diff --git a/framework/yii/console/controllers/MessageController.php b/framework/yii/console/controllers/MessageController.php
index 418062a..715fb5c 100644
--- a/framework/yii/console/controllers/MessageController.php
+++ b/framework/yii/console/controllers/MessageController.php
@@ -115,6 +115,13 @@ class MessageController extends Controller
 		}
 	}
 
+	/**
+	 * Extracts messages from a file
+	 *
+	 * @param string $fileName name of the file to extract messages from
+	 * @param string $translator name of the function used to translate messages
+	 * @return array
+	 */
 	protected function extractMessages($fileName, $translator)
 	{
 		echo "Extracting messages from $fileName...\n";
@@ -135,6 +142,15 @@ class MessageController extends Controller
 		return $messages;
 	}
 
+	/**
+	 * Writes messages into file
+	 *
+	 * @param array $messages
+	 * @param string $fileName name of the file to write to
+	 * @param boolean $overwrite if existing file should be overwritten without backup
+	 * @param boolean $removeOld if obsolete translations should be removed
+	 * @param boolean $sort if translations should be sorted
+	 */
 	protected function generateMessageFile($messages, $fileName, $overwrite, $removeOld, $sort)
 	{
 		echo "Saving messages to $fileName...";
diff --git a/framework/yii/helpers/base/HtmlPurifier.php b/framework/yii/helpers/base/HtmlPurifier.php
index 70fb6bd..799dabf 100644
--- a/framework/yii/helpers/base/HtmlPurifier.php
+++ b/framework/yii/helpers/base/HtmlPurifier.php
@@ -16,6 +16,13 @@ namespace yii\helpers\base;
  */
 class HtmlPurifier
 {
+	/**
+	 * Passes markup through HTMLPurifier making it safe to output to end user
+	 *
+	 * @param string $content
+	 * @param array|null $config
+	 * @return string
+	 */
 	public static function process($content, $config = null)
 	{
 		$purifier=\HTMLPurifier::instance($config);
diff --git a/framework/yii/helpers/base/Markdown.php b/framework/yii/helpers/base/Markdown.php
index 2e14da5..3e69015 100644
--- a/framework/yii/helpers/base/Markdown.php
+++ b/framework/yii/helpers/base/Markdown.php
@@ -37,6 +37,13 @@ class Markdown
 	 */
 	protected static $markdown;
 
+	/**
+	 * Converts markdown into HTML
+	 *
+	 * @param string $content
+	 * @param array $config
+	 * @return string
+	 */
 	public static function process($content, $config = array())
 	{
 		if (static::$markdown === null) {
diff --git a/framework/yii/i18n/GettextMessageSource.php b/framework/yii/i18n/GettextMessageSource.php
index 0eb7cb3..5e29487 100644
--- a/framework/yii/i18n/GettextMessageSource.php
+++ b/framework/yii/i18n/GettextMessageSource.php
@@ -31,6 +31,15 @@ class GettextMessageSource extends MessageSource
 	 */
 	public $useBigEndian = false;
 
+	/**
+	 * Loads the message translation for the specified language and category.
+	 * Child classes should override this method to return the message translations of
+	 * the specified language and category.
+	 * @param string $category the message category
+	 * @param string $language the target language
+	 * @return array the loaded messages. The keys are original messages, and the values
+	 * are translated messages.
+	 */
 	protected function loadMessages($category, $language)
 	{
 		$messageFile = Yii::getAlias($this->basePath) . '/' . $language . '/' . $this->catalog;