...
You can add as many reminder templates to this list as you'd like and have Recruiters or Service Center Users choose from these templates as they are sending out emails to Candidates or Hiring Managers. Best advice is to just provide a name for the template so it is clear to the Recruiters and Service Center Users what Reminder template they should pick.
We have provided the text for the default Reminder Notification that most IBM related accounts have here: Example Reminder Template.