When Start Host Notification is active, use this call to determine if a change has occured. It will reset the internal flags used to track changes--it is generally recommended that the Pause (18) function be used instead, since FlyHLLAPI does not diffentiate between OIA and screen updates, there is little utility to using Query Host Update unless there is some other need for a polling operation that incorporates other logic while waiting for a screen update.
Data String: blank character or session ID to check. In the multithreaded FlyHLLAPI environment, it is generally recommended that the blank be used and checks made by the thread actively connected to the session
Returns
RetCode: WHLLNOTAVAILABLE: Start Host Notification has not been called, WHLLBOTHUPDATE: screen has been changed, WHLLOK: no change has occurred.
