This command sets up a repeating event. The event will execute again every hour/day/week/month after initial execution as set by EVENT SET TIME. The interval defaults to NONE, which means that the event will execute only once.
Example:
/as event open set interval daily
Some events may be one-time only for a specific event, but many other scripts may be useful to automate and run regularly. Interval allows you to have scripts automatically trigger on a regular basis. Try to avoid setting monthly events to run on the 29th, 30th, or 31st of the month since not all months have more than 28 days.