This is sent to an application when IME needs to generate a WM_KEYDOWN or WM_KEYUP message. The form of the value to be sent is the same as the original English Windows WM_KEYDOWN and WM_KEYUP messages.
wParam
Same as English Windows WM_KEYDOWN or WM_KEYUP.
lParam
Same as English Windows WM_KEYDOWN or WM_KEYUP.
An application can handle these messages in the same way it handles the WM_KEYDOWN and WM_KEYUP messages. It can pass these messages to DefWindowProc to generate WM_KEYDOWN and WM_KEYUP messages with the same wParam and lParam parameters. This message is usually generated by IME to maintain message order.