def METHOD_NAME(self):
    # Write the <TitlesOfParts> element.
    parts_data = []
    self._xml_start_tag('TitlesOfParts')
    for part_name in self.part_names:
        parts_data.append(('lpstr', part_name))
    self._write_vt_vector('lpstr', parts_data)
    self._xml_end_tag('TitlesOfParts')