Zimbra Calendar is a full features calendar application and when Group calendar is enabled can include the ability to:
Schedule appointments, meetings, and establish recurring activities
Create multiple calendars
Subscribe to external calendars and view their calendar information from ZWC
Share calendars with others and delegate manager access to their calendars, if enabled
To enable Zimbra Calendar's full featured version, in the Features tab both Calendar and Group calendar must be checked.
To enable Zimbra Calendar as a personal calendar only, in the Features tab Calendar should be checked and Group calendar should not be checked.
If the Group calendar feature is not enabled, and Calendar is, users calendars become personal calendars. They can maintain their personal calendar for appointments, but cannot schedule or share calendars with others.