USAGE
        MSg <call> <message>

DESCRIPTION
        Sends a one-line message to another user of the node. The user
        in question must be in idle state (ie. not connected/connecting
        anywhere or running a program).

        If the user has an SSID other than zero, the SSID must be
        specified. If multiple users are logged in with the same
        callsign/SSID pair, those who are in idle state, get the message.

EXAMPLES
        msg k2mf Hello, Bawee!