An IfcEvent is something that happens that triggers an action or response.
HISTORY New entity in IFC4
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IfcEvent is used to capture information about particular things that happen or that may happen. Particularly used in work plans (or process maps) they identify e.g. a point at which a message containing information may be issued or at which a rule or constraint is invoked.
Identifies the predefined types of an event from which the type required may be set.
Identifies the predefined types of event trigger from which the type required may be set.
A user defined event trigger type, the value of which is asserted when the value of an event trigger type is declared as USERDEFINED.
The date and/or time at which an event occurs.
Either the PredefinedType attribute is unset, or the inherited attribute ObjectType must be asserted when the value of PredefinedType is set to USERDEFINED.
Either the EventTriggerType attribute is unset, or the attribute UserDefinedEventTriggerType must be asserted when the value of EventTriggerType is set to USERDEFINED.
An IfcEvent may be assigned to an IfcWorkCalendar to indicate times when such event is active using IfcRelAssignsToControl; otherwise the effective calendar is determined by the nearest IfcProcess ancestor with a calendar assigned.
IfcEvent may be contained within an IfcTask using the IfcRelNests relationship. The event is considered active during the time period of the enclosing task (including any assigned IfcWorkCalendar); that is such event may be triggered within the task time period but not outside of it. As an IfcEvent is considered to be atomic, no use is anticipated for nesting processes inside the event.
The IfcEvent defines the anticipated or actual occurrence of any event; common information about event types is handled by IfcEventType.
For building operation scenarios, IfcEvent may be assigned to a product (IfcElement subtype) using IfcRelAssignsToProduct to indicate a specific product occurrence that sources the event.
EXAMPLE An IfcSensor for a motion sensor may have a "Motion Sensed" event. If the IfcEvent is defined by an IfcEventType and the IfcEventType is assigned to a product type (using IfcRelAssignsToProduct), then the IfcEvent must be assigned to one or more occurrences of the specified product type using IfcRelAssignsToProduct.
The relationship IfcRelSequence is used to indicate control flow. An IfcEvent as a predecessor (IfcRelSequence.RelatingProcess) indicates that the succeeding process (typically IfcProcedure or IfcTask) is triggered in response to the event. An IfcEvent as a successor (IfcRelSequence.RelatedProcess) indicates that the completion of the preceeding process causes the event to be triggered. As events have zero duration, the IfcRelSequence.SequenceType attribute has no effect on an IfcEvent but still applies to the opposite end of the relationship if IfcTask is used.