"Scheduled", in this context, means “stored in the database in order to be sent later”. All notices with time-based triggering events, including due date/time, hold shelf expiration and request expiration, are scheduled, because we know when the notice will be sent. Only one scheduled notice is stored at a time; once that notice has been sent out, the "nextRunTime" field is updated with the next scheduled send date/time.
The oposite to "scheduled" is "immediate", e.g. when the notice is sent at the end of a check-out session, because we don't know when the notice will be sent, i.e. we cannot plan ahead exactly when the check-out session will end.

"Scheduled" is not opposite to "real-time", language used in previous releases that caused confusion! Rather, "sendInRealTime" determines whether a notice gets batched and sent overnight: 

• "sendInRealTime" : true – This refers to the option "Send throughout the day without multiple loans/items." for the tigger "Loan due date/time". I.e. the courtesy email is sent when the scheduled time is reach, NOT at a later time when being bundled with other reminders.
• "sendInRealTime" : false – This refers to the option "Send overnight with multiple loans/items by patron." for the tirgger ""Loan due date/time". I.e. the courtesy email is NOT send when the scheduled timed is reached, but at a later time when being bundled with other reminders.
  • Example for "sendInRealTime" : false: An item is checked out at 2 pm on a 3-day loan, with an overdue notice set to run every 1 day after it goes overdue So the overdue notice nextRunTime would be 2 PM + 3 days, but wouldn't actually run until 23:59 of +3 days. And the batch set of notices that runs on 23:59 would pick up ALL of the notices scheduled to run on that day.

The scheduled notices processor ("handler") runs every so often, to check whether there are any scheduled notices to send. The default setting in the module descriptor are as follows:
_ For Category = Loan + "sendInRealTime" : true, the scan is every 5 minutes.
_ For Category = Loan + "sendInRealTime" : false, the scan is every 2 minutes.
_ For Categroy = Request, the scan is every 2 minutes.
_ For Category = Fee/fines, the scan is every 2 minutes.

The scheduled notices processor can process up to 100 items every time it runs.

A scheduled notice references a template by ID only. The template is fetched just before sending the notice. As a result, any changes made to the referenced template from the time it was first scheduled and the time it is sent will be reflected in the notice sent to the patron.