Reference is the orientation layer over TreeDataGrid's generated API. Use it when you already know the package name, assembly name, namespace, or feature family and want the shortest path to the right narrative page and API subtree.
Start here when
you need the install identity, assembly name, and theme resource URI in one place
you know the namespace but not the best entry article
you want the generated API surface grouped by feature area rather than by raw type name
you are maintaining the docs site or API generation pipeline itself