Here are my outline specifications for the piCal reminder feature.

Let me know if you have any suggestions, additions, recommendations, or warnings. Thanks.

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Admin sets the reminder specifications:
a. Number of days in advance of events to send messages.
b. Intro text at the top of the auto email (e.g., "you are receiving this message because you subscribed.....")
c. Auto email subject (e.g., "WBF Event Reminder")

Registered users can then subscribe to an auto email reminder for
a. A specific event only
b. All events in a specific category
c. All events in the calendar
d. Users can modify their subscriptions anytime as they wish.

Crontab checks (once or twice a day?) and sends messages as required.

Make it all Multilanguage compatible.
Use as much XOOPs existing core as possilbe. - emailer, notifications, etc.
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