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Versions: 00 01 02 03 04 05 06 07 08 09 draft-ietf-calext-extensions

Network Working Group                                           C. Daboo
Internet-Draft                                                Apple Inc.
Intended status: Standards Track                       February 26, 2010
Expires: August 30, 2010


                      New Properties for iCalendar
                  draft-daboo-icalendar-extensions-00

Abstract

   This document defines a set of new properties for iCalendar data.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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   Drafts.

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   time.  It is inappropriate to use Internet-Drafts as reference
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   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on August 30, 2010.

Copyright Notice

   Copyright (c) 2010 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
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of



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   the Trust Legal Provisions and are provided without warranty as
   described in the BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
   3.  Modifications to Calendar Components . . . . . . . . . . . . .  3
   4.  Calendar Properties  . . . . . . . . . . . . . . . . . . . . .  5
     4.1.  CALENDAR-NAME Property . . . . . . . . . . . . . . . . . .  5
     4.2.  CALENDAR-DESCRIPTION Property  . . . . . . . . . . . . . .  6
     4.3.  CALENDAR-UID Property  . . . . . . . . . . . . . . . . . .  7
     4.4.  CALENDAR-URL Property  . . . . . . . . . . . . . . . . . .  7
     4.5.  CALENDAR-TZID Property . . . . . . . . . . . . . . . . . .  8
     4.6.  CALENDAR-REFRESH-INTERVAL Property . . . . . . . . . . . .  9
     4.7.  CALENDAR-COLOR Property  . . . . . . . . . . . . . . . . .  9
     4.8.  CALENDAR-IMAGE Property  . . . . . . . . . . . . . . . . . 10
   5.  Component Properties . . . . . . . . . . . . . . . . . . . . . 12
     5.1.  IMAGE Property . . . . . . . . . . . . . . . . . . . . . . 12
   6.  Property Parameters  . . . . . . . . . . . . . . . . . . . . . 13
     6.1.  DISPLAY Property Parameter . . . . . . . . . . . . . . . . 13
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
     8.1.  Property Registrations . . . . . . . . . . . . . . . . . . 14
     8.2.  Paramater Registrations  . . . . . . . . . . . . . . . . . 15
   9.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 15
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 15
     10.2. Informative References . . . . . . . . . . . . . . . . . . 16
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16




















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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 collates 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 been
   requesting recently.


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.



















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          calprops /= *(
                       ;
                       ; The following are OPTIONAL,
                       ; but MUST NOT occur more than once.
                       ;
                       calname / caldescription /
                       caluid / calurl / caltzid /
                       calrefresh / calcolor /
                       ;
                       ; The following are OPTIONAL,
                       ; and MAY occur more than once.
                       ;
                       calimg
                       ;
                       )

          eventprop /= *(
                        ;
                        ; The following are OPTIONAL,
                        ; and MAY occur more than once.
                        ;
                        image
                        ;
                        )

          todoprop /= *(
                       ;
                       ; The following are OPTIONAL,
                       ; and MAY occur more than once.
                       ;
                       image
                       ;
                       )

          jourprop /= *(
                       ;
                       ; The following are OPTIONAL,
                       ; and MAY occur more than once.
                       ;
                       image
                       ;
                       )









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4.  Calendar Properties

4.1.  CALENDAR-NAME Property

   Property Name:  CALENDAR-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 once in an iCalendar
      object.

   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.

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

          calname       = "CALENDAR-NAME" calnameparam ":" text CRLF

          calnameparam  = *(
                           ;
                           ; 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:

          CALENDAR-NAME:Company Vacation Days








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4.2.  CALENDAR-DESCRIPTION Property

   Property Name:  CALENDAR-DESCRIPTION

   Purpose:  This property specifies the description 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 once in an iCalendar
      object.

   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.

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

          caldesc       = "CALENDAR-DESCRIPTION" caldescparam ":" text
                          CRLF

          caldescparam  = *(
                           ;
                           ; 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:

          CALENDAR-DESCRIPTION:This calendar contains all the \
           official vacation days of our company.\nThese repre\
           sent paid time-off - make sure you have fun, we'll \
           be working you hard on the other days!





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4.3.  CALENDAR-UID Property

   Property Name:  CALENDAR-UID

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

   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:  The value of this property MUST be a globally unique
      identifier.  The generator of the property MUST guarantee that the
      value is unique.  This can be done following the recommendations
      in Section 3.8.4.7 of [RFC5545].  Implementations MUST be able to
      receive and persist values of at least 255 octets for this
      property, but they MUST NOT truncate values in the middle of a
      UTF-8 multi-octet sequence.

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

          caluid       = "CALENDAR-UID" caluidparam ":" text CRLF

          caluidparam  = *(";" other-param)

   Example:  The following is an example of this property:

          CALENDAR-UID:19960401T080045Z-4000F192713-0052@example.com

4.4.  CALENDAR-URL Property

   Property Name:  CALENDAR-URL

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

   Value Type:  URI

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






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   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.

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

          calurl       = "CALENDAR-URL" calurlparam ":" url CRLF

          calurlparam  = *(";" other-param)

   Example:  The following is an example of this property:

          CALENDAR-URL:http://calendars.example.com/holidays/canada.ics

4.5.  CALENDAR-TZID Property

   Property Name:  CALENDAR-TZID

   Purpose:  This property specifies the default time zone identifier
      for the calendar.

   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:

          caltzid       = "CALENDAR-TZID" caltzidparam ":" [tzidprefix]
                          text CRLF

          caltzidparam  = *(";" other-param)



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   Example:  The following is an example of this property:

          CALENDAR-TZID:America/New_York

4.6.  CALENDAR-REFRESH-INTERVAL Property

   Property Name:  CALENDAR-REFRESH-INTERVAL

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

   Value Type:  DURATION

   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 polling interval for checking for updates to the
      calendar data.  The value of this property SHOULD be used by
      calendar user agents as the polling interval for calendar data
      updates.

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

          calrefesh      = "CALENDAR-REFRESH-INTERVAL" calrefreshparam
                           ":" dur-value CRLF
                           ;consisting of a positive duration of time.

          calrefeshparam = *(";" other-param)

   Example:  The following is an example of this property:

          CALENDAR-REFRESH-INTERVAL:P1W

4.7.  CALENDAR-COLOR Property

   Property Name:  CALENDAR-COLOR

   Purpose:  This property specifies a color used for displaying the
      calendar data.






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   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.

   Description:  This property specifies a color that client MAY use
      when presenting the calendar 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

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

          calcolor       = "CALENDAR-COLOR" calcolorparam ":"
                           calcolorvalue CRLF

          calcolorparam  = *(";" other-param)

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

   Example:  The following is an example of this property:

          CALENDAR-COLOR:255;0;255

4.8.  CALENDAR-IMAGE Property

   Property Name:  CALENDAR-IMAGE

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

   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.



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

   Description:  This property specifies an image for an iCalendar
      object 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.

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

          calimg     = "CALENDAR-IMAGE" calimgparam ( ":" uri ) /
                       (
                         ";" "ENCODING" "=" "BASE64"
                         ";" "VALUE" "=" "BINARY"
                         ":" binary
                       )
                       CRLF

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







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   Example:  The following is an example of this property:

          CALENDAR-IMAGE;DISPLAY=BADGE;FMTTYPE=image/png:http://ex
           ample.com/images/holiday.png


5.  Component Properties

5.1.  IMAGE Property

   Property Name:  IMAGE

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

   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 a
      "VEVENT", "VTODO", or "VJOURNAL" calendar component.

   Description:  This property specifies an image for 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.

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









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          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 is OPTIONAL,
                        ; and MOST NOT occur more than once.
                        ;
                        (";" 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


6.  Property Parameters

6.1.  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 "CALENDAR-
      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.

      Servers and clients MUST treat x-name and iana-token values they
      don't recognize the same way as they would the "NONE" value.

   Example:

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


7.  Security Considerations

   TODO:Perhaps discuss issues with image processing related buffer
   overflows, accessing external URLs (privacy), etc.


8.  IANA Considerations

8.1.  Property Registrations

   This documents defines the following new iCalendar properties to be
   added to the registry defined in Section 8.2.3 of [RFC5545]:














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      +---------------------------+---------+----------------------+
      | Property                  | Status  | Reference            |
      +---------------------------+---------+----------------------+
      | CALENDAR-NAME             | Current | RFCXXXX, Section 4.1 |
      | CALENDAR-DESCRIPTION      | Current | RFCXXXX, Section 4.2 |
      | CALENDAR-UID              | Current | RFCXXXX, Section 4.3 |
      | CALENDAR-URL              | Current | RFCXXXX, Section 4.4 |
      | CALENDAR-TZID             | Current | RFCXXXX, Section 4.5 |
      | CALENDAR-REFRESH-INTERVAL | Current | RFCXXXX, Section 4.6 |
      | CALENDAR-COLOR            | Current | RFCXXXX, Section 4.7 |
      | CALENDAR-IMAGE            | Current | RFCXXXX, Section 4.8 |
      | IMAGE                     | Current | RFCXXXX, Section 5.1 |
      +---------------------------+---------+----------------------+

8.2.  Paramater Registrations

   This documents defines the following new iCalendar properties to be
   added to the registry defined in Section 8.2.3 of [RFC5545]:

          +--------------------+---------+----------------------+
          | Property Parameter | Status  | Reference            |
          +--------------------+---------+----------------------+
          | DISPLAY            | Current | RFCXXXX, Section 6.1 |
          +--------------------+---------+----------------------+


9.  Acknowledgments

   This specification came about via discussions at the Calendaring and
   Scheduling Consortium.


10.  References

10.1.  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.






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10.2.  Informative References

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


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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