code: function configureWrapper(name){
                          var _ = nvd3Utils.deepExtend(defaultWrapper(name), scope.options[name] || {});
  
                          if (scope._config.extended) scope.options[name] = _;
  
                          var wrapElement = angular.element('<div></div>').html(_['html'] || '')
                              .addClass(name).addClass(_.className)
                              .removeAttr('style')
                              .css(_.css);
  
                          if (!_['html']) wrapElement.text(_.text);
  
                          if (_.enable) {
                              if (name === 'title') element.prepend(wrapElement);
                              else if (name === 'subtitle') angular.element(element[0].querySelector('.title')).after(wrapElement);
                              else if (name === 'caption') element.append(wrapElement);
                          }
                      }
docs: Configure 'title', 'subtitle', 'caption'. nvd3 has no sufficient models for it yet.