public function validateAlphabetic($value, $charCount = null)
    {
        if (is_array($charCount)) {
            $charCount = $charCount[0];
        }

        // check for character limitation
        if ($charCount !== null) {
            $pattern = '/^[a-zA-Z???????]{0,'.$charCount.'}$/';
        } else {
            $pattern = '/^[A-Za-z???????]+$/';
        }

        // validation and return
        return (bool) preg_match($pattern, $value);
    }