RFC 2446
iCalendar Transport-Independent Interoperability Protocol (iTIP) Scheduling Events, BusyTime, To-dos and Journal Entries
3 Application Protocol Elements ITIP messages are "text/calendar" MIME entities that contain calendaring and scheduling information. The particular type of [iCAL] message is referred to as the "method type". Each method type is identified by a "METHOD" property specified as part of the "text/calendar" content type. The table below shows various combinations of calendar components and the method types that this memo supports. +=================================================+ | | VEVENT | VTODO | VJOURNAL | VFREEBUSY | |=================================================| |Publish | Yes | Yes | Yes | Yes | |Request | Yes | Yes | No | Yes | |Refresh | Yes | Yes | No | No | |Cancel | Yes | Yes | Yes | No | |Add | Yes | Yes | Yes | No | |Reply | Yes | Yes | No | Yes | |Counter | Yes | Yes | No | No | |Decline- | | | | | |Counter | Yes | Yes | No | No | +=================================================+ Each method type is defined in terms of its associated components and properties. Some components and properties are required, some are optional and others are excluded. The restrictions are expressed in this document using a simple "restriction table". The first column indicates the name of a component or property. Properties of the iCalendar object are not indented. Properties of a component are indented. The second column contains "MUST" if the component or property must be present, "MAY" if the component or property is optional, and "NOT" if the component or property must not be present. Entries in the second column sometimes contain comments for further clarification.
3.1 Common Component Restriction Tables The restriction table below applies to properties of the iCalendar object. That is, the properties at the outermost scope. The presence column uses the following values to assert whether a property is required, is optional and the number of times it may appear in the iCalendar object. Presence Value Description -------------------------------------------------------------- 1 One instance MUST be present 1+ At least one instance MUST be present 0 Instances of this property Must NOT be present 0+ Multiple instances MAY be present 0 or 1 Up to 1 instance of this property MAY be present --------------------------------------------------------------- The tables also call out "X-PROPERTY" and "X-COMPONENT" to show where vendor-specific properties and components can appear. The tables do not lay out the restrictions of property parameters. Those restrictions are defined in [iCAL]. Component/Property Presence ------------------- ---------------------------------------------- CALSCALE 0 or 1 PRODID 1 VERSION 1 Value MUST be "2.0" X-PROPERTY 0+ DateTime values MAY refer to a "VTIMEZONE" component. The property restrictions in the table below apply to any "VTIMEZONE" component in an ITIP message. Component/Property Presence ------------------- ---------------------------------------------- VTIMEZONE 0+ MUST be present if any date/time refers to timezone DAYLIGHT 0+ MUST be one or more of either STANDARD or DAYLIGHT COMMENT 0 or 1 DTSTART 1 MUST be local time format RDATE 0+ if present RRULE MUST NOT be present RRULE 0+ if present RDATE MUST NOT be present TZNAME 0 or 1 TZOFFSET 1 TZOFFSETFROM 1 TZOFFSETTO 1
X-PROPERTY 0+
LAST-MODIFIED 0 or 1
STANDARD 0+ MUST be one or more of either STANDARD or
DAYLIGHT
COMMENT 0 or 1
DTSTART 1 MUST be local time format
RDATE 0+ if present RRULE MUST NOT be present
RRULE 0+ if present RDATE MUST NOT be present
TZNAME 0 or 1
TZOFFSETFROM 1
TZOFFSETTO 1
X-PROPERTY 0+
TZID 1
TZURL 0 or 1
X-PROPERTY 0+
The property restrictions in the table below apply to any "VALARM"
component in an ITIP message.
Component/Property Presence
------------------- ----------------------------------------------
VALARM 0+
ACTION 1
ATTACH 0+
DESCRIPTION 0 or 1
DURATION 0 or 1 if present REPEAT MUST be present
REPEAT 0 or 1 if present DURATION MUST be present
SUMMARY 0 or 1
TRIGGER 1
X-PROPERTY 0+
3.2 Methods for VEVENT Calendar Components
This section defines the property set restrictions for the method
types that are applicable to the "VEVENT" calendar component. Each
method is defined using a table that clarifies the property
constraints that define the particular method.
The following summarizes the methods that are defined for the
"VEVENT" calendar component.
+================+==================================================+
| Method | Description |
|================+==================================================|
| PUBLISH | Post notification of an event. Used primarily as |
| | a method of advertising the existence of an |
| | event. |
| | |
| REQUEST | Make a request for an event. This is an explicit |
| | invitation to one or more "Attendees". Event |
| | Requests are also used to update or change an |
| | existing event. Clients that cannot handle |
| | REQUEST may degrade the event to view it as an |
| | PUBLISH. |
| | |
| REPLY | Reply to an event request. Clients may set their |
| | status ("partstat") to ACCEPTED, DECLINED, |
| | TENTATIVE, or DELEGATED. |
| | |
| ADD | Add one or more instances to an existing event. |
| | |
| CANCEL | Cancel one or more instances of an existing |
| | event. |
| | |
| REFRESH | A request is sent to an "Organizer" by an |
| | "Attendee" asking for the latest version of an |
| | event to be resent to the requester. |
| | |
| COUNTER | Counter a REQUEST with an alternative proposal, |
| | Sent by an "Attendee" to the "Organizer". |
| | |
| DECLINECOUNTER | Decline a counter proposal. Sent to an |
| | "Attendee" by the "Organizer". |
+================+==================================================+
3.2.1 PUBLISH
The "PUBLISH" method in a "VEVENT" calendar component is an
unsolicited posting of an iCalendar object. Any CU may add published
components to their calendar. The "Organizer" MUST be present in a
published iCalendar component. "Attendees" MUST NOT be present. Its
expected usage is for encapsulating an arbitrary event as an
iCalendar object. The "Organizer" may subsequently update (with
another "PUBLISH" method), add instances to (with an "ADD" method),
or cancel (with a "CANCEL" method) a previously published "VEVENT"
calendar component.
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ----------------------------------------------
METHOD 1 MUST equal "PUBLISH"
VEVENT 1+
DTSTAMP 1
DTSTART 1
ORGANIZER 1
SUMMARY 1 Can be null.
UID 1
RECURRENCE-ID 0 or 1 only if referring to an instance of a
recurring calendar component. Otherwise
it MUST NOT be present.
SEQUENCE 0 or 1 MUST be present if value is greater than
0, MAY be present if 0
ATTACH 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 Can be null
DTEND 0 or 1 if present DURATION MUST NOT be present
DURATION 0 or 1 if present DTEND MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PRIORITY 0 or 1
RDATE 0+
RELATED-TO 0+
RESOURCES 0 or 1 This property MAY contain a list of values
RRULE 0+
STATUS 0 or 1 MAY be one of TENTATIVE/CONFIRMED/CANCELLED
TRANSP 0 or 1
URL 0 or 1
X-PROPERTY 0+
ATTENDEE 0
REQUEST-STATUS 0
VALARM 0+
VFREEBUSY 0
VJOURNAL 0
VTODO 0
VTIMEZONE 0+ MUST be present if any date/time refers to
a timezone
X-COMPONENT 0+
3.2.2 REQUEST
The "REQUEST" method in a "VEVENT" component provides the following
scheduling functions:
. Invite "Attendees" to an event;
. Reschedule an existing event;
. Response to a REFRESH request;
. Update the details of an existing event, without rescheduling it;
. Update the status of "Attendees" of an existing event, without
rescheduling it;
. Reconfirm an existing event, without rescheduling it;
. Forward a "VEVENT" to another uninvited CU.
. For an existing "VEVENT" calendar component, delegate the role of
"Attendee" to another CU;
. For an existing "VEVENT" calendar component, changing the role of
"Organizer" to another CU.
The "Organizer" originates the "REQUEST". The recipients of the
"REQUEST" method are the CUs invited to the event, the "Attendees".
"Attendees" use the "REPLY" method to convey attendance status to the
"Organizer".
The "UID" and "SEQUENCE" properties are used to distinguish the
various uses of the "REQUEST" method. If the "UID" property value in
the "REQUEST" is not found on the recipient's calendar, then the
"REQUEST" is for a new "VEVENT" calendar component. If the "UID"
property value is found on the recipient's calendar, then the
"REQUEST" is for a rescheduling, an update, or a reconfirm of the
"VEVENT" calendar component.
For the "REQUEST" method, multiple "VEVENT" components in a single
iCalendar object are only permitted when for components with the same
"UID" property. That is, a series of recurring events may have
instance-specific information. In this case, multiple "VEVENT"
components are needed to express the entire series.
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
-----------------------------------------------------------------
METHOD 1 MUST be "REQUEST"
VEVENT 1+ All components MUST have the same UID
ATTENDEE 1+
DTSTAMP 1
DTSTART 1
ORGANIZER 1
SEQUENCE 0 or 1 MUST be present if value is greater than 0,
MAY be present if 0
SUMMARY 1 Can be null
UID 1
ATTACH 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 Can be null
DTEND 0 or 1 if present DURATION MUST NOT be present
DURATION 0 or 1 if present DTEND MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PRIORITY 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+
REQUEST-STATUS 0+
RESOURCES 0 or 1 This property MAY contain a list of values
RRULE 0+
STATUS 0 or 1 MAY be one of TENTATIVE/CONFIRMED
TRANSP 0 or 1
URL 0 or 1
X-PROPERTY 0+
VALARM 0+
VTIMEZONE 0+ MUST be present if any date/time refers to
a timezone
X-COMPONENT 0+
VFREEBUSY 0 VJOURNAL 0 VTODO 0 3.2.2.1 Rescheduling an Event The "REQUEST" method may be used to reschedule an event. A rescheduled event involves a change to the existing event in terms of its time or recurrence intervals and possibly the location or description. If the recipient CUA of a "REQUEST" method finds that the "UID" property value already exists on the calendar, but that the "SEQUENCE" (or "DTSTAMP") property value in the "REQUEST" method is greater than the value for the existing event, then the "REQUEST" method describes a rescheduling of the event. 3.2.2.2 Updating or Reconfirmation of an Event The "REQUEST" method may be used to update or reconfirm an event. An update to an existing event does not involve changes to the time or recurrence intervals, and might not involve a change to the location or description for the event. If the recipient CUA of a "REQUEST" method finds that the "UID" property value already exists on the calendar and that the "SEQUENCE" property value in the "REQUEST" is the same as the value for the existing event, then the "REQUEST" method describes an update of the event details, but no rescheduling of the event. The update "REQUEST" method is the appropriate response to a "REFRESH" method sent from an "Attendee" to the "Organizer" of an event. The "Organizer" of an event may also send unsolicited "REQUEST" methods. The unsolicited "REQUEST" methods may be used to update the details of the event without rescheduling it, to update the "partstat" parameter of "Attendees", or to reconfirm the event. 3.2.2.3 Delegating an Event to another CU Some calendar and scheduling systems allow "Attendees" to delegate their presence at an event to another calendar user. ITIP supports this concept using the following workflow. Any "Attendee" may delegate their right to participate in a calendar VEVENT to another CU. The implication is that the delegate participates in lieu of the original "Attendee"; NOT in addition to the "Attendee". The delegator MUST notify the "Organizer" of this action using the steps outlined below. Implementations may support or restrict delegation as they see fit. For instance, some implementations may restrict a delegate from delegating a "REQUEST" to another CU.
The "Delegator" of an event forwards the existing "REQUEST" to the "Delegate". The "REQUEST" method MUST include an "ATTENDEE" property with the calendar address of the "Delegate". The "Delegator" MUST also send a "REPLY" method to the "Organizer" with the "Delegator's" "ATTENDEE" property "partstat" parameter value set to "delegated". In addition, the "delegated-to" parameter MUST be included with the calendar address of the "Delegate". In response to the request, the "Delegate" MUST send a "REPLY" method to the "Organizer" and optionally, to the "Delegator". The "REPLY" method " SHOULD include the "ATTENDEE" property with the "delegated- from" parameter value of the "Delegator's" calendar address. The "Delegator" may continue to receive updates to the event even though they will not be attending. This is accomplished by the "Delegator" setting their "role" attribute to " NON-PARTICIPANT" in the "REPLY" to the "Organizer" 3.2.2.4 Changing the Organizer The situation may arise where the "Organizer" of a VEVENT is no longer able to perform the "Organizer" role and abdicates without passing on the "Organizer" role to someone else. When this occurs the "Attendees" of the VEVENT may use out-of-band mechanisms to communicate the situation and agree upon a new "Organizer". The new "Organizer" should then send out a new "REQUEST" with a modified version of the VEVENT in which the "SEQUENCE" number has been incremented and value of the "ORGANIZER" property has been changed to the calendar address of the new "Organizer". 3.2.2.5 Sending on Behalf of the Organizer There are a number of scenarios that support the need for a calendar user to act on behalf of the "Organizer" without explicit role changing. This might be the case if the CU designated as "Organizer" was sick or unable to perform duties associated with that function. In these cases iTIP supports the notion of one CU acting on behalf of another. Using the "sent-by" parameter, a calendar user could send an updated "VEVENT" REQUEST. In the case where one CU sends on behalf of another CU, the "Attendee" responses are still directed back towards the CU designated as "Organizer". 3.2.2.6 Forwarding to An Uninvited CU An "Attendee" invited to an event may invite another uninvited CU to the event. The invited "Attendee" accomplishes this by forwarding the original "REQUEST" method to the uninvited CU. The "Organizer" decides whether or not the uninvited CU is added to the attendee
list. If the "Organizer" decides not to add the uninvited CU no further action is required, however the "Organizer" MAY send the uninvited CU a "CANCEL" message. If the "Organizer" decides to add an uninvited CU, a new "ATTENDEE" property is added for the uninvited CU with its property parameters set as the "Organizer" deems appropriate. When forwarding a "REQUEST" to another CU, the forwarding "Attendee" MUST NOT make changes to the VEVENT property set. 3.2.2.7 Updating Attendee Status The "Organizer" of an event may also request updated status from one or more "Attendees. The "Organizer" sends a "REQUEST" method to the "Attendee" and sets the "ATTENDEE;RSVP=TRUE" property parameter. The "SEQUENCE" property for the event is not changed from its previous value. A recipient will determine that the only change in the "REQUEST" is that their "RSVP" property parameter indicates a request for updated status. The recipient SHOULD respond with a "REPLY" method indicating their current status with respect to the "REQUEST". 3.2.3 REPLY The "REPLY" method in a "VEVENT" calendar component is used to respond (e.g., accept or decline) to a "REQUEST" or to reply to a delegation "REQUEST". When used to provide a delegation response, the "Delegator" SHOULD include the calendar address of the "Delegate" on the "delegated-to" property parameter of the "Delegator's" "ATTENDEE" property. The "Delegate" SHOULD include the calendar address of the "Delegator" on the "delegated-from" property parameter of the "Delegate's" "ATTENDEE" property. The "REPLY" method may also be used to respond to an unsuccessful "REQUEST" method. Depending on the value of the "REQUEST-STATUS" property no scheduling action may have been performed. The "Organizer" of an event may receive the "REPLY" method from a CU not in the original "REQUEST". For example, a "REPLY" may be received from a "Delegate" to an event. In addition, the "REPLY" method may be received from an unknown CU (a "Party Crasher"). This uninvited "Attendee" may be accepted, or the "Organizer" may cancel the event for the uninvited "Attendee" by sending a "CANCEL" method to the uninvited "Attendee". An "Attendee" can include a message to the "Organizer" using the "COMMENT" property. For example, if the user indicates tentative acceptance and wants to let the "Organizer" know why, the reason can be expressed in the "COMMENT" property value.
The "Organizer" may also receive a "REPLY" from one CU on behalf of
another. Like the scenario enumerated above for the "Organizer",
"Attendees" may have another CU respond on their behalf. This is done
using the "sent-by" parameter.
The optional properties listed in the table below (those listed as
"0+" or "0 or 1") MUST NOT be changed from those of the original
request. If property changes are desired the COUNTER message must be
used.
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ----------------------------------------------
METHOD 1 MUST be "REPLY"
VEVENT 1+ All components MUST have the same UID
ATTENDEE 1 MUST be the address of the Attendee
replying.
DTSTAMP 1
ORGANIZER 1
RECURRENCE-ID 0 or 1 only if referring to an instance of a
recurring calendar component. Otherwise
it must NOT be present.
UID 1 MUST be the UID of the original REQUEST
SEQUENCE 0 or 1 MUST if non-zero, MUST be the sequence
number of the original REQUEST. MAY be
present if 0.
ATTACH 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
DTEND 0 or 1 if present DURATION MUST NOT be present
DTSTART 0 or 1
DURATION 0 or 1 if present DTEND MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PRIORITY 0 or 1
RDATE 0+
RELATED-TO 0+
RESOURCES 0 or 1 This property MAY contain a list of values
REQUEST-STATUS 0+
RRULE 0+
STATUS 0 or 1
SUMMARY 0 or 1
TRANSP 0 or 1
URL 0 or 1
X-PROPERTY 0+
VTIMEZONE 0 or 1 MUST be present if any date/time refers
to a timezone
X-COMPONENT 0+
VALARM 0
VFREEBUSY 0
VJOURNAL 0
VTODO 0
3.2.4 ADD
The "ADD" method in a "VEVENT" calendar component is used to add one
or more instances to an existing "VEVENT". Unlike the "REQUEST"
method, when using issuing an "ADD" method, the "Organizer" does not
send the full "VEVENT" description; only the new instance(s). The
"ADD" method is especially useful if there are instance-specific
properties to be preserved in a recurring "VEVENT". For instance, an
"Organizer" may have originally scheduled a weekly Thursday meeting.
At some point, several instances changed. Location or start time may
have changed, or some instances may have unique "DESCRIPTION"
properties. The "ADD" method allows the "Organizer" to add new
instances to an existing event using a single ITIP message without
redefining the entire recurring pattern.
The "UID" must be that of the existing event. If the "UID" property
value in the "ADD" is not found on the recipient's calendar, then the
recipient SHOULD send a "REFRESH" to the "Organizer" in order to be
updated with the latest version of the "VEVENT". If an "Attendee"
implementation does not support the "ADD" method it should respond
with a "REQUEST-STATUS" value of 3.14 and ask for a "REFRESH".
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ----------------------------------------------
METHOD 1 MUST be "ADD"
VEVENT 1
DTSTAMP 1
DTSTART 1
ORGANIZER 1
SEQUENCE 1 MUST be greater than 0
SUMMARY 1 Can be null
UID 1 MUST match that of the original event
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 Can be null
DTEND 0 or 1 if present DURATION MUST NOT be present
DURATION 0 or 1 if present DTEND MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PRIORITY 0 or 1
RDATE 0+
RELATED-TO 0+
RESOURCES 0 or 1 This property MAY contain a list of values
RRULE 0+
STATUS 0 or 1 MAY be one of TENTATIVE/CONFIRMED
TRANSP 0 or 1
URL 0 or 1
X-PROPERTY 0+
RECURRENCE-ID 0
REQUEST-STATUS 0
VALARM 0+
VTIMEZONE 0+ MUST be present if any date/time refers to
a timezone
X-COMPONENT 0+
VFREEBUSY 0
VTODO 0
VJOURNAL 0
3.2.5 CANCEL The "CANCEL" method in a "VEVENT" calendar component is used to send a cancellation notice of an existing event request to the "Attendees". The message is sent by the "Organizer" of the event. For a recurring event, either the whole event or instances of an event may be cancelled. To cancel the complete range of recurring event, the "UID" property value for the event MUST be specified and a "RECURRENCE-ID" MUST NOT be specified in the "CANCEL" method. In order to cancel an individual instance of the event, the "RECURRENCE-ID" property value for the event MUST be specified in the "CANCEL" method. There are two options for canceling a sequence of instances of a recurring "VEVENT" calendar component: (a) the "RECURRENCE-ID" property for an instance in the sequence MUST be specified with the "RANGE" property parameter value of THISANDPRIOR (or THISANDFUTURE) to indicate cancellation of the specified "VEVENT" calendar component and all instances before (or after); or (b) individual recurrence instances may be cancelled by specifying multiple "RECURRENCE-ID" properties corresponding to the instances to be cancelled. When a "VEVENT" is cancelled, the "SEQUENCE" property value MUST be incremented. This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST be "CANCEL" VEVENT 1+ All must have the same UID ATTENDEE 0+ MUST include all "Attendees" being removed the event. MUST include all "Attendees" if the entire event is cancelled. DTSTAMP 1 ORGANIZER 1 SEQUENCE 1 UID 1 MUST be the UID of the original REQUEST COMMENT 0 or 1 ATTACH 0+ CATEGORIES 0 or 1 This property may contain a list of values
CLASS 0 or 1
CONTACT 0+
CREATED 0 or 1
DESCRIPTION 0 or 1
DTEND 0 or 1 if present DURATION MUST NOT be present
DTSTART 0 or 1
DURATION 0 or 1 if present DTEND MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PRIORITY 0 or 1
RDATE 0+
RECURRENCE-ID 0 or 1 MUST be present if referring to one or
more or more recurring instances.
Otherwise it MUST NOT be present
RELATED-TO 0+
RESOURCES 0 or 1
RRULE 0+
STATUS 0 or 1 MUST be set to CANCELLED. If uninviting
specific "Attendees" then MUST NOT be
included.
SUMMARY 0 or 1
TRANSP 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+
VTODO 0
VJOURNAL 0
VFREEBUSY 0
VALARM 0
3.2.6 REFRESH
The "REFRESH" method in a "VEVENT" calendar component is used by
"Attendees" of an existing event to request an updated description
from the event "Organizer". The "REFRESH" method must specify the
"UID" property of the event to update. A recurrence instance of an
event may be requested by specifying the "RECURRENCE-ID" property
corresponding to the associated event. The "Organizer" responds with
the latest description and version of the event.
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ----------------------------------------------
METHOD 1 MUST be "REFRESH"
VEVENT 1
ATTENDEE 1 MUST be the address of requestor
DTSTAMP 1
ORGANIZER 1
UID 1 MUST be the UID associated with original
REQUEST
COMMENT 0 or 1
RECURRENCE-ID 0 or 1 MUST only if referring to an instance of a
recurring calendar component. Otherwise
it must NOT be present.
X-PROPERTY 0+
ATTACH 0
CATEGORIES 0
CLASS 0
CONTACT 0
CREATED 0
DESCRIPTION 0
DTEND 0
DTSTART 0
DURATION 0
EXDATE 0
EXRULE 0
GEO 0
LAST-MODIFIED 0
LOCATION 0
PRIORITY 0
RDATE 0
RELATED-TO 0
REQUEST-STATUS 0
RESOURCES 0
RRULE 0
SEQUENCE 0
STATUS 0
SUMMARY 0
TRANSP 0
URL 0
X-COMPONENT 0+
VTODO 0
VJOURNAL 0 VFREEBUSY 0 VTIMEZONE 0 VALARM 0 3.2.7 COUNTER The "COUNTER" method for a "VEVENT" calendar component is used by an "Attendee" of an existing event to submit to the "Organizer" a counter proposal to the event description. The "Attendee" sends this message to the "Organizer" of the event. The counter proposal is an iCalendar object consisting of a VEVENT calendar component describing the complete description of the alternate event. The "Organizer" rejects the counter proposal by sending the "Attendee" a VEVENT "DECLINECOUNTER" method. The "Organizer" accepts the counter proposal by rescheduling the event as described in section 3.2.2.1 Rescheduling an Event. This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST be "COUNTER" VEVENT 1 DTSTAMP 1 DTSTART 1 ORGANIZER 1 MUST be the "Organizer" of the original event SEQUENCE 1 MUST be present if value is greater than 0, MAY be present if 0 SUMMARY 1 Can be null UID 1 MUST be the UID associated with the REQUEST being countered ATTACH 0+ ATTENDEE 0+ Can also be used to propose other "Attendees" 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
DTEND 0 or 1 if present DURATION MUST NOT be present
DURATION 0 or 1 if present DTEND MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PRIORITY 0 or 1
RDATE 0+
RECURRENCE-ID 0 or 1 MUST only if referring to an instance of a
recurring calendar component. Otherwise it
MUST NOT be present.
RELATED-TO 0+
REQUEST-STATUS 0+
RESOURCES 0 or 1 This property may contain a list of values
RRULE 0+
STATUS 0 or 1 Value must be one of CONFIRMED/TENATIVE/
CANCELLED
TRANSP 0 or 1
URL 0 or 1
X-PROPERTY 0+
VALARM 0+
VTIMEZONE 0+ MUST be present if any date/time refers to
a timezone
X-COMPONENT 0+
VTODO 0
VJOURNAL 0
VFREEBUSY 0
3.2.8 DECLINECOUNTER
The "DECLINECOUNTER" method in a "VEVENT" calendar component is used
by the "Organizer" of an event to reject a counter proposal submitted
by an "Attendee". The "Organizer" must send the "DECLINECOUNTER"
message to the "Attendee" that sent the "COUNTER" method to the
"Organizer".
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ----------------------------------------------
METHOD 1 MUST be "DECLINECOUNTER"
VEVENT 1
DTSTAMP 1
ORGANIZER 1
UID 1 MUST, same UID specified in original
REQUEST and subsequent COUNTER
COMMENT 0 or 1
RECURRENCE-ID 0 or 1 MUST only if referring to an instance of a
recurring calendar component. Otherwise it
MUST NOT be present.
REQUEST-STATUS 0+
SEQUENCE 0 OR 1 MUST be present if value is greater than 0,
MAY be present if 0
X-PROPERTY 0+
ATTACH 0
ATTENDEE 0
CATEGORIES 0
CLASS 0
CONTACT 0
CREATED 0
DESCRIPTION 0
DTEND 0
DTSTART 0
DURATION 0
EXDATE 0
EXRULE 0
GEO 0
LAST-MODIFIED 0
LOCATION 0
PRIORITY 0
RDATE 0
RELATED-TO 0
RESOURCES 0
RRULE 0
STATUS 0
SUMMARY 0
TRANSP 0
URL 0
X-COMPONENT 0+
VTODO 0
VJOURNAL 0
VFREEBUSY 0
VTIMEZONE 0
VALARM 0
3.3 Methods For VFREEBUSY Components This section defines the property set for the methods that are applicable to the "VFREEBUSY" calendar component. Each of the methods is defined using a restriction table. This document only addresses the transfer of busy time information. Applications desiring free time information MUST infer this from available busy time information. The busy time information within the iCalendar object MAY be grouped into more than one "VFREEBUSY" calendar component. This capability allows busy time periods to be grouped according to some common periodicity, such as a calendar week, month, or year. In this case, each "VFREEBUSY" calendar component MUST include the "ATTENDEE", "DTSTART" and "DTEND" properties in order to specify the source of the busy time information and the date and time interval over which the busy time information covers. The "FREEBUSY" property value MAY include a list of values, separated by the COMMA character ([US-ASCII] decimal 44). Alternately, multiple busy time periods MAY be specified with multiple instances of the "FREEBUSY" property. Both forms MUST be supported by implementations conforming to this document. Duplicate busy time periods SHOULD NOT be specified in an iCalendar object. However, two different busy time periods MAY overlap. "FREEBUSY" properties should be sorted such that their values are in ascending order, based on the start time, and then the end time, with the earliest periods first. For example, today's busy time information should appear after yesterday's busy time information. And the busy time for this half-hour should appear after the busy time for earlier today. Since events may span a day boundary, free busy time period may also span a day boundary. Individual "A" requests busy time from individuals "B", "C" and "D". Individual "B" and "C" replies with busy time data to individual "A". Individual "D" does not support busy time requests and does not reply with any data. If the transport binding supports exception messages, then individual "D" returns an "unsupported capability" message to individual "A4.34.3". The following summarizes the methods that are defined for the "VFREEBUSY" calendar component.
|================|==================================================| | Method | Description | |================|==================================================| | PUBLISH | Publish unsolicited busy time data. | | REQUEST | Request busy time data. | | REPLY | Reply to a busy time request. | |================|==================================================| 3.3.1 PUBLISH The "PUBLISH" method in a "VFREEBUSY" calendar component is used to publish busy time data. The method may be sent from one CU to any other. The purpose of the method is to provide a message for sending unsolicited busy time data. That is, the busy time data is not being sent as a "REPLY" to the receipt of a "REQUEST" method. The "ATTENDEE" property must be specified in the busy time information. The value is the CU address of the originator of the busy time information. This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST be "PUBLISH" VFREEBUSY 1+ DTSTAMP 1 DTSTART 1 DateTime values must be in UTC DTEND 1 DateTime values must be in UTC FREEBUSY 1+ MUST be BUSYTIME. Multiple instances are allowed. Multiple instances must be sorted in ascending order ORGANIZER 1 MUST contain the address of originator of busy time data. COMMENT 0 or 1 CONTACT 0+ X-PROPERTY 0+ URL 0 or 1 Specifies busy time URL ATTENDEE 0 DURATION 0 REQUEST-STATUS 0 UID 0 X-COMPONENT 0+
VEVENT 0 VTODO 0 VJOURNAL 0 VTIMEZONE 0 VALARM 0 3.3.2 REQUEST The "REQUEST" method in a "VFREEBUSY" calendar component is used to ask a "Calendar User" for their busy time information. The request may be for a busy time information bounded by a specific date and time interval. This message only permits requests for busy time information. The message is sent from a "Calendar User" requesting the busy time information to one or more intended recipients. If the originator of the "REQUEST" method is not authorized to make a busy time request on the recipient's calendar system, then an exception message SHOULD be returned in a "REPLY" method, but no busy time data need be returned. This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST be "REQUEST" VFREEBUSY 1 ATTENDEE 1+ contain the address of the calendar store DTEND 1 DateTime values must be in UTC DTSTAMP 1 DTSTART 1 DateTime values must be in UTC ORGANIZER 1 MUST be the request originator's address UID 1 COMMENT 0 or 1 CONTACT 0+ X-PROPERTY 0+ FREEBUSY 0 DURATION 0 REQUEST-STATUS 0 URL 0 X-COMPONENT 0+ VALARM 0 VEVENT 0
VTODO 0 VJOURNAL 0 VTIMEZONE 0 3.3.3 REPLY The "REPLY" method in a "VFREEBUSY" calendar component is used to respond to a busy time request. The method is sent by the recipient of a busy time request to the originator of the request. The "REPLY" method may also be used to respond to an unsuccessful "REQUEST" method. Depending on the "REQUEST-STATUS" value, no busy time information may be returned. This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST be "REPLY" VFREEBUSY 1 ATTENDEE 1 (address of recipient replying) DTSTAMP 1 DTEND 1 DateTime values must be in UTC DTSTART 1 DateTime values must be in UTC FREEBUSY 1+ (values MUST all be of the same data type. Multiple instances are allowed. Multiple instances MUST be sorted in ascending order. Values MAY NOT overlap) ORGANIZER 1 MUST be the request originator's address UID 1 COMMENT 0 or 1 CONTACT 0+ REQUEST-STATUS 0+ URL 0 or 1 (specifies busy time URL) X-PROPERTY 0+ DURATION 0 SEQUENCE 0 X-COMPONENT 0+ VALARM 0 VEVENT 0 VTODO 0 VJOURNAL 0 VTIMEZONE 0
3.4 Methods For VTODO Components This section defines the property set for the methods that are applicable to the "VTODO" calendar component. Each of the methods is defined using a restriction table that specifies the property constraints that define the particular method. The following summarizes the methods that are defined for the "VTODO" calendar component. +================+==================================================+ | Method | Description | |================+==================================================| | PUBLISH | Post notification of a VTODO. Used primarily as | | | a method of advertising the existence of a VTODO.| | | | | REQUEST | Assign a VTODO. This is an explicit assignment to| | | one or more Calendar Users. The REQUEST method | | | is also used to update or change an existing | | | VTODO. Clients that cannot handle REQUEST MAY | | | degrade the method to treat it as a PUBLISH. | | | | | REPLY | Reply to a VTODO request. Attendees MAY set | | | PARTSTAT to ACCEPTED, DECLINED, TENTATIVE, | | | DELEGATED, PARTIAL, and COMPLETED. | | | | | ADD | Add one or more instances to an existing to-do. | | | | | CANCEL | Cancel one or more instances of an existing | | | to-do. | | | | | REFRESH | A request sent to a VTODO Organizer asking for | | | the latest version of a VTODO. | | | | | COUNTER | Counter a REQUEST with an alternative proposal. | | | | | DECLINECOUNTER | Decline a counter proposal by an Attendee. | +================+==================================================+ 3.4.1 PUBLISH The "PUBLISH" method in a "VTODO" calendar component has no associated response. It is simply a posting of an iCalendar object that maybe added to a calendar. It MUST have an "Organizer". It MUST NOT have "Attendees". Its expected usage is for encapsulating an arbitrary "VTODO" calendar component as an iCalendar object. The "Organizer" MAY subsequently update (with another "PUBLISH" method), add instances to (with an "ADD" method), or cancel (with a "CANCEL"
method) a previously published "VTODO" calendar component.
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ----------------------------------------------
METHOD 1 MUST be "PUBLISH"
VTODO 1+
DTSTAMP 1
DTSTART 1
ORGANIZER 1
PRIORITY 1
SEQUENCE 0 or 1 MUST be present if value is greater than
0, MAY be present if 0
SUMMARY 1 Can be null.
UID 1
ATTACH 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 Can be null
DUE 0 or 1 If present DURATION MUST NOT be present
DURATION 0 or 1 If present DUE MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PERCENT-COMPLETE 0 or 1
RDATE 0+
RECURRENCE-ID 0 or 1 MUST only if referring to an instance of a
recurring calendar component. Otherwise
it MUST NOT be present.
RELATED-TO 0+
RESOURCES 0 or 1 This property may contain a list of values
RRULE 0+
STATUS 0 or 1 MAY be one of COMPLETED/NEEDS ACTION/IN-
PROCESS/CANCELLED
URL 0 or 1
X-PROPERTY 0+
ATTENDEE 0
REQUEST-STATUS 0
VTIMEZONE 0+ MUST be present if any date/time refers to
a timezone
VALARM 0+
X-COMPONENT 0+
VFREEBUSY 0
VEVENT 0
VJOURNAL 0
3.4.2 REQUEST
The "REQUEST" method in a "VTODO" calendar component provides the
following scheduling functions:
. Assign a to-do to one or more "Calendar Users";
. Reschedule an existing to-do;
. Update the details of an existing to-do, without rescheduling
it;
. Update the completion status of "Attendees" of an existing
to-do, without rescheduling it;
. Reconfirm an existing to-do, without rescheduling it;
. Delegate/reassign an existing to-do to another "Calendar User".
The assigned "Calendar Users" are identified in the "VTODO" calendar
component by individual "ATTENDEE;ROLE=REQ-PARTICIPANT" property
value sequences.
The originator of a "REQUEST" is the "Organizer" of the to-do. The
recipient of a "REQUEST" is the "Calendar User" assigned the to-do.
The "Attendee" uses the "REPLY" method to convey their acceptance and
completion status to the "Organizer" of the "REQUEST".
The "UID", "SEQUENCE", and "DTSTAMP" properties are used to
distinguish the various uses of the "REQUEST" method. If the "UID"
property value in the "REQUEST" is not found on the recipient's
calendar, then the "REQUEST" is for a new to-do. If the "UID"
property value is found on the recipient's calendar, then the
"REQUEST" is a rescheduling, an update, or a reconfirm of the "VTODO"
calendar object.
If the "Organizer" of the "REQUEST" method is not authorized to make
a to-do request on the "Attendee's" calendar system, then an
exception is returned in the "REQUEST-STATUS" property of a
subsequent "REPLY" method, but no scheduling action is performed.
For the "REQUEST" method, multiple "VTODO" components in a single
iCalendar object are only permitted when for components with the same
"UID" property. That is, a series of recurring events may have
instance-specific information. In this case, multiple "VTODO"
components are needed to express the entire series.
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ----------------------------------------------
METHOD 1 MUST be "REQUEST"
VTODO 1+ All components must have the same UID
ATTENDEE 1+
DTSTAMP 1
DTSTART 1
ORGANIZER 1
PRIORITY 1
SEQUENCE 0 or 1 MUST be present if value is greater than
0, MAY be present if 0
SUMMARY 1 Can be null.
UID 1
ATTACH 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 Can be null
DUE 0 or 1 If present DURATION MUST NOT be present
DURATION 0 or 1 If present DUE MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PERCENT-COMPLETE 0 or 1
RDATE 0+
RECURRENCE-ID 0 or 1 present if referring to an instance of a
recurring calendar component. Otherwise
it MUST NOT be present.
RELATED-TO 0+
RESOURCES 0 or 1 This property may contain a list of
values
RRULE 0+
STATUS 0 or 1 MAY be one of COMPLETED/NEEDS ACTION/IN-
PROCESS
URL 0 or 1
X-PROPERTY 0+
REQUEST-STATUS 0
VALARM 0+
VTIMEZONE 0+ MUST be present if any date/time refers
to a timezone
X-COMPONENT 0+
VEVENT 0
VFREEBUSY 0
VJOURNAL 0
3.4.2.1 REQUEST for Rescheduling a VTODO
The "REQUEST" method may be used to reschedule a "VTODO" calendar
component.
Rescheduling a "VTODO" calendar component involves a change to the
existing "VTODO" calendar component in terms of its start or due time
or recurrence intervals and possibly the description. If the
recipient CUA of a "REQUEST" method finds that the "UID" property
value already exists on the calendar, but that the "SEQUENCE"
property value in the "REQUEST" is greater than the value for the
existing VTODO, then the "REQUEST" method describes a rescheduling of
the "VTODO" calendar component.
3.4.2.2 REQUEST for Update or Reconfirmation of a VTODO
The "REQUEST" method may be used to update or reconfirm a "VTODO"
calendar component. Reconfirmation is merely an update of "Attendee"
completion status or overall "VTODO" calendar component status.
An update to an existing "VTODO" calendar component does not involve
changes to the start or due time or recurrence intervals, nor
generally to the description for the "VTODO" calendar component. If
the recipient CUA of a "REQUEST" method finds that the "UID" property
value already exists on the calendar and that the "SEQUENCE" property
value in the "REQUEST" is the same as the value for the existing
event, then the "REQUEST" method describes an update of the "VTODO"
calendar component details, but not a rescheduling of the "VTODO"
calendar component.
The update "REQUEST" is the appropriate response to a "REFRESH"
method sent from an "Attendee" to the "Organizer" of a "VTODO"
calendar component.
Unsolicited "REQUEST" methods MAY be sent by the "Organizer" of a
"VTODO" calendar component. The unsolicited "REQUEST" methods are
used to update the details of the "VTODO" (without rescheduling it or updating the completion status of "Attendees") or the "VTODO" calendar component itself (i.e., reconfirm the "VTODO"). 3.4.2.3 REQUEST for Delegating a VTODO The "REQUEST" method is also used to delegate or reassign ownership of a "VTODO" calendar component to another "Calendar User". For example, it may be used to delegate an "Attendee's" role (i.e. "chair", or "participant") for a "VTODO" calendar component. The "REQUEST" method is sent by one of the "Attendees" of an existing "VTODO" calendar component to some other individual. An "Attendee" of a "VTODO" calendar component MUST NOT delegate to the "Organizer" of the event. For the purposes of this description, the "Attendee" delegating the "VTODO" calendar component is referred to as the "Delegator". The "Attendee" receiving the delegation request is referred to as the "Delegate". The "Delegator" of a "VTODO" calendar component MUST forward the existing "REQUEST" method for a "VTODO" calendar component to the "Delegate". The "VTODO" calendar component description MUST include the "Delegator's" up-to-date "VTODO" calendar component definition. The "REQUEST" method MUST also include an "ATTENDEE" property with the calendar address of the "Delegate". The "Delegator" MUST also send a "REPLY" method back to the "Organizer" with the "Delegator's" "Attendee" property "partstat" parameter value set to "DELEGATED". In addition, the "delegated-to" parameter MUST be included with the calendar address of the "Delegate". A response to the delegation "REQUEST" is sent from the "Delegate" to the "Organizer" and optionally, to the "Delegator". The "REPLY" method from the "Delegate" SHOULD include the "ATTENDEE" property with their calendar address and the "delegated-from" parameter with the value of the "Delegator's" calendar address. The delegation "REQUEST" method MUST assign a value for the "RSVP" property parameter associated with the "Delegator's" "Attendee" property to that of the "Delegate's" "ATTENDEE" property. For example if the "Delegator's" "ATTENDEE" property specifies "RSVP=TRUE", then the "Delegate's" "ATTENDEE" property MUST specify "RSVP=TRUE". 3.4.2.4 REQUEST Forwarded To An Uninvited Calendar User An "Attendee" assigned a "VTODO" calendar component may send the "VTODO" calendar component to another new CU, not previously associated with the "VTODO" calendar component. The current
"Attendee" assigned the "VTODO" calendar component does this by forwarding the original "REQUEST" method to the new CU. The new CU can send a "REPLY" to the "Organizer" of the "VTODO" calendar component. The reply contains an "ATTENDEE" property for the new CU. The "Organizer" ultimately decides whether or not the new CU becomes part of the to-do and is not obligated to do anything with a "REPLY" from a new (uninvited) CU. If the "Organizer" does not want the new CU to be part of the to-do, the new "ATTENDEE" property is not added to the "VTODO" calendar component. The "Organizer" MAY send the CU a "CANCEL" message to indicate that they will not be added to the to- do. If the "Organizer" decides to add the new CU, the new "ATTENDEE" property is added to the "VTODO" calendar component. Furthermore, the "Organizer" is free to change any "ATTENDEE" property parameter from the values supplied by the new CU to something the "Organizer" considers appropriate. 3.4.2.5 REQUEST Updated Attendee Status An "Organizer" of a "VTODO" may request an updated status from one or more "Attendees". The "Organizer" sends a "REQUEST" method to the "Attendee" with the "ATTENDEE;RSVP=TRUE" property sequence. The "SEQUENCE" property for the "VTODO" is not changed from its previous value. A recipient determines that the only change in the "REQUEST" is that their "RSVP" property parameter indicates a request for an updated status. The recipient SHOULD respond with a "REPLY" method indicating their current status with respect to the "REQUEST". 3.4.3 REPLY The "REPLY" method in a "VTODO" calendar component is used to respond (e.g., accept or decline) to a request or to reply to a delegation request. It is also used by an "Attendee" to update their completion status. When used to provide a delegation response, the "Delegator" MUST include the calendar address of the "Delegate" in the "delegated-to" parameter of the "Delegator's" "ATTENDEE" property. The "Delegate" MUST include the calendar address of the "Delegator" on the "delegated-from" parameter of the "Delegate's" "ATTENDEE" property. The "REPLY" method MAY also be used to respond to an unsuccessful "VTODO" calendar component "REQUEST" method. Depending on the "REQUEST-STATUS" value, no scheduling action may have been performed. The "Organizer" of a "VTODO" calendar component MAY receive a "REPLY" method from a "Calendar User" not in the original "REQUEST". For example, a "REPLY" method MAY be received from a "Delegate" of a "VTODO" calendar component. In addition, the "REPLY" method MAY be
received from an unknown "Calendar User", having been forwarded the
"REQUEST" by an original "Attendee" of the "VTODO" calendar
component. This uninvited "Attendee" MAY be accepted, or the
"Organizer" MAY cancel the "VTODO" calendar component for the
uninvited "Attendee" by sending them a "CANCEL" method.
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ---------------------------------------------
METHOD 1 MUST be "REPLY"
VTODO 1+ All component MUST have the same UID
ATTENDEE 1+
DTSTAMP 1
ORGANIZER 1
REQUEST-STATUS 1+
UID 1 MUST must be the address of the replying
attendee
ATTACH 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
DUE 0 or 1 If present DURATION MUST NOT be present
DURATION 0 or 1 If present DUE MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PERCENT-COMPLETE 0 or 1
PRIORITY 0 or 1
RDATE 0+
RELATED-TO 0+
RESOURCES 0 or 1 This property may contain a list of values
RRULE 0+
RECURRENCE-ID 0 or 1 MUST only if referring to an instance of a
Recurring calendar component. Otherwise it
MUST NOT be present
SEQUENCE 0 or 1 MUST be the sequence number of
the original REQUEST if greater than 0.
MAY be present if 0.
STATUS 0 or 1
SUMMARY 0 or 1 Can be null
URL 0 or 1
X-PROPERTY 0+
VTIMEZONE 0 or 1 MUST be present if any date/time refers to
a timezone
X-COMPONENT 0+
VALARM 0
VEVENT 0
VFREEBUSY 0
3.4.4 ADD
The "ADD" method in a "VTODO" calendar component is used to add one
or more instances to an existing to-do.
If the "UID" property value in the "ADD" is not found on the
recipient's calendar, then the recipient SHOULD send a "REFRESH" to
the "Organizer" in order to be updated with the latest version of the
"VTODO". If an "Attendee" implementation does not support the "ADD"
method it should respond with a "REQUEST-STATUS" value of 5.3 and ask
for a "REFRESH".
The "SEQUENCE" property value is incremented as the sequence of to-
dos has changed.
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ----------------------------------------------
METHOD 1 MUST be "ADD"
VTODO 1
DTSTAMP 1
ORGANIZER 1
PRIORITY 1
SEQUENCE 1 MUST be greater than 0
SUMMARY 1 Can be null.
UID 1 MUST match that of the original to-do
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 Can be null
DTSTART 0 or 1
DUE 0 or 1 If present DURATION MUST NOT be present
DURATION 0 or 1 If present DUE MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PERCENT-COMPLETE 0 or 1
RDATE 0+
RELATED-TO 0+
RESOURCES 0 or 1 This property may contain a list of
values
RRULE 0+
STATUS 0 or 1 MAY be one of COMPLETED/NEEDS ACTION/IN-
PROCESS
URL 0 or 1
X-PROPERTY 0+
RECURRENCE-ID 0
REQUEST-STATUS 0
VALARM 0+
VTIMEZONE 0+ MUST be present if any date/time refers
to a timezone
X-COMPONENT 0+
VEVENT 0
VJOURNAL 0
VFREEBUSY 0
3.4.5 CANCEL
The "CANCEL" method in a "VTODO" calendar component is used to send a
cancellation notice of an existing "VTODO" calendar request to the
"Attendees". The message is sent by the "Organizer" of a "VTODO"
calendar component to the "Attendees" of the "VTODO" calendar
component. For a recurring "VTODO" calendar component, either the
whole "VTODO" calendar component or instances of a "VTODO" calendar
component may be cancelled. To cancel the complete range of a
recurring "VTODO" calendar component, the "UID" property value for
the "VTODO" calendar component MUST be specified and a "RECURRENCE-
ID" MUST NOT be specified in the "CANCEL" method. In order to cancel
an individual instance of a recurring "VTODO" calendar component, the
"RECURRENCE-ID" property value for the "VTODO" calendar component
MUST be specified in the "CANCEL" method.
There are two options for canceling a sequence of instances of a
recurring "VTODO" calendar component:
(a) the "RECURRENCE-ID" property for an instance in the sequence MUST
be specified with the "RANGE" property parameter value of
THISANDPRIOR (or THISANDFUTURE) to indicate cancellation of the
specified "VTODO" calendar component and all instances before (or
after); or
(b) individual recurrence instances may be cancelled by specifying
multiple "RECURRENCE-ID" properties corresponding to the
instances to be cancelled.
When a "VTODO" is cancelled, the "SEQUENCE" property value MUST be
incremented.
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ---------------------------------------------
METHOD 1 MUST be "CANCEL"
VTODO 1
ATTENDEE 0+ include all "Attendees" being removed from
the todo. MUST include all "Attendees" if
the entire todo is cancelled.
UID 1 MUST echo original UID
DTSTAMP 1
ORGANIZER 1
SEQUENCE 1
ATTACH 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
DUE 0 or 1 If present DURATION MUST NOT be present
DURATION 0 or 1 If present DUE MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PERCENT-COMPLETE 0 or 1
RDATE 0+
RECURRENCE-ID 0 or 1 MUST only if referring to one or more
instances of a recurring calendar
component. Otherwise it MUST NOT be
present.
RELATED-TO 0+
RESOURCES 0 or 1 This property MAY contain a list of values
RRULE 0+
PRIORITY 0 or 1
STATUS 0 or 1 If present it MUST be set to "CANCELLED".
MUST NOT be used if purpose is to remove
"ATTENDEES" rather than cancel the entire
VTODO.
URL 0 or 1
X-PROPERTY 0+
REQUEST-STATUS 0
VTIMEZONE 0 or 1 MUST be present if any date/time refers to
a timezone
X-COMPONENT 0+
VALARM 0
VEVENT 0
VFREEBUSY 0
3.4.6 REFRESH
The "REFRESH" method in a "VTODO" calendar component is used by
"Attendees" of an existing "VTODO" calendar component to request an
updated description from the "Organizer" of the "VTODO" calendar
component. The "Organizer" of the "VTODO" calendar component MAY use
this method to request an updated status from the "Attendees". The
"REFRESH" method MUST specify the "UID" property corresponding to the
"VTODO" calendar component needing update.
A refresh of a recurrence instance of a "VTODO" calendar component
may be requested by specifying the "RECURRENCE-ID" property
corresponding to the associated "VTODO" calendar component. The
"Organizer" responds with the latest description and rendition of the
"VTODO" calendar component. In most cases this will be a REQUEST
unless the "VTODO" has been cancelled, in which case the ORGANIZER
MUST send a "CANCEL". This method is intended to facilitate machine
processing of requests for updates to a "VTODO" calendar component.
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ---------------------------------------------
METHOD 1 MUST be "REFRESH"
VTODO 1
ATTENDEE 1
DTSTAMP 1
UID 1 MUST echo original UID
RECURRENCE-ID 0 or 1 MUST only if referring to an instance of a
Recurring calendar component. Otherwise it
MUST NOT be present
X-PROPERTY 0+
ATTACH 0
CATEGORIES 0
CLASS 0
COMMENT 0
CONTACT 0
CREATED 0
DESCRIPTION 0
DTSTART 0
DUE 0
DURATION 0
EXDATE 0
EXRULE 0
GEO 0
LAST-MODIFIED 0
LOCATION 0
ORGANIZER 0
PERCENT-COMPLETE 0
PRIORITY 0
RDATE 0
RELATED-TO 0
REQUEST-STATUS 0
RESOURCES 0
RRULE 0
SEQUENCE 0
STATUS 0
URL 0
X-COMPONENT 0+
VALARM 0
VEVENT 0
VFREEBUSY 0
VTIMEZONE 0
3.4.7 COUNTER The "COUNTER" method in a "VTODO" calendar component is used by an "Attendee" of an existing "VTODO" calendar component to submit to the "Organizer" a counter proposal for the "VTODO" calendar component. The "Attendee" sends the message to the "Organizer" of the "VTODO" calendar component. The counter proposal is an iCalendar object consisting of a "VTODO" calendar component describing the complete description of the alternate "VTODO" calendar component. The "Organizer" rejects the counter proposal by sending the "Attendee" a "DECLINECOUNTER" method. The "Organizer" accepts the counter proposal by sending all of the "Attendees" of the "VTODO" calendar component a "REQUEST" method rescheduling the "VTODO" calendar component. In the latter case, the "Organizer" SHOULD reset the individual "RSVP" property parameter values to TRUE on each "ATTENDEE" property; in order to force a response by the "Attendees". This method type is an iCalendar object that conforms to the following property constraints: Component/Property Presence ------------------- ---------------------------------------------- METHOD 1 MUST be "COUNTER" VTODO 1 ATTENDEE 1+ DTSTAMP 1 ORGANIZER 1 PRIORITY 1 SUMMARY 1 Can be null UID 1 ATTACH 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 Can be null DTSTART 0 or 1 DUE 0 or 1 If present DURATION MUST NOT be present DURATION 0 or 1 If present DUE MUST NOT be present EXDATE 0+ EXRULE 0+ GEO 0 or 1 LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PERCENT-COMPLETE 0 or 1
RDATE 0+
RECURRENCE-ID 0 or 1 MUST only 3.5if referring to an instance of a
recurring calendar component. Otherwise it
MUST NOT be present.
RELATED-TO 0+
REQUEST-STATUS 0+
RESOURCES 0 or 1 This property MAY contain a list of values
RRULE 0 or 1
SEQUENCE 0 or 1 MUST echo the original SEQUENCE number.
MUST be present if non-zero. MAY be present
if zero.
STATUS 0 or 1 MAY be one of COMPLETED/NEEDS ACTION/IN-
PROCESS/CANCELLED
URL 0 or 1
X-PROPERTY 0+
VALARM 0+
VTIMEZONE 0 or 1 MUST be present if any date/time refers to
a timezone
X-COMPONENT 0+
VEVENT 0
VFREEBUSY 0
3.4.8 DECLINECOUNTER
The "DECLINECOUNTER" method in a "VTODO" calendar component is used
by an "Organizer" of "VTODO" calendar component to reject a counter
proposal offered by one of the "Attendees". The "Organizer" sends the
message to the "Attendee" that sent the "COUNTER" method to the
"Organizer".
This method type is an iCalendar object that conforms to the
following property constraints:
Component/Property Presence
------------------- ---------------------------------------------
METHOD 1 MUST be "DECLINECOUNTER"
VTODO 1
ATTENDEE 1+ MUST for all attendees
DTSTAMP 1
ORGANIZER 1
SEQUENCE 1 MUST echo the original SEQUENCE number
UID 1 MUST echo original UID
ATTACH 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
DUE 0 or 1 If present DURATION MUST NOT be present
DURATION 0 or 1 If present DUE MUST NOT be present
EXDATE 0+
EXRULE 0+
GEO 0 or 1
LAST-MODIFIED 0 or 1
LOCATION 0 or 1
PERCENT-COMPLETE 0 or 1
PRIORITY 0 or 1
RDATE 0+
RECURRENCE-ID 0 or 1 MUST only if referring to an instance of a
recurring calendar component. Otherwise
it MUST NOT be present.
RELATED-TO 0+
REQUEST-STATUS 0+
RESOURCES 0 or 1 This property MAY contain a list of values
RRULE 0+
STATUS 0 or 1 MAY be one of COMPLETED/NEEDS ACTION/IN-
PROCESS
URL 0 or 1
X-PROPERTY 0+
VTIMEZONE 0+ MUST be present if any date/time refers to
a timezone
X-COMPONENT 0+
VALARM 0
VEVENT 0
VFREEBUSY 0
(page 50 continued on part 3)
