private function checkVars(&$content, &$id, $yAlreadySet, &$decimalPointRemoved) {
        $nbCharContent = strlen($content);
        /* We check for "y" var in AI */
        if ($yAlreadySet) {
            /* We'll check if we have a decimal point */
            if (strpos($content, '.') !== false) {
                throw new CINParseException('gs1128', 'If you do not use any "y" variable, you have to insert a whole number.');
            }
        } elseif ($yAlreadySet !== null) {
            /* We need to replace the "y" var with the position of the decimal point */
            $pos = strpos($content, '.');
            if ($pos === false) {
                $pos = $nbCharContent - 1;
            }

            $id = str_replace('y', $nbCharContent - ($pos + 1), strtolower($id));
            $content = str_replace('.', '', $content);
            $decimalPointRemoved++;
        }

        return true;
    }