# iTIP: REFRESH and REPLY are accepted only from the event's attendees

# Organizer invites two attendees to a three-day series (1)
> put a@example.com attendee-checks@example.com
BEGIN:VCALENDAR
PRODID:-//Example/ExampleCalendarClient//EN
VERSION:2.0
BEGIN:VEVENT
UID:attendee-checks@example.com
SEQUENCE:0
ORGANIZER:mailto:a@example.com
ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:mailto:a@example.com
ATTENDEE;RSVP=TRUE:mailto:b@example.com
ATTENDEE;RSVP=TRUE:mailto:c@example.com
SUMMARY:Standup
DTSTART:20270104T180000Z
DTEND:20270104T183000Z
RRULE:FREQ=DAILY;COUNT=3
DTSTAMP:20261027T120000Z
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR

# Organizer invites two attendees to a three-day series (2)
> send

# Someone who was never invited asks for the event
> itip x@example.com a@example.com
BEGIN:VCALENDAR
PRODID:-//Example/ExampleCalendarClient//EN
METHOD:REFRESH
VERSION:2.0
BEGIN:VEVENT
UID:attendee-checks@example.com
ORGANIZER:mailto:a@example.com
ATTENDEE:mailto:x@example.com
DTSTAMP:20261027T130000Z
END:VEVENT
END:VCALENDAR

> send
SenderIsNotParticipant("x@example.com")

# Organizer removes the second attendee (1)
> put a@example.com attendee-checks@example.com
BEGIN:VCALENDAR
PRODID:-//Example/ExampleCalendarClient//EN
VERSION:2.0
BEGIN:VEVENT
UID:attendee-checks@example.com
SEQUENCE:1
ORGANIZER:mailto:a@example.com
ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:mailto:a@example.com
ATTENDEE;RSVP=TRUE:mailto:b@example.com
SUMMARY:Standup
DTSTART:20270104T180000Z
DTEND:20270104T183000Z
RRULE:FREQ=DAILY;COUNT=3
DTSTAMP:20261027T130000Z
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR

# Organizer removes the second attendee (2)
> send

# The removed attendee asks for the event again
> itip c@example.com a@example.com
BEGIN:VCALENDAR
PRODID:-//Example/ExampleCalendarClient//EN
METHOD:REFRESH
VERSION:2.0
BEGIN:VEVENT
UID:attendee-checks@example.com
ORGANIZER:mailto:a@example.com
ATTENDEE:mailto:c@example.com
DTSTAMP:20261027T140000Z
END:VEVENT
END:VCALENDAR

> send
SenderIsNotParticipant("c@example.com")

# The removed attendee replies to an instance the organizer hasn't changed
> itip c@example.com a@example.com
BEGIN:VCALENDAR
PRODID:-//Example/ExampleCalendarClient//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VEVENT
UID:attendee-checks@example.com
SEQUENCE:1
RECURRENCE-ID:20270105T180000Z
ORGANIZER:mailto:a@example.com
ATTENDEE;PARTSTAT=ACCEPTED:mailto:c@example.com
DTSTAMP:20261027T150000Z
END:VEVENT
END:VCALENDAR

> send
SenderIsNotParticipant("c@example.com")

# An attendee replies to one instance and adds a stranger to it
> itip b@example.com a@example.com
BEGIN:VCALENDAR
PRODID:-//Example/ExampleCalendarClient//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VEVENT
UID:attendee-checks@example.com
SEQUENCE:1
RECURRENCE-ID:20270105T180000Z
ORGANIZER;CN="Not A":mailto:a@example.com
ATTENDEE;PARTSTAT=DECLINED:mailto:b@example.com
ATTENDEE;PARTSTAT=ACCEPTED:mailto:mallory@example.org
DTSTAMP:20261027T160000Z
END:VEVENT
END:VCALENDAR

> send

# An attendee replies to a date the series doesn't have
> itip b@example.com a@example.com
BEGIN:VCALENDAR
PRODID:-//Example/ExampleCalendarClient//EN
METHOD:REPLY
VERSION:2.0
BEGIN:VEVENT
UID:attendee-checks@example.com
SEQUENCE:1
RECURRENCE-ID:20270110T180000Z
ORGANIZER:mailto:a@example.com
ATTENDEE;PARTSTAT=DECLINED:mailto:b@example.com
DTSTAMP:20261027T170000Z
END:VEVENT
END:VCALENDAR

> send

# Only the attendee's own answer reaches the organizer's copy
> get a@example.com attendee-checks@example.com
BEGIN:VCALENDAR
PRODID:-//Example/ExampleCalendarClient//EN
VERSION:2.0
BEGIN:VEVENT
ATTENDEE;PARTSTAT=DECLINED;SCHEDULE-STATUS=2.0:mailto:b@example.com
ORGANIZER:mailto:a@example.com
RECURRENCE-ID:20270105T180000Z
UID:attendee-checks@example.com
DTSTAMP:1
SEQUENCE:2
END:VEVENT
BEGIN:VEVENT
STATUS:CONFIRMED
SUMMARY:Standup
DTEND:20270104T183000Z
DTSTART:20270104T180000Z
ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:mailto:a@example.com
ATTENDEE;RSVP=TRUE:mailto:b@example.com
ORGANIZER:mailto:a@example.com
UID:attendee-checks@example.com
RRULE:FREQ=DAILY;COUNT=3
DTSTAMP:0
SEQUENCE:2
END:VEVENT
END:VCALENDAR