Intranets with shared tables and master sites
On the Intranets form, you can specify a master site
      for an intranet. Master sites are SyteLine sites
      that control some data for all other sites on an intranet. For example, master sites control
      any shared _all tables or shared user tables.
    An intranet defined as "External" (containing non-SyteLine sites) cannot have a master site defined for it.
You cannot delete an intranet that contains shared tables.