System-supplied; Source from which this task was launched.

Options:

Scheduled Trigger
If the instance was directly launched by a scheduled trigger, the Trigger (trigger_id) column is assigned the UUID of the scheduled trigger.
Trigger Monitor
If the instance is a monitor associated with monitor trigger, the Trigger (trigger_id) column is assigned the UUID of the monitor trigger.
Trigger Now / User Interface
If the instance was directly launched by a Trigger Now command, the Trigger (trigger_id) column is assigned the UUID of the trigger.
Trigger Now / System Operation
If the instance was directly launched by a Trigger Now command, the Trigger (trigger_id) column is assigned the UUID of the trigger and the Source Instance (source_instance) column will be assigned the UUID of the instance invoking the System Operation.
Trigger Now / Web Service
If the instance was directly launched by a Trigger Now command, the Trigger (trigger_id) column is assigned the UUID of the trigger.
Trigger Now / Command Line
If the instance was directly launched by a Trigger Now command, the Trigger (trigger_id) column is assigned the UUID of the trigger.
Workflow
If the instance was launched by a workflow, the Workflow (workflow_id) column is assigned the UUID of the workflow instance. Likewise, the Source Instance (source_instance) column will also be assigned the UUID of the workflow instance.
Launch Task / User Interface
If the instance was directly launched by the Launch Task command, the Source Instance (source_instance) column will be null.
Launch Task / System Operation
If the instance was directly launched by the Launch Task command, the Source Instance (source_instance) column will be assigned the UUID of the instance invoking the System Operation.
Launch Task / Web Service
If the instance was directly launched by the Launch Task command, the Source Instance (source_instance) column will be null.
Launch Task / Command Line
If the instance was directly launched by the Launch Task command, the Source Instance (source_instance) column will be null.
Recurring
If the instance was directly launched by a Recurring Task Instance, the Source Instance (source_instance) column will be assigned the UUID of the Recurring Task Instance.

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