public function quoteIdentifier( $identifier )
    {
        if ( sizeof( $this->identifierQuoteChars ) === 2 )
        {
            $identifier = 
                $this->identifierQuoteChars["start"]
                . str_replace( 
                    $this->identifierQuoteChars["end"],
                    $this->identifierQuoteChars["end"].$this->identifierQuoteChars["end"],
                    $identifier
                  )
                . $this->identifierQuoteChars["end"];
        }
        return $identifier;
    }