diff --git a/lib/plankton/plankton.d.ts b/lib/plankton/plankton.d.ts
index 8aeff70..5051ea6 100644
--- a/lib/plankton/plankton.d.ts
+++ b/lib/plankton/plankton.d.ts
@@ -1,11 +1,11 @@
 /**
  * @author fenris
  */
-declare type int = number;
+type int = number;
 /**
  * @author fenris
  */
-declare type float = number;
+type float = number;
 declare class Buffer {
     constructor(x: string, modifier?: string);
     toString(modifier?: string): string;
@@ -19,7 +19,7 @@ declare namespace lib_plankton.base {
 /**
  * @author fenris
  */
-declare type type_pseudopointer<type_value> = {
+type type_pseudopointer<type_value> = {
     value: type_value;
 };
 /**
@@ -810,6 +810,10 @@ declare namespace lib_plankton.call {
      * @author fenris
      */
     export function timeout(procedure: (() => void), delay_in_seconds: float): int;
+    /**
+     * @author fenris
+     */
+    export function loop(procedure: (() => void), delay_in_seconds: float): int;
     /**
      * Promise version of "setTimeout"
      *
@@ -1965,7 +1969,7 @@ declare namespace lib_plankton.storage.memory {
         clear(): Promise<void>;
         write(key: any, value: any): Promise<boolean>;
         delete(key: any): Promise<void>;
-        read(key: any): Promise<type_item>;
+        read(key: any): Promise<Awaited<type_item>>;
         search(term: any): Promise<{
             key: string;
             preview: string;
@@ -3393,17 +3397,19 @@ declare namespace lib_plankton.zoo_page {
     /**
      */
     type type_handler = ((parameters: Record<string, any>, target_element: Element) => void);
+    /**
+     */
+    type type_nav_entry_definition = {
+        location: type_location;
+        label: string;
+        groups: Array<string>;
+    };
     /**
      */
     export let _pool: Record<string, type_handler>;
     /**
      */
     export function encode(location: type_location): string;
-    /**
-     */
-    export function add_nav_entry(location: type_location, options?: {
-        label?: (null | string);
-    }): void;
     /**
      * encodes a location in the URL and loads it
      */
@@ -3413,12 +3419,17 @@ declare namespace lib_plankton.zoo_page {
     export function reload(): Promise<void>;
     /**
      */
-    export function register(location_name: string, handler: type_handler, options?: {}): void;
+    export function register(location_name: string, handler: type_handler): void;
     /**
      */
-    export function init(target_element: Element, options?: {
+    export function nav_set_groups(groups: (null | Array<string>)): void;
+    /**
+     */
+    export function init(target_element: Element, { "pool": pool, "fallback": fallback, "nav_entries": nav_entries, "nav_initial_groups": nav_initial_groups, }?: {
         pool?: Record<string, type_handler>;
         fallback?: (null | type_location);
+        nav_entries?: Array<type_nav_entry_definition>;
+        nav_initial_groups?: (null | Array<string>);
     }): void;
     /**
      */
diff --git a/lib/plankton/plankton.js b/lib/plankton/plankton.js
index db470e3..e04b6f9 100644
--- a/lib/plankton/plankton.js
+++ b/lib/plankton/plankton.js
@@ -1883,6 +1883,14 @@ var lib_plankton;
             /*window.*/ setTimeout(procedure, Math.floor(delay_in_seconds * 1000)));
         }
         call.timeout = timeout;
+        /**
+         * @author fenris
+         */
+        function loop(procedure, delay_in_seconds) {
+            return (
+            /*window.*/ setInterval(procedure, Math.floor(delay_in_seconds * 1000)));
+        }
+        call.loop = loop;
         /**
          * Promise version of "setTimeout"
          *
@@ -2143,7 +2151,7 @@ var __generator = (this && this.__generator) || function (thisArg, body) {
     function verb(n) { return function (v) { return step([n, v]); }; }
     function step(op) {
         if (f) throw new TypeError("Generator is already executing.");
-        while (_) try {
+        while (g && (g = 0, op[0] && (_ = 0)), _) try {
             if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
             if (y = 0, t) op = [op[0] & 2, t.value];
             switch (op[0]) {
@@ -6992,6 +7000,12 @@ var lib_plankton;
          * @author fenris
          */
         class class_relation {
+            /**
+             * @author fenris
+             */
+            check(value, reference) {
+                return this.predicate(value, reference);
+            }
             /**
              * @author fenris
              */
@@ -7001,12 +7015,6 @@ var lib_plankton;
                 this.name = name;
                 this.predicate = predicate;
             }
-            /**
-             * @author fenris
-             */
-            check(value, reference) {
-                return this.predicate(value, reference);
-            }
             /**
              * @author fenris
              */
@@ -9596,6 +9604,9 @@ var lib_plankton;
         /**
          */
         let _target_element = null;
+        /**
+         */
+        let _nav_entries;
         /**
          */
         function encode(location) {
@@ -9649,25 +9660,6 @@ var lib_plankton;
                 }
             }
         }
-        /**
-         */
-        function add_nav_entry(location, options = {}) {
-            options = Object.assign({
-                "label": null,
-            }, options);
-            let ul_element = document.querySelector("nav > ul");
-            {
-                let li_element = document.createElement("li");
-                {
-                    let a_element = document.createElement("a");
-                    a_element.setAttribute("href", encode(location));
-                    a_element.textContent = (options.label ?? location.name);
-                    li_element.appendChild(a_element);
-                }
-                ul_element.appendChild(li_element);
-            }
-        }
-        zoo_page.add_nav_entry = add_nav_entry;
         /**
          * retrieves the location from the set URL
          */
@@ -9689,21 +9681,27 @@ var lib_plankton;
         zoo_page.reload = reload;
         /**
          */
-        function register(location_name, handler, options = {}) {
-            options = Object.assign({}, options);
+        function register(location_name, handler) {
             zoo_page._pool[location_name] = handler;
         }
         zoo_page.register = register;
         /**
          */
-        function init(target_element, options = {}) {
-            options = Object.assign({
-                "pool": {},
-                "fallback": null,
-            }, options);
+        function nav_set_groups(groups) {
+            _nav_entries.forEach(nav_entry => {
+                const active = ((groups === null)
+                    ||
+                        groups.some(group => nav_entry.definition.groups.includes(group)));
+                nav_entry.element.classList.toggle("active", active);
+            });
+        }
+        zoo_page.nav_set_groups = nav_set_groups;
+        /**
+         */
+        function init(target_element, { "pool": pool = {}, "fallback": fallback = null, "nav_entries": nav_entries = [], "nav_initial_groups": nav_initial_groups = null, } = {}) {
             _target_element = target_element;
-            _fallback = options.fallback;
-            Object.entries(options.pool).forEach(([location_name, handler]) => {
+            _fallback = fallback;
+            Object.entries(pool).forEach(([location_name, handler]) => {
                 register(location_name, handler);
             });
             window.addEventListener("hashchange", () => {
@@ -9724,6 +9722,25 @@ var lib_plankton;
                     // do nothing
                 }
             });
+            // nav
+            {
+                let ul_element = document.querySelector("nav > ul");
+                _nav_entries = nav_entries.map(nav_entry_definition => {
+                    let li_element = document.createElement("li");
+                    {
+                        let a_element = document.createElement("a");
+                        a_element.setAttribute("href", encode(nav_entry_definition.location));
+                        a_element.textContent = (nav_entry_definition.label ?? nav_entry_definition.location.name);
+                        li_element.appendChild(a_element);
+                    }
+                    ul_element.appendChild(li_element);
+                    return {
+                        "definition": nav_entry_definition,
+                        "element": li_element,
+                    };
+                });
+                nav_set_groups(nav_initial_groups);
+            }
         }
         zoo_page.init = init;
         /**