Event Publishing Extensions to iCalendar
draft-ietf-calext-eventpub-extensions-19
| Document | Type | Active Internet-Draft (calext WG) | ||
|---|---|---|---|---|
| Author | Michael Douglass | |||
| Last updated | 2021-04-09 (latest revision 2021-03-26) | |||
| Replaces | draft-douglass-calendar-extension | |||
| Stream | Internet Engineering Task Force (IETF) | |||
| Intended RFC status | Proposed Standard | |||
| Formats | plain text xml pdf htmlized bibtex | |||
| Reviews | ||||
| Stream | WG state | Submitted to IESG for Publication (wg milestone: Jun 2019 - Send Event Publicati... ) | ||
| Document shepherd | Daniel Migault | |||
| Shepherd write-up | Show (last changed 2018-10-19) | |||
| IESG | IESG state | RFC Ed Queue | ||
| Action Holders |
(None)
|
|||
| Consensus Boilerplate | Yes | |||
| Telechat date | ||||
| Responsible AD | Barry Leiba | |||
| Send notices to | Daniel Migault <daniel.migault@ericsson.com> | |||
| IANA | IANA review state | Version Changed - Review Needed | ||
| IANA action state | RFC-Ed-Ack | |||
| RFC Editor | RFC Editor state | RFC-EDITOR | ||
| Details | ||||
Network Working Group M. Douglass
Internet-Draft Bedework
Updates: 5545 (if approved) March 26, 2021
Intended status: Standards Track
Expires: September 27, 2021
Event Publishing Extensions to iCalendar
draft-ietf-calext-eventpub-extensions-19
Abstract
This specification updates RFC5545 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 September 27, 2021.
Copyright Notice
Copyright (c) 2021 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 . . . . . . . . . . . . 3
1.2. Terms Used in This Document . . . . . . . . . . . . . . . 3
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 . . . . . . . . . . . . . . . . . . . . . 5
3.1.2.1. Reserving facilities . . . . . . . . . . . . . . 6
4. Modifications to Calendar Components . . . . . . . . . . . . 6
5. New Property Parameters . . . . . . . . . . . . . . . . . . . 7
5.1. Order . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.2. Schema . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.3. Derived . . . . . . . . . . . . . . . . . . . . . . . . . 9
6. New Properties . . . . . . . . . . . . . . . . . . . . . . . 10
6.1. Location Type . . . . . . . . . . . . . . . . . . . . . . 10
6.2. Participant Type . . . . . . . . . . . . . . . . . . . . 11
6.3. Resource Type . . . . . . . . . . . . . . . . . . . . . . 13
6.4. Calendar Address . . . . . . . . . . . . . . . . . . . . 14
6.5. Styled-Description . . . . . . . . . . . . . . . . . . . 14
6.6. Structured-Data . . . . . . . . . . . . . . . . . . . . . 16
7. New Components . . . . . . . . . . . . . . . . . . . . . . . 19
7.1. Participant . . . . . . . . . . . . . . . . . . . . . . . 19
7.1.1. Schedulable Participant . . . . . . . . . . . . . . . 21
7.2. Location . . . . . . . . . . . . . . . . . . . . . . . . 22
7.3. Resource . . . . . . . . . . . . . . . . . . . . . . . . 23
8. Extended examples . . . . . . . . . . . . . . . . . . . . . . 25
8.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . . . 25
8.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . . . 26
9. Security Considerations . . . . . . . . . . . . . . . . . . . 26
9.1. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9.2. Malicious Content . . . . . . . . . . . . . . . . . . . . 27
9.3. HTML Content . . . . . . . . . . . . . . . . . . . . . . 27
10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 27
10.1. Tracking . . . . . . . . . . . . . . . . . . . . . . . . 27
10.2. Revealing Locations . . . . . . . . . . . . . . . . . . 27
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
11.1. Additional iCalendar Registrations . . . . . . . . . . . 28
11.1.1. Properties . . . . . . . . . . . . . . . . . . . . . 28
11.1.2. Parameters . . . . . . . . . . . . . . . . . . . . . 28
11.1.3. Components . . . . . . . . . . . . . . . . . . . . . 29
11.2. New Registration Tables . . . . . . . . . . . . . . . . 29
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11.2.1. Participant Types . . . . . . . . . . . . . . . . . 29
11.2.2. Resource Types . . . . . . . . . . . . . . . . . . . 30
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 30
13. Normative References . . . . . . . . . . . . . . . . . . . . 30
Appendix A. Open issues . . . . . . . . . . . . . . . . . . . . 32
Appendix B. Change log . . . . . . . . . . . . . . . . . . . . . 32
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 35
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
components 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 [RFC2426] are likely to be
most useful to the receivers of such events as they may be used in
other applications - such as address books.
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.
1.2. Terms Used in This Document
Event: When the (perhaps with a capitalised 'E') word 'event' is
used we are referring to gatherings, formal or informal. For
example a sports event, a party or a concert.
Social Calendaring: Historically, calendar data and scheduling has
been heavily biased towards meetings in a corporate environment.
Some of the features defined in this document are to support a
more informal, i.e. social, model. For example, we may want to
record who is participating in a public event.
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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 defines a number
of components rather than properties. This is a better match for the
way [W3C.REC-xml-20081126] and JSON [RFC8259] handle such structures
and allows richer definitions.
It also allows for the addition of extra properties inside the
components and resolves some of the problems of trying to add
detailed information as a parameter.
3. Typed References
The properties and components defined here can all reference external
meta-data which may be used by applications to provide further
information to users. By providing type information, 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.
As always, clients should exercise caution in following references to
external data.
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 the VLOCATION component, rich information about multiple
locations can be communicated in a STRUCTURED-DATA property, for
example, address, region, country, postal code as well as other
information such as parking availability, nearby 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 locations looking for those of particular interest. The
LOCATION-TYPE property and STRUCTURED-DATA FMTTYPE parameter, if
supplied, can be used to help the selection.
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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 be used to provide useful extra data
about an attendee. For example a location inside the PARTICIPANT
gives the actual location of a remote attendee. (But see the note
about privacy.)
Alternatively the PARTICIPANT component can be used to provide a
reference - perhaps the address for mailing lists.
3.1. Use Cases
The main motivation for these changes 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.
An event can also be created for publication which will have a
PARTICIPANT component for the pianist providing a reference to vCard
[RFC2426] information about the performer. This event would also
hold information about parking, local subway stations and the venue
itself. In addition, there may 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.
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The embedded location information can guide the traveler 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 many attendees none of which are co-located. The
current ATTENDEE property does not allow for the addition of such
meta-data. The PARTICIPANT component 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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; Addition of PARTICIPANT, VLOCATION and VRESOURCE
; as valid components
eventc = "BEGIN" ":" "VEVENT" CRLF
eventprop *alarmc *participantc *locationc *resourcec
"END" ":" "VEVENT" CRLF
; Addition of properties STYLED-DESCRIPTION and STRUCTURED-DATA
eventprop =/ *styleddescription
*sdataprop
; Addition of PARTICIPANT, VLOCATION and VRESOURCE
; as valid components
todoc = "BEGIN" ":" "VTODO" CRLF
todoprop *alarmc *participantc *locationc *resourcec
"END" ":" "VTODO" CRLF
; Addition of properties STYLED-DESCRIPTION, STRUCTURED-DATA
todoprop =/ *styleddescription
*sdataprop
; Addition of PARTICIPANT, VLOCATION and VRESOURCE
; as valid components
journalc = "BEGIN" ":" "VJOURNAL" CRLF
jourprop *participantc *locationc *resourcec
"END" ":" "VJOURNAL" CRLF
; Addition of properties STYLED-DESCRIPTION, STRUCTURED-DATA
jourprop =/ *styleddescription
*sdataprop
; Addition of PARTICIPANT, VLOCATION and VRESOURCE
; as valid components
freebusyc = "BEGIN" ":" "VFREEBUSY" CRLF
fbprop *participantc *locationc *resourcec
"END" ":" "VFREEBUSY" CRLF
; Addition of property STYLED-DESCRIPTION
fbprop =/ *styleddescription
5. New Property Parameters
5.1. Order
Parameter name: ORDER
Purpose: To define ordering for the associated property.
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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
specifies 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 ordered last, that is, the property
will appear after any other instances of the same property with
any value of ORDER.
When any ORDER parameters have the same value all the associated
properties appear as a group within which there is no defined
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.
This parameter MUST NOT be applied to a property that does not
allow multiple instances.
Example uses: The ORDER may be applied to the PARTICIPANT-TYPE
property to indicate the relative importance of the participant,
for example as a sponsor or a performer. For example, ORDER=1
could define the principal performer or soloist.
5.2. Schema
Parameter Name: SCHEMA
Purpose: To specify the schema used for the content of a
"STRUCTURED-DATA" property value.
Format Definition:
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
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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:ICAgIDxzY3JpcHQgdHlwZT0iYXBwb
GljYXRpb24vbGQranNvbiI+CiAgICB7CiAgICAgICJAY29
udGV4dCI6ICJodHRwOi8vc2NoZW1hLm9yZyIsCiAgICAgICJAdHlwZSI
6ICJGbGlnaHRSZXNlcnZhdGlvbiIsCiAgICAgICJyZXNlcnZhdGlvbkl
kIjogIlJYSjM0UCIsCiAgICAgICJyZXNlcnZhdGlvblN0YXR1cyI6ICJ
odHRwOi8vc2NoZW1hLm9yZy9SZXNlcnZhdGlvbkNvbmZpcm1lZCIsCiA
gICAgICJwYXNzZW5nZXJQcmlvcml0eVN0YXR1cyI6ICJGYXN0IFRyYWN
rIiwKICAgICAgInBhc3NlbmdlclNlcXVlbmNlTnVtYmVyIjogIkFCQzE
yMyIsCiAgICAgICJzZWN1cml0eVNjcmVlbmluZyI6ICJUU0EgUHJlQ2h
lY2siLAogICAgICAidW5kZXJOYW1lIjogewogICAgICAgICJAdHlwZSI
6ICJQZXJzb24iLAogICAgICAgICJuYW1lIjogIkV2YSBHcmVlbiIKICA
gICAgfSwKICAgICAgInJlc2VydmF0aW9uRm9yIjogewogICAgICAgICJ
AdHlwZSI6ICJGbGlnaHQiLAogICAgICAgICJmbGlnaHROdW1iZXIiOiA
iVUExMTAiLAogICAgICAgICJwcm92aWRlciI6IHsKICAgICAgICAgICJ
AdHlwZSI6ICJBaXJsaW5lIiwKICAgICAgICAgICJuYW1lIjogIkNvbnR
pbmVudGFsIiwKICAgICAgICAgICJpYXRhQ29kZSI6ICJDTyIsCiAgICA
gICAgICAiYm9hcmRpbmdQb2xpY3kiOiAiaHR0cDovL3NjaGVtYS5vcmc
vWm9uZUJvYXJkaW5nUG9saWN5IgogICAgICAgIH0sCiAgICAgICAgInN
lbGxlciI6IHsKICAgICAgICAgICJAdHlwZSI6ICJBaXJsaW5lIiwKICA
gICAgICAgICJuYW1lIjogIlVuaXRlZCIsCiAgICAgICAgICAiaWF0YUN
vZGUiOiAiVUEiCiAgICAgICAgfSwKICAgICAgICAiZGVwYXJ0dXJlQWl
ycG9ydCI6IHsKICAgICAgICAgICJAdHlwZSI6ICJBaXJwb3J0IiwKICA
gICAgICAgICJuYW1lIjogIlNhbiBGcmFuY2lzY28gQWlycG9ydCIsCiA
gICAgICAgICAiaWF0YUNvZGUiOiAiU0ZPIgogICAgICAgIH0sCiAgICA
gICAgImRlcGFydHVyZVRpbWUiOiAiMjAxNy0wMy0wNFQyMDoxNTowMC0
wODowMCIsCiAgICAgICAgImFycml2YWxBaXJwb3J0IjogewogICAgICA
gICAgIkB0eXBlIjogIkFpcnBvcnQiLAogICAgICAgICAgIm5hbWUiOiA
iSm9obiBGLiBLZW5uZWR5IEludGVybmF0aW9uYWwgQWlycG9ydCIsCiA
gICAgICAgICAiaWF0YUNvZGUiOiAiSkZLIgogICAgICAgIH0sCiAgICA
gICAgImFycml2YWxUaW1lIjogIjIwMTctMDMtMDVUMDY6MzA6MDAtMDU
6MDAiCiAgICAgIH0KICAgIH0KICAgIDwvc2NyaXB0Pg==
5.3. Derived
Parameter Name: DERIVED
Purpose: To specify that the value of the associated property is
derived from some other property value or values.
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Format Definition:
This parameter is defined by the following notation:
derivedparam = "DERIVED" "=" ("TRUE" / "FALSE")
; Default is FALSE
Description: This property parameter MAY be specified on any
property when the value is derived from some other property or
properties. When present with a value of TRUE clients MUST NOT
update the property.
As an example, if a STYLED-DESCRIPTION property is present with
FMTTYPE="application/rtf" then there may be an additional STYLED-
DESCRIPTION property with FMTTYPE="text/html" and DERIVED=TRUE and
a value created from the rtf value.
Example:
STYLED-DESCRIPTION;FMTTYPE=text/html;
DERIVED=TRUE:<html>...</html>
6. New Properties
This specification makes use of the NAME property which is defined in
[RFC7986]
6.1. Location Type
Property name: LOCATION-TYPE
Purpose: To specify the type(s) of a location.
Value type: The value type for this property is TEXT. The allowable
values are defined below.
Description: This property MAY be specified in VLOCATION components
and provides a way to differentiate multiple locations. For
example, it allows event producers to provide location information
for the venue and the parking.
Format Definition:
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This property is defined by the following notation:
loctype = "LOCATION-TYPE" loctypeparam ":"
text *("," text)
CRLF
loctypeparam = *(";" other-param)
Multiple values may be used if the location has multiple purposes,
for example a hotel and a restaurant.
Values for this parameter are taken from the values defined in
[RFC4589] section 3. New location types SHOULD be registered in
the manner laid down in section 5 of that specification.
6.2. 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 once 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:
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This property is defined by the following notation:
participanttype = "PARTICIPANT-TYPE" partvalueparam ":"
partvalue CRLF
partvalue = ("ACTIVE"
/ "INACTIVE"
/ "SPONSOR"
/ "CONTACT"
/ "BOOKING-CONTACT"
/ "EMERGENCY-CONTACT"
/ "PUBLICITY-CONTACT"
/ "PLANNER-CONTACT"
/ "PERFORMER"
/ "SPEAKER"
/ iana-token) ; Other IANA-registered
; values
partvalueparam = *(";" other-param)
Example:
The following is an example of this property:
PARTICIPANT-TYPE:SPEAKER
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 role - 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
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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
6.3. Resource Type
Property name: RESOURCE-TYPE
Purpose: To specify the type of resource.
Value type: The value type for this property is TEXT. The allowable
values are defined below.
Format Definition:
This property is defined by the following notation:
restypeprop = "RESOURCE-TYPE" restypeparam ":"
restypevalue CRLF
restypevalue = ("ROOM"
/ "PROJECTOR"
/ "REMOTE-CONFERENCE-AUDIO"
/ "REMOTE-CONFERENCE-VIDEO"
/ iana-token) ; Other IANA-registered
; values
restypeparam = *(";" other-param)
Description: This property MAY be specified in VRESOURCE components
and provides a way to differentiate multiple resources.
The registered values are described below. New resource types
SHOULD be registered in the manner laid down in this
specification.
ROOM: A room for the event/meeting.
PROJECTOR: Projection equipment.
REMOTE-CONFERENCE-AUDIO: Audio remote conferencing facilities.
REMOTE-CONFERENCE-VIDEO: Video remote conferencing facilities.
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6.4. Calendar Address
Property name: CALENDAR-ADDRESS
Purpose: To specify the calendar address for a participant.
Value type: CAL-ADDRESS
Property Parameters: IANA-registered, or non-standard property
parameters can be specified on this property.
Conformance: This property MAY be specified once within a
PARTICIPANT component.
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 property is defined by the following notation:
calendaraddress = "CALENDAR-ADDRESS" caladdressparam ":"
cal-address CRLF
caladdressparam = *(";" other-param)
6.5. Styled-Description
Property name: STYLED-DESCRIPTION
Purpose: This property provides for one or more rich-text
descriptions to replace 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-registered, non-standard, id, alternate
text representation, format type, derived and language property
parameters can be specified on this property.
Conformance: The property can be specified multiple times in the
"VEVENT", "VTODO", "VJOURNAL", "VFREEBUSY", "PARTICIPANT", or
"VALARM" calendar components.
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If it does appear more than once there MUST be exactly one
instance of the property with no DERIVED parameter or
DERIVED=FALSE. All others MUST have DERIVED=TRUE.
Additionally, if there is one or more STYLED-DESCRIPTION property
then the DESCRIPTION property should be either absent or have the
parameter DERIVED=TRUE.
Description: This property supports rich-text descriptions, for
example HTML. Event publishers typically wish to provide more and
better formatted information about the event.
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. In the PARTICIPANT component it provides
a detailed description of the participant.
VALUE=TEXT is used to provide rich-text inline as the property
value.
VALUE=URI is used to provide a link to rich-text content which is
expected to be displayed inline as part of the event.
In either case the DESCRIPTION property should be absent or
contain a plain text rendering of the styled text.
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" and process the content as defined in
[W3C.REC-html51-20171003]
Multiple STYLED-DESCRIPTION properties may be used to provide
different formats or different language variants. However all but
one MUST have DERIVED=TRUE.
Format Definition:
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This property is defined by the following notation:
styleddescription = "STYLED-DESCRIPTION" styleddescparam ":"
styleddescval CRLF
styleddescparam = *(
; The following is REQUIRED,
; but MUST NOT occur more than once.
;
(";" "VALUE" "=" ("URI" / "TEXT")) /
;
; The following are OPTIONAL,
; but MUST NOT occur more than once.
;
(";" altrepparam) / (";" languageparam) /
(";" fmttypeparam) / (";" derivedparam) /
;
; the following is OPTIONAL
; and MAY occur more than once
;
(";" other-param)
)
styleddescval = ( uri / text )
;Value MUST match value type
Example:
The following is an example of this property. It points to an html
description.
STYLED-DESCRIPTION;VALUE=URI:http://example.org/desc001.html
6.6. Structured-Data
Property Name: STRUCTURED-DATA
Purpose: This property specifies ancillary data associated with the
calendar component.
Value Type: There is no default value type for this property. The
value type can be set to TEXT, BINARY or URI
Property Parameters: IANA-registered, 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 MUST be present for text or inline binary
encoded content information.
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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: 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 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.
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. Additionally some implementations
manage attachments by stripping them out and replacing with a link
to the resource. Thus a new property to support inclusion of
schema data is warranted.
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Format Definition:
This property is defined by the following notation:
sdataprop = "STRUCTURED-DATA" sdataparam
(
";" "VALUE" "=" "TEXT"
":" text
) /
(
";" "ENCODING" "=" "BASE64"
";" "VALUE" "=" "BINARY"
":" binary
) /
(
";" "VALUE" "=" "URI"
":" uri
)
CRLF
sdataparam = *(
;
; The following is OPTIONAL for a URI value,
; REQUIRED 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
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7. New Components
7.1. Participant
Component name: PARTICIPANT
Purpose: This component provides information about a participant in
an event or task.
Conformance: This component can be specified multiple times in a
"VEVENT", "VTODO", "VJOURNAL" or "VFREEBUSY" calendar component.
Description: This component provides information about a participant
in a calendar component. A participant may be an attendee in a
scheduling sense and the ATTENDEE property may be specified in
addition. Participants can be individuals or organizations, for
example a soccer team, the spectators or the musicians.
STRUCTURED-DATA properties if present may refer to definitions of
the participant - such as a vCard.
The CALENDAR-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 component is defined by the following notation:
participantc = "BEGIN" ":" "PARTICIPANT" CRLF
partprop *locationc *resourcec
"END" ":" "PARTICIPANT" CRLF
partprop = *(
;
; The following are REQUIRED,
; but MUST NOT occur more than once.
;
participanttype / uid /
;
; The following are OPTIONAL,
; but MUST NOT occur more than once.
;
calendaraddress / created / description / dtstamp /
geo / last-mod / priority / seq /
status / summary / url /
;
; The following are OPTIONAL,
; and MAY occur more than once.
;
attach / categories / comment /
contact / location / rstatus / related /
resources / strucloc / strucres / styleddescription /
sdataprop / iana-prop
;
)
Note: When the PRIORITY is supplied it defines the ordering of
PARTICIPANT components with the same value for the PARTICIPANT-
TYPE property.
Privacy Issues: When a LOCATION is supplied it provides information
about the location of a participant at a given time or times.
This may represent an unacceptable privacy risk for some
participants. User agents MUST NOT broadcast this information
without the express permission of the participants whose location
would be exposed. For further comments see Section 10
Example:
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The following is an example of this component. It contains a
STRUCTURED-DATA property which points to a vCard providing
information about the event participant.
BEGIN:PARTICIPANT
UID: em9lQGZvb2GFtcGxlLmNvbQ
PARTICIPANT-TYPE:PERFORMER
STRUCTURED-DATA;VALUE=URI:
http://dir.example.com/vcard/aviolinist.vcf
END:PARTICIPANT
Example:
The following is an example for the primary contact.
BEGIN:PARTICIPANT
UID: em9lQGZvb2GFtcGxlLmNvbQ
STRUCTURED-DATA;VALUE=URI;
http://dir.example.com/vcard/contacts/contact1.vcf
PARTICIPANT-TYPE:CONTACT
DESCRIPTION:A contact
END:PARTICIPANT
Example:
The following is an example for a participant with contact and
location.
BEGIN:PARTICIPANT
UID: em9lQGZvb2GFtcGxlLmNdrt
STRUCTURED-DATA;VALUE=URI;
http://dir.example.com/vcard/contacts/my-card.vcf
PARTICIPANT-TYPE:SPEAKER
DESCRIPTION:A participant
BEGIN:VLOCATION
UID:123456-abcdef-98765432
NAME:My home location
STRUCTURED-DATA;VALUE=URI:
http://dir.example.com/addresses/my-home.vcf
END:VLOCATION
END:PARTICIPANT
7.1.1. 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.
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For backwards compatibility with existing clients and servers when
used to schedule events and tasks the ATTENDEE property MUST be used
to specify the sheduling parameters as defined for that property.
For other, future uses the CALENDAR-ADDRESS property MUST be used to
specify those parameters.
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.
7.2. Location
Component name: VLOCATION
Purpose: This component provides rich information about the location
of an event using the structured data property or optionally a
plain text typed value.
Conformance: This component can be specified multiple times in a
"VEVENT", "VTODO", "VJOURNAL", "VFREEBUSY" or "PARTICIPANT"
calendar component.
Description: There may be a number of locations associated with an
event. This component provides detailed information about a
location.
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..
STRUCTURED-DATA properties if present may refer to representations
of the location - such as a vCard.
Format Definition:
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This component is defined by the following notation:
locationc = "BEGIN" ":" "VLOCATION" CRLF
locprop
"END" ":" "VLOCATION" CRLF
locprop = *(
;
; The following are REQUIRED,
; but MUST NOT occur more than once.
;
uid /
;
; The following are OPTIONAL,
; but MUST NOT occur more than once.
;
description / geo / loctype / name /
;
; The following are OPTIONAL,
; and MAY occur more than once.
;
sdataprop / iana-prop
The NAME property is defined in [RFC7986]
Example:
The following is an example of this component. It points to a venue.
BEGIN:VLOCATION
UID:123456-abcdef-98765432
NAME:The venue
STRUCTURED-DATA;VALUE=URI:
http://dir.example.com/venues/big-hall.vcf
END:VLOCATION
7.3. Resource
Component name: VRESOURCE
Purpose: This component 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.
Conformance: This component can be specified multiple times in a
"VEVENT", "VTODO", "VJOURNAL", "VFREEBUSY" or "PARTICIPANT"
calendar component.
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Description: When used in a component this component provides
information about resources used for the event such as rooms,
projectors, conferencing capabilities.
The RESOURCE-TYPE value registry provides a place in which
resource types may be registered.
STRUCTURED-DATA properties if present may refer to representations
of the resource - such as a vCard.
Format Definition:
This component is defined by the following notation:
resourcec = "BEGIN" ":" "VRESOURCE" CRLF
resprop
"END" ":" "VRESOURCE" CRLF
resprop = *(
;
; The following are REQUIRED,
; but MUST NOT occur more than once.
;
uid /
;
; The following are OPTIONAL,
; but MUST NOT occur more than once.
;
description / geo / name / restype /
;
; The following are OPTIONAL,
; and MAY occur more than once.
;
sdataprop / iana-prop
The NAME property is defined in [RFC7986]
Example:
The following is an example of this component. It refers to a
projector.
BEGIN:VRESOURCE
UID:456789-abcdef-98765432
NAME:The projector
RESOURCE-TYPE:projector
STRUCTURED-DATA;VALUE=URI:http://dir.example.com/projectors/3d.vcf
END:VRESOURCE
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8. 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.
8.1. Example 1
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:20200215T145739Z
DESCRIPTION: Piano Sonata No 3\n
Piano Sonata No 30
DTSTAMP:20200215T145739Z
DTSTART;TZID=America/New_York:20200315T150000Z
DTEND;TZID=America/New_York:20200315T163000Z
LAST-MODIFIED:20200216T145739Z
SUMMARY:Beethoven Piano Sonatas
UID:123456
IMAGE;VALUE=URI;DISPLAY=BADGE;FMTTYPE=image/png:h
ttp://example.com/images/concert.png
BEGIN:PARTICIPANT
PARTICIPANT-TYPE:SPONSOR
UID:dG9tQGZvb2Jhci5xlLmNvbQ
STRUCTURED-DATA;VALUE=URI:http://example.com/sponsor.vcf
END:PARTICIPANT
BEGIN:PARTICIPANT
PARTICIPANT-TYPE:PERFORMER:
UID:em9lQGZvb2GFtcGxlLmNvbQ
STRUCTURED-DATA;VALUE=URI:http://www.example.com/people/johndoe.vcf
END:PARTICIPANT
BEGIN:VLOCATION
UID:123456-abcdef-98765432
NAME:The venue
STRUCTURED-DATA;VALUE=URI:http://dir.example.com/venues/big-hall.vcf
END:VLOCATION
BEGIN:VLOCATION
UID:123456-abcdef-87654321
NAME:Parking for the venue
STRUCTURED-DATA;VALUE=URI:http://dir.example.com/venues/parking.vcf
END:VLOCATION
END:VEVENT
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8.2. Example 2
The following is an example of a VEVENT describing a meeting. One of
the attendees is a remote participant.
BEGIN:VEVENT
CREATED:20200215T145739Z
DTSTAMP:20200215T145739Z
DTSTART;TZID=America/New_York:20200315T150000Z
DTEND;TZID=America/New_York:20200315T163000Z
LAST-MODIFIED:20200216T145739Z
SUMMARY:Conference planning
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:
UID:v39lQGZvb2GFtcGxlLmNvbQ
STRUCTURED-DATA;VALUE=URI:http://www.example.com/people/b.vcf
LOCATION:At home
END:PARTICIPANT
END:VEVENT
9. Security Considerations
This specification extends [RFC5545] and makes further use of
possibly linked data. While calendar data is not unique in this
regard it is worth reminding implementors of some of the dangers and
safeguards.
9.1. URIs
See [RFC3986] for a discussion of the security considerations
relating to URIs. Because of the issues discussed there and below,
clients SHOULD NOT follow URIs and fetch content automatically, and
should only do so at the explicit request of the user.
Fetching remote resources carries inherent risks. Connections must
only be allowed on well known ports, using allowed protocols
(generally just HTTP/HTTPS on their default ports). The URL must be
resolved externally and not allowed to access internal resources.
Connecting to an external source reveals IP (and therefore generally
location) information.
A maliciously constructed iCalendar object may contain a very large
number of URIs. In the case of published calendars with a large
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number of subscribers, such objects could be widely distributed.
Implementations should be careful to limit the automatic fetching of
linked resources to reduce the risk of this being an amplification
vector for a denial-of-service attack.
9.2. Malicious Content
For the "STRUCTURED-DATA" property, agents need to be aware that a
client could attack underlying storage by sending extremely large
values and could attack processing time by uploading a recurring
event with a large number of overrides and then repeatedly adding,
updating and deleting structured data.
Agents should set reasonable limits on storage size and number of
instances and apply those constraints. Calendar protocols should
ensure there is a way to report on such limits being exceeded.
Malicious content could be introduced into the calendar server by way
of the "STRUCTURED-DATA" property and propagated to many end users
via scheduling. Servers SHOULD check this property for malicious or
inappropriate content. Upon detecting such content, servers SHOULD
remove the property,
9.3. HTML Content
When processing HTML content, applications need to be aware of the
many security and privacy issues, as described in the IANA
considerations section of [W3C.REC-html51-20171003]
10. Privacy Considerations
10.1. Tracking
Properties with a "URI" value type can expose their users to privacy
leaks as any network access of the URI data can be tracked both by a
network observer and by the entity hosting the remote resource.
Clients SHOULD NOT automatically download data referenced by the URI
without explicit instruction from users.
To help alleviate some of the concerns protocols and services could
provide proxy services for downloading referenced data.
10.2. Revealing Locations
The addition of location information to the new participant component
provides information about the location of participants at a given
time. This information MUST NOT be distributed to other participants
without those participant's express permission. Note that there may
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be a number of participants who may be unaware of their inclusion in
the data.
Agents processing and distributing calendar data must be aware that
it has the property of providing information about a future time when
a given individual may be at a particular location, which could
enable targeted attacks against that individual.
The same may be true of other information contained in the
participant component. In general, revealing only as much as is
absolutely necessary should be the approach taken.
For example, there may be some privacy considerations relating to the
ORDER parameter, as it provides an indication of the organizer's
perception of the relative importance of other participants.
11. IANA Considerations
11.1. Additional iCalendar Registrations
11.1.1. Properties
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 6.4 |
| LOCATION-TYPE | Current | RFCXXXX, Section 6.1 |
| PARTICIPANT-TYPE | Current | RFCXXXX, Section 6.2 |
| RESOURCE-TYPE | Current | RFCXXXX, Section 6.3 |
| STRUCTURED-DATA | Current | RFCXXXX, Section 6.6 |
| STYLED-DESCRIPTION | Current | RFCXXXX, Section 6.5 |
+--------------------+---------+----------------------+
11.1.2. Parameters
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 |
+--------------------+---------+----------------------+
| ORDER | Current | RFCXXXX, Section 5.1 |
| SCHEMA | Current | RFCXXXX, Section 5.2 |
| DERIVED | Current | RFCXXXX, Section 5.3 |
+--------------------+---------+----------------------+
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11.1.3. Components
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 7.1 |
| VLOCATION | Current | RFCXXXX, Section 7.2 |
| VRESOURCE | Current | RFCXXXX, Section 7.3 |
+-------------+---------+----------------------+
11.2. New Registration Tables
This section defines new registration tables for PARTICIPANT-TYPE and
RESOURCE-TYPE values. These tables are updated using the same
approaches laid down in Section 8.2.1 of [RFC5545]
This document creates new IANA registries for participant and
resource types. IANA will maintain these registries and, following
the policies outlined in [RFC8126], new tokens are assigned after
Expert Review. The Expert Reviewer will generally consult the IETF
GeoPRIV working group mailing list or its designated successor.
Updates or deletions of tokens from the registration follow the same
procedures. The expert review should be guided by a few common sense
considerations. For example, tokens should not be specific to a
country, region, organization, or company; they should be well-
defined and widely recognized. The expert's support of IANA will
include providing IANA with the new token(s) when the update is
provided only in the form of a schema, and providing IANA with the
new schema element(s) when the update is provided only in the form of
a token. To ensure widespread usability across protocols, tokens
MUST follow the character set restrictions for XML Names [3]. Each
registration must include the name of the token and a brief
description similar to the ones offered herein for the initial
registrations contained this document:
11.2.1. Participant Types
The following table has been used to initialize the participant types
registry.
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+-------------------+---------+----------------------+
| Participant Type | Status | Reference |
+-------------------+---------+----------------------+
| ACTIVE | Current | RFCXXXX, Section 6.2 |
| INACTIVE | Current | RFCXXXX, Section 6.2 |
| SPONSOR | Current | RFCXXXX, Section 6.2 |
| CONTACT | Current | RFCXXXX, Section 6.2 |
| BOOKING-CONTACT | Current | RFCXXXX, Section 6.2 |
| EMERGENCY-CONTACT | Current | RFCXXXX, Section 6.2 |
| PUBLICITY-CONTACT | Current | RFCXXXX, Section 6.2 |
| PLANNER-CONTACT | Current | RFCXXXX, Section 6.2 |
| PERFORMER | Current | RFCXXXX, Section 6.2 |
| SPEAKER | Current | RFCXXXX, Section 6.2 |
+-------------------+---------+----------------------+
11.2.2. Resource Types
The following table has been used to initialize the resource types
registry.
+-------------------------+---------+----------------------+
| Resource Type | Status | Reference |
+-------------------------+---------+----------------------+
| PROJECTOR | Current | RFCXXXX, Section 6.3 |
| ROOM | Current | RFCXXXX, Section 6.3 |
| REMOTE-CONFERENCE-AUDIO | Current | RFCXXXX, Section 6.3 |
| REMOTE-CONFERENCE-VIDEO | Current | RFCXXXX, Section 6.3 |
+-------------------------+---------+----------------------+
12. 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
technical committee and the following individuals for contributing
their ideas and support:
Cyrus Daboo, John Haug, Dan Mendell, Ken Murchison, Scott Otis.
13. 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>.
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[RFC2426] Dawson, F. and T. Howes, "vCard MIME Directory Profile",
RFC 2426, DOI 10.17487/RFC2426, September 1998,
<https://www.rfc-editor.org/info/rfc2426>.
[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>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[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>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
[W3C.REC-html51-20171003]
Faulkner, S., Eicholz, A., Leithead, T., and A. Danilo,
"HTML 5.1 2nd Edition", World Wide Web Consortium
Recommendation REC-html51-20171003, October 2017,
<https://www.w3.org/TR/2017/REC-html51-20171003>.
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[W3C.REC-xml-20081126]
Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
Edition)", World Wide Web Consortium Recommendation REC-
xml-20081126, November 2008,
<https://www.w3.org/TR/2008/REC-xml-20081126>.
Appendix A. Open issues
None at the moment
Appendix B. Change log
To be deleted on publication
calext-v19 2021-03-25 MD
o Revert ABNF to RFC5545 format.
o Add missing DERIVED parameter registration.
o Fix small error in an example (missing space at start).
calext-v18 2021-??-?? MD
o Fix incorrect participant type property name in PARTICIPANT.
o Allow parameters on LOCATION-TYPE.
calext-v17 2021-01-03 MD
o Remove STRUCTURED-LOCATION property, add VLOCATION component.
o Remove STRUCTURED-RESOURCE property, add VRESOURCE component.
o Make LOCATION-TYPE multi-valued property for location.
o Make RESOURCE-TYPE multi-valued property for resource.
o Tidy up abnf.
calext-v16 2019-10-09 MD
o Make LOCTYPE multi-valued.
o Add all ATTENDEE scheduling parameters to CALENDAR-ADDRESS.
calext-v15 2019-10-08 MD
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o Address various DICUSS points.
calext-v14 2019-06-11 MD
o Definition of event and social calendaring.
o Remove redefinition of SOURCE - use STRUCTURED-DATA.
calext-v13 2019-05-26 MD
o Respond to various issues.
calext-v12 2019-02-28 MD
o Fix styled-description example. Respond to various AD issues.
Some typos.
calext-v11 2019-02-27 MD
o Add DERIVED parameter for styled-description, RELATED parameter
for structured-location
calext-v09 2018-08-30 MD
o Sorted out inconsistencies in refs to 5546
calext-v08 2018-07-06 MD
o Add some text for equal ORDER values
o Switched scheduleaddress to calendaraddress in participant abnf.
Also added more properties
o Fixed PARTICIPANT abnf
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/PARTICIPANT-TYPE inconsistency
calext-v03 2017-10-09 MD
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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
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
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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...
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
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Michael Douglass
Bedework
226 3rd Street
Troy, NY 12180
USA
Email: mdouglass@bedework.com
URI: http://bedework.com
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