There exist use-cases where I want information to be publicly known, but I don’t necessarily want details to be public.

So today I went to enter an appointment for my doctor into the calendar, sending an invite to my boss, so he’ll at least know I’ll be out of the office. But there’s no way, no model, for me to put secured information on the event. If I want to put details about the appointment in the actual item, I need to have another, secured appointment. I want to know that it’s my Doctor’s appointment to get that goiter removed, as opposed to that cardiac study next week, but I want the rest of the world to only know that I’m out busy, and my boss to know that I’m at the Doctors (and not just blowing off work).

Again, this is a failure of the technology to provide mechanisms to evolve these features into our data. One of the promises of XML provided for the possibility of this - you could have a schema element that was encrypted while the rest of it was not. Yet none of our data-interchange standards encourage this.