There's a few things wrong about this part anyway- namely that we've got FDWs now, and there's certainly other cluster-wide things that exist beyond the specific items listed, so I wonder if perhaps we should just stop trying to list everything here.
Inspiring answer! After some inquiry I became aware, that we do not have only 2 levels of 'belong-to' but 3: tables, views, operators, and much more objects belong to a schema; schemata, extensions (e.g. FDW), and more(?) belong to a database; databases, roles, tablespaces, and more belong to a cluster. Two aspects of 'belong-to' are: object names are unique within their level, and objects are automatically known everywhere within their level.
Information about such dependencies and their consequences is spread across different chapters of the documentation and the System Catalog. Of course the chapter about roles/users is not suitable to explain the details. But it's important to know the hierarchy, it shut be summarized somewhere.
Kind regards, J. Purtz
