How is this different to what you get from an iCal export type menu item in JEvents?

iCal-Format. I was not aware that the file extension *.ical stands for the same file format as *.ics. I just looked it up after your comment.

Current JEvents Functions. I searched in JEvents documentation and FAQs and in the settings: I just found an option to make an export button visible on the event detail page to export a single event.
After reading your post precisely I discoverd that I can make a menu item to export a whole calendar to make an internet calendar which a user can subscribe to with his calendar software (e.g. Outlook, EMClient, Google Calendar, mobile phone app). I will test this. But it looks to be what I searched for and I can work with it. Thank you.

To improve it

• the file could be exported to the server directly
  
• ideally the file would be updated by cronjobs
  
• It becomes more difficult, if one calendar contains events with different rights. Eventually a different calendar has to be generated for each user. In that case it would be important to change the calender when the rights/usergroups are changed.
  
• there would be needed an option to tell the user the adress of the new calendar he wants to subscribe to
  

It sounds great. I searched where to generate this link and found, it seems to work with the link created with with the men item "export ical". I did not expect this link to work (a notice somewhere might help the user, maybe as tooltip) but I inserted this link in MS Outlook as an Internet calendar and it seems to work.