A shared calendar is like any other calendar, except other people have access to it and it also appears in their calendar lists. You can share existing personal calendars in your calendar list. You choose whom to share the calendar with, and what rights to grant each user. Then, users can post calendar entries to the shared calendar. You can’t share your main calendar.
In Remote and Caching modes, changes in a shared calendar are updated whenever you connect to the master GroupWise system.