8.5.3.9 IfcTaskTime

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8.5.3.9.1 Semantic definition

IfcTaskTime captures the time-related information about a task including the different types (actual or scheduled) of starting and ending times.

All given values should be provided by the application; the IFC schema does not deal with dependencies between task time values. There is also no consistency check through where rules that guarantee a meaningful population of time values. Thus, an application is responsible to provide reasonable values and, if an application receives task times, has to make consistency checks by their own.

IfcTaskTime furthermore provides a generic mechanism to differentiate between user given time values and time values derived from user given time values and other constraints such as work calendars and assigned resources.

8.5.3.9.2 Entity inheritance

8.5.3.9.3 Attributes

#	Attribute	Type	Description
IfcSchedulingTime (3)
1	Name	OPTIONAL IfcLabel	Optional name for the time definition.
2	DataOrigin	OPTIONAL IfcDataOriginEnum	Specifies the origin of the scheduling time entity. It currently differentiates between predicted, simulated, measured, and user defined values.
3	UserDefinedDataOrigin	OPTIONAL IfcLabel	Value of the data origin if DataOrigin attribute is USERDEFINED.
Click to show 3 hidden inherited attributes Click to hide 3 inherited attributes
IfcTaskTime (17)
4	DurationType	OPTIONAL IfcTaskDurationEnum	Enables to specify the type of duration values for ScheduleDuration, ActualDuration and RemainingTime. The duration type is either work time or elapsed time.
5	ScheduleDuration	OPTIONAL IfcDuration	The amount of time which is scheduled for completion of a task. The value might be measured or somehow calculated, which is defined by ScheduleDataOrigin. The value is either given as elapsed time or work time, which is defined by DurationType. NOTE Scheduled Duration may be calculated as the time from scheduled start date to scheduled finish date.
6	ScheduleStart	OPTIONAL IfcDateTime	The date on which a task is scheduled to be started. The value might be measured or somehow calculated, which is defined by ScheduleDataOrigin. NOTE The scheduled start date must be greater than or equal to the earliest start date.
7	ScheduleFinish	OPTIONAL IfcDateTime	The date on which a task is scheduled to be finished. The value might be measured or somehow calculated, which is defined by ScheduleDataOrigin. NOTE The scheduled finish date must be greater than or equal to the earliest finish date.
8	EarlyStart	OPTIONAL IfcDateTime	The earliest date on which a task can be started. It is a calculated value.
9	EarlyFinish	OPTIONAL IfcDateTime	The earliest date on which a task can be finished. It is a calculated value.
10	LateStart	OPTIONAL IfcDateTime	The latest date on which a task can be started. It is a calculated value.
11	LateFinish	OPTIONAL IfcDateTime	The latest date on which a task can be finished. It is a calculated value.
12	FreeFloat	OPTIONAL IfcDuration	The amount of time during which the start or finish of a task may be varied without any effect on the overall programme of work. It is a calculated elapsed time value.
13	TotalFloat	OPTIONAL IfcDuration	The difference between the duration available to carry out a task and the scheduled duration of the task. It is a calculated elapsed time value. NOTE Total Float time may be calculated as being the difference between the scheduled duration of a task and the available duration from earliest start to latest finish. Float time may be either positive, zero or negative. Where it is zero or negative, the task becomes critical.
14	IsCritical	OPTIONAL IfcBoolean	A flag which identifies whether a scheduled task is a critical item within the programme. NOTE A task becomes critical when the float time becomes zero or negative.
15	StatusTime	OPTIONAL IfcDateTime	The date or time at which the status of the tasks within the schedule is analyzed.
16	ActualDuration	OPTIONAL IfcDuration	The actual duration of the task. It is a measured value. The value is either given as elapsed time or work time, which is defined by DurationType.
17	ActualStart	OPTIONAL IfcDateTime	The date on which a task is actually started. It is a measured value. NOTE The scheduled start date must be greater than or equal to the earliest start date. No constraint is applied to the actual start date with respect to the scheduled start date since a task may be started earlier than had originally been scheduled if circumstances allow.
18	ActualFinish	OPTIONAL IfcDateTime	The date on which a task is actually finished.
19	RemainingTime	OPTIONAL IfcDuration	The amount of time remaining to complete a task. It is a predicted value. The value is either given as elapsed time or work time, which is defined by DurationType. NOTE The time remaining in which to complete a task may be determined both for tasks which have not yet started and those which have. Remaining time for a task not yet started has the same value as the scheduled duration. For a task already started, remaining time is calculated as the difference between the scheduled finish and the point of analysis.
20	Completion	OPTIONAL IfcPositiveRatioMeasure	The extent of completion expressed as a ratio or percentage. It is a measured value.

Table 8.5.3.9.B

8.5.3.9.4 Examples

Figure 8.5.3.9.A

Construction Scheduling Task

8.5.3.9.5 Formal representation

ENTITY IfcTaskTime
 SUPERTYPE OF (ONEOF
	(IfcTaskTimeRecurring))
 SUBTYPE OF (IfcSchedulingTime);
	DurationType : OPTIONAL IfcTaskDurationEnum;
	ScheduleDuration : OPTIONAL IfcDuration;
	ScheduleStart : OPTIONAL IfcDateTime;
	ScheduleFinish : OPTIONAL IfcDateTime;
	EarlyStart : OPTIONAL IfcDateTime;
	EarlyFinish : OPTIONAL IfcDateTime;
	LateStart : OPTIONAL IfcDateTime;
	LateFinish : OPTIONAL IfcDateTime;
	FreeFloat : OPTIONAL IfcDuration;
	TotalFloat : OPTIONAL IfcDuration;
	IsCritical : OPTIONAL IfcBoolean;
	StatusTime : OPTIONAL IfcDateTime;
	ActualDuration : OPTIONAL IfcDuration;
	ActualStart : OPTIONAL IfcDateTime;
	ActualFinish : OPTIONAL IfcDateTime;
	RemainingTime : OPTIONAL IfcDuration;
	Completion : OPTIONAL IfcPositiveRatioMeasure;
END_ENTITY;