title: Can a default service/module in a Google App Engine app be a sibling of a non-default one in terms of folder structure?
body: <p>Update: <code>modules</code> are called <code>services</code> these days.</p>
  
  <p>I would like to organize my project's modules into various subfolders, where each subfolder contains code pertaining to each module. In particular, I would like the folder containing the default module to be on the same level as other modules (i.e. they are all siblings). I am following the diagram shown in the <a href="https://cloud.google.com/appengine/docs/standard/python/an-overview-of-app-engine" rel="nofollow noreferrer">Modules documentation</a>:</p>
  
  <p><a href="https://i.stack.imgur.com/aQb6d.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/aQb6d.png" alt="diagram"></a><br>
  <sub>(source: <a href="https://cloud.google.com/appengine/docs/images/modules_yaml_files2.png" rel="nofollow noreferrer">google.com</a>)</sub>  </p>
  
  <p>However, what confuses me is the statement "<a href="https://cloud.google.com/appengine/docs/standard/python/config/appref?hl=en" rel="nofollow noreferrer">Important: The app.yaml file must be located in your application's root directory</a>". Does this imply that the default module (and its app.yaml) must be in the project root directory, and therefore, be the parent of non-default modules?</p>