Yep, if you contact them about it they'll provide you with more info. Both CardDAV and CalDAV will be available, documented and all, to the public in September/October. When I emailed them earlier today about it (pure coincidence) they gave me the necessary info on CardDAV and also directed me to a post[0] made by another beta tester explaining both DAV services in more detail.

[0] https://www.billdietrich.me/SecureCommunication.html?expanda...