INT 6F - 10-NET - SEND
        AH = 04h
        DS:BX -> record
                12 BYTEs receiving node's ID
                        if first byte has high-order bit set, message is
                           directed to the CT_RGATE vector at the receiver
                        if second byte is 00h, first byte is taken as a CB
                           channel number and delivered to all nodes on same
                           channel
                   WORD  length of data at DX
        DS:DX -> data (max 1024 bytes)
Return: CF set on error
            AX = error code (see AH=00h)
        CF clear if successful