...
An unlimited scope is always at the top of the scope hierarchy, which means it cannot have a parent scope. An unlimited scope has new resources added automatically, so you will not need to modify it to include new elements. To create an unlimited scope for enterprises and/or datacenters, you must be logged in as a user with a corresponding your user must have the appropriate unlimited scope.
You can create a scope hierarchy for sharing resources to tenants that are below an administrator's own scope in a hierarchy. So administrators can share VM templates and VApp specs with tenants in child scopes of their scope, but administrators manage only the tenants within their own scope.
...