diff --git a/core/modules/filter/filter.admin.inc b/core/modules/filter/filter.admin.inc
index b4a7008..e8c7838 100644
--- a/core/modules/filter/filter.admin.inc
+++ b/core/modules/filter/filter.admin.inc
@@ -1,15 +1,15 @@
 <?php
-
 /**
  * @file
  * Admin page callbacks for the filter module.
  */
 
 /**
- * Menu callback; Displays a list of all text formats and allows them to be rearranged.
+ * Form constructor for listing and rearranging text formats.
  *
- * @ingroup forms
+ * @see filter_menu()
  * @see filter_admin_overview_submit()
+ * @ingroup forms
  */
 function filter_admin_overview($form) {
   // Overview of all formats.
@@ -45,6 +45,9 @@ function filter_admin_overview($form) {
   return $form;
 }
 
+/**
+ * Form submission handler for filter_admin_overview().
+ */
 function filter_admin_overview_submit($form, &$form_state) {
   foreach ($form_state['values']['formats'] as $id => $data) {
     if (is_array($data) && isset($data['weight'])) {
@@ -95,7 +98,9 @@ function theme_filter_admin_overview($variables) {
 }
 
 /**
- * Menu callback; Display a text format form.
+ * Page callback: Displays the text format add/edit form.
+ *
+ * @see filter_menu()
  */
 function filter_admin_format_page($format = NULL) {
   if (!isset($format->name)) {
@@ -109,11 +114,11 @@ function filter_admin_format_page($format = NULL) {
 }
 
 /**
- * Generate a text format form.
+ * Form constructor for the text format add/edit form.
  *
- * @ingroup forms
  * @see filter_admin_format_form_validate()
  * @see filter_admin_format_form_submit()
+ * @ingroup forms
  */
 function filter_admin_format_form($form, &$form_state, $format) {
   $is_fallback = ($format->format == filter_fallback_format());
@@ -287,7 +292,9 @@ function theme_filter_admin_format_filter_order($variables) {
 }
 
 /**
- * Validate text format form submissions.
+ * Form validation handler for filter_admin_format_form().
+ *
+ * @see filter_admin_format_form_submit()
  */
 function filter_admin_format_form_validate($form, &$form_state) {
   $format_format = trim($form_state['values']['format']);
@@ -304,7 +311,9 @@ function filter_admin_format_form_validate($form, &$form_state) {
 }
 
 /**
- * Process text format form submissions.
+ * Form submission hanlder for filter_admin_format_form().
+ *
+ * @see filter_admin_format_form_validate()
  */
 function filter_admin_format_form_submit($form, &$form_state) {
   // Remove unnecessary values.
@@ -336,10 +345,11 @@ function filter_admin_format_form_submit($form, &$form_state) {
 }
 
 /**
- * Menu callback; confirm deletion of a format.
+ * Form constructor for text format deletion confirmation form.
  *
- * @ingroup forms
+ * @see filter_menu()
  * @see filter_admin_disable_submit()
+ * @ingroup forms
  */
 function filter_admin_disable($form, &$form_state, $format) {
   $form['#format'] = $format;
@@ -353,7 +363,7 @@ function filter_admin_disable($form, &$form_state, $format) {
 }
 
 /**
- * Process filter disable form submission.
+ * Form submission handler for filter_format_disable().
  */
 function filter_admin_disable_submit($form, &$form_state) {
   $format = $form['#format'];
diff --git a/core/modules/filter/filter.admin.js b/core/modules/filter/filter.admin.js
index 3bc6233..93b695a 100644
--- a/core/modules/filter/filter.admin.js
+++ b/core/modules/filter/filter.admin.js
@@ -1,3 +1,8 @@
+/**
+ * @file
+ * Attaches adminstration-specific behavior for the Filter module.
+ */
+
 (function ($) {
 
 Drupal.behaviors.filterStatus = {
diff --git a/core/modules/filter/filter.api.php b/core/modules/filter/filter.api.php
index 6675e4a..0341706 100644
--- a/core/modules/filter/filter.api.php
+++ b/core/modules/filter/filter.api.php
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * @file
  * Hooks provided by the Filter module.
diff --git a/core/modules/filter/filter.css b/core/modules/filter/filter.css
index f731733..b826512 100644
--- a/core/modules/filter/filter.css
+++ b/core/modules/filter/filter.css
@@ -1,3 +1,7 @@
+/**
+ * @file
+ * Stylesheet for the Filter module.
+ */
 
 .text-format-wrapper .form-item {
   margin-bottom: 0;
diff --git a/core/modules/filter/filter.js b/core/modules/filter/filter.js
index c286159..4265387 100644
--- a/core/modules/filter/filter.js
+++ b/core/modules/filter/filter.js
@@ -1,3 +1,8 @@
+/**
+ * @file
+ * Attaches behavior for the Filter module.
+ */
+
 (function ($) {
 
 /**
diff --git a/core/modules/filter/filter.module b/core/modules/filter/filter.module
index 3b8942f..d2cd56a 100644
--- a/core/modules/filter/filter.module
+++ b/core/modules/filter/filter.module
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * @file
  * Framework for handling filtering of content.
@@ -71,6 +70,7 @@ function filter_theme() {
  * Implements hook_element_info().
  *
  * @see filter_process_format()
+ * @see text_format_wrapper()
  */
 function filter_element_info() {
   $type['text_format'] = array(
@@ -132,13 +132,16 @@ function filter_menu() {
 }
 
 /**
- * Access callback for deleting text formats.
+ * Access callback: Checks access for deleting text formats.
  *
  * @param $format
  *   A text format object.
+ *
  * @return
  *   TRUE if the text format can be disabled by the current user, FALSE
  *   otherwise.
+ *
+ * @see filter_menu()
  */
 function _filter_disable_format_access($format) {
   // The fallback format can never be disabled.
@@ -146,7 +149,7 @@ function _filter_disable_format_access($format) {
 }
 
 /**
- * Load a text format object from the database.
+ * Loads a text format object from the database.
  *
  * @param $format_id
  *   The format ID.
@@ -164,7 +167,7 @@ function filter_format_load($format_id) {
 }
 
 /**
- * Save a text format object to the database.
+ * Saves a text format object to the database.
  *
  * @param $format
  *   A format object using the properties:
@@ -187,6 +190,9 @@ function filter_format_load($format_id) {
  *       enabled in the text format. If omitted, the filter will be disabled.
  *     - 'settings': (optional) An array of configured settings for the filter.
  *       See hook_filter_info() for details.
+ *
+ * @return
+ *   SAVED_NEW or SAVED_UPDATED
  */
 function filter_format_save($format) {
   $format->name = trim($format->name);
@@ -269,7 +275,7 @@ function filter_format_save($format) {
 }
 
 /**
- * Disable a text format.
+ * Disables a text format.
  *
  * There is no core facility to re-enable a disabled format. It is not deleted
  * to keep information for contrib and to make sure the format ID is never
@@ -311,7 +317,9 @@ function filter_format_exists($format_id) {
 }
 
 /**
- * Display a text format form title.
+ * Title callback: Displays a text format form title.
+ *
+ * @see filter_menu()
  */
 function filter_admin_format_title($format) {
   return $format->name;
@@ -348,6 +356,7 @@ function filter_permission() {
  *
  * @param $format
  *   An object representing a text format.
+ *
  * @return
  *   The machine-readable permission name, or FALSE if the provided text format
  *   is malformed or is the fallback format (which is available to all users).
@@ -383,6 +392,7 @@ function filter_modules_disabled($modules) {
  * @param $account
  *   (optional) If provided, only those formats that are allowed for this user
  *   account will be returned. All formats will be returned otherwise.
+ *
  * @return
  *   An array of text format objects, keyed by the format ID and ordered by
  *   weight.
@@ -441,6 +451,7 @@ function filter_formats_reset() {
  *
  * @param $format
  *   An object representing the text format.
+ *
  * @return
  *   An array of role names, keyed by role ID.
  */
@@ -459,6 +470,7 @@ function filter_get_roles_by_format($format) {
  *
  * @param $rid
  *   The user role ID to retrieve text formats for.
+ *
  * @return
  *   An array of text format objects that are allowed for the role, keyed by
  *   the text format ID and ordered by weight.
@@ -493,6 +505,7 @@ function filter_get_formats_by_role($rid) {
  * @param $account
  *   (optional) The user account to check. Defaults to the currently logged-in
  *   user.
+ *
  * @return
  *   The ID of the user's default text format.
  *
@@ -533,6 +546,9 @@ function filter_default_format($account = NULL) {
  * Any modules implementing a format deletion functionality must not delete
  * this format.
  *
+ * @return
+ *   The ID of the fallback text format.
+ *
  * @see hook_filter_format_disable()
  * @see filter_default_format()
  */
@@ -555,7 +571,7 @@ function filter_fallback_format_title() {
 }
 
 /**
- * Return a list of all filters provided by modules.
+ * Returns a list of all filters provided by modules.
  */
 function filter_get_filters() {
   $filters = &drupal_static(__FUNCTION__, array());
@@ -586,14 +602,16 @@ function filter_get_filters() {
 }
 
 /**
- * Helper function for sorting the filter list by filter name.
+ * Sorts an array of filters by filter name.
+ *
+ * Callback for uasort() within filter_get_filters().
  */
 function _filter_list_cmp($a, $b) {
   return strcmp($a['title'], $b['title']);
 }
 
 /**
- * Check if text in a certain text format is allowed to be cached.
+ * Checks if text in a certain text format is allowed to be cached.
  *
  * This function can be used to check whether the result of the filtering
  * process can be cached. A text format may allow caching depending on the
@@ -601,6 +619,7 @@ function _filter_list_cmp($a, $b) {
  *
  * @param $format_id
  *   The text format ID to check.
+ *
  * @return
  *   TRUE if the given text format allows caching, FALSE otherwise.
  */
@@ -610,13 +629,14 @@ function filter_format_allowcache($format_id) {
 }
 
 /**
- * Helper function to determine whether the output of a given text format can be cached.
+ * Determines whether the output of a given text format can be cached.
  *
  * The output of a given text format can be cached when all enabled filters in
  * the text format allow caching.
  *
  * @param $format
  *   The text format object to check.
+ *
  * @return
  *   TRUE if all the filters enabled in the given text format allow caching,
  *   FALSE otherwise.
@@ -638,7 +658,7 @@ function _filter_format_is_cacheable($format) {
 }
 
 /**
- * Retrieve a list of filters for a given text format.
+ * Retrieves a list of filters for a given text format.
  *
  * Note that this function returns all associated filters regardless of whether
  * they are enabled or disabled. All functions working with the filter
@@ -692,7 +712,7 @@ function filter_list_format($format_id) {
 }
 
 /**
- * Run all the enabled filters on a piece of text.
+ * Runs all the enabled filters on a piece of text.
  *
  * Note: Because filters can inject JavaScript or execute PHP code, security is
  * vital here. When a user supplies a text format, you should validate it using
@@ -714,6 +734,9 @@ function filter_list_format($format_id) {
  *   The caller may set this to FALSE when the output is already cached
  *   elsewhere to avoid duplicate cache lookups and storage.
  *
+ * @return
+ *   The filtered text.
+ *
  * @ingroup sanitization
  */
 function check_markup($text, $format_id = NULL, $langcode = '', $cache = FALSE) {
@@ -782,8 +805,8 @@ function check_markup($text, $format_id = NULL, $langcode = '', $cache = FALSE)
  *   the text format id specified in #format or the user's default format by
  *   default, if NULL.
  *
- * The resulting value for the element will be an array holding the value and the
- * format.  For example, the value for the body element will be:
+ * The resulting value for the element will be an array holding the value and
+ * the format. For example, the value for the body element will be:
  * @code
  *   $form_state['values']['body']['value'] = 'foo';
  *   $form_state['values']['body']['format'] = 'foo';
@@ -931,7 +954,7 @@ function filter_process_format($element) {
 }
 
 /**
- * #pre_render callback for #type 'text_format' to hide field value from prying eyes.
+ * #pre_render callback: Hide field value of 'text_format' elements
  *
  * To not break form processing and previews if a user does not have access to a
  * stored text format, the expanded form elements in filter_process_format() are
@@ -996,7 +1019,24 @@ function filter_access($format, $account = NULL) {
 }
 
 /**
- * Helper function for fetching filter tips.
+ * Retrieves filter tips.
+ *
+ * @param $format_id
+ *   The ID of the text format for which to retrieve tips, or -1 to return tips
+ *   for all formats accessible to the current user.
+ * @param $long
+ *   Boolean indicating whether the long form of tips should be returned.
+ *
+ * @return
+ *   An array, keyed by text format name. For each format, the value is another
+ *   array keyed by filter name. The values of the inner arrays are arrays
+ *   of the form:
+ *   @code
+ *     array(
+ *       'tip' => 'Tip text',
+ *       'id'  => FILTER_ID
+ *     )
+ *   @endcode
  */
 function _filter_tips($format_id, $long = FALSE) {
   global $user;
@@ -1030,14 +1070,14 @@ function _filter_tips($format_id, $long = FALSE) {
 /**
  * Parses an HTML snippet and returns it as a DOM object.
  *
- * This function loads the body part of a partial (X)HTML document
- * and returns a full DOMDocument object that represents this document.
- * You can use filter_dom_serialize() to serialize this DOMDocument
- * back to a XHTML snippet.
+ * This function loads the body part of a partial (X)HTML document and returns a
+ * full DOMDocument object that represents this document. You can use
+ * filter_dom_serialize() to serialize this DOMDocument back to a XHTML snippet.
  *
  * @param $text
- *   The partial (X)HTML snippet to load. Invalid mark-up
- *   will be corrected on import.
+ *   The partial (X)HTML snippet to load. Invalid mark-up will be corrected on
+ *   import.
+ *
  * @return
  *   A DOMDocument that represents the loaded (X)HTML snippet.
  */
@@ -1052,15 +1092,16 @@ function filter_dom_load($text) {
 /**
  * Converts a DOM object back to an HTML snippet.
  *
- * The function serializes the body part of a DOMDocument
- * back to an XHTML snippet.
+ * The function serializes the body part of a DOMDocument back to an XHTML
+ * snippet.
  *
- * The resulting XHTML snippet will be properly formatted
- * to be compatible with HTML user agents.
+ * The resulting XHTML snippet will be properly formatted to be compatible with
+ * HTML user agents.
  *
  * @param $dom_document
  *   A DOMDocument object to serialize, only the tags below
  *   the first <body> node will be converted.
+ *
  * @return
  *   A valid (X)HTML snippet, as a string.
  */
diff --git a/core/modules/filter/filter.pages.inc b/core/modules/filter/filter.pages.inc
index dbbbe4c..f48b725 100644
--- a/core/modules/filter/filter.pages.inc
+++ b/core/modules/filter/filter.pages.inc
@@ -1,5 +1,4 @@
 <?php
-
 /**
  * @file
  * User page callbacks for the filter module.
@@ -7,7 +6,9 @@
 
 
 /**
- * Menu callback; show a page with long filter tips.
+ * Page callback: Displays a page with long filter tips.
+ *
+ * @see filter_menu()
  */
 function filter_tips_long() {
   $format_id = arg(2);
diff --git a/core/modules/filter/filter.test b/core/modules/filter/filter.test
index 2bafd47..41dc576 100644
--- a/core/modules/filter/filter.test
+++ b/core/modules/filter/filter.test
@@ -1,12 +1,11 @@
 <?php
-
 /**
  * @file
  * Tests for filter.module.
  */
 
 /**
- * Tests for text format and filter CRUD operations.
+ * Tests the text format and filter CRUD operations.
  */
 class FilterCRUDTestCase extends DrupalWebTestCase {
   public static function getInfo() {
@@ -22,7 +21,7 @@ class FilterCRUDTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Test CRUD operations for text formats and filters.
+   * Tests CRUD operations for text formats and filters.
    */
   function testTextFormatCRUD() {
     // Add a text format with minimum data only.
@@ -73,7 +72,7 @@ class FilterCRUDTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Verify that a text format is properly stored.
+   * Verifies that a text format is properly stored.
    */
   function verifyTextFormat($format) {
     $t_args = array('%format' => $format->name);
@@ -111,7 +110,7 @@ class FilterCRUDTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Verify that filters are properly stored for a text format.
+   * Verifies that filters are properly stored for a text format.
    */
   function verifyFilters($format) {
     // Verify filter database records.
@@ -184,7 +183,9 @@ class FilterAdminTestCase extends DrupalWebTestCase {
     $this->web_user = $this->drupalCreateUser(array('create page content', 'edit own page content'));
     $this->drupalLogin($this->admin_user);
   }
-
+  /**
+   * Tests the text format adminstration functionality.
+   */
   function testFormatAdmin() {
     // Add text format.
     $this->drupalGet('admin/config/content/formats');
@@ -249,7 +250,7 @@ class FilterAdminTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Test filter administration functionality.
+   * Tests the filter administration functionality.
    */
   function testFilterAdmin() {
     // URL filter.
@@ -459,6 +460,9 @@ class FilterFormatAccessTestCase extends DrupalWebTestCase {
     ));
   }
 
+  /**
+   * Tests the text format permission handling.
+   */
   function testFormatPermissions() {
     // Make sure that a regular user only has access to the text format they
     // were granted access to, as well to the fallback format.
@@ -495,6 +499,9 @@ class FilterFormatAccessTestCase extends DrupalWebTestCase {
     $this->assertTrue(isset($options[filter_fallback_format()]), t('The fallback format appears as an option when adding a new node.'));
   }
 
+  /**
+   * Tests the text format role handling.
+   */
   function testFormatRoles() {
     // Get the role ID assigned to the regular user; it must be the maximum.
     $rid = max(array_keys($this->web_user->roles));
@@ -516,7 +523,7 @@ class FilterFormatAccessTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Test editing a page using a disallowed text format.
+   * Tests editing a page using a disallowed text format.
    *
    * Verifies that regular users and administrators are able to edit a page,
    * but not allowed to change the fields which use an inaccessible text
@@ -638,7 +645,7 @@ class FilterFormatAccessTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Rebuild text format and permission caches in the thread running the tests.
+   * Rebuilds text format and permission caches in the thread running the tests.
    */
   protected function resetFilterCaches() {
     filter_formats_reset();
@@ -655,6 +662,9 @@ class FilterDefaultFormatTestCase extends DrupalWebTestCase {
     );
   }
 
+  /**
+   * Tests default text format handling.
+   */
   function testDefaultTextFormats() {
     // Create two text formats, and two users. The first user has access to
     // both formats, but the second user only has access to the second one.
@@ -698,7 +708,7 @@ class FilterDefaultFormatTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Rebuild text format and permission caches in the thread running the tests.
+   * Rebuilds text format and permission caches in the thread running the tests.
    */
   protected function resetFilterCaches() {
     filter_formats_reset();
@@ -715,6 +725,9 @@ class FilterNoFormatTestCase extends DrupalWebTestCase {
     );
   }
 
+  /**
+   * Tests the fallback text format.
+   */
   function testCheckMarkupNoFormat() {
     // Create some text. Include some HTML and line breaks, so we get a good
     // test of the filtering that is applied to it.
@@ -727,7 +740,7 @@ class FilterNoFormatTestCase extends DrupalWebTestCase {
 }
 
 /**
- * Security tests for missing/vanished text formats or filters.
+ * Tests security aspects for missing/vanished text formats or filters.
  */
 class FilterSecurityTestCase extends DrupalWebTestCase {
   public static function getInfo() {
@@ -745,7 +758,7 @@ class FilterSecurityTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Test that filtered content is emptied when an actively used filter module is disabled.
+   * Tests whehter filtered content is emptied when a filter module is disabled.
    */
   function testDisableFilterModule() {
     // Create a new node.
@@ -776,7 +789,7 @@ class FilterSecurityTestCase extends DrupalWebTestCase {
 }
 
 /**
- * Unit tests for core filters.
+ * Tests core filters.
  */
 class FilterUnitTestCase extends DrupalUnitTestCase {
   public static function getInfo() {
@@ -788,7 +801,7 @@ class FilterUnitTestCase extends DrupalUnitTestCase {
   }
 
   /**
-   * Test the line break filter.
+   * Tests the line break filter.
    */
   function testLineBreakFilter() {
     // Setup dummy filter object.
@@ -1048,7 +1061,7 @@ class FilterUnitTestCase extends DrupalUnitTestCase {
   }
 
   /**
-   * Test filter settings, defaults, access restrictions and similar.
+   * Tests filter settings, defaults, access restrictions and similar things.
    *
    * @todo This is for functions like filter_filter and check_markup, whose
    *   functionality is not completely focused on filtering. Some ideas:
@@ -1104,7 +1117,7 @@ class FilterUnitTestCase extends DrupalUnitTestCase {
   }
 
   /**
-   * Test the spam deterrent.
+   * Tests the spam deterrent no-follow filter.
    */
   function testNoFollowFilter() {
     // Setup dummy filter object.
@@ -1135,7 +1148,7 @@ class FilterUnitTestCase extends DrupalUnitTestCase {
   }
 
   /**
-   * Test the loose, admin HTML filter.
+   * Tests the permissive admin HTML filter.
    */
   function testFilterXSSAdmin() {
     // DRUPAL-SA-2008-044
@@ -1522,7 +1535,7 @@ www.example.com with a newline in comments -->
   }
 
   /**
-   * Test the HTML corrector filter.
+   * Tests the HTML corrector filter.
    *
    * @todo This test could really use some validity checking function.
    */
@@ -1713,7 +1726,10 @@ body {color:red}
   }
 
   /**
-   * Asserts that a text transformed to lowercase with HTML entities decoded does contains a given string.
+   * Asserts that a normalized string contains a given other string.
+   *
+   * Normalization here means transforming the string to lowercase and decoding
+   * HTML entities.
    *
    * Otherwise fails the test with a given message, similar to all the
    * SimpleTest assert* functions.
@@ -1737,7 +1753,10 @@ body {color:red}
   }
 
   /**
-   * Asserts that text transformed to lowercase with HTML entities decoded does not contain a given string.
+   * Asserts that a normalized string does not contains a given other string.
+   *
+   * Normalization here means transforming the string to lowercase and decoding
+   * HTML entities.
    *
    * Otherwise fails the test with a given message, similar to all the
    * SimpleTest assert* functions.
@@ -1780,7 +1799,7 @@ class FilterHooksTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Test that hooks run correctly on creating, editing, and deleting a text format.
+   * Tests that hooks run correctly on creating, editing, and deleting a format.
    */
   function testFilterHooks() {
     // Add a text format.