"Attendees" are allowed to make some changes to a scheduling object resource, though key properties such as start time, end time, location, and summary are typically under the control of the "Organizer".
Servers MUST allow "Attendees" to make the following iCalendar data changes, subject to other restrictions, such as access privileges and preconditions:
1. change their own "PARTSTAT" iCalendar property parameter value.
2. add, modify, or remove any "TRANSP" iCalendar properties.
3. add, modify, or remove any "PERCENT-COMPLETE" iCalendar properties.
4. add, modify, or remove any "COMPLETED" iCalendar properties.
5. add, modify, or remove any "VALARM" iCalendar components.
6. add, modify, or remove the "CALSCALE" iCalendar property within the top-level "VCALENDAR" component.
7. modify the "PRODID" iCalendar property within the top-level "VCALENDAR" component.
8. add "EXDATE" iCalendar properties and possibly remove components for overridden recurrence instances.
9. add, modify, or remove any "CREATED", "DTSTAMP", and "LAST-MODIFIED" iCalendar properties.
10. add, modify, or remove "SCHEDULE-STATUS" iCalendar property parameters on "ATTENDEE" properties that have a "SCHEDULE-AGENT" parameter set to "CLIENT".
11. add new components to represent overridden recurrence instances, provided the only changes to the recurrence instance follow the rules above.
The server MUST return an error with the CALDAV:allowed-attendee- scheduling-object-change precondition code (Section 3.2.4.4) when the "Attendee" attempts to change the iCalendar data in a manner forbidden by the server.