When the due time arrives, the timer is signaled and the thread that set the timer calls the optional completion routine. The CreateWaitableTimer or OpenWaitableTimer function returns this handle. Specifies when the state of the timer is to be set to signaled, in 100 nanosecond intervals. Positive values indicate absolute time.
Negative values indicate relative time.
The actual timer accuracy depends on the capability of your hardware. If lPeriod is zero, the timer is signaled once. If lPeriod is greater than zero, the timer is periodic. A periodic timer automatically reactivates each time the period elapses, until the timer is canceled using the CancelWaitableTimer function or reset using SetWaitableTimer . If lPeriod is less than zero, the function fails.