Library /sys$common/syshlp/tcpip$ucp_help.hlb SET, SERVICE, Qualifiers, /USER_NAME  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /USER_NAME=vms_user_account

    Required.

    OpenVMS account information for users working on client systems.
    Required for a user to access the service.

    The user must also be defined in the system user authorization
    file (SYSUAF.DAT).