Send Datagram Command (Net Bios, 20h)

        This command is used to send a datagram message. The Net Bios
        does not necessarily detect whether the message was successfully
        delivered. The NUM field associates the datagram with a local
        name. The CALLNAME field specifies the destination name (may be
        a group name). BUFADR and BUFLEN contain the address and length
        of the message. Maximum allowable length is 512 bytes.