This policy setting determines what restrictions apply to users who publish their calendars on Microsoft® Office Online or third-party WebDAV servers.
If you enable this policy setting, calendars that are published on Office Online must have restricted access (users other than the calendar owner/publisher who wish to view the calendar can only do so if they receive invitations from the calendar owner) and users cannot publish their calendars to third-party DAV servers.
If you disable or do not configure this policy setting, users can share their calendars with others by publishing them to the Microsoft Office Online Calendar Sharing Services and to a server that supports the World Wide Web Distributed Authoring and Versioning (WebDAV) protocol. Office Online allows users to choose whether to restrict access to their calendars to people they invite, or allow unrestricted access to anyone who knows the URL to reach the calendar. DAV access restrictions can only be achieved through server and folder permissions, and might require the assistance of a server administrator to set up and maintain.