VMS Help CMS, SHOW, LIBRARY, Qualifiers, /OUTPUT[=file-specification]  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Directs CMS to write output to the specified file, except for any
    warning and error messages, which are written to SYS$OUTPUT and
    SYS$ERROR. CMS creates a new file if you do not specify /APPEND.
    If you omit the /OUTPUT qualifier (or if you specify /OUTPUT
    but do not provide a file specification), CMS directs output to
    the default output device (SYS$OUTPUT). If you omit either the
    file name or the file type component, CMS supplies the missing
    component from the default specification.