For PostgreSQL 7.3 backends, the system logic has been changed in Administrator 2.0.
Most objects are no longer classified as system and user. Those that are classified as system objects now have menus that provide all the functionality of the menus for the equivalent user object. However, there are few cases where these menu action would be accepted by the backend.
The change was made because most of the system objects have now been contained in schema pg_catalog. Furthermore, changes to certain system objects are possible (for example, privileges on functions, change system-view owner, and so on). The "System object" category is also quite limited now. Starting in PostgreSQL 7.3, the Administrator classifies only the following into system and user objects:
Languages
Casts
Columns under a table.