From c8c6882fc4ef8de11d1d5fa402b4303a06ab4079 Mon Sep 17 00:00:00 2001
From: Qiang Xue <qiang.xue@gmail.com>
Date: Sun, 8 Dec 2013 13:28:06 -0500
Subject: [PATCH] updated doc.

---
 framework/yii/captcha/CaptchaValidator.php | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/framework/yii/captcha/CaptchaValidator.php b/framework/yii/captcha/CaptchaValidator.php
index 424de2d..83996d5 100644
--- a/framework/yii/captcha/CaptchaValidator.php
+++ b/framework/yii/captcha/CaptchaValidator.php
@@ -18,6 +18,10 @@ use yii\validators\Validator;
  *
  * CaptchaValidator should be used together with [[CaptchaAction]].
  *
+ * Note that once CAPTCHA validation succeeds, a new CAPTCHA will be generated automatically. As a result,
+ * CAPTCHA validation should not be used in AJAX validation mode because it may fail the validation
+ * even if a user enters the same code as shown in the CAPTCHA image which is actually different from the latest CAPTCHA code.
+ *
  * @author Qiang Xue <qiang.xue@gmail.com>
  * @since 2.0
  */