Triggers when the specified directory is modified (including created or deleted). If the corresponding directory does not exist at the point that the trigger is initialized, the trigger will poll periodically (approx. every minute) for this directory to be created.
Avoid monitoring one level down (eg c:\temp) as the trigger will also set up a monitor on the parent directory (in this case, c:\), as well, so that changes to the specified directory can be spotted, like it being created. Monitoring c:\ will be very intensive on the machine as every file operation the operating system does will trigger it.