the Calendar Selectors activities?id=CRX/Standard/userhome/guest and activities?id=CRX/Standard/tracker/shared . 9.3.4 Calendaring / Free Busy Free Busy is part of the iCalendar standard ( RFC 2445 ) for calendar data exchange (see also Wikipedia ). Many calendar clients rely on this information for group scheduling. openCRX can derive free busy information on-the-fly from the