-global $menu, $submenu, $parent_file; //For when admin-header is included from within a function.
-$parent_file = apply_filters("parent_file", $parent_file); // For plugins to move submenu tabs around.
+/**
+ * For when admin-header is included from within a function.
+ *
+ * @global array $menu
+ * @global array $submenu
+ * @global string $parent_file
+ * @global string $submenu_file
+ */
+global $menu, $submenu, $parent_file, $submenu_file;
+
+/**
+ * Filters the parent file of an admin menu sub-menu item.
+ *
+ * Allows plugins to move sub-menu items around.
+ *
+ * @since MU
+ *
+ * @param string $parent_file The parent file.
+ */
+$parent_file = apply_filters( 'parent_file', $parent_file );
+
+/**
+ * Filters the file of an admin menu sub-menu item.
+ *
+ * @since 4.4.0
+ *
+ * @param string $submenu_file The submenu file.
+ * @param string $parent_file The submenu item's parent file.
+ */
+$submenu_file = apply_filters( 'submenu_file', $submenu_file, $parent_file );