public static function cleanup($vcard)
    {
        // convert Apple X-ABRELATEDNAMES into X-* fields for better compatibility
        $vcard = preg_replace_callback(
            '/item(\d+)\.(X-ABRELATEDNAMES)([^:]*?):(.*?)item\1.X-ABLabel:(?:_\$!<)?([\w() -]*)(?:>!\$_)?./s',
            array('self', 'x_abrelatednames_callback'),
            $vcard);

        // Cleanup
        $vcard = preg_replace(array(
                // convert special types (like Skype) to normal type='skype' classes with this simple regex ;)
                '/item(\d+)\.(TEL|EMAIL|URL)([^:]*?):(.*?)item\1.X-ABLabel:(?:_\$!<)?([\w() -]*)(?:>!\$_)?./si',
                '/^item\d*\.X-AB.*$/mi',  // remove cruft like item1.X-AB*
                '/^item\d*\./mi',         // remove item1.ADR instead of ADR
                '/\n+/',                 // remove empty lines
                '/^(N:[^;\R]*)$/m',      // if N doesn't have any semicolons, add some
            ),
            array(
                '\2;type=\5\3:\4',
                '',
                '',
                "\n",
                '\1;;;;',
            ), $vcard);

        // convert X-WAB-GENDER to X-GENDER
        if (preg_match('/X-WAB-GENDER:(\d)/', $vcard, $matches)) {
            $value = $matches[1] == '2' ? 'male' : 'female';
            $vcard = preg_replace('/X-WAB-GENDER:\d/', 'X-GENDER:' . $value, $vcard);
        }

        return $vcard;
    }