function unparse ( $data = array(), $fields = array(), $append = false , $is_php = false, $delimiter = null) {
		if ( !is_array($data) || empty($data) ) $data = &$this->data;
		if ( !is_array($fields) || empty($fields) ) $fields = &$this->titles;
		if ( $delimiter === null ) $delimiter = $this->delimiter;
		
		$string = ( $is_php ) ? "<?php header('Status: 403'); die(' '); ?>".$this->linefeed : '' ;
		$entry = array();
		
		// create heading
		if ( $this->heading && !$append && !empty($fields) ) {
			foreach( $fields as $key => $value ) {
				$entry[] = $this->_enclose_value($value);
			}
			$string .= implode($delimiter, $entry).$this->linefeed;
			$entry = array();
		}
		
		// create data
		foreach( $data as $key => $row ) {
			foreach( $row as $field => $value ) {
				$entry[] = $this->_enclose_value($value);
			}
			$string .= implode($delimiter, $entry).$this->linefeed;
			$entry = array();
		}
		
		return $string;
	}