

Identity

The Identity concept applies to this entity.

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

Object Typing

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

Type | Description
--- | ---
IfcTaskType | Indicates a task type consisting of re-usable control logic to be executed.
Table 14 — IfcTask Object Typing

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

Object Nesting

The Object Nesting concept applies to this entity as shown in Table 15.

Type | Description
--- | ---
IfcEvent | Events indicate notifications which may be handled or raised according to sequencing.
IfcProcedure | Procedures indicate calls to invoke behavior on devices.
IfcTask | Tasks indicate logic to be executed, which may run in parallel to other tasks.
Table 15 — IfcTask Object Nesting

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

Task Scheduling

The Task Scheduling concept applies to this entity.

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

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 IfcLabel;
WorkMethod | : | OPTIONAL IfcLabel;
IsMilestone | : | BOOLEAN;
Priority | : | OPTIONAL INTEGER;
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;

EXPRESS-G diagram

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).
TaskTime | : | Time related information for the task. IFC4 CHANGE Attribute added
PredefinedType | : | Identifies the predefined types of a task from which the type required may be set. IFC4 CHANGE Attribute added

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 IfcLabel;

| 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 IfcIdentifier;
LongDescription | : | OPTIONAL IfcText;

| INVERSE

| ENTITY IfcTask

Status | : | OPTIONAL IfcLabel;
WorkMethod | : | OPTIONAL IfcLabel;
IsMilestone | : | BOOLEAN;
Priority | : | OPTIONAL INTEGER;
TaskTime | : | OPTIONAL IfcTaskTime;
PredefinedType | : | OPTIONAL IfcTaskTypeEnum;

END_ENTITY;

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