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Network Working Group M. Douglass
Internet-Draft Spherical Cow Group
Updates: 5545,5546 (if approved) May 15, 2018
Intended status: Standards Track
Expires: November 16, 2018
Event Publishing Extensions to iCalendar
draft-ietf-calext-eventpub-extensions-07
Abstract
This specification updates [RFC5545] and [RFC5546] by introducing a
number of new iCalendar properties and components which are of
particular use for event publishers and in social networking.
This specification also defines a new STRUCTURED-DATA property for
iCalendar [RFC5545] to allow for data that is directly pertinent to
an event or task to be included with the calendar data.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 16, 2018.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions Used in This Document . . . . . . . . . . . . 4
2. Components and properties . . . . . . . . . . . . . . . . . . 4
3. Typed References . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.1. Piano Concert Performance . . . . . . . . . . . . . . 5
3.1.2. Itineraries . . . . . . . . . . . . . . . . . . . . . 6
3.1.2.1. Reserving facilities . . . . . . . . . . . . . . 6
4. Modifications to Calendar Components . . . . . . . . . . . . 6
5. New Property Parameters . . . . . . . . . . . . . . . . . . . 7
5.1. Loctype . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.2. Restype . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.3. Order . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.4. Schema . . . . . . . . . . . . . . . . . . . . . . . . . 9
6. Redefined Property SOURCE . . . . . . . . . . . . . . . . . . 10
7. New Properties . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Participant Type . . . . . . . . . . . . . . . . . . . . 12
7.2. Calendar Address . . . . . . . . . . . . . . . . . . . . 13
7.3. Styled-Description . . . . . . . . . . . . . . . . . . . 14
7.4. Structured-Location . . . . . . . . . . . . . . . . . . . 16
7.5. Structured-Resource . . . . . . . . . . . . . . . . . . . 17
7.6. Structured-Data . . . . . . . . . . . . . . . . . . . . . 19
8. New Components . . . . . . . . . . . . . . . . . . . . . . . 21
8.1. Participant . . . . . . . . . . . . . . . . . . . . . . . 22
8.2. Schedulable Participant . . . . . . . . . . . . . . . . . 24
9. Extended examples . . . . . . . . . . . . . . . . . . . . . . 24
9.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . . . 24
9.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . . . 25
10. Security Considerations . . . . . . . . . . . . . . . . . . . 26
11. Privacy Considerations . . . . . . . . . . . . . . . . . . . 26
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
12.1. Additional iCalendar Registrations . . . . . . . . . . . 27
12.1.1. Property Registrations . . . . . . . . . . . . . . . 27
12.1.2. Parameter Registrations . . . . . . . . . . . . . . 27
12.1.3. Component Registrations . . . . . . . . . . . . . . 27
12.2. New Registration Tables . . . . . . . . . . . . . . . . 28
12.2.1. Participant Types Registry . . . . . . . . . . . . . 28
12.2.2. Resource Types Registry . . . . . . . . . . . . . . 28
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 28
14. Normative References . . . . . . . . . . . . . . . . . . . . 29
Appendix A. Open issues . . . . . . . . . . . . . . . . . . . . 30
Appendix B. Change log . . . . . . . . . . . . . . . . . . . . . 30
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Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 32
1. Introduction
The currently existing iCalendar standard [RFC5545] lacks useful
methods for referencing additional, external information relating to
calendar components. Additionally there is no standard way to
provide rich text descriptions or meta-data associated with the
event.
Current practice is to embed this information as links in the
description or to add non-standard properties as defined in [RFC5545]
section 3.8.8.2.
This document updates [RFC5545] to define a number of properties and
a component referencing such external information that can provide
additional information about an iCalendar component. The intent is
to allow interchange of such information between applications or
systems (e.g., between clients, between client and server, and
between servers). Formats such as VCARD are likely to be most useful
to the receivers of such events as they may be used in other
applications - such as address books.
This specification defines a new PARTICIPANT component. Many people
or groups may participate in an event. This component provides
detailed information. Such participants may act as attendees to the
event (or derived events) or may just provide a reference - perhaps
for mailing lists.
The following properties are defined in this specification
STYLED-DESCRIPTION: Supports HTML descriptions. Event publishers
typically wish to provide more and better formatted information
about the event.
STRUCTURED-LOCATION: There may be a number of locations associated
with an event. This provides detailed information about the
location.
STRUCTURED-RESOURCE: Events need resources such as rooms,
projectors, conferencing capabilities.
STRUCTURED-DATA: The existing properties in iCalendar cover key
elements of events and tasks such as start time, end time,
location, summary, etc. However, different types of events often
have other specific "fields" that it is useful to include in the
calendar data. For example, an event representing an airline
flight could include the airline, flight number, departure and
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arrival airport codes, check-in and gate-closing times etc. As
another example, a sporting event might contain information about
the type of sport, the home and away teams, the league the teams
are in, information about nearby parking, etc.
PARTICIPANT-TYPE: Used in the PARTICIPANT component to define the
type.
CALENDAR-ADDRESS: Used in the PARTICIPANT component to provide the
calendar address of the participant.
In addition the SOURCE property defined in [RFC7986] is redefined to
allow VALUE=TEXT and broaden its usage.
1.1. Conventions Used in This Document
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Components and properties
Previous extensions to the calendaring standards have been largely
restricted to the addition of properties or parameters. This is
partly because iCalendar libraries had trouble handling components
nested deeper than those defined in [RFC5545]
In a break with this 'tradition' this specification introduces one of
these extensions as a component rather than a property. This is a
better match for the way XML and JSON handles such structures and
allows richer definitions.
It also allows for the addition of extra properties inside the
component and resolves some of the problems of trying to add detailed
information as a parameter.
3. Typed References
The properties defined here can all reference external meta-data
which may be used by applications to provide enhanced value to users.
By providing type information as parameters, clients and servers are
able to discover interesting references and make use of them, perhaps
for indexing or the presenting of additional related information for
the user.
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The [RFC5545] LOCATION property provides only an unstructured single
text value for specifying the location where an event (or task) will
occur. This is inadequate for use cases where structured location
information (e.g. address, region, country, postal code) is required
or preferred, and limits widespread adoption of iCalendar in those
settings.
Using STRUCTURED-LOCATION, information about a number of interesting
locations can be communicated, for example, address, region, country,
postal code as well as other informations such as the parking,
restaurants and the venue. Servers and clients can retrieve the
objects when storing the event and use them to index by geographic
location.
When a calendar client receives a calendar component it can search
the set of supplied properties looking for those of particular
interest. The TYPE and FMTTYPE parameters, if supplied, can be used
to help the selection.
The PARTICIPANT component is designed to handle common use cases in
event publication. It is generally important to provide information
about the organizers of such events. Sponsors wish to be referenced
in a prominent manner. In social calendaring it is often important
to identify the active participants in the event, for example a
school sports team, and the inactive participants, for example the
parents.
The PARTICIPANT component can also be used to provide useful extra
data about an attendee. For example a LOCATION property inside the
PARTICIPANT gives the actual location of a remote attendee.
3.1. Use Cases
The main motivation for these properties has been event publication
but there are opportunities for use elsewhere. The following use
cases will describe some possible scenarios.
3.1.1. Piano Concert Performance
In putting together a concert there are many participants: piano
tuner, performer, stage hands etc. In addition there are sponsors
and various contacts to be provided. There will also be a number of
related locations. A number of events can be created, all of which
relate to the performance in different ways.
There may be an iTip [RFC5546] meeting request for the piano tuner
who will arrive before the performance. Other members of staff may
also receive meeting requests.
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An event can also be created for publication which will have a
PARTICIPANT component for the pianist providing a reference to vcard
information about the performer. This event would also hold
information about parking, local subway stations and the venue
itself. In addition, there will be sponsorship information for
sponsors of the event and perhaps paid sponsorship properties
essentially advertising local establishments.
3.1.2. Itineraries
These additions also provide opportunities for the travel industry.
When booking a flight the PARTICIPANT component can be used to
provide references to businesses at the airports and to car hire
businesses at the destination.
The embedded location information can guide the traveller at the
airport or to their final destination. The contact information can
provide detailed information about the booking agent, the airlines,
car hire companies and the hotel.
3.1.2.1. Reserving facilities
For a meeting, the size of a room and the equipment needed depends to
some extent on the number of attendees actually in the room.
A meeting may have 10 attendees non of which are co-located. The
current ATTENDEE property dos not allow for the additon of such meta-
data. The PARTICIPANT property allows attendees to specify their
location.
4. Modifications to Calendar Components
The following changes to the syntax defined in iCalendar [RFC5545]
are made here. New elements are defined in subsequent sections.
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eventc = "BEGIN" ":" "VEVENT" CRLF
eventprop *alarmc *participantc
"END" ":" "VEVENT" CRLF
eventprop =/ *(
;
; The following are OPTIONAL,
; and MAY occur more than once.
;
styleddescription / strucloc / strucres / sdataprop
;
)
todoc = "BEGIN" ":" "VTODO" CRLF
todoprop *alarmc *participantc
"END" ":" "VTODO" CRLF
todoprop =/ *(
;
; The following are OPTIONAL,
; and MAY occur more than once.
;
styleddescription / strucloc / strucres / sdataprop
;
)
journalc = "BEGIN" ":" "VJOURNAL" CRLF
jourprop *participantc
"END" ":" "VJOURNAL" CRLF
jourprop =/ *(
;
; The following are OPTIONAL,
; and MAY occur more than once.
;
styleddescription / sdataprop
;
)
5. New Property Parameters
This specification makes use of the LABEL parameter which is defined
in [RFC7986]
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5.1. Loctype
Parameter name: LOCTYPE
Purpose: To specify the type of location.
Format Definition:
This parameter is defined by the following notation:
loctypeparam = "LOCTYPE" "=" param-value
Description: This parameter MAY be specified on STRUCTURED-LOCATION
and provides a way to differentiate multiple properties. For
example, it allows event producers to provide location information
for the venue and the parking.
Values for this parameter are taken from the values defined in
[RFC4589]. New location types SHOULD be registered in the manner
laid down in that specification
5.2. Restype
Parameter name: RESTYPE
Purpose: To specify the type of resource.
Format Definition:
This parameter is defined by the following notation:
restypeparam = "RESTYPE" "=" restypevalue CRLF
restypevalue = ("ROOM"
/ "PROJECTOR"
/ "REMOTE-CONFERENCE-AUDIO"
/ "REMOTE-CONFERENCE-VIDEO"
/ x-name ; Experimental status
/ iana-token) ; Other IANA-registered
; values
Description: This parameter MAY be specified on STRUCTURED-RESOURCE
and provides a way to differentiate multiple properties.
The registered values are described below. New resource types
SHOULD be registered in the manner laid down in this specification
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ROOM: A room for the event/meeting.
PROJECTOR: Projection equipment.
REMOTE-CONFERENCE-AUDIO: Audio remote conferencing facilities.
REMOTE-CONFERENCE-VIDEO: Video remote conferencing facilities.
5.3. Order
Parameter name: ORDER
Purpose: To define ordering for the associated property.
Format Definition:
This parameter is defined by the following notation:
orderparam = "ORDER" "=" integer ;Must be greater than or equal to 1
Description: The ORDER parameter is OPTIONAL and is used to indicate
the relative ordering of the corresponding instance of a property.
Its value MUST be an integer greater than or equal to 1 that
quantifies the order with 1 being the first in the ordering.
When the parameter is absent, the default MUST be to interpret the
property instance as being at the lowest level of ordering, that
is, the property will appear after any other instances of the same
property with any value of ORDER.
Note that the value of this parameter is to be interpreted only in
relation to values assigned to other corresponding instances of
the same property in the same entity. A given value, or the
absence of a value, MUST NOT be interpreted on its own.
This parameter MAY be applied to any property that allows multiple
instances.
5.4. Schema
Parameter Name: SCHEMA
Purpose: To specify the schema used for the content of a
"STRUCTURED-DATA" property value.
Format Definition:
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This parameter is defined by the following notation:
schemaparam = "SCHEMA" "=" DQUOTE uri DQUOTE
Description: This property parameter SHOULD be specified on
"STRUCTURED-DATA" properties. When present it provides
identifying information about the nature of the content of the
corresponding "STRUCTURED-DATA" property value. This can be used
to supplement the media type information provided by the "FMTTYPE"
parameter on the corresponding property.
Example:
STRUCTURED-DATA;FMTTYPE=application/ld+json;
SCHEMA="https://schema.org/FlightReservation";
ENCODING=BASE64;VALUE=BINARY:Zm9vYmFy
6. Redefined Property SOURCE
The SOURCE property defined in [RFC7986] is redefined to allow
VALUE=TEXT and broaden its usage to any component.
Property name: SOURCE
Purpose: This property provides a reference to information about a
component such as a participant possibly as a vcard or optionally
a plain text typed value.
Value type: The default value type for this property is URI. The
value type can also be set to TEXT to indicate plain text content.
Property Parameters: Non-standard or format type parameters can be
specified on this property.
Conformance: This property MAY be appear in any iCalendar component.
Description: This property provides information about the component
in which it appears.
In a resource or participant it may provide a reference to a vcard
giving directory information.
In a VCALENDAR component this property identifies a location where
a client can retrieve updated data for the calendar. Clients
SHOULD honor any specified "REFRESH-INTERVAL" value when
periodically retrieving data. Note that this property differs
from the "URL" property in that "URL" is meant to provide an
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alternative representation of the calendar data rather than the
original location of the data.
In a calendar entity component such as an event the SOURCE
property may provide a reference to the original source of the
event. This may be used by aggregators to provide a link back.
Format Definition:
This property is defined by the following notation:
source = "SOURCE" sourceparam
(
(
";" "VALUE" "=" "URI"
":" uri
) /
(
";" "VALUE" "=" "TEXT"
":" text
)
)
CRLF
sourceparam = *(
;
; the following are OPTIONAL
; but MUST NOT occur more than once
;
(";" fmttypeparam) /
;
; the following is OPTIONAL
; and MAY occur more than once
;
(";" other-param)
;
)
Example:
The following is an example referring to a VCARD.
SOURCE;FMTTYPE=text/vcard;VALUE=URL:
http://dir.example.com/vcard/contacts/contact1.vcf
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7. New Properties
7.1. Participant Type
Property name: PARTICIPANT-TYPE
Purpose: To specify the type of participant.
Value type: The value type for this property is TEXT. The allowable
values are defined below.
Property Parameters: Non-standard parameters can be specified on
this property.
Conformance: This property MUST be specified within a PARTICIPANT
component.
Description: This property defines the type of participation in
events or tasks. Participants can be individuals or
organizations, for example a soccer team, the spectators, or the
musicians.
Format Definition:
This parameter is defined by the following notation:
participanttype = "PARTICIPANT-TYPE" "=" partvalue CRLF
partvalue = ("ACTIVE"
/ "INACTIVE"
/ "SPONSOR"
/ "CONTACT"
/ "BOOKING-CONTACT"
/ "EMERGENCY-CONTACT"
/ "PUBLICITY-CONTACT"
/ "PLANNER-CONTACT"
/ "PERFORMER"
/ "SPEAKER"
/ x-name ; Experimental status
/ iana-token) ; Other IANA-registered
; values
Example:
The following is an example of this property:
PARTICIPANT-TYPE:SPEAKER
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The registered values for the PARTICIPANT-TYPE property have the
meanings described here:
ACTIVE: A participant taking an active role - for example a team
member.
INACTIVE: A participant taking an inactive part - for example an
audience member.
SPONSOR: A sponsor of the event. The ORDER parameter may be used
with this participant type to define the relative order of
multiple sponsors.
CONTACT: Contact information for the event. The ORDER parameter may
be used with this participant type to define the relative order of
multiple contacts.
BOOKING-CONTACT: Contact information for reservations or payment
EMERGENCY-CONTACT: Contact in case of emergency
PUBLICITY-CONTACT: Contact for publicity
PLANNER-CONTACT: Contact for the event planner or organizer
PERFORMER: A performer - for example the soloist or the accompanist.
The ORDER parameter may be used with this participant type to
define the relative order of multiple performers. For example,
ORDER=1 could define the principal performer or soloist.
SPEAKER: Speaker at an event
7.2. Calendar Address
Property name: CALENDAR-ADDRESS
Purpose: To specify the calendar address for a participant.
Value type: CAL-ADDRESS
Property Parameters: IANA or non-standard property parameters can be
specified on this property.
Conformance: This property MAY be specified within a PARTICIPANT
component.
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Description: This property provides a calendar user address for the
participant. If there is an ATTENDEE property with the same value
then the participant is schedulable.
Format Definition:
This parameter is defined by the following notation:
calendaraddress = "CALENDAR-ADDRESS" "=" cal-address
7.3. Styled-Description
Property name: STYLED-DESCRIPTION
Purpose: This property provides for one or more rich-text
descriptions to replace or augment that provided by the
DESCRIPTION property.
Value type: There is no default value type for this property. The
value type can be set to URI or TEXT. Other text-based value
types can be used when defined in the future. Clients MUST ignore
any properties with value types they do not understand.
Property Parameters: IANA, non-standard, id, alternate text
representation, format type, and language property parameters can
be specified on this property.
Conformance: The property can be specified multiple times in the
"VEVENT", "VTODO", "VJOURNAL", or "VALARM" calendar components.
Description: This property is used in the "VEVENT" and "VTODO" to
capture lengthy textual descriptions associated with the activity.
This property is used in the "VJOURNAL" calendar component to
capture one or more textual journal entries. This property is
used in the "VALARM" calendar component to capture the display
text for a DISPLAY category of alarm, and to capture the body text
for an EMAIL category of alarm.
VALUE=TEXT is used to provide rich-text variants of the plain-text
DESCRIPTION property.
VALUE=URI is used to provide a link to rich-text content which is
expected to be displayed inline as part of the event.
The intent of this property is limited to providing a styled and/
or language specific version of the DESCRIPTION property. The URL
property should be used to link to websites or other related
information.
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Applications MAY attempt to guess the media type of the resource
via inspection of its content if and only if the media type of the
resource is not given by the "FMTTYPE" parameter. If the media
type remains unknown, calendar applications SHOULD treat it as
type "text/html".
Multiple STYLED-DESCRIPTION properties may be used to provide
different formats or different language variants.
Format Definition:
This property is defined by the following notation:
styleddescription = "STYLED-DESCRIPTION" styleddescparam ":"
(
(
";" "VALUE" "=" "URI"
":" uri
) /
(
";" "VALUE" "=" "TEXT"
":" text
)
)
CRLF
styleddescparam = *(
;
; The following are OPTIONAL,
; but MUST NOT occur more than once.
;
(";" altrepparam) / (";" languageparam) /
(";" fmttypeparam) /
;
; the following is OPTIONAL
; and MAY occur more than once
;
(";" other-param)
)
Example:
The following is an example of this property. It points to an html
description.
STYLED-DESCRIPTION;VALUE=URI:http://example.org/desc001.html
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7.4. Structured-Location
Property name: STRUCTURED-LOCATION
Purpose: This property provides a typed reference to external
information about the location of an event or optionally a plain
text typed value.
Value type: There is no default value type for this property. The
value type can be set to URI or TEXT.
Property Parameters: IANA, non-standard, label, loctype or format
type parameters can be specified on this property.
Conformance: This property MAY be specified zero or more times in
any iCalendar component.
Description: When used in a component the value of this property
provides information about the event venue or of related services
such as parking, dining, stations etc..
When a LABEL parameter is supplied the language of the label must
match that of the content and of the LANGUAGE parameter if
present.
Format Definition:
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This property is defined by the following notation:
strucloc = "STRUCTURED-LOCATION" struclocparam
(
(
";" "VALUE" "=" "URI"
":" uri
) /
(
";" "VALUE" "=" "TEXT"
":" text
)
)
CRLF
struclocparam = *(
;
; the following are OPTIONAL
; but MUST NOT occur more than once
;
(";" fmttypeparam) /
(";" labelparam) /
(";" languageparam) /
(";" loctypeparam) /
;
; the following is OPTIONAL
; and MAY occur more than once
;
(";" other-param)
)
Example:
The following is an example of this property. It points to a venue.
STRUCTURED-LOCATION;LABEL="The venue":
http://dir.example.com/venues/big-hall.vcf
7.5. Structured-Resource
Property name: STRUCTURED-RESOURCE
Purpose: This property provides a typed reference to external
information about a resource or optionally a plain text typed
value. Typically a resource is anything that might be required or
used by a calendar entity and possibly has a directory entry.
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Value type: There is no default value type for this property. The
value type can be set to URI or TEXT.
Property Parameters: IANA, non-standard, label, restype or format
type parameters can be specified on this property.
Conformance: This property MAY be specified zero or more times in
any iCalendar component.
Description: When used in a component the value of this property
provides information about resources used for the event.
Such resources may be a room or a projector. This RESTYPE value
registry provides a place in which resource types may be
registered for use by scheduling sevices.
When a LABEL parameter is supplied the language of the label must
match that of the content and of the LANGUAGE parameter if
present.
Format Definition:
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This property is defined by the following notation:
strucres = "STRUCTURED-RESOURCE" strucresparam /
(
(
";" "VALUE" "=" "URI"
":" uri
) /
(
";" "VALUE" "=" "TEXT"
":" text
)
)
CRLF
strucresparam = *(
;
; the following are OPTIONAL
; but MUST NOT occur more than once
;
(";" fmttypeparam) /
(";" labelparam) /
(";" languageparam) /
(";" restypeparam) /
;
; the following is OPTIONAL
; and MAY occur more than once
;
(";" other-param)
)
Example:
The following is an example of this property. It refers to a
projector.
STRUCTURED-RESOURCE;value=uri;restype="projector":
http://dir.example.com/projectors/3d.vcf
7.6. Structured-Data
Property Name: STRUCTURED-DATA
Purpose: This property specifies ancillary data associated with the
calendar component.
Value Type: TEXT, BINARY or URI
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Property Parameters: IANA, non-standard, inline encoding, and value
data type property parameters can be specified on this property.
The format type and schema parameters can be specified on this
property and are RECOMMENDED for text or inline binary encoded
content information.
Conformance: This property can be specified multiple times in an
iCalendar object. Typically it would be used in "VEVENT",
"VTODO", or "VJOURNAL" calendar components.
Description: This property is used to specify ancillary data in some
structured format either directly (inline) as a "TEXT" or "BINARY"
value, or as a link via a "URI" value.
Rather than define new iCalendar properties for the variety of
event types that might occur, it would be better to leverage
existing schemas for such data. For example, schemas available at
https://schema.org include different event types. By using
standard schemas, interoperability can be improved between
calendar clients and non-calendaring systems that wish to generate
or process the data.
This property allows the direct inclusion of ancillary data whose
schema is defined elsewhere. This property also includes
parameters to clearly identify the type of the schema being used
so that clients can quickly and easily spot what is relevant
within the calendar data and present that to users or process it
within the calendaring system.
iCalendar does support an "ATTACH" property which can be used to
include documents or links to documents within the calendar data.
However, that property does not allow data to be included as a
"TEXT" value (a feature that "STRUCTURED-DATA" does allow), plus
attachments are often treated as "opaque" data to be processed by
some other system rather than the calendar client. Thus the
existing "ATTACH" property is not sufficient to cover the specific
needs of inclusion of schema data. Extending the "ATTACH"
property to support a new value type would likely cause
interoperability problems. Thus a new property to support
inclusion of schema data is warranted.
Format Definition:
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This property is defined by the following notation:
sdataprop = "STRUCTURED-DATA" sdataparam
(":" text) /
(
";" "ENCODING" "=" "BASE64"
";" "VALUE" "=" "BINARY"
":" binary
) /
(
";" "VALUE" "=" "URI"
":" uri
)
CRLF
sdataparam = *(
;
; The following is OPTIONAL for a URI value,
; RECOMMENDED for a TEXT or BINARY value,
; and MUST NOT occur more than once.
;
(";" fmttypeparam) /
(";" schemaparam) /
;
; The following is OPTIONAL,
; and MAY occur more than once.
;
(";" other-param)
;
)
Example: The following is an example of this property:
STRUCTURED-DATA;FMTTYPE=application/ld+json;
SCHEMA="https://schema.org/SportsEvent";
VALUE=TEXT:{\n
"@context": "http://schema.org"\,\n
"@type": "SportsEvent"\,\n
"homeTeam": "Pittsburgh Pirates"\,\n
"awayTeam": "San Francisco Giants"\n
}\n
8. New Components
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8.1. Participant
Component name: PARTICIPANT
Purpose: This component provides information about a participant in
an event or optionally a plain text typed value.
Conformance: This component MAY be appear in any iCalendar
component.
Description: This component provides information about an
participant in an event, task or poll. A participant may be an
attendee in a scheduling sense and the ATTENDEE property may be
specified in addition. Participants in events can be individuals
or organizations, for example a soccer team, the spectators, or
the musicians.
The SOURCE property if present may refer to an external definition
of the participant - such as a vcard.
The STRUCTURED-ADDRESS property if present will provide a cal-
address. If an ATTENDEE property has the same value the
participant is considered schedulable. The PARTICIPANT component
can be used to contain additional meta-data related to the
attendee.
Format Definition:
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This property is defined by the following notation:
participantc = "BEGIN" ":" "PARTICIPANT" CRLF
partprop *alarmc
"END" ":" "PARTICIPANT" CRLF
partprop = *(
;
; The following are REQUIRED,
; but MUST NOT occur more than once.
;
dtstamp / participanttype /
;
; The following are OPTIONAL,
; but MUST NOT occur more than once.
;
created / description / last-mod / priority / seq /
source / status / scheduleaddress / summary / url /
;
; The following are OPTIONAL,
; and MAY occur more than once.
;
attach / categories / comment /
contact / rstatus / related /
resources / x-prop / iana-prop
;
)
Note: When the PRIORITY is supplied it defines the ordering of
PARTICIPANT components with the same value for the TYPE parameter.
Example:
The following is an example of this component. It contains a SOURCE
property which points to a VCARD providing information about the
event participant.
BEGIN:PARTICIPANT
PARTICIPANT-TYPE:PRINCIPAL_PERFORMER
SOURCE:http://dir.example.com/vcard/aviolinist.vcf
END:PARTICIPANT
Example:
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The following is an example for the primary contact.
BEGIN: PARTICIPANT
SOURCE;FMTTYPE=text/vcard;
http://dir.example.com/vcard/contacts/contact1.vcf
PARTICIPANT-TYPE:PRIMARY-CONTACT
DESCRIPTION:A contact:
END:PARTICIPANT
8.2. Schedulable Participant
A PARTICIPANT component may represent someone or something that needs
to be scheduled as defined for ATTENDEE in [RFC5545] and [RFC5546].
The PARTICIPANT component may also represent someone or something
that is NOT to receive scheduling messages.
A PARTICIPANT component is defined to be schedulable if
o It contains a CALENDAR-ADDRESS property
o That property value is the same as the value for an ATTENDEE
property.
If both of these conditions apply then the participant defined by the
value of the URL property will take part in scheduling operations as
defined in [RFC5546].
An appropriate use for the PARTICIPANT component in scheduling would
be to store SEQUENCE and DTSTAMP properties associated with replies
from each ATTENDEE. A LOCATION property within the PARTICIPANT
component might allow better selection of meeting times when
participants are in different timezones.
9. Extended examples
The following are some examples of the use of the properties defined
in this specification. They include additional properties defined in
[RFC7986] which includes IMAGE.
9.1. Example 1
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The following is an example of a VEVENT describing a concert. It
includes location information for the venue itself as well as
references to parking and restaurants.
BEGIN:VEVENT
CREATED:20170216T145739Z
DESCRIPTION: Piano Sonata No 3\n
Piano Sonata No 30
DTSTAMP:20171116T145739Z
DTSTART;TZID=America/New_York:20170315T150000Z
DTEND;TZID=America/New_York:20170315T163000Z
LAST-MODIFIED:20170216T145739Z
SUMMARY:Beethoven Piano Sonatas
UID:123456
STRUCTURED-LOCATION;LABEL="The venue":
http://dir.example.com/venues/big-hall.vcf
STRUCTURED-LOCATION;LABEL="The venue":
http://dir.example.com/venues/parking.vcf
IMAGE;VALUE=URI;DISPLAY=BADGE;FMTTYPE=image/png:h
ttp://example.com/images/concert.png
BEGIN:PARTICIPANT
PARTICIPANT-TYPE:SPONSOR
SOURCE:http://example.com/sponsor.vcf
END:PARTICIPANT
BEGIN:PARTICIPANT
PARTICIPANT-TYPE:PERFORMER:
SOURCE:http://www.example.com/people/johndoe.vcf
END:PARTICIPANT
END:VEVENT
9.2. Example 2
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The following is an example of a VEVENT describing a meeting. One of
the attendees is a remote participant.
BEGIN:VEVENT
CREATED:20170216T145739Z
DTSTAMP:20101116T145739Z
DTSTART;TZID=America/New_York:20170315T150000Z
DTEND;TZID=America/New_York:20170315T163000Z
LAST-MODIFIED:20170216T145739Z
SUMMARY:Conference plaaning
UID:123456
ORGANIZER:mailto:a@example.com
ATTENDEE;PARTSTAT=ACCEPTED;CN=A:mailto:a@example.com
ATTENDEE;RSVP=TRUE;CN=B:mailto:b@example.com
BEGIN:PARTICIPANT
PARTICIPANT-TYPE:ACTIVE:
SOURCE:http://www.example.com/people/b.vcf
LOCATION:At home
END:PARTICIPANT
END:VEVENT
10. Security Considerations
Applications using these properties need to be aware of the risks
entailed in using the URIs provided as values. See [RFC3986] for a
discussion of the security considerations relating to URIs.
Security considerations relating to the "ATTACH" property, as
described in [RFC5545], are applicable to the "STRUCTURED-DATA"
property.
11. Privacy Considerations
Properties with a "URI" value type can expose their users to privacy
leaks as any network access of the URI data can be tracked. Clients
SHOULD NOT automatically download data referenced by the URI without
explicit instruction from users. This specification does not
introduce any additional privacy concerns beyond those described in
[RFC5545].
12. IANA Considerations
This section defines updates to the tables defined in [RFC5545] and
new tables.
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12.1. Additional iCalendar Registrations
12.1.1. Property Registrations
This document defines the following new iCalendar properties to be
added to the registry defined in Section 8.2.3 of [RFC5545]:
+---------------------+---------+----------------------+
| Property | Status | Reference |
+---------------------+---------+----------------------+
| CALENDAR-ADDRESS | Current | RFCXXXX, Section 7.2 |
| PARTICIPANT-TYPE | Current | RFCXXXX, Section 7.1 |
| SOURCE | Current | RFCXXXX, Section 6 |
| STRUCTURED-DATA | Current | RFCXXXX, Section 7.6 |
| STYLED-DESCRIPTION | Current | RFCXXXX, Section 7.3 |
| STRUCTURED-LOCATION | Current | RFCXXXX, Section 7.4 |
| STRUCTURED-RESOURCE | Current | RFCXXXX, Section 7.5 |
+---------------------+---------+----------------------+
12.1.2. Parameter Registrations
This document defines the following new iCalendar property parameters
to be added to the registry defined in Section 8.2.4 of [RFC5545]:
+--------------------+---------+----------------------+
| Property Parameter | Status | Reference |
+--------------------+---------+----------------------+
| LOCTYPE | Current | RFCXXXX, Section 5.1 |
| ORDER | Current | RFCXXXX, Section 5.3 |
| RESTYPE | Current | RFCXXXX, Section 5.2 |
| SCHEMA | Current | RFCXXXX, Section 5.4 |
+--------------------+---------+----------------------+
12.1.3. Component Registrations
This document defines the following new iCalendar components to be
added to the registry defined in Section 8.3.1 of [RFC5545]:
+-------------+---------+----------------------+
| Component | Status | Reference |
+-------------+---------+----------------------+
| PARTICIPANT | Current | RFCXXXX, Section 8.1 |
+-------------+---------+----------------------+
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12.2. New Registration Tables
This section defines new registration tables for PARTICIPANT-TYPE and
RESTYPE values. These tables maybe updated using the same approaches
laid down in Section 8.2.1 of [RFC5545]
12.2.1. Participant Types Registry
The following table has been used to initialize the participant types
registry.
+-------------------+---------+----------------------+
| Participant Type | Status | Reference |
+-------------------+---------+----------------------+
| ACTIVE | Current | RFCXXXX, Section 7.1 |
| INACTIVE | Current | RFCXXXX, Section 7.1 |
| SPONSOR | Current | RFCXXXX, Section 7.1 |
| CONTACT | Current | RFCXXXX, Section 7.1 |
| BOOKING-CONTACT | Current | RFCXXXX, Section 7.1 |
| EMERGENCY-CONTACT | Current | RFCXXXX, Section 7.1 |
| PUBLICITY-CONTACT | Current | RFCXXXX, Section 7.1 |
| PLANNER-CONTACT | Current | RFCXXXX, Section 7.1 |
| PERFORMER | Current | RFCXXXX, Section 7.1 |
| SPEAKER | Current | RFCXXXX, Section 7.1 |
+-------------------+---------+----------------------+
12.2.2. Resource Types Registry
The following table has been used to initialize the resource types
registry.
+-------------------------+---------+----------------------+
| Resource Type | Status | Reference |
+-------------------------+---------+----------------------+
| PROJECTOR | Current | RFCXXXX, Section 5.2 |
| ROOM | Current | RFCXXXX, Section 5.2 |
| REMOTE-CONFERENCE-AUDIO | Current | RFCXXXX, Section 5.2 |
| REMOTE-CONFERENCE-VIDEO | Current | RFCXXXX, Section 5.2 |
+-------------------------+---------+----------------------+
13. Acknowledgements
The author would like to thank Chuck Norris of eventful.com for his
work which led to the development of this RFC.
The author would also like to thank the members of CalConnect, The
Calendaring and Scheduling Consortium, the Event Publication
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technical committee and the following individuals for contributing
their ideas and support:
Cyrus Daboo, John Haug, Dan Mendell, Ken Murchison, Scott Otis,
14. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC4589] Schulzrinne, H. and H. Tschofenig, "Location Types
Registry", RFC 4589, DOI 10.17487/RFC4589, July 2006,
<https://www.rfc-editor.org/info/rfc4589>.
[RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)",
RFC 5545, DOI 10.17487/RFC5545, September 2009,
<https://www.rfc-editor.org/info/rfc5545>.
[RFC5546] Daboo, C., Ed., "iCalendar Transport-Independent
Interoperability Protocol (iTIP)", RFC 5546,
DOI 10.17487/RFC5546, December 2009,
<https://www.rfc-editor.org/info/rfc5546>.
[RFC7986] Daboo, C., "New Properties for iCalendar", RFC 7986,
DOI 10.17487/RFC7986, October 2016,
<https://www.rfc-editor.org/info/rfc7986>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[W3C.REC-xml-20060816]
Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fourth
Edition)", World Wide Web Consortium Recommendation REC-
xml-20060816, August 2006,
<http://www.w3.org/TR/2006/REC-xml-20060816>.
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Appendix A. Open issues
None at the moment
Appendix B. Change log
calext-v04 2017-10-11 MD
o Change SCHEDULE-ADDRESS to CALENDAR-ADDRESS
o Explicitly broaden scope of SOURCE
o Add initial registry for RESTYPE and move new tables into separate
section.
o Fix PARTTYPE/PARTICPANT-TYPE inconsistency
calext-v03 2017-10-09 MD
o Mostly typographical and other minor changes
calext-v02 2017-04-20 MD
o Add SCHEDULE-ADDRESS property
o PARTICIPANT becomes a component rather than a property. Turn many
of the former parameters into properties.
o Use existing ATTENDEE property for scheduling.
calext-v01 2017-02-18 MD
o Change ASSOCIATE back to PARTICIPANT
o PARTICIPANT becomes a component rather than a property. Turn many
of the former parameters into properties.
calext-v00 2016-08-?? MD
o Name changed - taken up by calext working group
v06 2016-06-26 MD
o Fix up abnf
o change ref to ietf from daboo
o take out label spec - use Cyrus spec
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v05 2016-06-14 MD
o Remove GROUP and HASH. they can be dealt with elsewhere if desired
o Change ORDER to integer >= 1.
o Incorporate Structured-Data into this specification.
v04 2014-02-01 MD
o Added updates attribute.
o Minor typos.
o Resubmitted mostly to refresh the draft.
v03 2013-03-06 MD
o Replace PARTICIPANT with ASSOCIATE plus related changes.
o Added section showing modifications to components.
o Replace ID with GROUP and modify HASH.
o Replace TITLE param with LABEL.
o Fixed STYLED-DESCRIPTION in various ways, correct example.
v02 2012-11-02 MD
o Collapse sections with description of properties and the use cases
into a section with sub-sections.
o New section to describe relating properties.
o Remove idref and upgrade hash to have the reference
o No default value types on properties..
v01 2012-10-18 MD Many changes.
o SPONSOR and STRUCTURED-CONTACT are now in PARTICIPANT
o Add a STRUCTURED-RESOURCE property
o STYLED-DESCRIPTION to handle rich text
o Much more...
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2011-01-07
o Remove MEDIA - it's going in the Cyrus RFC
o Rename EXTENDED-... to STRUCTURED-...
o Add TYPE parameter to SPONSOR
v00 2007-10-19 MD Initial version
Author's Address
Michael Douglass
Spherical Cow Group
226 3rd Street
Troy, NY 12180
USA
Email: mdouglass@sphericalcowgroup.com
URI: http://sphericalcowgroup.com
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