This mode defines an asynchronous environment between the application and the devices that are in this mode; the application and the devices operate independently of each other.
GPHIGS manages an input queue containing the event reports, arranged in the order in which they arrive, coming from all the devices which are in EVENT mode on all the open workstations. An event report contains the identifier of the workstation originating the event, the identification of an input device and an input value coming from this device. The application can thus retrieve input from the queue without affecting device operation. Event reports are generated in an asynchronous manner, only on user action, by the input devices in EVENT mode.
The application program can remove the oldest event report from the queue and examine its contents. It can also delete from the queue all the event reports coming from a specified input device.
We say that a given input device operates interactively when it is in SAMPLE or EVENT mode, and when it is in REQUEST mode only during execution of the REQUEST <input class> function. Outside this period, we say that interaction with the device is suspended.