New Add-In files will be included in the calendar.
Use the Add-Ins admin page to set colors, etc.
Add-In files can be in Calcium or vCalendar format.
To automatically retrieve an Add-In file from a
location on the web, just enter the URL, e.g.
(A URL starting with webcal:// will work too.)
You can automatically refresh Add-Ins that were
originally retrieved from the web. If the URL has
changed, you'll need to delete it and retrieve it
again. Refreshing an Add-In will remove any existing
user subscriptions to individual events from that