Which ringtone setting for which events?

In the ringtone style details, there are several different items that you can set ringtones for. Most of them are pretty clear to me, except for the ones labeled "Alarms" and "Reminders". What phone events are these for?

At first I thought "Alarms" was for the alarm clock feature, but when you define an alarm you choose the ringtone right in that screen. Maybe these are for calendar event alarms?

As for "Reminders", I have no idea.