Network Working Group                                           C. Daboo
Internet-Draft                                                Apple Inc.
Intended status: Standards Track                           April 7, 2011
Expires: October 9, 2011


                      New Properties for iCalendar
                  draft-daboo-icalendar-extensions-04

Abstract

   This document defines a set of new properties for iCalendar 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 http://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 October 9, 2011.

Copyright Notice

   Copyright (c) 2011 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
   (http://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
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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.







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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
   3.  Modifications to Calendar Components . . . . . . . . . . . . .  3
   4.  Properties . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     4.1.  NAME Property  . . . . . . . . . . . . . . . . . . . . . .  5
     4.2.  DESCRIPTION Property . . . . . . . . . . . . . . . . . . .  6
     4.3.  UID Property . . . . . . . . . . . . . . . . . . . . . . .  6
     4.4.  URL Property . . . . . . . . . . . . . . . . . . . . . . .  6
     4.5.  TIMEZONE-ID Property . . . . . . . . . . . . . . . . . . .  7
     4.6.  REFRESH-INTERVAL Property  . . . . . . . . . . . . . . . .  7
     4.7.  COLOR Property . . . . . . . . . . . . . . . . . . . . . .  8
     4.8.  IMAGE Property . . . . . . . . . . . . . . . . . . . . . .  9
     4.9.  BROADCAST Property . . . . . . . . . . . . . . . . . . . . 10
     4.10. CONFERENCE Property  . . . . . . . . . . . . . . . . . . . 12
   5.  Property Parameters  . . . . . . . . . . . . . . . . . . . . . 14
     5.1.  ALTURI Property Parameter  . . . . . . . . . . . . . . . . 14
     5.2.  DISPLAY Property Parameter . . . . . . . . . . . . . . . . 14
     5.3.  FEATURE Property Parameter . . . . . . . . . . . . . . . . 15
     5.4.  INFO Property Parameter  . . . . . . . . . . . . . . . . . 16
     5.5.  REGION Property Parameter  . . . . . . . . . . . . . . . . 16
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 17
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 17
     7.1.  Property Registrations . . . . . . . . . . . . . . . . . . 17
     7.2.  Parameter Registrations  . . . . . . . . . . . . . . . . . 18
     7.3.  Display Types Registry . . . . . . . . . . . . . . . . . . 18
     7.4.  Feature Types Registry . . . . . . . . . . . . . . . . . . 18
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 19
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 19
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 19
   Appendix A.  Change History (To be removed by RFC Editor
                before publication) . . . . . . . . . . . . . . . . . 19
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 20
















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1.  Introduction

   The iCalendar [RFC5545] data format is used to represent calendar
   data and is used with iTIP [RFC5546] to handle scheduling operations
   between calendar users. iCalendar is in widespread use, and in
   accordance with provisions in that specification, extension elements
   have been added by various vendors to the data format in order to
   support and enhance capabilities.  This specification collects a
   number of these ad-hoc extensions and uses the new IANA registry
   capability defined in [RFC5545] to register standard variants with
   clearly defined definitions and semantics.  In addition, some new
   elements are introduced for features that vendors have recently been
   requesting.


2.  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
   [RFC2119].

   The notation used in this memo is the ABNF notation of [RFC5234] as
   used by iCalendar [RFC5545].  Any syntax elements shown below that
   are not explicitly defined in this specification come from iCalendar
   [RFC5545].


3.  Modifications to Calendar Components

   The following changes to the syntax defined in iCalendar [RFC5545]
   are made here.  New elements are defined in subsequent sections.


   calprops /= *(
                ;
                ; The following are OPTIONAL,
                ; but MUST NOT occur more than once.
                ;
                uid / url / timezid /
                refresh / color /
                ;
                ; The following are OPTIONAL,
                ; and MAY occur more than once.
                ;
                name / description / image
                ;
                )



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   eventprop /= *(
                 ;
                 ; The following are OPTIONAL,
                 ; but MUST NOT occur more than once.
                 ;
                 color /
                 ;
                 ; The following are OPTIONAL,
                 ; and MAY occur more than once.
                 ;
                 image / broadcast / conference
                 ;
                 )

   todoprop /= *(
                ;
                ; The following are OPTIONAL,
                ; but MUST NOT occur more than once.
                ;
                color /
                ;
                ; The following are OPTIONAL,
                ; and MAY occur more than once.
                ;
                image / broadcast / conference
                ;
                )

   jourprop /= *(
                ;
                ; The following are OPTIONAL,
                ; but MUST NOT occur more than once.
                ;
                color /
                ;
                ; The following are OPTIONAL,
                ; and MAY occur more than once.
                ;
                image
                ;
                )


4.  Properties







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4.1.  NAME Property

   Property Name:  NAME

   Purpose:  This property specifies the name of the calendar.

   Value Type:  TEXT

   Property Parameters:  IANA, non-standard, alternate text
      representation, and language property parameters can be specified
      on this property.

   Conformance:  This property can be specified multiple times in an
      iCalendar object.  However, each property MUST represent the name
      of the calendar in a different language.

   Description:  This property is used to specify a name (a short, one-
      line description) of the iCalendar object that can be used by
      calendar user agents when presenting the calendar data to a user.
      Whilst a calendar only has a single name, multiple language
      variants can be specified by including this property multiple
      times with different "LANGUAGE" parameter values on each.

   Format Definition:  This property is defined by the following
      notation:

   name       = "NAME" nameparam ":" text CRLF

   nameparam  = *(
                 ;
                 ; The following are OPTIONAL,
                 ; but MUST NOT occur more than once.
                 ;
                 (";" altrepparam) / (";" languageparam) /
                 ;
                 ; The following is OPTIONAL,
                 ; and MAY occur more than once.
                 ;
                 (";" other-param)
                 ;
                 )

   Example:  The following is an example of this property:

   NAME:Company Vacation Days






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4.2.  DESCRIPTION Property

   This specification modifies the definition of the "DESCRIPTION"
   property to allow it to be defined on an iCalendar object.  The
   following additions are made to the definition of this property.

   Purpose:  This property specifies the description of the calendar.

   Conformance:  This property can be specified multiple times in an
      iCalendar object.  However, each property MUST represent the
      description of the calendar in a different language.

   Description:  This property is used to specify a lengthy textual
      description of the iCalendar object that can be used by calendar
      user agents when describing the nature of the calendar data to a
      user.  Whilst a calendar only has a single description, multiple
      language variants can be specified by including this property
      multiple times with different "LANGUAGE" parameter values on each.

4.3.  UID Property

   This specification modifies the definition of the "UID" property to
   allow it to be defined on an iCalendar object.  The following
   additions are made to the definition of this property.

   Purpose:  This property specifies the persistent, globally unique
      identifier for the iCalendar object.

   Conformance:  This property can be specified once in an iCalendar
      object.

4.4.  URL Property

   This specification modifies the definition of the "URL" property to
   allow it to be defined on an iCalendar object.  The following
   additions are made to the definition of this property.

   Purpose:  This property specifies a URL from where the calendar data
      was retrieved or where it can be refreshed.

   Conformance:  This property can be specified once in an iCalendar
      object.

   Description:  This property specifies a URL identifying the source of
      the calendar data and a location from where updates can be
      retrieved.





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4.5.  TIMEZONE-ID Property

   Property Name:  TIMEZONE-ID

   Purpose:  This property specifies the default time zone identifier
      for the iCalendar object as a whole.

   Value Type:  TEXT

   Property Parameters:  IANA and non-standard property parameters can
      be specified on this property.

   Conformance:  This property can be specified once in an iCalendar
      object.

   Description:  This property specifies a time zone identifier that
      represents the default timezone for which floating time or all-day
      events in the iCalendar object can be assumed to be relative to.
      It can also be used to choose an initial time zone for use when
      creating new components in the iCalendar object.  A "VTIMEZONE"
      component having a "TZID" property matching the value specified in
      this property MUST be present in the iCalendar object.

   Format Definition:  This property is defined by the following
      notation:

   timezid      = "TIMEZONE-ID" timezidparam
                    ":" text CRLF
                    ;Same value syntax as "TZID" property.

   timezidparam = *(";" other-param)

   Example:  The following is an example of this property:

   TIMEZONE-ID:America/New_York

4.6.  REFRESH-INTERVAL Property

   Property Name:  REFRESH-INTERVAL

   Purpose:  This property specifies a suggested minimum interval for
      polling for changes of the calendar data from the original source
      of that data.

   Value Type:  DURATION






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   Property Parameters:  IANA and non-standard property parameters can
      be specified on this property.

   Conformance:  This property can be specified once in an iCalendar
      object.

   Description:  This property specifies a positive duration that gives
      a suggested minimum polling interval for checking for updates to
      the calendar data.  The value of this property SHOULD be used by
      calendar user agents to limit the polling interval for calendar
      data updates to the minimum interval specified.

   Format Definition:  This property is defined by the following
      notation:

   refresh      = "REFRESH-INTERVAL" refreshparam
                    ":" dur-value CRLF
                    ;consisting of a positive duration of time.

   refreshparam = *(";" other-param)

   Example:  The following is an example of this property:

   REFRESH-INTERVAL:P1W

4.7.  COLOR Property

   Property Name:  COLOR

   Purpose:  This property specifies a color used for displaying the
      calendar, event, todo, or journal data.

   Value Type:  INTEGER.  The value MUST be three SEMICOLON-separated
      INTEGER values.

   Property Parameters:  IANA and non-standard property parameters can
      be specified on this property.

   Conformance:  This property can be specified once in an iCalendar
      object, or "VEVENT", "VTODO", or "VJOURNAL" calendar components.

   Description:  This property specifies a color that client MAY use
      when presenting the relevant data to a user.  Typically this would
      appear as the "background" color of events or tasks.  The value
      MUST be an RGB value with integer value components in the range
      0..255.  If a color is specified on a VEVENT, VTODO or VJOURNAL
      that SHOULD override any color specified on the enclosing
      iCalendar object.



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   Format Definition:  This property is defined by the following
      notation:

   color          = "COLOR" colorparam ":" colorvalue CRLF

   colorparam     = *(";" other-param)

   colorvalue     = integer ";" integer ";" integer
                    ; Red, green, and blue values in the range
                    ; 0 - 255.

   Example:  The following is an example of this property:

   COLOR:255;0;255

4.8.  IMAGE Property

   Property Name:  IMAGE

   Purpose:  This property specifies an image associated with the
      calendar or a calendar component.

   Value Type:  The default value type for this property is URI.  The
      value type can also be set to BINARY to indicate inline binary
      encoded content information.  The value MUST refer to or be data
      with a media type of "image".

   Property Parameters:  IANA, non-standard, display, inline encoding,
      and value data type property parameters can be specified on this
      property.  The format type parameter can be specified on this
      property and is RECOMMENDED for inline binary encoded content
      information.

   Conformance:  This property can be specified multiple times in an
      iCalendar object, or "VEVENT", "VTODO", or "VJOURNAL" calendar
      components.

   Description:  This property specifies an image for an iCalendar
      object or a calendar component via a uri or directly with inline
      data that can be used by calendar user agents when presenting the
      calendar data to a user.  Multiple properties MAY be used to
      specify alternative sets of images with, for example, varying
      media subtypes, resolutions or sizes.  When multiple properties
      are present, calendar user agents SHOULD display only one of them,
      picking one that provides the most appropriate image quality, or
      display none.  The "DISPLAY" parameter is used to indicate the
      intended display mode for the image.  An "ALTURI" parameter is
      used to provide a "clickable" image where the URI in the parameter



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      value can be "launched" by a click on the image in the calendar
      user agent.

   Format Definition:  This property is defined by the following
      notation:

   image      = "IMAGE" imageparam ( ":" uri ) /
                (
                  ";" "ENCODING" "=" "BASE64"
                  ";" "VALUE" "=" "BINARY"
                  ":" binary
                )
                CRLF

   imageparam = *(
                 ;
                 ; The following is OPTIONAL for a URI value,
                 ; RECOMMENDED for a BINARY value,
                 ; and MUST NOT occur more than once.
                 ;
                 (";" fmttypeparam) /
                 ;
                 ; The following are OPTIONAL,
                 ; and MUST NOT occur more than once.
                 ;
                 (";" alturiparam) / (";" displayparam) /
                 ;
                 ; The following is OPTIONAL,
                 ; and MAY occur more than once.
                 ;
                 (";" other-param)
                 ;
                 )

   Example:  The following is an example of this property:

   IMAGE;DISPLAY=BACKGROUND;FMTTYPE=image/png:htt
    p://example.com/images/party.png

4.9.  BROADCAST Property

   Property Name:  BROADCAST

   Purpose:  This property specifies information for accessing a
      broadcast of the event or task.






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   Value Type:  URI.

   Property Parameters:  IANA, non-standard, feature, information,
      language and region property parameters can be specified on this
      property.

   Conformance:  This property can be specified multiple times in a
      "VEVENT" or "VTODO" calendar component.

   Description:  This property specifies information for accessing a
      broadcast system for attendees of a meeting or to-do.  This might
      be a feed: URI [RFC3496] for a live-blog of the event, or it might
      be an http: URI [RFC2616] for a web-based blog, or it might be an
      rtsp: URI [RFC2326] for an audio stream.

      A broadcast is expected to be a uni-directional communication
      channel, as opposed to a bi-directional channel which is instead
      indicated by the "CONFERENCE" property (see Section 4.10).

      The "FEATURE" property parameter is used to describe the key
      capabilities of the broadcast system to allow a client to choose
      the ones that give the required level of interaction from a set of
      multiple properties.

      The "INFO" property paramater is used to convey additional details
      on the use of the URI.  For example, access codes for the system.

      The "LANGUAGE" property parameter is used to indicate the language
      associated with the property, and in particular any "INFO"
      property parameter.

      The "REGION" property parameter is used to indicate the region
      where this property is valid.  For example, an audio system could
      have several streaming servers that appropriate in different
      geographic regions.  This property parameter can be used to
      differentiate those values so that a location aware device could
      pick the most appropriate one automatically.

   Format Definition:  This property is defined by the following
      notation:











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   broadcast = "BROADCAST" broadparam  ":" uri CRLF

   broadparam  = *(
                  ;
                  ; The following are OPTIONAL,
                  ; and MUST NOT occur more than once.
                  ;
                  (";" featureparam) / (";" infoparam) /
                  (";" languageparam) / (";" regionparam) /
                  ;
                  ; The following is OPTIONAL,
                  ; and MAY occur more than once.
                  ;
                  (";" other-param)
                  ;
                  )

   Example:  The following are examples of this property:

   BROADCAST;FEATURE=AUDIO;REGION=CA;rtsp://stream.ca.example.com/event
   BROADCAST;FEATURE=AUDIO;REGION=US;rtsp://stream.us.example.com/event
   BROADCAST;FEATURE=AUDIO;REGION=UK;rtsp://stream.uk.example.com/event
   BROADCAST;FEATURE=FEED;INFO=Live blog:http://blog.example.com/event
    ence.example.com

4.10.  CONFERENCE Property

   Property Name:  CONFERENCE

   Purpose:  This property specifies information for accessing a
      conferencing system.

   Value Type:  URI.

   Property Parameters:  IANA, non-standard, feature, information,
      language and region property parameters can be specified on this
      property.

   Conformance:  This property can be specified multiple times in a
      "VEVENT" or "VTODO" calendar component.

   Description:  This property specifies information for accessing a
      conferencing system for attendees of a meeting or to-do.  This
      might be a tel: URI [RFC3496] for a telephone-based conference
      number dial-in (with access codes included), or it might be an
      http: URI [RFC2616] for a web-based video chat, or a URI for an
      instant messaging group chat room.  If a specific URI for a
      conferencing system is not available, a data: URI [RFC2397]



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      containing a text description can be used.

      A conference system is expected to be a bi-directional
      communication channel, as opposed to a uni-directional "feed"
      which is instead indicated by the "BROADCAST" property (see
      Section 4.9).

      The "FEATURE" property parameter is used to describe the key
      capabilities of the conference system to allow a client to choose
      the ones that give the required level of interaction from a set of
      multiple properties.

      The "INFO" property paramater is used to convey additional details
      on the use of the URI.  For example, the URIs or access codes for
      the moderator and attendee of a teleconference system could be
      different, and the "INFO" property parameter could be used to
      "tag" each "CONFERENCE" property to indicate which is which.

      The "LANGUAGE" property parameter is used to indicate the language
      associated with the property, and in particular any "INFO"
      property parameter.

      The "REGION" property parameter is used to indicate the region
      where this property is valid.  For example, a telephone based
      conference system could have several local access numbers that are
      applicable in different geographic regions.  This property
      parameter can be used to differentiate those values so that a
      location aware device could pick the most appropriate one
      automatically.

   Format Definition:  This property is defined by the following
      notation:

   conference = "CONFERENCE" confparam  ":" uri CRLF

   confparam  = *(
                 ;
                 ; The following are OPTIONAL,
                 ; and MUST NOT occur more than once.
                 ;
                 (";" featureparam) / (";" infoparam) /
                 (";" languageparam) / (";" regionparam) /
                 ;
                 ; The following is OPTIONAL,
                 ; and MAY occur more than once.
                 ;
                 (";" other-param)
                 ;



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                 )

   Example:  The following are examples of this property:

   CONFERENCE;FEATURE=AUDIO;INFO=Moderator dial-in;REGION=US-PA:tel:+
    1-412-555-0123,,,654321
   CONFERENCE;FEATURE=AUDIO;INFO=Attendee dial-in;REGION=US-PA:tel:+1
    -412-555-0123,,,555123
   CONFERENCE;FEATURE=AUDIO;INFO=Attendee dial-in;REGION=CA:tel:+1-88
    8-555-0456,,,555123
   CONFERENCE;FEATURE=CHAT;INFO=Chat room:xmpp:chat-123@confer
    ence.example.com


5.  Property Parameters

5.1.  ALTURI Property Parameter

   Parameter Name:  ALTURI

   Purpose:  To specify a URI alternative to a property value.

   Format Definition:  This property parameter is defined by the
      following notation:

   alturiparam = "ALTURI" "=" DQUOTE uri DQUOTE

   Description:  This property parameter MAY be specified on "IMAGE"
      properties.

   Example:

   IMAGE;FMTTYPE=image/png:ALTURI="http://ex
    ample.com/clicked-image1":http://example
    .com/images/party.png

5.2.  DISPLAY Property Parameter

   Parameter Name:  DISPLAY

   Purpose:  To specify different ways in which an image for a calendar
      or component can be displayed.

   Format Definition:  This property parameter is defined by the
      following notation:






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   displayparam = "DISPLAY" "="
                  ("BADGE" /       ; A small "badge" image
                   "BACKGROUND" /  ; Use as a background image
                   "OVERLAY" /     ; Use as an overlay image
                   "BANNER" /      ; Use as a "banner" across the top
                   x-name /        ; Experimental type
                   iana-token)     ; Other IANA registered type
                                   ;
                                   ; Default is BADGE

   Description:  This property parameter MAY be specified on "IMAGE" or
      "IMAGE" properties.  In the absence of this parameter, the value
      "BADGE" MUST be used for the default behavior.  The value
      determines how a client ought to present an image supplied in
      iCalendar data to the user.

      Values for this parameter are registered with IANA as per
      Section 7.3.  New values can be added to this registry following
      the procedure outlined in Section 8.2.1 of [RFC5545].

      Servers and clients MUST handle x-name and iana-token values they
      don't recognize by not displaying any image at all.

   Example:

   IMAGE;DISPLAY=BANNER;FMTTYPE=image/png:htt
    p://example.com/images/weather-cloudy.png

5.3.  FEATURE Property Parameter

   Parameter Name:  FEATURE

   Purpose:  To specify a feature or features of a conference or
      broadcast system.

   Format Definition:  This property parameter is defined by the
      following notation:

   featureparam = "FEATURE" "=" featuretext *("," featuretext)
   featuretext  =  ("AUDIO" /      ; Audio capability
                    "CHAT" /       ; Chat or instanst messaging
                    "FEED" /       ; Blog or Atom feed
                    "SCREEN" /     ; Screen sharing
                    "VIDEO" /      ; Video capability
                    x-name /       ; Experimental type
                    iana-token)    ; Other IANA registered type





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   Description:  This property parameter MAY be specified on "BROADCAST"
      or "CONFERENCE" properties.

   Example:

   BROADCAST;FEATURE=AUDIO:rtsp://audio.example.com/event
   CONFERENCE;FEATURE=AUDIO,VIDEO:http://video-chat.ex
    ample.com/;group-id=1234

5.4.  INFO Property Parameter

   Parameter Name:  INFO

   Purpose:  To specify descriptive text about a property.

   Format Definition:  This property parameter is defined by the
      following notation:

   infoparam = "INFO" "=" paramtext

   Description:  This property parameter MAY be specified on "BROADCAST"
      and "CONFERENCE" properties.

   Example:

   BROADCAST;INFO=Audio stream;FEATURE=AUDIO:rtsp://
    audio.example.com/event
   CONFERENCE;INFO="Web video chat, access code=7654
    3";:http://video-chat.example.com/;group-id=1234

5.5.  REGION Property Parameter

   Parameter Name:  REGION

   Purpose:  To specify a region or regions where a broadcast or
      conference system is valid.

   Format Definition:  This property parameter is defined by the
      following notation:

   regionparam = "REGION" "=" regiontext *("," regiontext)
   regiontext  = paramtext ; an ISO3166-1 or ISO3166-2 code

   Description:  This property parameter MAY be specified on "BROADCAST"
      or "CONFERENCE" properties.






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   Example:

   CONFERENCE;FEATURE=AUDIO;INFO=Moderator dial-in;REGION=US-PA:tel:+1
    -412-555-0123,,,654321


6.  Security Considerations

   Several of the new properties or parameters defined by this
   specification allow reference to "external" URIs.  Care MUST be taken
   when accessing data at external URIs as malicious content could be
   present.  In addition, access to those URIs could be tracked, leading
   to loss of privacy.

   Clients MUST by default prompt users before automatically accessing a
   broadcast or conference system for the first time to prevent
   attackers from being able to trigger access to a host computer simply
   by sending an event invitation.


7.  IANA Considerations

7.1.  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                            |
   +------------------+---------+--------------------------------------+
   | NAME             | Current | RFCXXXX, Section 4.1                 |
   | DESCRIPTION      | Current | RFC5545 Section 3.8.1.5, RFCXXXX,    |
   |                  |         | Section 4.2                          |
   | UID              | Current | RFC5545 Section 3.8.4.7, RFCXXXX,    |
   |                  |         | Section 4.3                          |
   | URL              | Current | RFC5545 Section 3.8.4.6, RFCXXXX,    |
   |                  |         | Section 4.4                          |
   | TIMEZONE-ID      | Current | RFCXXXX, Section 4.5                 |
   | REFRESH-INTERVAL | Current | RFCXXXX, Section 4.6                 |
   | COLOR            | Current | RFCXXXX, Section 4.7                 |
   | IMAGE            | Current | RFCXXXX, Section 4.8                 |
   | BROADCAST        | Current | RFCXXXX, Section 4.9                 |
   | CONFERENCE       | Current | RFCXXXX, Section 4.10                |
   +------------------+---------+--------------------------------------+







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7.2.  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            |
          +--------------------+---------+----------------------+
          | ALTURI             | Current | RFCXXXX, Section 5.1 |
          | DISPLAY            | Current | RFCXXXX, Section 5.2 |
          | FEATURE            | Current | RFCXXXX, Section 5.3 |
          | INFO               | Current | RFCXXXX, Section 5.4 |
          | REGION             | Current | RFCXXXX, Section 5.5 |
          +--------------------+---------+----------------------+

7.3.  Display Types Registry

   This document defines the following new iCalendar value registry as
   per Section 8.2.6 of [RFC5545]:

             +--------------+---------+----------------------+
             | Display Type | Status  | Reference            |
             +--------------+---------+----------------------+
             | BADGE        | Current | RFCXXXX, Section 5.2 |
             | BACKGROUND   | Current | RFCXXXX, Section 5.2 |
             | OVERLAY      | Current | RFCXXXX, Section 5.2 |
             | BANNER       | Current | RFCXXXX, Section 5.2 |
             +--------------+---------+----------------------+

7.4.  Feature Types Registry

   This document defines the following new iCalendar value registry as
   per Section 8.2.6 of [RFC5545]:

             +--------------+---------+----------------------+
             | Feature Type | Status  | Reference            |
             +--------------+---------+----------------------+
             | AUDIO        | Current | RFCXXXX, Section 5.3 |
             | CHAT         | Current | RFCXXXX, Section 5.3 |
             | FEED         | Current | RFCXXXX, Section 5.3 |
             | SCREEN       | Current | RFCXXXX, Section 5.3 |
             | VIDEO        | Current | RFCXXXX, Section 5.3 |
             +--------------+---------+----------------------+








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8.  Acknowledgments

   Thanks to the following for feedback: Bernard Desruisseaux, Mike
   Douglass, Arnaud Quillaud, and Dave Thewlis.  This specification came
   about via discussions at the Calendaring and Scheduling Consortium.


9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC5545]  Desruisseaux, B., "Internet Calendaring and Scheduling
              Core Object Specification (iCalendar)", RFC 5545,
              September 2009.

9.2.  Informative References

   [RFC2326]  Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time
              Streaming Protocol (RTSP)", RFC 2326, April 1998.

   [RFC2397]  Masinter, L., "The "data" URL scheme", RFC 2397,
              August 1998.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC3496]  Malis, A. and T. Hsiao, "Protocol Extension for Support of
              Asynchronous Transfer Mode (ATM) Service Class-aware
              Multiprotocol Label Switching (MPLS) Traffic Engineering",
              RFC 3496, March 2003.

   [RFC5546]  Daboo, C., "iCalendar Transport-Independent
              Interoperability Protocol (iTIP)", RFC 5546,
              December 2009.


Appendix A.  Change History (To be removed by RFC Editor before
             publication)

   Changes in -04:




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   1.  TZID changed to new property TIMEZONE-ID.

   2.  Minor formal syntax changes.

   Changes in -03:

   1.  Dropped CALENDAR- prefix

   2.  DESCRIPTION, UID and TZID now based on existing RFC5545
       properties

   3.  COLOR now on both the calendar and component level

   4.  IMAGE now on both the calendar and component level

   5.  Added FEATURE and REGION parameters to CONFERENCE property

   6.  Added ALTURI parameter to IMAGE property

   7.  Added FEED value to FEATURE parameter

   8.  Added BROADCAST property and clarified that CONFERENCE is for bi-
       direction channels and BROADCAST is for uni-directional.

   Changes in -02:

   1.  Minor wording changes.

   2.  Interval is now described as the "minimum interval".

   3.  Added CONFERENCE property and INFO parameter.

   Changes in -01:

   1.  Fixed DISPLAY parameter handling of x- and iana tokens to state
       that clients ignore the image if the token is not recognized.

   2.  Allow language variants for CALENDAR-NAME and CALENDAR-
       DESCRIPTION.

   3.  Added registry for DISPLAY values.










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Author's Address

   Cyrus Daboo
   Apple Inc.
   1 Infinite Loop
   Cupertino, CA  95014
   USA

   Email: cyrus@daboo.name
   URI:   http://www.apple.com/









































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