/FILENAME
       /NOFILENAME (default)

    When the /FILENAME qualifier is used, the output-file-spec is
    treated as a default file specification and as much as possible
    of the file name, if any, specified in the Content-type: header
    line is used to generate the actual output file name. The default
    is /NOFILENAME in which case any file name specified in the
    Content-type: header line is ignored.