JMAP: The Specs
The specifications for the core JMAP protocol and access to mail stores using JMAP have been finalised and published. The JMAP working group is currently working on the calendars and sharing specs, with tasks and contacts expected to follow.
These specs are not yet final and will change before publication. There are undoubtably edge cases that are not yet covered. If you find one, please email firstname.lastname@example.org or make a pull request on GitHub if you have a proposed fix.
JMAP was designed in conjunction with new JSON-based file formats for contacts and calendars, which can also be used standalone or in other protocols.
JMAP Calendars uses JSCalendar (RFC 8984) as the data format for events.
JMAP Contacts will use JSContact (currently under development) as the data format for contacts.