Update app-vuex-store.md

source/guide/app-vuex-store.md

@@ -111,5 +111,13 @@ export default {
 </script>
 ```
 
+## Using Multiple Modules
+
+Within each Vuex Module, properties are accessed as `state`, e.g., `state.drawerState = opened`. If you have multiple modules within you Vuex store, you can reference from one module to another using `rootState`. For example, if you had a separate `users` module and you needed to access the current user's userID in the `showcase` module, you could use:
+
+```js
+const currentUser = rootState.users.currentUser.userID
+```
+
 ## Store Code Splitting
 You can take advantage of the [PreFetch Feature](/guide/app-prefetch-feature.html#Store-Code-Splitting) to code split code for modules.