diff --git a/core/lib/Drupal/Core/File/File.php b/core/lib/Drupal/Core/File/File.php
index b35f5ee..2e5e67d 100644
--- a/core/lib/Drupal/Core/File/File.php
+++ b/core/lib/Drupal/Core/File/File.php
@@ -22,6 +22,13 @@ class File extends Entity {
   public $fid;
 
   /**
+   * The file UUID.
+   *
+   * @var string
+   */
+  public $uuid;
+
+  /**
    * The file language code.
    *
    * @var string
diff --git a/core/modules/comment/comment.install b/core/modules/comment/comment.install
index 4b3c9fc..0a147b5 100644
--- a/core/modules/comment/comment.install
+++ b/core/modules/comment/comment.install
@@ -91,6 +91,12 @@ function comment_schema() {
         'not null' => TRUE,
         'description' => 'Primary Key: Unique comment ID.',
       ),
+      'uuid' => array(
+        'description' => 'Unique Key: Universally unique identifier for this entity.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => FALSE,
+      ),
       'pid' => array(
         'type' => 'int',
         'not null' => TRUE,
@@ -183,6 +189,9 @@ function comment_schema() {
       'comment_created' => array('created'),
     ),
     'primary key' => array('cid'),
+    'unique keys' => array(
+      'uuid' => array('uuid'),
+    ),
     'foreign keys' => array(
       'comment_node' => array(
         'table' => 'node',
@@ -282,6 +291,32 @@ function comment_update_8000() {
 }
 
 /**
+ * Create a UUID column for comments.
+ *
+ * @todo UUID upgrade path: http://drupal.org/node/1642526
+ */
+function comment_update_8001() {
+  $spec = array(
+    'description' => 'Unique Key: Universally unique identifier for this entity.',
+    'type' => 'varchar',
+    'length' => 128,
+    'not null' => FALSE,
+  );
+  $keys = array(
+    'unique keys' => array(
+      'uuid' => array('uuid'),
+    ),
+  );
+  // Account for sites having the contributed UUID module installed.
+  if (db_field_exists('comment', 'uuid')) {
+    db_change_field('comment', 'uuid', 'uuid', $spec, $keys);
+  }
+  else {
+    db_add_field('comment', 'uuid', $spec, $keys);
+  }
+}
+
+/**
  * @} End of "addtogroup updates-7.x-to-8.x".
  * The next series of updates should start at 9000.
  */
diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index a6230f2..815fce3 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -109,6 +109,7 @@ function comment_entity_info() {
         'id' => 'cid',
         'bundle' => 'node_type',
         'label' => 'subject',
+        'uuid' => 'uuid',
       ),
       'bundles' => array(),
       'view modes' => array(
diff --git a/core/modules/comment/lib/Drupal/comment/Comment.php b/core/modules/comment/lib/Drupal/comment/Comment.php
index 101a679..a7bacd4 100644
--- a/core/modules/comment/lib/Drupal/comment/Comment.php
+++ b/core/modules/comment/lib/Drupal/comment/Comment.php
@@ -22,6 +22,13 @@ class Comment extends Entity {
   public $cid;
 
   /**
+   * The comment UUID.
+   *
+   * @var string
+   */
+  public $uuid;
+
+  /**
    * The parent comment ID if this is a reply to a comment.
    *
    * @var integer
diff --git a/core/modules/entity/entity.api.php b/core/modules/entity/entity.api.php
index 02d8754..5359376 100644
--- a/core/modules/entity/entity.api.php
+++ b/core/modules/entity/entity.api.php
@@ -76,6 +76,9 @@
  *       'subject' should be specified here. If complex logic is required to
  *       build the label, a 'label callback' should be defined instead (see
  *       the 'label callback' section above for details).
+ *     - uuid (optional): The name of the property that contains the universally
+ *       unique identifier of the entity, which is used to distinctly identify
+ *       an entity across different systems.
  *   - bundle keys: An array describing how the Field API can extract the
  *     information it needs from the bundle objects for this type (e.g
  *     $vocabulary objects for terms; not applicable for nodes). This entry can
@@ -147,6 +150,7 @@ function hook_entity_info() {
         'id' => 'nid',
         'revision' => 'vid',
         'bundle' => 'type',
+        'uuid' => 'uuid',
       ),
       'bundle keys' => array(
         'bundle' => 'type',
diff --git a/core/modules/entity/entity.module b/core/modules/entity/entity.module
index a66b1e8..7514458 100644
--- a/core/modules/entity/entity.module
+++ b/core/modules/entity/entity.module
@@ -5,7 +5,9 @@
  * Entity API for handling entities like nodes or users.
  */
 
+use Drupal\entity\EntityFieldQuery;
 use Drupal\entity\EntityMalformedException;
+use Drupal\entity\EntityStorageException;
 use Drupal\entity\EntityInterface;
 
 /**
@@ -217,6 +219,64 @@ function entity_load($entity_type, $id, $reset = FALSE) {
 }
 
 /**
+ * Loads an entity by UUID.
+ *
+ * Note that some entity types may not support UUIDs.
+ *
+ * @see hook_entity_info()
+ *
+ * @param string $entity_type
+ *   The entity type to load; e.g., 'node' or 'user'.
+ * @param string $uuid
+ *   The UUID of the entity to load.
+ * @param bool $reset
+ *   Whether to reset the internal cache for the requested entity type.
+ *
+ * @return EntityInterface|FALSE
+ *   The entity object, or FALSE if there is no entity with the given UUID.
+ *
+ * @todo Provide an entity CRUD controller API to execute proper property-based
+ *   lookups. This uses an EntityFieldQuery, since the $conditions parameter of
+ *   EntityStorageControllerInterface::load() is deprecated, although it would
+ *   be the most simple solution for entity-level properties that are expected
+ *   to universally exist for all entity types. At the same time, the entire
+ *   logic of this function absolutely belongs into the entity storage
+ *   controller, which has all required information readily at hand. However, we
+ *   do not want to pollute EntityStorageControllerInterface with property
+ *   specific ::loadByUUID() methods; a generic ::loadByProperty() method would
+ *   be more appropriate, but potentially breaks the separation of concerns.
+ *   Overall, this is way too much code to retrieve a single entity and the API
+ *   definitely has to be cleaned up for Drupal 8.
+ */
+function entity_load_by_uuid($entity_type, $uuid, $reset = FALSE) {
+  $entity_info = entity_get_info($entity_type);
+  if (empty($entity_info['entity keys']['uuid'])) {
+    throw new EntityStorageException("Entity type $entity_type does not support UUIDs.");
+  }
+  $uuid_key = $entity_info['entity keys']['uuid'];
+
+  // Look up the entity ID for the given UUID.
+  $entity_query = new EntityFieldQuery();
+  $result = $entity_query
+    ->entityCondition('entity_type', $entity_type)
+    ->propertyCondition($uuid_key, $uuid)
+    ->range(0, 1)
+    ->execute();
+
+  if (empty($result[$entity_type])) {
+    return FALSE;
+  }
+
+  $controller = entity_get_controller($entity_type);
+  if ($reset) {
+    $controller->resetCache();
+  }
+  $id = key($result[$entity_type]);
+  $entities = $controller->load(array($id));
+  return isset($entities[$id]) ? $entities[$id] : FALSE;
+}
+
+/**
  * Loads multiple entities from the database.
  *
  * This function should be used whenever you need to load more than one entity
diff --git a/core/modules/entity/lib/Drupal/entity/DatabaseStorageController.php b/core/modules/entity/lib/Drupal/entity/DatabaseStorageController.php
index 8d89341..8c4f3c8 100644
--- a/core/modules/entity/lib/Drupal/entity/DatabaseStorageController.php
+++ b/core/modules/entity/lib/Drupal/entity/DatabaseStorageController.php
@@ -8,6 +8,8 @@
 namespace Drupal\entity;
 
 use PDO;
+use Drupal\Component\Uuid\Uuid;
+
 
 /**
  * Defines a base entity controller class.
@@ -59,6 +61,15 @@ class DatabaseStorageController implements EntityStorageControllerInterface {
   protected $idKey;
 
   /**
+   * Name of entity's UUID database table field, if it supports UUIDs.
+   *
+   * Has the value FALSE if this entity does not use UUIDs.
+   *
+   * @var string
+   */
+  protected $uuidKey;
+
+  /**
    * Name of entity's revision database table field, if it supports revisions.
    *
    * Has the value FALSE if this entity does not use revisions.
@@ -95,6 +106,14 @@ class DatabaseStorageController implements EntityStorageControllerInterface {
     $this->hookLoadArguments = array();
     $this->idKey = $this->entityInfo['entity keys']['id'];
 
+    // Check if the entity type supports UUIDs.
+    if (!empty($this->entityInfo['entity keys']['uuid'])) {
+      $this->uuidKey = $this->entityInfo['entity keys']['uuid'];
+    }
+    else {
+      $this->uuidKey = FALSE;
+    }
+
     // Check if the entity type supports revisions.
     if (!empty($this->entityInfo['entity keys']['revision'])) {
       $this->revisionKey = $this->entityInfo['entity keys']['revision'];
@@ -366,7 +385,16 @@ class DatabaseStorageController implements EntityStorageControllerInterface {
    */
   public function create(array $values) {
     $class = isset($this->entityInfo['entity class']) ? $this->entityInfo['entity class'] : 'Drupal\entity\Entity';
-    return new $class($values, $this->entityType);
+
+    $entity = new $class($values, $this->entityType);
+
+    // Assign a new UUID if there is none yet.
+    if ($this->uuidKey && !isset($entity->{$this->uuidKey})) {
+      $uuid = new Uuid();
+      $entity->{$this->uuidKey} = $uuid->generate();
+    }
+
+    return $entity;
   }
 
   /**
diff --git a/core/modules/entity/lib/Drupal/entity/Tests/EntityUUIDTest.php b/core/modules/entity/lib/Drupal/entity/Tests/EntityUUIDTest.php
new file mode 100644
index 0000000..c2f42c5
--- /dev/null
+++ b/core/modules/entity/lib/Drupal/entity/Tests/EntityUUIDTest.php
@@ -0,0 +1,65 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\entity\Tests\EntityUUIDTest.
+ */
+
+namespace Drupal\entity\Tests;
+
+use Drupal\Component\Uuid\Uuid;
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Tests creation, saving, and loading of entity UUIDs.
+ */
+class EntityUUIDTest extends WebTestBase {
+  public static function getInfo() {
+    return array(
+      'name' => 'Entity UUIDs',
+      'description' => 'Tests creation, saving, and loading of entity UUIDs.',
+      'group' => 'Entity API',
+    );
+  }
+
+  function setUp() {
+    parent::setUp(array('entity_test'));
+  }
+
+  /**
+   * Tests UUID generation in entity CRUD operations.
+   */
+  function testCRUD() {
+    // Verify that no UUID is auto-generated when passing one for creation.
+    $uuid_service = new Uuid();
+    $uuid = $uuid_service->generate();
+    $custom_entity = entity_create('entity_test', array(
+      'name' => $this->randomName(),
+      'uuid' => $uuid,
+    ));
+    $this->assertIdentical($custom_entity->get('uuid'), $uuid);
+    // Save this entity, so we have more than one later.
+    $custom_entity->save();
+
+    // Verify that a new UUID is generated upon creating an entity.
+    $entity = entity_create('entity_test', array('name' => $this->randomName()));
+    $uuid = $entity->get('uuid');
+    $this->assertTrue($uuid);
+
+    // Verify that the new UUID is different.
+    $this->assertNotEqual($custom_entity->get('uuid'), $uuid);
+
+    // Verify that the UUID is retained upon saving.
+    $entity->save();
+    $this->assertIdentical($entity->get('uuid'), $uuid);
+
+    // Verify that the UUID is retained upon loading.
+    $entity_loaded = entity_test_load($entity->id(), TRUE);
+    $this->assertIdentical($entity_loaded->get('uuid'), $uuid);
+
+    // Verify that entity_load_by_uuid() loads the same entity.
+    $entity_loaded_by_uuid = entity_load_by_uuid('entity_test', $uuid, TRUE);
+    $this->assertIdentical($entity_loaded_by_uuid->get('uuid'), $uuid);
+    $this->assertEqual($entity_loaded_by_uuid, $entity_loaded);
+  }
+}
diff --git a/core/modules/entity/tests/modules/entity_test/entity_test.install b/core/modules/entity/tests/modules/entity_test/entity_test.install
index c0c7703..1bef390 100644
--- a/core/modules/entity/tests/modules/entity_test/entity_test.install
+++ b/core/modules/entity/tests/modules/entity_test/entity_test.install
@@ -43,6 +43,12 @@ function entity_test_schema() {
         'not null' => TRUE,
         'description' => 'Primary Key: Unique entity-test item ID.',
       ),
+      'uuid' => array(
+        'description' => 'Unique Key: Universally unique identifier for this entity.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => FALSE,
+      ),
       'name' => array(
         'description' => 'The name of the test entity.',
         'type' => 'varchar',
@@ -72,6 +78,9 @@ function entity_test_schema() {
       'uid' => array('users' => 'uid'),
     ),
     'primary key' => array('id'),
+    'unique keys' => array(
+      'uuid' => array('uuid'),
+    ),
   );
   return $schema;
 }
diff --git a/core/modules/entity/tests/modules/entity_test/entity_test.module b/core/modules/entity/tests/modules/entity_test/entity_test.module
index f97d2e9..67c3085 100644
--- a/core/modules/entity/tests/modules/entity_test/entity_test.module
+++ b/core/modules/entity/tests/modules/entity_test/entity_test.module
@@ -17,6 +17,7 @@ function entity_test_entity_info() {
     'fieldable' => TRUE,
     'entity keys' => array(
       'id' => 'id',
+      'uuid' => 'uuid',
     ),
   );
   // Optionally specify a translation handler for testing translations.
diff --git a/core/modules/node/lib/Drupal/node/Node.php b/core/modules/node/lib/Drupal/node/Node.php
index cee6967..fad5c4f 100644
--- a/core/modules/node/lib/Drupal/node/Node.php
+++ b/core/modules/node/lib/Drupal/node/Node.php
@@ -29,6 +29,13 @@ class Node extends Entity {
   public $vid;
 
   /**
+   * The node UUID.
+   *
+   * @var string
+   */
+  public $uuid;
+
+  /**
    * The node content type (bundle).
    *
    * @var string
diff --git a/core/modules/node/node.install b/core/modules/node/node.install
index 7382320..054991d 100644
--- a/core/modules/node/node.install
+++ b/core/modules/node/node.install
@@ -18,6 +18,12 @@ function node_schema() {
         'unsigned' => TRUE,
         'not null' => TRUE,
       ),
+      'uuid' => array(
+        'description' => 'Unique Key: Universally unique identifier for this entity.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => FALSE,
+      ),
       // Defaults to NULL in order to avoid a brief period of potential
       // deadlocks on the index.
       'vid' => array(
@@ -117,6 +123,7 @@ function node_schema() {
     ),
     'unique keys' => array(
       'vid' => array('vid'),
+      'uuid' => array('uuid'),
     ),
     'foreign keys' => array(
       'node_revision' => array(
@@ -568,6 +575,32 @@ function node_update_8003() {
 }
 
 /**
+ * Create a UUID column for nodes.
+ *
+ * @todo UUID upgrade path: http://drupal.org/node/1642526
+ */
+function node_update_8004() {
+  $spec = array(
+    'description' => 'Unique Key: Universally unique identifier for this entity.',
+    'type' => 'varchar',
+    'length' => 128,
+    'not null' => FALSE,
+  );
+  $keys = array(
+    'unique keys' => array(
+      'uuid' => array('uuid'),
+    ),
+  );
+  // Account for sites having the contributed UUID module installed.
+  if (db_field_exists('node', 'uuid')) {
+    db_change_field('node', 'uuid', 'uuid', $spec, $keys);
+  }
+  else {
+    db_add_field('node', 'uuid', $spec, $keys);
+  }
+}
+
+/**
  * @} End of "addtogroup updates-7.x-to-8.x"
  * The next series of updates should start at 9000.
  */
diff --git a/core/modules/node/node.module b/core/modules/node/node.module
index 319f422..6a0e990 100644
--- a/core/modules/node/node.module
+++ b/core/modules/node/node.module
@@ -204,6 +204,7 @@ function node_entity_info() {
         'revision' => 'vid',
         'bundle' => 'type',
         'label' => 'title',
+        'uuid' => 'uuid',
       ),
       'bundle keys' => array(
         'bundle' => 'type',
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 16bac0f..08d97c8 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -866,6 +866,12 @@ function system_schema() {
         'unsigned' => TRUE,
         'not null' => TRUE,
       ),
+      'uuid' => array(
+        'description' => 'Unique Key: Universally unique identifier for this entity.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => FALSE,
+      ),
       'uid' => array(
         'description' => 'The {users}.uid of the user who is associated with the file.',
         'type' => 'int',
@@ -931,6 +937,7 @@ function system_schema() {
       'timestamp' => array('timestamp'),
     ),
     'unique keys' => array(
+      'uuid' => array('uuid'),
       'uri' => array('uri'),
     ),
     'primary key' => array('fid'),
@@ -1938,6 +1945,32 @@ function system_update_8011() {
 }
 
 /**
+ * Create a UUID column for managed files.
+ *
+ * @todo UUID upgrade path: http://drupal.org/node/1642526
+ */
+function system_update_8012() {
+  $spec = array(
+    'description' => 'Unique Key: Universally unique identifier for this entity.',
+    'type' => 'varchar',
+    'length' => 128,
+    'not null' => FALSE,
+  );
+  $keys = array(
+    'unique keys' => array(
+      'uuid' => array('uuid'),
+    ),
+  );
+  // Account for sites having the contributed UUID module installed.
+  if (db_field_exists('file_managed', 'uuid')) {
+    db_change_field('file_managed', 'uuid', 'uuid', $spec, $keys);
+  }
+  else {
+    db_add_field('file_managed', 'uuid', $spec, $keys);
+  }
+}
+
+/**
  * @} End of "defgroup updates-7.x-to-8.x".
  * The next series of updates should start at 9000.
  */
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 75b1fa2..4fee147 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -280,6 +280,7 @@ function system_entity_info() {
       'entity keys' => array(
         'id' => 'fid',
         'label' => 'filename',
+        'uuid' => 'uuid',
       ),
       'static cache' => FALSE,
     ),
diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/Term.php b/core/modules/taxonomy/lib/Drupal/taxonomy/Term.php
index f036f18..929422c 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/Term.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/Term.php
@@ -22,6 +22,13 @@ class Term extends Entity {
   public $tid;
 
   /**
+   * The term UUID.
+   *
+   * @var string
+   */
+  public $uuid;
+
+  /**
    * The taxonomy vocabulary ID this term belongs to.
    *
    * @var integer
diff --git a/core/modules/taxonomy/taxonomy.install b/core/modules/taxonomy/taxonomy.install
index 14b6956..361dc6a 100644
--- a/core/modules/taxonomy/taxonomy.install
+++ b/core/modules/taxonomy/taxonomy.install
@@ -32,6 +32,12 @@ function taxonomy_schema() {
         'not null' => TRUE,
         'description' => 'Primary Key: Unique term ID.',
       ),
+      'uuid' => array(
+        'description' => 'Unique Key: Universally unique identifier for this entity.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => FALSE,
+      ),
       'vid' => array(
         'type' => 'int',
         'unsigned' => TRUE,
@@ -75,6 +81,9 @@ function taxonomy_schema() {
       ),
     ),
     'primary key' => array('tid'),
+    'unique keys' => array(
+      'uuid' => array('uuid'),
+    ),
     'foreign keys' => array(
       'vocabulary' => array(
         'table' => 'taxonomy_vocabulary',
@@ -300,3 +309,29 @@ function taxonomy_update_8001() {
     }
   }
 }
+
+/**
+ * Create a UUID column for taxonomy terms.
+ *
+ * @todo UUID upgrade path: http://drupal.org/node/1642526
+ */
+function taxonomy_update_8002() {
+  $spec = array(
+    'description' => 'Unique Key: Universally unique identifier for this entity.',
+    'type' => 'varchar',
+    'length' => 128,
+    'not null' => FALSE,
+  );
+  $keys = array(
+    'unique keys' => array(
+      'uuid' => array('uuid'),
+    ),
+  );
+  // Account for sites having the contributed UUID module installed.
+  if (db_field_exists('taxonomy_term_data', 'uuid')) {
+    db_change_field('taxonomy_term_data', 'uuid', 'uuid', $spec, $keys);
+  }
+  else {
+    db_add_field('taxonomy_term_data', 'uuid', $spec, $keys);
+  }
+}
diff --git a/core/modules/taxonomy/taxonomy.module b/core/modules/taxonomy/taxonomy.module
index 6697a0a..b31bab9 100644
--- a/core/modules/taxonomy/taxonomy.module
+++ b/core/modules/taxonomy/taxonomy.module
@@ -120,6 +120,7 @@ function taxonomy_entity_info() {
         'id' => 'tid',
         'bundle' => 'vocabulary_machine_name',
         'label' => 'name',
+        'uuid' => 'uuid',
       ),
       'bundle keys' => array(
         'bundle' => 'machine_name',
diff --git a/core/modules/user/lib/Drupal/user/User.php b/core/modules/user/lib/Drupal/user/User.php
index 992923c..25e27f1 100644
--- a/core/modules/user/lib/Drupal/user/User.php
+++ b/core/modules/user/lib/Drupal/user/User.php
@@ -22,6 +22,13 @@ class User extends Entity {
   public $uid;
 
   /**
+   * The user UUID.
+   *
+   * @var string
+   */
+  public $uuid;
+
+  /**
    * The unique user name.
    *
    * @var string
diff --git a/core/modules/user/user.install b/core/modules/user/user.install
index 5ec57da..abb985b 100644
--- a/core/modules/user/user.install
+++ b/core/modules/user/user.install
@@ -132,6 +132,12 @@ function user_schema() {
         'description' => 'Primary Key: Unique user ID.',
         'default' => 0,
       ),
+      'uuid' => array(
+        'description' => 'Unique Key: Universally unique identifier for this entity.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => FALSE,
+      ),
       'name' => array(
         'type' => 'varchar',
         'length' => 60,
@@ -246,6 +252,7 @@ function user_schema() {
       'picture' => array('picture'),
     ),
     'unique keys' => array(
+      'uuid' => array('uuid'),
       'name' => array('name'),
     ),
     'primary key' => array('uid'),
@@ -442,5 +449,31 @@ function user_update_8002() {
 }
 
 /**
+ * Create a UUID column for users.
+ *
+ * @todo UUID upgrade path: http://drupal.org/node/1642526
+ */
+function user_update_8003() {
+  $spec = array(
+    'description' => 'Unique Key: Universally unique identifier for this entity.',
+    'type' => 'varchar',
+    'length' => 128,
+    'not null' => FALSE,
+  );
+  $keys = array(
+    'unique keys' => array(
+      'uuid' => array('uuid'),
+    ),
+  );
+  // Account for sites having the contributed UUID module installed.
+  if (db_field_exists('users', 'uuid')) {
+    db_change_field('users', 'uuid', 'uuid', $spec, $keys);
+  }
+  else {
+    db_add_field('users', 'uuid', $spec, $keys);
+  }
+}
+
+/**
  * @} End of "addtogroup updates-7.x-to-8.x".
  */
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index 1e7aa99..156c61b 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -154,6 +154,7 @@ function user_entity_info() {
       'entity class' => 'Drupal\user\User',
       'entity keys' => array(
         'id' => 'uid',
+        'uuid' => 'uuid',
       ),
       'bundles' => array(
         'user' => array(