code: function(_id,_form,_clazz,_param,_fbox){
              var _parent,
                  _cch = _cache[_id],
                  _cls = _class+' '+(_clazz||'');
              _form = _e._$get(_form);
              if (!!_form){
                  _parent = _e._$create('div',_cls);
                  _form.appendChild(_parent);
                  _e._$dataset(_form,'id',_id);
                  _doInitParam(_form,_param);
              }else{
                  _parent = _e._$create('form',_cls);
                  _e._$dataset(_parent,'id',_id);
                  _doInitParam(_parent,_param);
                  (_fbox||document.body).appendChild(_parent);
              }
              _cch.pid = _e._$id(_parent);
          }
docs: build parent