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jCal: The JSON format for iCalendar
draft-ietf-jcardcal-jcal-09

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 7265.
Authors Philipp Kewisch , Cyrus Daboo , Mike Douglass
Last updated 2014-03-24 (Latest revision 2014-02-19)
Replaces draft-kewisch-et-al-icalendar-in-json
RFC stream Internet Engineering Task Force (IETF)
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Reviews
Additional resources Mailing list discussion
Stream WG state Submitted to IESG for Publication
Document shepherd Peter Saint-Andre
Shepherd write-up Show Last changed 2014-01-06
IESG IESG state Became RFC 7265 (Proposed Standard)
Consensus boilerplate Yes
Telechat date (None)
Needs a YES. Needs 10 more YES or NO OBJECTION positions to pass.
Responsible AD Pete Resnick
Send notices to jcardcal-chairs@tools.ietf.org, draft-ietf-jcardcal-jcal@tools.ietf.org, jcardcal@ietf.org
IANA IANA review state IANA OK - Actions Needed
draft-ietf-jcardcal-jcal-09
JSON data formats for vCard and iCalendar                     P. Kewisch
Internet-Draft                                                   Mozilla
Intended status: Standards Track                                C. Daboo
Expires: August 22, 2014                                     Apple, Inc.
                                                             M. Douglass
                                                                     RPI
                                                       February 18, 2014

                  jCal: The JSON format for iCalendar
                      draft-ietf-jcardcal-jcal-09

Abstract

   This specification defines "jCal", a JSON format for iCalendar data.
   The iCalendar data format is a text format for capturing and
   exchanging information normally stored within a calendaring and
   scheduling application, for example tasks and events.  JSON is a
   lightweight, text-based, language-independent data interchange format
   commonly used in internet applications.

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 August 22, 2014.

Copyright Notice

   Copyright (c) 2014 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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   to this document.  Code Components extracted from this document must
   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
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   4
   3.  Converting from iCalendar to jCal . . . . . . . . . . . . . .   4
     3.1.  Pre-processing  . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  iCalendar Stream and Objects (RFC5545 section 3.4)  . . .   5
     3.3.  Components (RFC5545 section 3.6)  . . . . . . . . . . . .   6
     3.4.  Properties (RFC5545 section 3.7 and 3.8)  . . . . . . . .   6
       3.4.1.  Special Cases for Properties  . . . . . . . . . . . .   7
         3.4.1.1.  GEO Property (RFC5545 Section 3.8.1.6)  . . . . .   8
         3.4.1.2.  REQUEST-STATUS Property (RFC5545 Section 3.8.8.3)   8
     3.5.  Parameters (RFC5545 section 3.2)  . . . . . . . . . . . .   9
       3.5.1.  VALUE parameter . . . . . . . . . . . . . . . . . . .  10
       3.5.2.  Multi-value Parameters  . . . . . . . . . . . . . . .  11
     3.6.  Values (RFC5545 section 3.3)  . . . . . . . . . . . . . .  11
       3.6.1.  Binary (RFC5545 section 3.3.1)  . . . . . . . . . . .  12
       3.6.2.  Boolean  (RFC5545 section 3.3.2)  . . . . . . . . . .  12
       3.6.3.  Calendar User Address (RFC5545 section 3.3.3) . . . .  12
       3.6.4.  Date (RFC5545 section 3.3.4)  . . . . . . . . . . . .  12
       3.6.5.  Date-Time (RFC5545 section 3.3.5) . . . . . . . . . .  13
       3.6.6.  Duration (RFC5545 section 3.3.6)  . . . . . . . . . .  13
       3.6.7.  Float (RFC5545 section 3.3.7) . . . . . . . . . . . .  14
       3.6.8.  Integer (RFC5545 section 3.3.8) . . . . . . . . . . .  14
       3.6.9.  Period of Time (RFC5545 section 3.3.9)  . . . . . . .  14
       3.6.10. Recurrence Rule (RFC5545 section 3.3.10)  . . . . . .  15
       3.6.11. Text (RFC5545 section 3.3.11) . . . . . . . . . . . .  16
       3.6.12. Time (RFC5545 section 3.3.12) . . . . . . . . . . . .  16
       3.6.13. URI (RFC5545 section 3.3.13)  . . . . . . . . . . . .  17
       3.6.14. UTC Offset (RFC5545 section 3.3.14) . . . . . . . . .  17
     3.7.  Extensions  . . . . . . . . . . . . . . . . . . . . . . .  17
   4.  Converting from jCal into iCalendar . . . . . . . . . . . . .  18
   5.  Handling Unrecognized Properties or Parameters  . . . . . . .  18
     5.1.  Converting iCalendar into jCal  . . . . . . . . . . . . .  19
     5.2.  Converting jCal into iCalendar  . . . . . . . . . . . . .  19
     5.3.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  19
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  21
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
     7.1.  UNKNOWN iCalendar Value Data Type . . . . . . . . . . . .  22
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  23
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  23
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  23
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  24

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   Appendix A.  Implementation Status (to be removed prior to
                publication as an RFC, as well as the reference to
                RFC6982) . . . . . . . . . . . . . . . . . . . . . .  24
   Appendix B.  ABNF Schema  . . . . . . . . . . . . . . . . . . . .  25
   Appendix C.  Examples . . . . . . . . . . . . . . . . . . . . . .  27
     C.1.  Example 1 . . . . . . . . . . . . . . . . . . . . . . . .  27
       C.1.1.  iCalendar Data  . . . . . . . . . . . . . . . . . . .  27
       C.1.2.  jCal Data . . . . . . . . . . . . . . . . . . . . . .  27
     C.2.  Example 2 . . . . . . . . . . . . . . . . . . . . . . . .  28
       C.2.1.  iCalendar Data  . . . . . . . . . . . . . . . . . . .  28
       C.2.2.  jCal Data . . . . . . . . . . . . . . . . . . . . . .  29
   Appendix D.  Change History (to be removed prior to publication
                as an RFC) . . . . . . . . . . . . . . . . . . . . .  31
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  33

1.  Introduction

   The iCalendar data format [RFC5545] is a widely deployed interchange
   format for calendaring and scheduling data.  While many applications
   and services consume and generate calendar data, iCalendar is a
   specialized format that requires its own parser/generator.  In
   contrast, JSON-based formats as defined in [RFC4627] are the native
   format for JavaScript widgets and libraries and it is appropriate to
   have a standard form of calendar data that is easier to work with
   than iCalendar.

   The purpose of this specification is to define "jCal", a JSON format
   for iCalendar data.  jCal is defined as a straightforward mapping
   into JSON from iCalendar, so that iCalendar data can be converted to
   JSON, and then back to iCalendar, without losing any semantic meaning
   in the data.  Anyone creating jCal calendar data according to this
   specification will know that their data can be converted to a valid
   iCalendar representation as well.

   The key design considerations are essentially the same as those for
   [RFC6321], that is:

      Round-tripping (converting an iCalendar instance to jCal and back)
      will give the same semantic result as the starting point.  For
      example, all components, properties and property parameters are
      guaranteed to be preserved.

      Ordering of elements and case of property and parameter names will
      not necessarily be preserved.

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      The iCalendar data semantics are to be preserved, allowing a
      simple consumer to easily browse the data in jCal.  A full
      understanding of iCalendar is still required in order to modify
      and/or fully comprehend the calendar data.

      Extensions to the underlying iCalendar specification must not lead
      to requiring an update to jCal.

2.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   The underlying format used for jCal is JSON.  Consequently, the terms
   "object" and "array" as well as the four primitive types (strings,
   numbers, booleans, and null) are to be interpreted as described in
   Section 1 of [RFC4627].

   Some examples in this document contain "partial" JSON documents used
   for illustrative purposes.  In these examples, three periods "..."
   are used to indicate a portion of the document that has been removed
   for compactness.

3.  Converting from iCalendar to jCal

   This section describes how iCalendar data is converted to jCal using
   a simple mapping between the iCalendar data model and JSON elements.

   In [RFC5545], iCalendar objects are comprised of a set of
   "components", "properties", "parameters" and "values".  The top level
   of iCalendar data typically contains a stream of iCalendar objects,
   each of which can be considered a "component".  A "component" can
   contain other "components" or "properties".  A "property" has a
   "value" and a set of zero or more "parameters".  Each of these
   entities have a representation in jCal, defined in the following
   sections.  The representation of a iCalendar object in JSON will be
   named "jCal object" throughout this document.

3.1.  Pre-processing

   iCalendar uses a line folding mechanism to limit lines of data to a
   maximum line length (typically 75 octets) to ensure maximum
   likelihood of preserving data integrity as it is transported via
   various means (e.g., email) - see Section 3.1 of [RFC5545].

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   iCalendar data uses an "escape" character sequence for text values
   and property parameter values.  See Section 3.1 and 3.3 of [RFC5545]
   as well as [RFC6868].

   When converting from iCalendar to jCal, first iCalendar lines MUST be
   unfolded.  Afterwards, any iCalendar escaping MUST be unescaped.
   Finally JSON escaping (e.g., for control characters) MUST be applied.

   The reverse order applies when converting from jCal to iCalendar.
   First, JSON escaping MUST be unescaped.  Afterwards, iCalendar
   escaping MUST be applied.  Finally, long lines SHOULD be folded as
   described in [RFC5545].

   iCalendar uses a base64 encoding for binary data.  However, it does
   not restrict the encoding from being applied to non-binary value
   types.  So the following rules are applied when processing a property
   with the "ENCODING" property parameter set to "BASE64":

   o  If the property value type is "BINARY", the base64 encoding MUST
      be preserved.

   o  If the value type is not "BINARY", the "ENCODING" property
      parameter MUST be removed, and the value MUST be base64 decoded.

   When base64 encoding and decoding is used, it MUST conform to
   Section 4 of [RFC4648], which is the base64 method used in [RFC5545].

   One key difference in the formatting of values used in iCalendar and
   jCal is that in jCal the specification uses date/time values aligned
   with the extended format of [ISO.8601.2004], which is more commonly
   used in internet applications that make use of the JSON format.  The
   sections of this document describing the various date and time
   formats contain more information on the use of the complete
   representation, reduced accuracy or truncated representation.

3.2.  iCalendar Stream and Objects (RFC5545 section 3.4)

   At the top level of the iCalendar object model is an "iCalendar
   stream".  This stream encompasses multiple "iCalendar objects".  As
   the typical use case is transporting a single iCalendar object, there
   is no defined equivalent to an "iCalendar stream" in jCal.  To
   transport multiple jCal objects in a stream, a simple JSON array can
   be used.

   Example:

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   ["vcalendar",
     [ /* Add jCal properties in place of this comment */ ],
     [ /* Add jCal components in place of this comment */ ]
   ]

3.3.  Components (RFC5545 section 3.6)

   Each iCalendar component, delimited by "BEGIN" and "END", will be
   converted to a fixed length array with three fields that have a
   specific structure:

   1.  A string with the name of the iCalendar component, but in
       lowercase.

   2.  An array of jCal properties as described in Section 3.4.

   3.  An array of jCal components, representing the sub-components of
       the component in question.

   This mapping applies to the top level iCalendar objects, as well as
   individual sub-components in the same way.  The iCalendar to jCal
   component mapping is valid for both current iCalendar components and
   any new iCalendar components added in the future.  Conversion is to
   be done in the same way.

   While the grouping of properties and sub-components does not retain
   the original order specified in the iCalendar data, the semantics of
   a component are preserved.

   Example:

   ["vevent",
     [ /* Add jCal properties in place of this comment */ ],
     [ /* Add jCal components in place of this comment */ ]
   ]

3.4.  Properties (RFC5545 section 3.7 and 3.8)

   iCalendar properties, whether they apply to the "VCALENDAR" object or
   to a component, are handled in a consistent way in the jCal format.

   Each individual iCalendar property is represented in jCal by an array
   with three fixed elements, followed by one or more additional
   elements, depending on if the property is a multi-value property as
   described in Section 3.1.2 of [RFC5545].

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   The array consists of the following fixed elements:

   1.  The name of the property, as a lowercase string.  The iCalendar
       format specifies that property names are case-insensitive, and
       recommends that they be rendered in uppercase.  In jCal, they
       MUST be in lowercase.

   2.  An object containing the parameters as described in Section 3.5.
       If the property has no parameters, an empty object is used to
       represent that.

   3.  The type identifier string of the value, in lowercase.  Due to
       special casing of certain properties as described in
       Section 3.4.1, it is important that parsers check both the type
       identifier and the value data type and do not rely on assumptions
       based on the property name.

   The remaining elements of the array are used for one or more values
   of the property.  For single-value properties, the array has exactly
   four elements; for multi-valued properties, as described in [RFC5545]
   Section 3.1.2, each value is another element, and there can be any
   number of additional elements.

   In the following example, the "categories" property is multi-valued
   and has two values, while the summary property is single-valued:

   Example:

   ["vevent",
     [
       ["summary", {}, "text", "Meeting with Fred"],
       ["categories", {}, "text", "Meetings", "Work"]
       ...
     ],
     [ /* sub-components */ ]
   ]

3.4.1.  Special Cases for Properties

   This section describes some properties that have special handling
   when converting to jCal.

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3.4.1.1.  GEO Property (RFC5545 Section 3.8.1.6)

   In iCalendar, the "GEO" property value is defined as a semi-colon
   separated list of two "FLOAT" values, the first representing latitude
   and the second longitude.

   In jCal, the value for the "geo" property value is represented as an
   array of two values.  The first value of the property represents the
   latitude, the second value represents the longitude.

   When converting from jCal to iCalendar, the two values MUST be
   converted using a semi-colon as the separator character.

   Example

   ["vevent",
     [
       ["geo", {}, "float", [ 37.386013, -122.082932 ] ]
       ...
     ],
     ...
   ]

3.4.1.2.  REQUEST-STATUS Property (RFC5545 Section 3.8.8.3)

   In iCalendar, the "REQUEST-STATUS" property value is defined as a
   semi-colon separated list of two or three "TEXT" values.  The first
   represents a code, the second a description, and the third any
   additional data.

   In jCal, the value for the "request-status" property value is
   represented as an array with two or three values.  The first array
   element corresponds to the code, the second element corresponds to
   the description and the third element corresponds to the additional
   data.  Each value is represented using a string value.  If there is
   no additional data in the iCalendar value, the last element of the
   array SHOULD NOT be present.

   When converting from jCal to iCalendar, the two or three values MUST
   be converted using a semi-colon as the separator character.

   iCalendar Example:

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   BEGIN:VEVENT
   ...
   REQUEST-STATUS:2.0;Success
   REQUEST-STATUS:3.7;Invalid calendar user;ATTENDEE:
    mailto:jsmith@example.com
   ...
   END:VEVENT

   jCal Example:

   ["vevent":
     [
       ["request-status", {}, "text", ["2.0", "Success"] ],
       ["request-status", {}, "text",
          [
           "3.7",
           "Invalid calendar user",
           "ATTENDEE:mailto:jsmith@example.org"
          ]
       ],
       ...
     ],
     ...
   ]

3.5.  Parameters (RFC5545 section 3.2)

   Property parameters are represented as a JSON object where each key-
   value pair represents the iCalendar parameter name and its value.
   The name of the parameter MUST be in lowercase, the original case of
   the parameter value MUST be preserved.  For example, the "PARTSTAT"
   property parameter is represented in jCal by the "partstat" key.  Any
   new iCalendar parameters added in the future will be converted in the
   same way.

   Example:

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   ["vevent":
     [
       ["attendee",
        {
          "partstat": "ACCEPTED",
          "rsvp": "TRUE",
          "role": "REQ-PARTICIPANT"
        },
        "cal-address",
        "mailto:jsmith@example.org"
       ],
       ["summary", {}, "text", "Meeting"],
       ...
     ],
     ...
   ]

3.5.1.  VALUE parameter

   iCalendar defines a "VALUE" property parameter (Section 3.2.20 of
   [RFC5545]).  This property parameter MUST NOT be added to the
   parameters object.  Instead, the value type is signaled through the
   type identifier in the third element of the array describing the
   property.  When converting a property from iCalendar to jCal, the
   value type is determined as follows:

   1.  If the property has a "VALUE" parameter, that parameter's value
       is used as the value type.

   2.  If the property has no "VALUE" parameter but has a default value
       type, the default value type is used.

   3.  If the property has no "VALUE" parameter and has no default value
       type, "unknown" is used.

   Converting from jCal into iCalendar is done as follows:

   1.  If the property's value type is "unknown", no "VALUE" parameter
       is included.

   2.  If the property's value type is the default type for that
       property, no "VALUE" parameter is included.

   3.  Otherwise, a "VALUE" parameter is included, and the value type is
       used as the parameter value.

   See Section 5 for information on handling unknown value types.

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3.5.2.  Multi-value Parameters

   In [RFC5545], some parameters allow using a COMMA-separated list of
   values.  To ease processing in jCal, the value to such parameters
   MUST be represented in an array containing the separated values.  The
   array elements MUST be string values.  Single-value parameters can be
   represented either using a single string value or an array with one
   string element.  A jCal parser MUST be able to understand both value
   data types.  An example for a such parameter is the iCalendar
   "DELEGATED-FROM" and "DELEGATED-TO" parameter, more such parameters
   may be added in extensions.

   The iCalendar specification requires encapsulation between DQUOTE
   characters if a parameter value contains a colon, a semicolon or a
   comma.  These extra DQUOTE characters do not belong to the actual
   parameter value, and hence are not included when the parameter is
   converted to jCal.

   Example 1:

   ["attendee",
    {
      "delegated-to": ["mailto:jdoe@example.org",
                       "mailto:jqpublic@example.org"]
    },
    "cal-address",
    "mailto:jsmith@example.org"
   ]

   Example 2:

   ["attendee",
    {
      "delegated-to": "mailto:jdoe@example.org"
    },
    "cal-address",
    "mailto:jsmith@example.org"
   ]

3.6.  Values (RFC5545 section 3.3)

   The following subsections specify how iCalendar property value data
   types, which are defined in the subsections of [RFC5545] Section 3.3,
   are represented in jCal.

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3.6.1.  Binary (RFC5545 section 3.3.1)

   Description:  iCalendar "BINARY" property values are represented by a
      property with type identifier "binary".  The value element is a
      JSON string with base64 encoded data, conforming to Section 4 of
      [RFC4648], which is the base64 method used in [RFC5545].

   Example:

   ["attach", {}, "binary", "SGVsbG8gV29ybGQh"]

3.6.2.  Boolean (RFC5545 section 3.3.2)

   Description:  iCalendar "BOOLEAN" property values are represented by
      a property with the type identifier "boolean".  The value is a
      JSON boolean value.

   Example:

   ["x-non-smoking", {}, "boolean", true]

3.6.3.  Calendar User Address (RFC5545 section 3.3.3)

   Description:  iCalendar "CAL-ADDRESS" property values are represented
      by a property with the type identifier "cal-address".  The value
      is a JSON string with the URI as described in [RFC3986].

   Example:

   ["attendee", {}, "cal-address", "mailto:kewisch@example.com"]

3.6.4.  Date (RFC5545 section 3.3.4)

   Description:  iCalendar "DATE" property values are represented by a
      property with the type identifier "date".  The value elements are
      JSON strings with the same date value specified by [RFC5545], but
      represented using the extended format of the complete
      representation specified in [ISO.8601.2004], Section 4.1.2.2.
      Other variations, for example representation with reduced
      accuracy, MUST NOT be used.

   ABNF Schema:

   date = year "-" month "-" day ;YYYY-MM-DD

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   Example:

   ["dtstart", {}, "date", "2011-05-17"]

3.6.5.  Date-Time (RFC5545 section 3.3.5)

   Description:  iCalendar "DATE-TIME" property values are represented
      by a property with the type identifier "date-time".  The value
      elements are JSON strings with the same date value specified by
      [RFC5545], but represented using the extended format of the
      complete representation specified in [ISO.8601.2004],
      Section 4.3.2.  Other variations, for example representation with
      reduced accuracy, MUST NOT be used.  The same restrictions with
      respect to leap seconds and timezone offsets as specified in
      [RFC5545] Section 3.3.5 apply.

   ABNF Schema:

   date-complete = year "-" month "-" day ;YYYY-MM-DD
   time-complete =  hour ":" minute ":" second [zone] ; HH:MM:SS
   datetime = date-complete "T" time-complete

   Examples:

   ["dtstart", {}, "date-time", "2012-10-17T12:00:00"],
   ["dtstamp", {}, "date-time", "2012-10-17T12:00:00Z"],
   ["dtend",
    { "tzid": "Europe/Berlin" },
    "date-time",
    "2011-10-17T13:00:00"
   ]

3.6.6.  Duration (RFC5545 section 3.3.6)

   Description:  iCalendar "DURATION" property values are represented by
      a property with the type identifier "duration".  The value
      elements are JSON strings with the same duration value specified
      by [RFC5545].

   Example:

   ["duration", {}, "duration", "P1D"]

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3.6.7.  Float (RFC5545 section 3.3.7)

   Description:  iCalendar "FLOAT" property values are represented by a
      property with the type identifier "float".  The value elements are
      JSON primitive number values.

   Example:

   ["x-grade", {}, "float", 1.3]

3.6.8.  Integer (RFC5545 section 3.3.8)

   Description:  vCard "INTEGER" property values are represented by a
      property with the type identifier "integer".  The value elements
      are JSON primitive number values which MUST resolve to an integer
      value in the range specified in [RFC5545], Section 3.3.8.  Thus a
      fractional and/or exponential part are only allowed under limited
      circumstances.

   Examples:

   ["percent-complete", {}, "integer", 42]

3.6.9.  Period of Time (RFC5545 section 3.3.9)

   Description:  iCalendar "PERIOD" property values are represented by a
      jCal property with the type identifier "period".  The value
      element is an array of JSON strings, with the first element
      representing the start of the period and the second element
      representing the end of the period.  As in [RFC5545], the start of
      the period is always formatted as a date-time value and the end of
      the period MUST be either a date-time or duration value.  Any
      date, date-time or duration values contained in the period value
      MUST be formatted in accordance to the rules for date, date-time
      or duration values specified in this document.

   Example:

   ["freebusy",
    { "fbtype": "FREE" },
    "period",
    ["1997-03-08T16:00:00Z", "P1D"]
   ]

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3.6.10.  Recurrence Rule (RFC5545 section 3.3.10)

   Description:  iCalendar "RECUR" property values are represented by a
      property with the type identifier "recur".  The value elements are
      objects describing the structured data as specified by [RFC5545].
      Each rule part is described by the combination of key and value.
      The key specifies the name of the rule part and MUST be converted
      to lowercase.  The value of the rule part MUST be mapped by the
      following rules:

      *  The value of the "freq" and "wkst" rule parts MUST be a string
         as specified in [RFC5545], with case preserved.

      *  The value of the "until" rule part MUST be a date or date-time
         value formatted in accordance to the rules for date or date-
         time specified in this document.

      *  The "count" and "interval" rule parts MUST be specified as a
         single JSON number value.

      *  The following rule parts can have one or more numeric values:
         "bysecond", "byminute", "byhour", "bymonthday", "byyearday",
         "byweekno", "bymonth", and "bysetpos".  If a rule part contains
         multiple values, an array of numbers MUST be used for that rule
         part.  Single-valued rule parts can be represented either using
         a single number value, omitting the array completely, or an
         array with one number element.  A jCal parser MUST be able to
         understand both data types.

      *  Similarly, the "byday" rule part can have one or more string
         values.  If it contains multiple values, an array of strings
         MUST be used.  As before, a single-valued rule part can be
         represented either using a single string value or an array with
         one string element, both of which a jCal parser MUST be able to
         understand.

   Example 1:

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   ["rrule",
    {},
    "recur",
    {
      "freq": "YEARLY",
      "count": 5,
      "byday": [ "-1SU", "2MO" ],
      "bymonth": 10
    }
   ]

   Example 2:

   ["rrule",
    {},
    "recur",
    {
      "freq": "MONTHLY",
      "interval": 2,
      "bymonthday": [ 1, 15, -1 ],
      "until": "2013-10-01"
    }
   ]

3.6.11.  Text (RFC5545 section 3.3.11)

   Description:  iCalendar "TEXT" property values are represented by a
      property with the type identifier "text".  The value elements are
      JSON strings.

   Example:

   ["comment", {}, "text", "hello, world"]

3.6.12.  Time (RFC5545 section 3.3.12)

   Description:  iCalendar "TIME" property values are represented by a
      property with the type identifier "time".  The value elements are
      JSON strings with the same time value specified by [RFC5545], but
      represented using the extended format of the complete
      representation specified in [ISO.8601.2004], Section 4.2.2.2.
      Other variations, for example representation with reduced
      accuracy, MUST NOT be used.  The same restrictions with respect to
      leap seconds, time fractions, and timezone offsets as specified in
      [RFC5545] Section 3.3.12 apply.

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   ABNF Schema:

   time-complete =  hour ":" minute ":" second [zone] ; HH:MM:SS

   Example:

   ["x-time-local", {}, "time", "12:30:00"],
   ["x-time-utc", {}, "time", "12:30:00Z"],
   ["x-time-offset", { "tzid": "Europe/Berlin" }, "time", "12:30:00"]

3.6.13.  URI (RFC5545 section 3.3.13)

   Description:  iCalendar "URI" property values are represented by a
      property with the type identifier "uri".  The value elements are
      JSON strings representing the URI.

   Example:

   ["tzurl", {}, "uri", "http://example.org/tz/Europe-Berlin.ics"]

3.6.14.  UTC Offset (RFC5545 section 3.3.14)

   Description:  iCalendar "UTC-OFFSET" property values are represented
      by a property with the type identifier "utc-offset".  The value
      elements are JSON strings with the same UTC offset value specified
      by [RFC5545], with the exception that the hour and minute
      components are separated by a ":" character, for consistency with
      the [ISO.8601.2004] timezone offset, extended format.

   Example:

   ["tzoffsetfrom", {}, "utc-offset", "-05:00"],
   ["tzoffsetto", {}, "utc-offset", "+12:45"]

3.7.  Extensions

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   iCalendar extension properties and property parameters (those with an
   "X-" prefix in their name) are handled in the same way as other
   properties and property parameters: the property is represented by an
   array, the property parameter represented by an object.  The property
   or parameter name uses the same name as for the iCalendar extension,
   but in lowercase.  For example, the "X-FOO" property in iCalendar
   turns into the "x-foo" jCal property.  See Section 5 for how to deal
   with default values for unrecognized extension properties or property
   parameters.

4.  Converting from jCal into iCalendar

   When converting component, property and property parameter values,
   the names SHOULD be converted to uppercase.  Although iCalendar names
   are case insensitive, common practice is to keep them all uppercase
   following the actual definitions in [RFC5545].

   Character escaping and line folding MUST be applied to the resulting
   iCalendar data as required by [RFC5545] and [RFC6868].

   Non-binary value types MUST NOT be base64 encoded.

   When converting to iCalendar, the VALUE parameter MUST be added to
   properties whose default value type is unknown, but do not have a
   jCal type identifier "unknown".  The VALUE parameter MAY be omitted
   for properties using the default value type.  The VALUE parameter
   MUST be omitted for properties which have the jCal type identifier
   "unknown".

5.  Handling Unrecognized Properties or Parameters

   In iCalendar, properties can have one or more value types as
   specified by their definition, with one of those values being defined
   as the default.  When a property uses its default value type, the
   "VALUE" property parameter does not need to be specified on the
   property.  For example, "DTSTART"'s default value type is "DATE-
   TIME", so "VALUE=DATE-TIME" need not be set as a property parameter.
   However, "DTSTART" also allows a "DATE" value to be specified, and if
   that is used, "VALUE=DATE" has to be set as a property parameter.

   When new properties are defined or "X-" properties used, an iCalendar
   to jCal converter might not recognize them, and not know what the
   appropriate default value types are, yet they need to be able to
   preserve the values.  A similar issue arises for unrecognized
   property parameters.

   In jCal, a new "unknown" property value type is introduced.  Its
   purpose is to allow preserving unknown property values when round-

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   tripping between jCal and iCalendar.  To avoid collisions, this
   specification reserves the UNKNOWN property value type in iCalendar.
   It MUST NOT be used in any iCalendar as specified by [RFC5545], nor
   any extensions to it.  The type is hence registered to the iCalendar
   Value Data Types registry in Section 7.1.

5.1.  Converting iCalendar into jCal

   Any property that does not include a "VALUE" property parameter and
   whose default value type is not known, MUST be converted to a
   primitive JSON string.  The content of that string is the unprocessed
   value text.  Also, value type MUST be set to "unknown".

   To correctly implement this format, it is critical that if the
   default type is not known that the type "unknown" is used.  If this
   requirement is ignored and for example "text" is used, additional
   escaping may occur which breaks round-tripping values.

   Any unrecognized property parameter MUST be converted to a string
   value, with its content set to the property parameter value text,
   treated as if it were a "TEXT" value.

5.2.  Converting jCal into iCalendar

   In jCal the value type is always explicitly specified.  It is
   converted to iCalendar using the iCalendar VALUE parameter, except in
   the following two cases:

   o  If the value type specified in jCal matches the default value type
      in iCalendar, the VALUE parameter MAY be omitted.

   o  If the value type specified in jCal is set to "unknown", the VALUE
      parameter MUST NOT be specified.  The value MUST be taken over in
      iCalendar without processing.

5.3.  Examples

   The following is an example of an unrecognized iCalendar property
   (that uses a "DATE-TIME" value as its default), and the equivalent
   jCal representation of that property.

   iCalendar:

   X-COMPLAINT-DEADLINE:20110512T120000Z

   jCal:

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   ["x-complaint-deadline", {}, "unknown", "20110512T120000Z"]

   The following is an example of how to cope with jCal data where the
   parser was unable to identify the type.  Note how the "unknown" value
   type is not added to the iCalendar data and escaping, aside from
   standard JSON string escaping, is not processed.

   jCal:

   ["x-coffee-data", {}, "unknown", "Stenophylla;Guinea\\,Africa"]

   iCalendar:

   X-COFFEE-DATA:Stenophylla;Guinea\,Africa

   The following is an example of a jCal property (where the
   corresponding iCalendar property uses a "INTEGER" value as its
   default), and the equivalent iCalendar representation of that
   property.

   jCal:

   ["percent-complete", {}, "integer", 95]

   iCalendar:

   PERCENT-COMPLETE:95

   The following is an example of an unrecognized iCalendar property
   parameter (that uses a "FLOAT" value as its default) specified on a
   recognized iCalendar property, and the equivalent jCal representation
   of that property and property parameter.

   iCalendar:

   DTSTART;X-SLACK=30.3;VALUE=DATE:20110512

   jCal:

   ["dtstart", { "x-slack": "30.3" }, "date", "2011-05-12"]

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6.  Security Considerations

   This specification defines how iCalendar data can be "translated"
   between two different data formats - the original text format and
   JSON - with a one-to-one mapping to ensure all the semantic data in
   one format (properties, parameters and values) are preserved in the
   other.  It does not change the semantic meaning of the underlying
   data itself, or impose or remove any security considerations that
   apply to the underlying data.

   The use of JSON as a format does have its own inherent security risks
   as discussed in Section 7 of [RFC4627].  Even though JSON is
   considered a safe subset of JavaScript, it should be kept in mind
   that a flaw in the parser processing JSON could still impose a threat
   which doesn't arise with conventional iCalendar data.

   With this in mind, a parser for JSON data should be used for jCal
   that is aware of the security implications.  For example, the use of
   JavaScript's eval() function is only allowed using the regular
   expression in Section 6 of [RFC4627].  A native parser with full
   awareness of the JSON format should be preferred.

   In addition, it is expected that this new format will result in
   iCalendar data being more widely disseminated (e.g., with use in web
   applications rather than just dedicated calendaring applications).

   In all cases, application developers have to conform to the semantics
   of the iCalendar data as defined by [RFC5545] and associated
   extensions, and all of the security considerations described in
   Section 7 of [RFC5545], or any associated extensions, are applicable.

7.  IANA Considerations

   This document defines a MIME media type for use with iCalendar in
   JSON data.  This media type SHOULD be used for the transfer of
   calendaring data in JSON.

   Type name:  application

   Subtype name:  calendar+json

   Required parameters:  none

   Optional parameters:  "method", "component" and "optinfo" as defined
      for the text/calendar media type in [RFC5545], Section 8.1.

   Encoding considerations:  Same as encoding considerations of
      application/json as specified in [RFC4627], Section 6.

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   Security considerations:  See Section 6.

   Interoperability considerations:  This media type provides an
      alternative format for iCalendar data based on JSON.

   Published specification:  This specification.

   Applications which use this media type:  Applications that currently
      make use of the text/calendar media type can use this as an
      alternative.  Similarly, Applications that use the application/
      json media type to transfer calendaring data can use this to
      further specify the content.

   Fragment identifier considerations:  N/A

   Additional information:

      Deprecated alias names for this type:  N/A

      Magic number(s):  N/A

      File extension(s):  N/A

      Macintosh file type code(s):  N/A

   Person & email address to contact for further information:
      calsify@ietf.org

   Intended usage:  COMMON

   Restrictions on usage:  There are no restrictions on where this media
      type can be used.

   Author:  See the "Author's Address" section of this document.

   Change controller:  IETF

7.1.  UNKNOWN iCalendar Value Data Type

   IANA is asked to add the following entry to the iCalendar Data Types
   registry:

   Value name:  UNKNOWN

   Purpose:  To allow preserving property values whose default value
      type is not known during round-tripping between jCal and
      iCalendar.

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   Format definition:  (Not applicable)

   Description:  The UNKNOWN value data type is reserved for the
      exclusive use of the jCal format.  Its use is described in
      Section 5 of this document.

   Example:  As this registration serves as a reservation of the UNKNOWN
      type so that it is not used in iCalendar, there is no applicable
      iCalendar example.  Examples of its usage in jCal can be found in
      this document.

   IANA is asked to make the "Status" column for this entry in the
   registry say, "Reserved - Do not use" and to make the "Reference"
   column refer to Section 5 of this document.

8.  Acknowledgments

   The authors would like to thank the following for their valuable
   contributions: William Gill, Erwin Rehme, and Dave Thewlis, Simon
   Perreault, Michael Angstadt, Peter Saint-Andre, Bert Greevenbosch,
   Javier Godoy.  This specification originated from the work of the
   XML-JSON technical committee of the Calendaring and Scheduling
   Consortium.

9.  References

9.1.  Normative References

   [ISO.8601.2004]
              International Organization for Standardization, ""Data
              elements and interchange formats -- Information
              interchange -- Representation of dates and times" ", ISO
              8601, 12 2004.

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

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66, RFC
              3986, January 2005.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, October 2006.

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

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

   [RFC6321]  Daboo, C., Douglass, M., and S. Lees, "xCal: The XML
              Format for iCalendar", RFC 6321, August 2011.

   [RFC6868]  Daboo, C., "Parameter Value Encoding in iCalendar and
              vCard", RFC 6868, February 2013.

9.2.  Informative References

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627, July 2006.

   [RFC6982]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", RFC 6982, July
              2013.

   [calconnect-artifacts]
              The Calendaring and Scheduling Consortium, "Code Artifacts
              and Schemas", ,
              <http://www.calconnect.org/artifacts.shtml>.

Appendix A.  Implementation Status (to be removed prior to publication
             as an RFC, as well as the reference to RFC6982)

   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in [RFC6982].
   The description of implementations in this section is intended to
   assist the IETF in its decision processes in progressing drafts to
   RFCs.  Please note that the listing of any individual implementation
   here does not imply endorsement by the IETF.  Furthermore, no effort
   has been spent to verify the information presented here that was
   supplied by IETF contributors.  This is not intended as, and must not
   be construed to be, a catalog of available implementations or their
   features.  Readers are advised to note that other implementations may
   exist.

   According to [RFC6982], "this will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature.
   It is up to the individual working groups to use this information as
   they see fit".

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   1.  ICAL.js - Philipp Kewisch, James Lal.  A JavaScript parser for
       iCalendar (rfc5545)

       Source:  https://github.com/mozilla-comm/ical.js/

       Maturity:  production

       Coverage:  All aspects of this draft, up to version 01.  Includes
             an online validator.  (as of rev 847c67c501, 2013-02-14)

       Licensing:  MPL, Mozilla Public License 2.0

   2.  Py Calendar - Cyrus Daboo.  iCalendar/vCard Library

       Source:  https://svn.calendarserver.org/repository/calendarserver
             /PyCalendar/branches/json/

       Maturity:  production

       Coverage:  All aspects of this draft, up to version 01.

       Licensing:  Apache License, Version 2.0

   Additionally, interoperability testing of this draft is an ongoing
   effort under members of calconnect, the Calendaring and Scheduling
   Consortium.  CalDAV Vendors are looking into supporting this draft.

Appendix B.  ABNF Schema

   Below is an ABNF schema as per [RFC5234] for iCalendar in JSON.  ABNF
   Symbols not described here are taken from [RFC4627].  The schema is
   non-normative and given for reference only.

   The numeric section numbers given in the comments refer to section in
   [RFC5545].  Additional semantic restrictions apply, especially
   regarding the allowed properties and sub-components per component.
   Details on these restrictions can be found in this document and
   [RFC5545].

   Additional schemas may be available on the internet at
   [calconnect-artifacts].

   ; A jCal Object is a component with the component-name "vcalendar".
   ; Restrictions to which properties and sub-components may be
   ; specified are to be taken from RFC5545.
   jcalobject = component

   ; A jCal component consists of the name string, properties array and

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   ; component array
   component = begin-array
               DQUOTE component-name DQUOTE value-separator
               properties-array value-separator
               components-array
               end-array

   components-array = begin-array
                      [ component *(value-separator component) ]
                      end-array

   ; A jCal property consists of the name string, parameters object,
   ; type string and one or more values as specified in this document.
   property = begin-array
              DQUOTE property-name DQUOTE value-separator
              params-object value-separator
              DQUOTE type-name DQUOTE
              propery-value *(value-separator property-value)
              end-array
   properties-array = begin-array
                      [ property *(value-separator property) ]
                      end-array

   ; Property values depend on the type-name. Aside from the value types
   ; mentioned here, extensions may make use of other JSON value types.
   ; The non-terminal symbol structured-prop-value covers the special
   ; cases for GEO and REQUEST-STATUS
   property-value = simple-prop-value / structured-prop-value
   simple-prop-value = string / number / true / false
   structured-prop-value =
       begin-array
       [ structured-element *(value-separator structured-element) ]
       end-array
   structured-element = simple-prop-value

   ; The jCal params-object is a JSON object which follows the semantic
   ; guidelines described in this document.
   params-object = begin-object
                   [ params-member *(value-separator params-member) ]
                   end-object
   params-member = DQUOTE param-name DQUOTE name-separator param-value
   param-value = string / param-multi
   param-multi = begin-array
                 [ string *(value-separtor string) ]
                 end-array

   ; The type MUST be a valid type as described by this document. New
   ; value types can be added by extensions.

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   type-name = "binary" / "boolean" / "cal-address" / "date" /
               "date-time" / "duration" / "float" / "integer" /
               "period" / "recur" / "text" / "time" / "uri" /
               "utc-offset" / x-type

   ; Component, property, parameter and type names MUST be lowercase.
   ; Additional semantic restrictions apply as described by this
   ; document and RFC5545.
   component-name = lowercase-name
   property-name = lowercase-name
   param-name = lowercase-name
   x-type = lowercase-name
   lowercase-name = 1*(%x61-7A / DIGIT / "-")

Appendix C.  Examples

   This section contains two examples of iCalendar objects with their
   jCal representation.

C.1.  Example 1

C.1.1.  iCalendar Data

   BEGIN:VCALENDAR
   CALSCALE:GREGORIAN
   PRODID:-//Example Inc.//Example Calendar//EN
   VERSION:2.0
   BEGIN:VEVENT
   DTSTAMP:20080205T191224Z
   DTSTART:20081006
   SUMMARY:Planning meeting
   UID:4088E990AD89CB3DBB484909
   END:VEVENT
   END:VCALENDAR

C.1.2.  jCal Data

   ["vcalendar",
     [
       ["calscale", {}, "text", "GREGORIAN"],
       ["prodid", {}, "text", "-//Example Inc.//Example Calendar//EN"],
       ["version", {}, "text", "2.0"]
     ],
     [
       ["vevent",

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         [
           ["dtstamp", {}, "date-time", "2008-02-05T19:12:24Z"],
           ["dtstart", {}, "date", "2008-10-06"],
           ["summary", {}, "text", "Planning meeting"],
           ["uid", {}, "text", "4088E990AD89CB3DBB484909"]
         ],
         []
       ]
     ]
   ]

C.2.  Example 2

C.2.1.  iCalendar Data

   BEGIN:VCALENDAR
   VERSION:2.0
   PRODID:-//Example Corp.//Example Client//EN
   BEGIN:VTIMEZONE
   LAST-MODIFIED:20040110T032845Z
   TZID:US/Eastern
   BEGIN:DAYLIGHT
   DTSTART:20000404T020000
   RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
   TZNAME:EDT
   TZOFFSETFROM:-0500
   TZOFFSETTO:-0400
   END:DAYLIGHT
   BEGIN:STANDARD
   DTSTART:20001026T020000
   RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
   TZNAME:EST
   TZOFFSETFROM:-0400
   TZOFFSETTO:-0500
   END:STANDARD
   END:VTIMEZONE
   BEGIN:VEVENT
   DTSTAMP:20060206T001121Z
   DTSTART;TZID=US/Eastern:20060102T120000
   DURATION:PT1H
   RRULE:FREQ=DAILY;COUNT=5
   RDATE;TZID=US/Eastern;VALUE=PERIOD:20060102T150000/PT2H
   SUMMARY:Event #2
   DESCRIPTION:We are having a meeting all this week at 12 pm fo
    r one hour\, with an additional meeting on the first day 2 h
    ours long.\nPlease bring your own lunch for the 12 pm meetin
    gs.

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   UID:00959BC664CA650E933C892C@example.com
   END:VEVENT
   BEGIN:VEVENT
   DTSTAMP:20060206T001121Z
   DTSTART;TZID=US/Eastern:20060104T140000
   DURATION:PT1H
   RECURRENCE-ID;TZID=US/Eastern:20060104T120000
   SUMMARY:Event #2 bis
   UID:00959BC664CA650E933C892C@example.com
   END:VEVENT
   END:VCALENDAR

C.2.2.  jCal Data

   ["vcalendar",
     [
       ["prodid", {}, "text", "-//Example Corp.//Example Client//EN"],
       ["version", {}, "text", "2.0"]
     ],
     [
       ["vtimezone",
         [
           ["last-modified", {}, "date-time", "2004-01-10T03:28:45Z"],
           ["tzid", {}, "text", "US/Eastern"]
         ],
         [
           ["daylight",
             [
               ["dtstart", {}, "date-time", "2000-04-04T02:00:00"],
               ["rrule",
                 {},
                 "recur",
                 {
                   "freq": "YEARLY",
                   "byday": "1SU",
                   "bymonth": 4
                 }
               ],
               ["tzname", {}, "text", "EDT"],
               ["tzoffsetfrom", {}, "utc-offset", "-05:00"],
               ["tzoffsetto", {}, "utc-offset", "-04:00"]
             ],
             []
           ],
           ["standard",
             [
               ["dtstart", {}, "date-time", "2000-10-26T02:00:00"],

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               ["rrule",
                 {},
                 "recur",
                 {
                   "freq": "YEARLY",
                   "byday": "1SU",
                   "bymonth": 10
                 }
               ],
               ["tzname", {}, "text", "EST"],
               ["tzoffsetfrom", {}, "utc-offset", "-04:00"],
               ["tzoffsetto", {}, "utc-offset", "-05:00"]
             ],
             []
           ]
         ]
       ],
       ["vevent",
         [
           ["dtstamp", {}, "date-time", "2006-02-06T00:11:21Z"],
           ["dtstart",
             { "tzid": "US/Eastern" },
             "date-time",
             "2006-01-02T12:00:00"
           ],
           ["duration", {}, "duration", "PT1H"],
           ["rrule", {}, "recur", { "freq": "DAILY", "count": 5 } ],
           ["rdate",
             { "tzid": "US/Eastern" },
             "period",
             "2006-01-02T15:00:00/PT2H"
           ],
           ["summary", {}, "text", "Event #2"],
           ["description",
            {},
            "text",
            // Note that comments and string concatenation are not
            // allowed per JSON specification and is used here only
            // to avoid long lines.
            "We are having a meeting all this week at 12 pm for one " +
            "hour, with an additional meeting on the first day 2 " +
            "hours long.\nPlease bring your own lunch for the 12 pm " +
            "meetings."
           ],
           ["uid", {}, "text", "00959BC664CA650E933C892C@example.com"]
         ],
         []
       ],

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       ["vevent",
         [
           ["dtstamp", {}, "date-time", "2006-02-06T00:11:21Z"],
           ["dtstart",
             { "tzid": "US/Eastern" },
             "date-time",
             "2006-01-02T14:00:00"
           ],
           ["duration", {}, "duration", "PT1H"],
           ["recurrence-id",
             { "tzid": "US/Eastern" },
             "date-time",
             "2006-01-04T12:00:00"
           ],
           ["summary", {}, "text", "Event #2"],
           ["uid", {}, "text", "00959BC664CA650E933C892C@example.com"]
         ],
         []
       ]
     ]
   ]

Appendix D.  Change History (to be removed prior to publication as an
             RFC)

   draft-kewisch-et-al-icalendar-in-json-01

      *  Added information on how to handle multi-value parameter.  The
         decision leads to a cleaner draft for a similar proposal for
         vcard.

      *  Removed the open discussion point section regarding the mime
         media type in favor of adding one.

      *  Minor corrections in wording and typo fixes.

   draft-kewisch-et-al-icalendar-in-json-02

      *  Added implementation status section.

      *  Removed various text tables that just show a conversion from
         uppercase to lowercase.

      *  Changed value format for RECUR and PERIOD types

      *  Minor corrections in wording and typo fixes.

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   draft-ietf-jcardcal-jcal-00

      *  Publication as a WG draft

   draft-ietf-jcardcal-jcal-01

      *  Changed handling of GEO and REQUEST-STATUS to align with jCard

      *  Corrections and additions to the ABNF Section

      *  Added a further sentence on preprocessing and escaping to
         clarify that JSON escaping must be used.

   draft-ietf-jcardcal-jcal-02

      *  Changed handling of unknown property parameter types.

      *  Minor corrections and fixing typos.

   draft-ietf-jcardcal-jcal-03

      *  Changed wording around RECUR value handling.

      *  Minor corrections and fixing typos.

   draft-ietf-jcardcal-jcal-04

      *  Changed wording around RECUR value handling again.

   draft-ietf-jcardcal-jcal-05

      *  Added reference to rfc6868 for both directions

      *  Resolved a few MAY/SHOULD conflicts

      *  Improved UNKNOWN registration by only putting iCalendar related
         information into the registration template.

      *  Removed the stream construct, replaced with general information
         on how to handle iCalendar streams.

      *  Corrected some examples and ABNF

   draft-ietf-jcardcal-jcal-06

      *  Corrected trailing commas in some examples.

      *  Corrected rrule examples to use object syntax.

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      *  Corrected "request-status" example to use an array.

      *  Updated UNKNOWN registration text as per iCalendar expert
         suggestion.

   draft-ietf-jcardcal-jcal-07

      *  Minor fix in an example.

   draft-ietf-jcardcal-jcal-08

      *  Editorial changes for alignment with draft-ietf-jcardcal-jcard.

   draft-ietf-jcardcal-jcal-09

      *  Editorial changes in preparation for IETF last call.

      *  Removed reference to jcard draft

      *  Made more clear that parsers MUST be able to understand both
         single-valued and array data types.

Authors' Addresses

   Philipp Kewisch
   Mozilla Corporation
   650 Castro Street, Suite 300
   Mountain View, CA  94041
   USA

   EMail: mozilla@kewis.ch
   URI:   http://www.mozilla.org/

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

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

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   Mike Douglass
   Rensselaer Polytechnic Institute
   110 8th Street
   Troy, NY  12180
   USA

   EMail: douglm@rpi.edu
   URI:   http://www.rpi.edu/

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