docs: function(propertyName){
          var text, type, valueConverter,
              valueEl = _getElementsByTagNameNS(
                this._cellNode, _xmlnsDataset, "", propertyName
              ), value;
          if (valueEl.length) {
            valueEl = valueEl[0];
            text = _getElementValue(valueEl);
            valueConverter = this._cellProperties[propertyName];
            if (!valueConverter) {
                type = _getAttributeNS(
                    valueEl,
                    _xmlnsSchemaInstance,
                    _xmlnsSchemaInstancePrefix,
                    "type"
                );
                valueConverter = _getValueConverter(type);
            }
            value = valueConverter(text);
          }
          else {
            value = null;
          }
          return value;
      }