Avieri is a standard for saving an addressbook on an IMAP Server in a fashion that every IMAP-compliant email-client can access it. This site offers information about the specification for avieri and tries to give information on all implementations.
For a quick information about what avieri is, you should visit the About Avieri page. For an in-depth view take a look at the avieri specifications. If you just want to know the basic syntax, see the Syntax Overview.
At the moment there are no implementations of the protocol available.