IN HANDLE KeyedEventHandle,
IN PVOID Key,
IN BOOLEAN Alertable,
IN PLARGE_INTEGER Timeout OPTIONAL );
Function with similar functionality as NtReleaseKeyedEvent. In my opinion it is not needed and exists only for future vision of KeyedEvent objects or just as a mistake.
KeyedEventHandle
HANDLE for previously opened KeyedEvent object.
Key
Value to wait for, must have lowest bit clear.
Alertable
If set, waiting can be broken by alerting thread.