Component/Property Presence
------------------- ---------------------------------------------
METHOD 1 MUST be "CANCEL"
VJOURNAL 1+ All MUST have the same UID
DTSTAMP 1
ORGANIZER 1
SEQUENCE 1
UID 1 MUST be the UID of the original REQUEST
ATTACH 0+
ATTENDEE 0+
CATEGORIES 0 or 1 This property MAY contain a list of values
CLASS 0 or 1
COMMENT 0 or 1
CONTACT 0+
CREATED 0 or 1
DESCRIPTION 0 or 1
DTSTART 0 or 1
EXDATE 0+
EXRULE 0+
LAST-MODIFIED 0 or 1
RDATE 0+
RECURRENCE-ID 0 or 1 only if referring to an instance of a
recurring calendar component. Otherwise
it MUST NOT be present.
RELATED-TO 0+
RRULE 0+
STATUS 0 or 1 MAY be present, must be "CANCELLED" if
present
SUMMARY 0 or 1
URL 0 or 1
X-PROPERTY 0+
REQUEST-STATUS 0
VTIMEZONE 0+ MUST be present if any date/time refers to
a timezone
X-COMPONENT 0+
VALARM 0
VEVENT 0
VFREEBUSY 0
VTODO 0