When the useFNS feature is on, you can use both the old and new ways of naming calendars. When you choose Show Other Calendar from the Browse menu, you can enter simply rosanna to browse user rosanna's calendar. Or you could enter rosanna@alto to name the calendar directly. The new names can be entered wherever a calendar name is expected (Show Other Calendar, Initial Calendar View in Display Settings Options, Browse list editor, Browse short list, and so on).
For location-independent naming to work, there must be a name space that holds registered information about where the calendars are.