Tags: Displayed but not editable due to Apple API limitations.
Subtasks: Converted to standalone Reminders when the parent Reminder is moved to a different list.
Due date: Retains any time components, if changed.
Start date: Used for organizing to-dos without altering due dates. Not visible in the Reminders app but supported internally. Time components added to or removed from the due date in the Reminders app may cause a start date shift of ±1 day.