code: def _getNumberOfRequiredVerificationsVocabulary(self):
          
          bsve = self.bika_setup.getNumberOfRequiredVerifications()
          bsval = "%s (%s)" % (_("System default"), str(bsve))
          items = [(-1, bsval), (1, '1'), (2, '2'), (3, '3'), (4, '4')]
          return IntDisplayList(list(items))
docs: Returns a DisplayList with the available options for the
          multi-verification list: 'system default', '1', '2', '3', '4'
          :returns: DisplayList with the available options for the
          multi-verification list