'Called from _archive_composite_dataset to add central file to archive.
Unless subclassed, this will add the main dataset file (argument data_filename)
to the archive, as an HTML file with its filename derived from the dataset name
(argument outfname).
Returns a tuple of boolean, string, string: (error, msg, messagetype)'

def _archive_main_file(self, archive, display_name, data_filename):

    (error, msg, messagetype) = (False, '', '')
    archname = ('%s.html' % display_name)
    try:
        archive.add(data_filename, archname)
    except IOError:
        error = True
        log.exception('Unable    to    add    composite    parent    %s    to    temporary    library    download    archive', data_filename)
        msg = 'Unable    to    create    archive    for    download,    please    report    this    error'
        messagetype = 'error'
    return (error, msg, messagetype)
