This function converts 16-bit unsigned integers from host byte
    order to network byte order.
    Data bytes transmitted over the network are expected to be
    in network byte order. Some hosts, like OpenVMS, have an
    internal data representation format that is different from the
    network byte order; this is called the host byte order. Network
    byte order places the byte with the most significant bits at
    lower addresses, but OpenVMS host byte order places the most
    significant bits at the highest address.
    This function is most often used with ports returned by the
    getservent() function. To convert port numbers from OpenVMS host
    byte order to network byte order, use the htons() function.
                                   NOTE
       The 64-bit return from OpenVMS Alpha and I64 systems has
       zero-extended bits in the high 32 bits of R0.