[tero]

Interesting ideas for formalization and metadata, jeroendh. Some comments on those:

Calendar.txt is indeed a personal calendar. So feel free to violate the spec as much as you need or want to. My main use for calendar.txt is editing with text editor, and thus, I have not given emphasis to automatic modification.

Time notation is ISO-8601 date and week number. In my view, ISO-8601 is an international standard and not tied to a specific country. I find it convenient to read and sort.

I use local time for physical events. For international calls, I just write down the timezone "13:00Z" or "11:00EET" (update: or mark it in my local time).

At-sign "@" for context was chosen to match todo.txt, as I also use that. As the calendar is personal, it does not need to be fully machine readble. But for your example on email addresses, you could still do it: @WORK email [e-mail]. The context starts with an at "@", email does not.

Full stop "." is easy to type on a cell phone. It's true that a rare char would be more suitable for automatic parsing.

Thanks for the ideas!