+### 'nav_info'
+is called after the navigational menu is build in include/nav.php.
+$b is an array containing $nav from nav.php.
+
+### 'template_vars'
+is called before vars are passed to the template engine to render the page.
+The registered function can add,change or remove variables passed to template.
+$b is an array with:
+
+ 'template' => filename of template
+ 'vars' => array of vars passed to template
+
+
+