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 explicit 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.
Figure 1 — Task type relationships
Identifies the predefined types of a task type from which the type required may be set.
The method of work used in carrying out a task.
The attribute ProcessType must be asserted when the value of PredefinedType is set to USERDEFINED.
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.