DAVx⁵ stores all task information in the database (content provider) of the OpenTasks app, so OpenTasks must be installed for task synchronization.
The OpenTasks app is not only a content provider, but also provides a graphical user interface (GUI) for manipulating tasks (see illustration). However, the GUI currently doesn't implement all things which are supported by the content provider, like
- recurring tasks, and
- task categories.
To view and edit these advanced things on your Android device, you need (additionally to OpenTasks) an app that provides a GUI for them.
At the moment, the only app we know for that is aCalendar+, which provides a GUI for subtasks support. If you know other apps, please let us know.