diff --git a/core/modules/system/system.api.php b/core/modules/system/system.api.php
index 8ef7556..49cf05e 100644
--- a/core/modules/system/system.api.php
+++ b/core/modules/system/system.api.php
@@ -2318,37 +2318,39 @@ function hook_requirements($phase) {
 /**
  * Define the current version of the database schema.
  *
- * A Drupal schema definition is an array structure representing one or
- * more tables and their related keys and indexes. A schema is defined by
+ * A Drupal schema definition is an array structure representing one or more
+ * tables and their related keys and indexes. A schema is defined by
  * hook_schema() which must live in your module's .install file.
  *
- * This hook is called at install and uninstall time, and in the latter
- * case, it cannot rely on the .module file being loaded or hooks being known.
- * If the .module file is needed, it may be loaded with drupal_load().
+ * This hook is called at install and uninstall time, and in the latter case, it
+ * cannot rely on the .module file being loaded or hooks being known. If the
+ * .module file is needed, it may be loaded with drupal_load().
  *
- * The tables declared by this hook will be automatically created when
- * the module is first enabled, and removed when the module is uninstalled.
- * This happens before hook_install() is invoked, and after hook_uninstall()
- * is invoked, respectively.
+ * The tables declared by this hook will be automatically created when the
+ * module is first enabled, and removed when the module is uninstalled. This
+ * happens before hook_install() is invoked, and after hook_uninstall() is
+ * invoked, respectively.
  *
  * By declaring the tables used by your module via an implementation of
  * hook_schema(), these tables will be available on all supported database
  * engines. You don't have to deal with the different SQL dialects for table
  * creation and alteration of the supported database engines.
  *
- * See the Schema API Handbook at http://drupal.org/node/146843 for
- * details on schema definition structures.
+ * See the Schema API Handbook at http://drupal.org/node/146843 for details on
+ * schema definition structures.
  *
- * @return
+ * @return array
  *   A schema definition structure array. For each element of the
  *   array, the key is a table name and the value is a table structure
  *   definition.
  *
+ * @see hook_schema_alter()
+ *
  * @ingroup schemaapi
  */
 function hook_schema() {
   $schema['node'] = array(
-    // example (partial) specification for table "node"
+    // Example (partial) specification for table "node".
     'description' => 'The base table for nodes.',
     'fields' => array(
       'nid' => array(