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Internet This specification defines updates to RFC5546 iTip which allow scheduling using the "PARTICIPANT" calendar components specified in RFC9073. New properties are also defined for use within the "PARTICIPANT" calendar component.

Introduction This specification details how the "PARTICIPANT" calendar component introduced in may be used for scheduling in place of "ATTENDEE" and "ORGANIZER" properties. Additionally, some properties are defined in this specification to be used within the "PARTICIPANT" calendar component. For "VEVENT", "VTODO", "VFREEBUSY", and "VAVAILABILITY" calendar components; the "ORGANIZER" and "ATTENDEE" properties MUST be supplied as specified in . For new components such as the "VPOLL" calendar component, defined elsewhere, only "PARTICIPANT" calendar components MUST be used. A participant object that takes part in group scheduling MUST have the following characteristics:

• It MUST have a calendar address as defined in .
• It must have one or more scheduling roles defined in PARTICIPANT-TYPE
• Exactly 1 PARTICIPANT MUST have the OWNER role

Scheduling with "PARTICIPANT" calendar components behaves exactly as with "ATTENDEE" and "ORGANIZER" properties. When iTip specifies the setting of "ATTENDEE" or "ORGANIZER" property parameters then the appropriate properties will be set within the "PARTICIPANT" calendar component.

Terms and definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in . The notation used in this memo to (re-)define iCalendar elements is the ABNF notation of as used by . Any syntax elements shown below that are not explicitly defined in this specification come from iCalendar . Additionally, the following terms are used:

participant Represents an agent that takes part in scheduling or publishing. A participant may be a human, for example an attendee, or a resource, for example a conference room.

publishable A component which takes part in publishing operations.

schedulable A component which takes part in scheduling operations.

owner The "Owner" of a "Schedulable" component is equivalent to the "Organizer" in . As such, there may be only one "Owner" though future specifications may relax or extend that constraint. The "Owner" is indicated by a role of "OWNER".

iCalendar Extensions

New Property Parameters

Required

Parameter name

REQUIRED

Purpose

To specify whether the associated property is required in the current context.

Format Definition

This parameter is defined by the following notation:

Description

This parameter MAY be specified on "REPLY-URL" property and, if the value is TRUE, indicates the "Owner" requires all replies to be made via the specified service rather than iTip replies.

New Properties

Reply-URL

Property name

REPLY-URL

Purpose

This property may be used in scheduling messages to indicate additional reply methods, for example a web-service.

Value type

URI

Property Parameters

Non-standard, required or iana parameters can be specified on this property.

Conformance

This property MAY be specified once in any schedulable component.

Description

When used in a scheduling message this property indicates an additional or required service that can be used to reply. Typically, this would be a web service of some form. When the "REQUIRED" property parameter is absent then this property provides an alternative to standard iTip based scheduling. When the "REQUIRED" property parameter is present then this property provides the only mechanism by which participants can reply. This allows the implementation of a web-based service without the ability to accept incoming mail for example.

Format Definition

This property is defined by the following notation:

Redefined participation type This specification redefines the "PARTICIPANT-TYPE" property allowing it to take multiple values and extending those values to align with roles. There are also changes to the description to clarify its use defining the roles that participant takes.

Property name

PARTICIPANT-TYPE

Purpose

This property is equivalent to the "ROLE" property parameter but includes more values to align with .

Value Type

The value type for this property is TEXT. The allowable values are defined below.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MUST be specified once within a "PARTICIPANT" calendar component.

Description

This property defines the type of participation, that is the roles the participant takes.
It includes the values defined in . Note that the kind of participant, for example individual or group, is defined in the "KIND" property specified here. Some of the roles are required for the participant to be a "schedulable" object. These are the roles that are shown below.

Format Definition

This property is defined by the following notation:

The values have the same meaning as defined in and . Other roles defined here have no direct equivalent in To map "ROLE" property parameter values to "PARTICIPANT-TYPE" property values use the following.

RFC5545 ROLE	PARTICIPANT-TYPE
CHAIR	CHAIR
REQ-PARTICIPANT	ATTENDEE
OPT-PARTICIPANT	OPTIONAL
NON-PARTICIPANT	INFORMATIONAL

The following table shows those roles that MUST appear in the "PARTICIPANT-TYPE" property for group-scheduling. Additionally, the mapping for "PARTICIPANT-TYPE" property values to values are shown.

PARTICIPANT-TYPE	RFC5545 ROLE
OWNER	Create ORGANIZER
ATTENDEE	REQ-PARTICIPANT
OPTIONAL	OPT-PARTICIPANT
INFORMATIONAL	NON-PARTICIPANT
CHAIR	CHAIR
Subsequent values have no equivalent
CONTACT
VOTER
ACTIVE
INACTIVE
SPONSOR
BOOKING-CONTACT
EMERGENCY-CONTACT
PUBLICITY-CONTACT
PLANNER-CONTACT
PERFORMER
SPEAKER

Examples

• PARTICIPANT-TYPE=OWNER,... equivalent to the "ORGANIZER" property
• PARTICIPANT-TYPE=ATTENDEE,... equivalent to the "ATTENDEE" property

New Participant Properties for iTip The following properties are defined to be used within the "PARTICIPANT" calendar component during scheduling and take the place of "ATTENDEE" and "ORGANIZER" properties and parameters.

Kind

Property name

KIND

Purpose

This is what kind of entity this participant is, if known.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified in a "PARTICIPANT" calendar component.

Description

When used in a "PARTICIPANT" calendar component this property indicates the kind of entity, individual, group etc.
It takes the values shown below which are a redefinition of the "CUTYPE" property parameter values defined in and aligned with .

Format Definition

This property is defined by the following notation:

Participation-status

Property name

PARTICIPATION-STATUS

Purpose

This property is used in the "PARTICIPANT" calendar component to indicate the participation status - if any.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified in a "PARTICIPANT" calendar component.

Description

When used in a "PARTICIPANT" calendar component this property indicates what status, if any, the participant has.
It takes the same values as the "PARTSTAT" property parameter defined in .

Format Definition

This property is defined by the following notation:

Participation delegated from

Property name

PARTICIPATION-DELEGATED-FROM

Purpose

This property is used in the "PARTICIPANT" calendar component to indicate who has delegated their participation to this participant.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified in a "PARTICIPANT" calendar component 0 or more times.

Description

This property specifies a calendar user that has delegated their participation in a group-scheduled component to the calendar user specified by the component.

Format Definition

This property is defined by the following notation:

Participation delegated to

Property name

PARTICIPATION-DELEGATED-TO

Purpose

To specify the calendar user to whom the calendar user specified by the component has delegated participation.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified in a "PARTICIPANT" calendar component 0 or more times.

Description

This property specifies the calendar user that has been delegated participation in a group-scheduled component by the calendar user specified by the component.

Format Definition

This property is defined by the following notation:

Member of

Property name

MEMBER-OF

Purpose

To specify the group or list membership of the calendar user specified by the component.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified in a "PARTICIPANT" calendar component 0 or more times.

Description

This property identifies the group or list membership for the calendar user specified by the component.

Format Definition

This property is defined by the following notation:

Lang

Property name

LANG

Purpose

This is the language tag, as defined in , that best describes the participant's preferred language, if known.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified in any appropriate component.

Format Definition

This property is defined by the following notation:

Expect reply

Property name

EXPECT-REPLY

Purpose

If true, the organizer is expecting the participant to notify them of their participation status.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified once in the "PARTICIPANT" calendar component.

Format Definition

This property is defined by the following notation:

Scheduling-agent

Property name

SCHEDULING-AGENT

Purpose

This is who is responsible for sending scheduling messages with this calendar object to the participant.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified once in the "PARTICIPANT" calendar component.

Format Definition

This property is defined by the following notation:

The value MUST be one of the following values from the registry defined in , or a vendor-specific value.

SERVER

The calendar server will send the scheduling messages.

CLIENT

The calendar client will send the scheduling messages.

NONE

No scheduling messages are to be sent to this participant.

Scheduling-force-send

Property name

SCHEDULING-FORCE-SEND

Purpose

A client may set the property on a participant to true to request that the server send a scheduling message to the participant when it would not normally do so (e.g., if no significant change is made the object or the scheduleAgent is set to client). The property MUST NOT be stored in the object on the server or appear in a scheduling message.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified once in the "PARTICIPANT" calendar component.

Format Definition

This property is defined by the following notation:

Description

This property MAY be specified in "PARTICIPANT" calendar components for which the "SCHEDULE-AGENT" property is set to the value "SERVER" or is absent. This property is used to force a server to send a scheduling message to a specific calendar user in situations where the server would not send a scheduling message otherwise (e.g., when no change that warrants the delivery of a new scheduling message was performed on the scheduling object resource). An "Owner" MAY specify this property for a PARTICIPANT with the value "REQUEST" to force a "REQUEST" scheduling message to be sent to the user. Participants who are not the "Owner" MAY specify this property in the "Owner" PARTICIPANT with the value "REPLY" to force a "REPLY" scheduling message to be sent to the "Owner". Servers MUST NOT preserve this property in scheduling object resources, nor include it in any scheduling messages sent as the result of a scheduling operation. Clients MUST NOT include this property in any scheduling messages that they themselves send. Servers MUST set the "SCHEDULING-STATUS" property of the participant to 2.5 (i.e., "Success; unknown, non-standard property value ignored."; see ) when the "SCHEDULE-FORCE-SEND" property is set to an iana-token value they do not recognize.

Scheduling-status

Property name

SCHEDULING-STATUS

Purpose

This is a list of status codes, returned from the processing of the most recent scheduling message sent to this participant. The status codes MUST be valid statcode values as defined in the ABNF in Section 3.8.8.3 of [RFC5545]. Servers MUST only add or change this property when they send a scheduling message to the participant. Clients SHOULD NOT change or remove this property if it was provided by the server. Clients MAY add, change, or remove the property for participants where the client is handling the scheduling.This property MUST NOT be included in scheduling messages.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified in any appropriate component.

Format Definition

This property is defined by the following notation:

Scheduling-dtstamp

Property name

SCHEDULING-DTSTAMP

Purpose

This is the timestamp for the most recent response from this participant. This is the updated property of the last response when using iTIP. It can be compared to the updated property in future responses to detect and discard older responses delivered out of order.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified in any appropriate component.

Format Definition

This property is defined by the following notation:

Invited-by

Property name

INVITED-BY

Purpose

This is the calendar address of the participant who added this participant to the entity, if known.

Property Parameters

Non-standard or iana parameters can be specified on this property.

Conformance

This property MAY be specified in any appropriate component.

Format Definition

This property is defined by the following notation:

Attendee parameters mapping

Parameter	iCalendar PARTICIPANT
CN	NAME (defined in
CUTYPE	KIND (defined here)
DELEGATED-FROM	PARTICIPATION-DELEGATED-FROM
DELEGATED-TO	PARTICIPATION-DELEGATED-TO (Defined here)
DIR	LINK
LANGUAGE	LANG (defined here)
MEMBER	MEMBER-OF (defined here)
PARTSTAT	PARTICIPATION-STATUS (defined here)
ROLE	PARTICIPATION-TYPE (Updated here)
RSVP	EXPECT-REPLY (Defined here)
SENT-BY

Security Considerations There should be no new security risks additional to those noted in .

IANA Considerations

Parameter Registrations This document defines the following new iCalendar property parameters to be added to the registry defined in :

Property Parameter	Status	Reference
REQUIRED	Current

Property Registrations This document defines the following new iCalendar properties to be added to the registry defined in :

Property	Status	Reference
EXPECT-REPLY	Current
INVITED-BY	Current
KIND	Current
LANG	Current
MEMBER-OF	Current
PARTICIPATION-DELEGATED-FROM	Current
PARTICIPATION-DELEGATED-TO	Current
PARTICIPATION-STATUS	Current
REPLY-URL	Current
SCHEDULING-AGENT	Current
SCHEDULING-DTSTAMP	Current
SCHEDULING-FORCE-SEND	Current
SCHEDULING-STATUS	Current

Updated Participant Type Registrations This updates the participant types registry defined in

Participant Type	Status	Reference
OWNER	Current	RFC8984
ATTENDEE	Current	RFC8984
OPTIONAL	Current	RFC8984
INFORMATIONAL	Current	RFC8984
CHAIR	Current	RFC8984

Acknowledgements The authors would like to thank the members of the Calendaring and Scheduling Consortium (CalConnect) for contributing their ideas and support.

Normative References IETF StandardsTrackDocuments In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. IETF ABNFbackus-naur formaugmented backus-naur formrule definitionsencodingcore lexical analyzer Internet technical specifications often need to define a formal syntax. Over the years, a modified version of Backus-Naur Form (BNF), called Augmented BNF (ABNF), has been popular among many Internet specifications. The current specification documents ABNF. It balances compactness and simplicity with reasonable representational power. The differences between standard BNF and ABNF involve naming rules, repetition, alternatives, order-independence, and value ranges. This specification also supplies additional rule definitions and encoding for a core lexical analyzer of the type common to several Internet specifications. [STANDARDS-TRACK] IETF calsifycalschedcalschcaldavcalendarcalendaringmeetingeventtaskto-dojournalappointmentagendascheduleschedulingicalicalendaritipimiptext/calendarischedulexCalendar This document defines the iCalendar data format for representing and exchanging calendaring and scheduling information such as events, to-dos, journal entries, and free/busy information, independent of any particular calendar service or protocol. [STANDARDS-TRACK] IETF calendarscheduling This document specifies a protocol that uses the iCalendar object specification to provide scheduling interoperability between different calendaring systems. This is done without reference to a specific transport protocol so as to allow multiple methods of communication between systems. Subsequent documents will define profiles of this protocol that use specific, interoperable methods of communication between systems. The iCalendar Transport-Independent Interoperability Protocol (iTIP) complements the iCalendar object specification by adding semantics for group scheduling methods commonly available in current calendaring systems. These scheduling methods permit two or more calendaring systems to perform transactions such as publishing, scheduling, rescheduling, responding to scheduling requests, negotiating changes, or canceling. [STANDARDS-TRACK] IETF language tagsprivate interchange This document describes the structure, content, construction, and semantics of language tags for use in cases where it is desirable to indicate the language used in an information object. It also describes how to register values for use in language tags and the creation of user-defined extensions for private interchange. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. IETF calsifycalschedcalschcalendarcalendaringwebcalicalicalendarischeduleitipimiptext/calendarhttp This document defines extensions to the Calendaring Extensions to WebDAV (CalDAV) "calendar-access" feature to specify a standard way of performing scheduling operations with iCalendar-based calendar components. This document defines the "calendar-auto-schedule" feature of CalDAV. [STANDARDS-TRACK] IETF alarmscalendaringiCalendar This document defines a set of new properties for iCalendar data and extends the use of some existing properties to the entire iCalendar object. IETF JSONiCalendarcalendareventsdatetime This specification defines a data model and JSON representation of calendar data that can be used for storage and data exchange in a calendaring and scheduling environment. It aims to be an alternative and, over time, successor to the widely deployed iCalendar data format. It also aims to be unambiguous, extendable, and simple to process. In contrast to the jCal format, which is also based on JSON, JSCalendar is not a direct mapping from iCalendar but defines the data model independently and expands semantics where appropriate. IETF iCalendarproperties This specification updates RFC 5545 by introducing a number of new iCalendar properties and components that are of particular use for event publishers and in social networking. This specification also defines a new "STRUCTURED-DATA" property for iCalendar (RFC 5545) to allow for data that is directly pertinent to an event or task to be included with the calendar data. IETF iCalendarlinkrelated-torelationships This specification updates the iCalendar RELATED-TO property defined in RFC 5545 by adding new relation types and introduces new iCalendar properties (LINK, CONCEPT, and REFID) to allow better linking and grouping of iCalendar components and related data.