CardBook integration

Issue generated from Tuleap's migration script. Originally submitted by: Óvári (ovari)

GNU Ring protocol for CardBook address book integration

Mr Philippe Vigneau, developer of the CardBook add-on for Thunderbird, would like to add GNU Ring to his Contacts program.
https://addons.mozilla.org/thunderbird/addon/cardbook/

Would you please advise what protocol Ring uses?

It would be appreciated if you would communicated directly with Mr Vigneau, email cardbook.thunderbird@gmail.com. Mr Vigneau speaks French and English.

Thanking you in advance.

P.S. It will then enable the "Ring (software)" Wikipedia entry to be updated from:
* Address book integration in GNOME and KDE
to:
* Address book integration in CardBook, GNOME and KDE
https://en.wikipedia.org/wiki/Ring_(software)