diff --git a/modules/block/block.api.php b/modules/block/block.api.php
index 312eb11..e63994e 100644
--- a/modules/block/block.api.php
+++ b/modules/block/block.api.php
@@ -253,8 +253,9 @@ function hook_block_view($delta = '') {
  * specific block.
  *
  * @param $data
- *   An array of data, as returned from the hook_block_view() implementation of
- *   the module that defined the block:
+ *   The data as returned from the hook_block_view() implementation of the
+ *   module that defined the block. This could be an empty array or NULL value
+ *   (if the block is empty) or an array containing:
  *   - subject: The default localized title of the block.
  *   - content: Either a string or a renderable array representing the content
  *     of the block. You should check that the content is an array before trying
@@ -287,8 +288,9 @@ function hook_block_view_alter(&$data, $block) {
  * specific block, rather than implementing hook_block_view_alter().
  *
  * @param $data
- *   An array of data, as returned from the hook_block_view() implementation of
- *   the module that defined the block:
+ *   The data as returned from the hook_block_view() implementation of the
+ *   module that defined the block. This could be an empty array or NULL value
+ *   (if the block is empty) or an array containing:
  *   - subject: The localized title of the block.
  *   - content: Either a string or a renderable array representing the content
  *     of the block. You should check that the content is an array before trying