Under Settings → Calendar subscription there is an address https://your-domain.com/kalender.ics?key=…. Add it in Google Calendar ("Other calendars → From URL"), Outlook ("Subscribe to calendar") or on the iPhone ("Add subscribed calendar") – the dates update automatically (every few hours, depending on the calendar app). It contains due inspections, active reservations and return dates of open loans; with &nur=pruefungen, &nur=reservierungen or &nur=ausleihen only one part. "Renew key" invalidates old subscriptions.
