The Blackouts Best Effort feature allows you to create blackouts on aggregate targets, such as groups or systems, for which you do not have Blackout Target (or Higher) privileges on all members of the aggregate target.

Here, an Enterprise Manager administrator has Blackout Target privilege on an aggregate target but do not have OPERATOR privilege on its member/associated targets. You should ideally create a Full Blackout on this aggregate target. When defining the blackout, you are allowed to select any member target, even those member targets for which you have no Blackout Target privileges.

When the blackout actually starts, Enterprise Manager checks privileges on each member target and only blackout those on which you have Blackout Target( or Higher) privileges. This automated privilege check and target blackout selection is Enterprise Manager's "best effort" at blacking out the aggregate target.