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

       /CLI=cli-filespec
       /NOCLI

    Specifies the name of a command language interpreter (CLI) to
    be used by the subprocess. The default CLI is the same as the
    parent process (defined in SYSUAF). If you specify the /CLI
    qualifier, the attributes of the parent process are copied to
    the subprocess.

    The CLI you specify must be located in SYS$SYSTEM and have the
    file type .EXE.