If a flight is controlled  [e.g., has a  Controlled Time of Arrival (CTA), and Arrival Slot (ASLOT)] and then the flight is cancelled, the slot hold status indicates whether the slot associated with this flight is being held, or would be held, by the Airspace User for the next compression.<br/><br/>The compression algorithm will not automatically fill slots that are held. If a flight is not controlled the slot hold has no effect, although users may set the slot hold in anticipation of a flight becoming controlled. A slot hold may only be set for flights that are cancelled. One of two entries: HOLD (if true), RELEASE (if false) ."<br/>