@delta I got the gist of Delta Chat, and want to look further into it when time allows. I once set up an in-house #XMPP server (Prosody) for family use, and it worked pretty well. Especially for voice calling.

We fell back to Signal though, because some family don't really have secure endpoint devices, and Signal is good at time-limiting messages in chats.

@csolisr @inthehands An external system or method would need to enforce that only some fields can be changed (Description) while others can't (start date or location, for example). At that point, every participant would need this system to govern their calendars.

Then we have an issue with end-user adoption via compliant apps. Take vJournal, for example. An extension to CalDAV. The number of clients that support it is miserably small. Nobody has even heard of it.

@inthehands It seems like only a complicated, proprietary calendaring app could support this by running amok of existing IEEE standards, such as CalDAV.

It's really down to having the event description be non-personal ("Coffee"), or exporting/sharing an event via ics file, so that each party has their own version, and can edit it independently.