/sys$common/syshlp/helplib.hlb SET, HOST, /LAT, Qualifiers, /DESTINATION_PORT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /DESTINATION_PORT=port-name

    Specifies the port on a node to which you want to connect. The
    /NODE qualifier is required when you specify the /DESTINATION_
    PORT qualifier. The port must be available and must offer the
    service you specify. OpenVMS and certain other LAT service node
    systems ignore the /DESTINATION_PORT qualifier.