docs: function(data) {
          var ret = null; 
          
          if (!data) {
              ret = (this.response.error !== '');
          } else {
              data = OpenLayers.Format.XML.prototype.read.apply(this, [data]);
              var errorNodes = data.documentElement.getElementsByTagName("ERROR");
              ret = (errorNodes !== null && errorNodes.length > 0);
          }
  
          return ret;
      }