VMS Help RUN, Process, Qualifiers, /UIC  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /UIC=uic

    Specifies that the created process be a detached process and
    assigns it a user identification code (UIC). Specify the UIC by
    using standard UIC format as described in the OpenVMS Guide to
    System Security.