What would you include in a manifesto for deep work?

I got talking to a twitter acquaintance about finding work with an employer who abides by a commitment to deep work

In order for this to happen employers would have to commit to some kind of manifesto. So what would be on yours?

Some starters: - Certain number of hours of protected time each day (no replying to calls, emails, etc)? - A status system whereby people can change their current status to deep work and therefore not be bothered?