additional_fields['residues'] = array('table' => 'feature', 'field' => 'residues');
	}
	function query() { 
		$this->ensure_my_table();
		$this->add_additional_fields(); 
	}
  function render($values) {
    // add a 
 every 100 bp
    return ereg_replace("(.{100})","\\1
",$values->feature_residues);
  }
}