diff --git a/includes/common.inc b/includes/common.inc
index d7b413c..1800330 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -92,11 +92,12 @@ define('JS_THEME', 100);
 define('HTTP_REQUEST_TIMEOUT', -1);
 
 /**
- * Constants defining cache granularity for blocks and renderable arrays.
+ * @defgroup block_caching Block Caching
+ * @{
+ * Constants that define each block's caching state.
  *
  * Modules specify the caching patterns for their blocks using binary
- * combinations of these constants in their hook_block_info():
- *   $block[delta]['cache'] = DRUPAL_CACHE_PER_ROLE | DRUPAL_CACHE_PER_PAGE;
+ * combinations of these constants in their hook_block_info().
  * DRUPAL_CACHE_PER_ROLE is used as a default when no caching pattern is
  * specified. Use DRUPAL_CACHE_CUSTOM to disable standard block cache and
  * implement
@@ -156,6 +157,10 @@ define('DRUPAL_CACHE_PER_PAGE', 0x0004);
 define('DRUPAL_CACHE_GLOBAL', 0x0008);
 
 /**
+ * @} End of "defgroup block_caching".
+ */
+
+/**
  * Adds content to a specified region.
  *
  * @param $region
diff --git a/modules/block/block.api.php b/modules/block/block.api.php
index 3cd52f8..312eb11 100644
--- a/modules/block/block.api.php
+++ b/modules/block/block.api.php
@@ -55,6 +55,7 @@
  *       viewed.
  *     - DRUPAL_CACHE_GLOBAL: The block is the same for every user on every page
  *       where it is visible.
+ *     - DRUPAL_CACHE_CUSTOM: The module implements its own caching system.
  *     - DRUPAL_NO_CACHE: The block should not get cached.
  *   - properties: (optional) Array of additional metadata to add to the block.
  *     Common properties include: