diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 178702b..f15d9a5 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -634,14 +634,24 @@ function _theme($hook, $variables = array()) {
 }
 
 /**
- * Returns the path to the current themed element.
- *
- * It can point to the active theme or the module handling a themed
- * implementation. For example, when invoked within the scope of a theming call
- * it will depend on where the theming function is handled. If implemented from
- * a module, it will point to the module. If implemented from the active theme,
- * it will point to the active theme. When called outside the scope of a
- * theming call, it will always point to the active theme.
+ * Returns the path to a theme or to a module implementing hook_theme().
+ *
+ * The path points either to the current active theme or during a rendering
+ * process the path points to the theme or module that registered the theme
+ * function or template by implementing hook_theme().
+ *
+ * During rendering, elements in the render array tree are eventually passed to
+ * the internal _theme() function, which decides which theme function or
+ * template to use. In this context, the return value of path_to_theme() will be
+ * the directory path of the theme or module that did register this particular
+ * theme hook.
+ *
+ * @return string
+ *   A directory path relative to the Drupal root directory.
+ *
+ * @see hook_theme()
+ * @see drupal_render()
+ * @see _theme()
  */
 function path_to_theme() {
   global $theme_path;