Is there such a thing as a "standard" contacts book?

[David Fletcher]

A few months ago, I moved all of my email into maildirs on my home
server, and I now use it with dovecot-IMAP. This is truly wonderful
after what I'd been doing before because it matters not which PC I use
to access my server or which mail client I use, be it Evolution,
Thunderbird, kmail or ms-mail on Vista.

Now, what I would love to see is a solution that I can run locally on my
server that does the same goodness for an address book as maildir and
IMAP has done for my email. For instance, I don't think I have any
particular objection to using Thunderbird for email, but I was only able
with reasonable ease to transfer my contacts from kmail to Evolution.

I like to have all my data on my own server in my own home with my own
backups, so I'm not interested in any cloud solutions.

Dave