Users can interact only with services that are available in groups which they are a member of. It is important to understand that when a group subscribes to a service, an instance of that service belonging to that group is created. A group can subscribe to a service more than once, thereby creating more than one instance of the service for its users. Most groups in the Actua intranet have at least two Announcements services, each one serving a different audience. A key principle in the design of the group system was flexibility.
Groups have no relationship to each other, they are autonomous.
Connections or relationships between groups are emergent properties of the system, created by the facts of which users are members of which groups. Groups do not inherit properties from each other. Instead, the users of the system can have as many or as few groups as they wish. The groups are simply a means of bringing together a particular audience of users with services they hopefully find useful. That flexibility applies to the permissions of users within the groups and service instances as well.