Notifications really needs to be fixed. It should not take intervals as a number of seconds. This is broken. What it should be doing to taking a service contract implementation to generate the time for the next notification.
I outlined some ideas in a bug report: https://openacs.org/bugtracker/openacs/com/notifications/bug?bug%5fnumber=586
Item types are per-calendar currently which means you need to copy in the types for each calendar. This is obviously flexible, but difficult to keep track of, especially if you want to combine a group calendar's items with a personal calendar.
