The following Maintenance objects control access to various system resources:
Read access to Maintenance/Info/TestNetwork is needed to access the System → Information → Test Network and Servers page. (Alternatively, it can also be accessed with profile and Settings/TestFetch read access, since the Test Page Fetches form may use profile settings and the page is also reachable via Tools → Test Fetch. However this will not grant access to the Test Network form.)
A Maintenance/Settings ACE is also needed for certain system settings/actions not on the System Wide Settings page. These include SSL certificates, Backup/Restore Settings, System Replication Target Status, and creating missing replication profiles.
The exception is Enable or Disable Access Control Lists: these can only and always be performed by the admin user, regardless of ACLs (e.g. for emergency reset). Note: giving a user write perms on Settings, directly or indirectly, can allow them to override anything on the system, e.g. via externally-modified save and restore settings. Also, note that a user with physical access to the machine could overwrite settings, e.g. re-install the software.
Various objects under Maintenance/Settings, such as Thesaurus, Mounts etc. control other specific system actions.