diff --git a/core/lib/Drupal/Core/TypedData/Annotation/DataType.php b/core/lib/Drupal/Core/TypedData/Annotation/DataType.php
index 7778267..c0569ab 100644
--- a/core/lib/Drupal/Core/TypedData/Annotation/DataType.php
+++ b/core/lib/Drupal/Core/TypedData/Annotation/DataType.php
@@ -12,6 +12,26 @@
 /**
  * Defines a data type annotation object.
  *
+ * The typed data API allows modules to support any kind of data based upon
+ * pre-defined primitive types and interfaces for complex data and lists.
+ *
+ * Defined data types may map to one of the pre-defined primitive types in
+ * \Drupal\Core\TypedData\Primitive or may be complex data types, containing on
+ * or more data properties. Typed data objects for complex data types have to
+ * implement the \Drupal\Core\TypedData\ComplexDataInterface. Further interface
+ * that may be implemented are:
+ *  - \Drupal\Core\TypedData\AccessibleInterface
+ *  - \Drupal\Core\TypedData\TranslatableInterface
+ *
+ * Furthermore, lists of data items are represented by objects implementing the
+ * \Drupal\Core\TypedData\ListInterface. A list contains items of the same data
+ * type, is ordered and may contain duplicates. The classed used for a list of
+ * items of a certain type may be specified using the 'list class' key.
+ *
+ * @see \Drupal::typedData()
+ * @see Drupal\Core\TypedData\TypedDataManager::create()
+ * @see hook_data_type_info_alter()
+ *
  * @Annotation
  */
 class DataType extends Plugin {
@@ -42,9 +62,30 @@ class DataType extends Plugin {
   public $description;
 
   /**
-   * The name of the list class for the data type.
+   * The typed data class used for wrapping multiple data items of the type.
+   * Must implement the \Drupal\Core\TypedData\ListInterface.
    *
    * @var string
    */
   public $list_class = '\Drupal\Core\TypedData\ItemList';
+
+  /**
+   * The pre-defined primitive type that this data type maps to.
+   *
+   * If set, it must be a constant defined by \Drupal\Core\TypedData\Primitive
+   * such as \Drupal\Core\TypedData\Primitive::STRING.
+   *
+   * @var string
+   */
+  public $primitive_type;
+
+  /**
+   * An array of validation constraints for this type.
+   *
+   * @var array
+   *
+   * @see \Drupal\Core\TypedData\TypedDataManager::getConstraints().
+   */
+  public $constraints;
+
 }