Policy for an Internet registry

I'm a lazy beginner in P3P and I would like to know if there is an
already existing policy file for an Internet domain
registry. Registries are the entities which keep the databases of
domains for a given Top Level Domain like .fr *and* which keep the
"social" information, individual names, addresses, etc, which are
reachable by whois and similar services.

Not that I want to use it out-of-the-box which would defeat the
purpose of P3P. But I want to use it as a way to learn P3P and as a
check list of things I could otherwise forget about.

For instance, we plan to let contacts decide if they want their phone
number published or not. I do not really see how to say it in P3P. The
"required" attribute seems the solution but it is an attribute of
PURPOSE's child, not of the DATA elements? I wanted to write:

<DATA ref="#user.home-info.online.telecom.telephone" required="opt-out"/> 

But it seems illegal.