NAME
    CMD_FLUSH -- abort all I/O requests (immediate)

FUNCTION
    CMD_FLUSH aborts all stopped I/O at the unit.

IO REQUEST
    io_Message      mn_ReplyPort set if quick I/O is not possible
    io_Device       preset by the call to opendevice
    io_Command      CMD_FLUSH
    io_Flags        IOB_QUICK set if quick I/O is possible