Navigation - How to define the structure of the navigation tree via the NavigationItemAttribute

In the meantime, you should use the Model Editor to create such a navigation structure.

There are several solutions for cases when DevExpress.Persistent.Base > NavigationItemAttribute is insufficient to define a simple navigation structure (item and its parent group):

1. Implement a custom attribute and customize the generated navigation structure in the application model based on the value of your custom attribute.
Refer to the  Access Business Object's Metadata, Extend and Customize the Application Model in Code and NavigationItemNodeGenerator Class help articles for more details.
The idea is to read your custom attribute data from your object type metadata and then customize the navigation items structure accordingly.
The E2813, T545484, S130117 and Q420500 tickets contain examples on making a custom navigation structure using ModelNodesGeneratorUpdater. For more examples, refer to the How to: Create Additional ListView Nodes in Code using a Generator Updater  article, the XAF source code or the eXpand Framework's implementation on GitHub at https://github.com/expand/eXpand/blob/594c32f6ca84c1785368e493ec16f98d98655cf6/Xpand/Xpand.Persistent/Xpand.Persistent.Base/General/XpandNavigationItem.cs

2. Customize the navigation items structure at the ShowNavigationItemController level as described at Navigation - Make it easier to sort/reorder navigation items in code.

3. Use the XpandNavigationItem attribute from eXpand Framework: http://www.expandframework.com/blog/3-apobekiaris/65-make-your-navigation-behave.html