I have a site with the "Invite only" option checked, it's description reads (emphasis mine):
Public registration is disabled, all new users must be explicitly invited by other members or staff.
However, I've found that only staff have a button to invite in their profile page. The "must approve users" option is not checked. Is a higher trust level required (and not documented), or is this a bug? I'd like any user to be able to send invites.