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rfc:rfc6321

Internet Engineering Task Force (IETF) C. Daboo Request for Comments: 6321 Apple, Inc. Category: Standards Track M. Douglass ISSN: 2070-1721 RPI

                                                               S. Lees
                                                             Microsoft
                                                           August 2011
                 xCal: The XML Format for iCalendar

Abstract

 This specification defines "xCal", an XML format for iCalendar data.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6321.

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
 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.

Daboo, et al. Standards Track [Page 1] RFC 6321 xCal August 2011

Table of Contents

 1. Introduction ....................................................3
 2. Conventions Used in This Document ...............................4
 3. Converting from iCalendar to xCal ...............................4
    3.1. Pre-Processing .............................................4
    3.2. iCalendar Stream (RFC 5545, Section 3.4) ...................5
    3.3. Components (RFC 5545, Section 3.6) .........................6
    3.4. Properties (RFC 5545, Sections 3.7 and 3.8) ................6
         3.4.1. Special Cases for Properties ........................8
                3.4.1.1. Multi-Valued Properties ....................8
                3.4.1.2. GEO Property ...............................9
                3.4.1.3. REQUEST-STATUS Property ....................9
    3.5. Parameters (RFC 5545, Section 3.2) ........................10
         3.5.1. VALUE Parameter ....................................11
    3.6. Values (RFC 5545, Section 3.3) ............................11
         3.6.1. Binary (RFC 5545, Section 3.3.1) ...................12
         3.6.2. Boolean  (RFC 5545, Section 3.3.2) .................12
         3.6.3. Calendar User Address (RFC 5545, Section 3.3.3) ....12
         3.6.4. Date (RFC 5545, Section 3.3.4) .....................12
         3.6.5. Date-Time (RFC 5545, Section 3.3.5) ................13
         3.6.6. Duration (RFC 5545, Section 3.3.6) .................13
         3.6.7. Float (RFC 5545, Section 3.3.7) ....................13
         3.6.8. Integer (RFC 5545, Section 3.3.8) ..................14
         3.6.9. Period of Time (RFC 5545, Section 3.3.9) ...........14
         3.6.10. Recurrence Rule (RFC 5545, Section 3.3.10) ........14
         3.6.11. Text (RFC 5545, Section 3.3.11) ...................15
         3.6.12. Time (RFC 5545, Section 3.3.12) ...................15
         3.6.13. URI (RFC 5545, Section 3.3.13) ....................15
         3.6.14. UTC Offset (RFC 5545, Section 3.3.14) .............16
    3.7. Extensions ................................................16
 4. Converting from xCal into iCalendar ............................16
    4.1. Converting XML Extensions into iCalendar ..................16
    4.2. The XML Property for iCalendar ............................17
 5. Handling Unrecognized Properties or Parameters .................18
 6. Security Considerations ........................................19
 7. IANA Considerations ............................................20
    7.1. Namespace Registration ....................................20
    7.2. Media Type ................................................20
    7.3. iCalendar Property Registrations ..........................21
 8. Acknowledgments ................................................22
 9. References .....................................................22
    9.1. Normative References ......................................22
    9.2. Informative References ....................................22

Daboo, et al. Standards Track [Page 2] RFC 6321 xCal August 2011

 Appendix A. RELAX NG Schema .......................................23
 Appendix B. Examples ..............................................49
   B.1. Example 1 ..................................................49
     B.1.1. iCalendar Data .........................................49
     B.1.2. XML Data ...............................................49
   B.2. Example 2 ..................................................50
     B.2.1. iCalendar Data .........................................50
     B.2.2. XML Data ...............................................51

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, XML-based formats are widely used for interoperability
 between applications, and the many tools that generate, parse, and
 manipulate XML make it easier to work with than iCalendar.
 The purpose of this specification is to define "xCal", an XML format
 for iCalendar data. xCal is defined as a straightforward mapping into
 XML from iCalendar, so that iCalendar data can be converted to XML,
 and then back to iCalendar, without losing any semantic meaning in
 the data.  Anyone creating xCal calendar data according to this
 specification will know that their data can be converted to a valid
 iCalendar representation as well.
 Key design considerations are:
    Round-tripping (converting an iCalendar instance to xCal and back)
    will give the same semantic result as the starting point.  That
    is, all components, properties, and property parameters are
    guaranteed to be preserved, with the exception of those that have
    default values.
    xCal preserves the semantics of the iCalendar data.  While a
    simple consumer can easily browse the calendar data in xCal, a
    full understanding of iCalendar is still required in order to
    modify and/or fully comprehend the calendar data.
    xCal has the ability to handle many extensions to the underlying
    iCalendar specification without requiring an update to this
    document.

Daboo, et al. Standards Track [Page 3] RFC 6321 xCal August 2011

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].
 When XML element types in the namespace
 "urn:ietf:params:xml:ns:icalendar-2.0" are referenced in this
 document outside of the context of an XML fragment, the string "IC:"
 will be prefixed to the element types.
 Some examples in this document contain "partial" XML 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 xCal

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

3.1. Pre-Processing

 iCalendar uses a line folding mechanism to limit lines of data to a
 maximum line length (typically 72 characters) to ensure maximum
 likelihood of preserving data integrity as it is transported via
 various means (e.g., email) -- see Section 3.1 of [RFC5545].  Prior
 to converting iCalendar data into xCal, all folded lines MUST be
 unfolded.
 iCalendar data uses an "escape" character sequence for text values
 and property parameter values.  When such text elements are converted
 into xCal, the escaping MUST be removed.
 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 MUST be 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 are used, they MUST conform to
 Section 4 of [RFC4648], which is the base64 method used in [RFC5545].

Daboo, et al. Standards Track [Page 4] RFC 6321 xCal August 2011

 One key difference in the formatting of values used in iCalendar and
 xCal is that, in xCal, the specification uses date/time and UTC
 offset values aligned with the syntax of
 [W3C.REC-xmlschema-2-20041028] to aid with XML processing.

3.2. iCalendar Stream (RFC 5545, Section 3.4)

 At the top level of the iCalendar object model is an "iCalendar
 stream".  This object encompasses multiple "iCalendar objects".  In
 xCal, the entire stream is contained in the root IC:icalendar XML
 element.
 An iCalendar stream can contain one or more iCalendar objects.  Each
 iCalendar object, delimited by "BEGIN:VCALENDAR" and "END:VCALENDAR",
 is enclosed by the IC:vcalendar XML element.
 Example:
 <?xml version="1.0" encoding="utf-8"?>
 <icalendar xmlns="urn:ietf:params:xml:ns:icalendar-2.0">
   <vcalendar>
   ...
   </vcalendar>
 </icalendar>
 iCalendar objects are comprised of a set of "components",
 "properties", "parameters", and "values".  A "component" can contain
 other "components" or "properties".  A "property" has a value and a
 set of zero or more "parameters".
 In xCal, component elements, for example, IC:vevent and IC:vtodo, are
 contained within an IC:components XML element.  Within the component
 element, another IC:components element could appear (representing
 components nested within components) or the IC:properties XML element
 could appear.  IC:properties is used to encapsulate iCalendar
 properties.
 Each iCalendar property will be mapped to its own XML element as
 described below.  Within each of these elements, there is zero or one
 IC:parameters XML element used to encapsulate any iCalendar property
 parameters.  Additionally there will be one or more XML elements
 representing the value of the iCalendar property.

Daboo, et al. Standards Track [Page 5] RFC 6321 xCal August 2011

 Example:
 <?xml version="1.0" encoding="utf-8"?>
 <icalendar xmlns="urn:ietf:params:xml:ns:icalendar-2.0">
   <vcalendar>
     <properties>
     ...
     </properties>
     <components>
     ...
     </components>
   </vcalendar>
 </icalendar>
        +------------------+--------------+------------------+
        | Item             | XML element  | XML Definition   |
        +------------------+--------------+------------------+
        | iCalendar Stream | IC:icalendar | Appendix A # 3.4 |
        | VCALENDAR        | IC:vcalendar | Appendix A # 3.6 |
        +------------------+--------------+------------------+

3.3. Components (RFC 5545, Section 3.6)

 Each calendar component in the "VCALENDAR" object, delimited by
 "BEGIN" and "END", will be converted to an enclosing XML element with
 the same name, but in lowercase.  As an example, the table below
 shows iCalendar-to-xCal mappings for current iCalendar components.
 Any new iCalendar components added in the future will be converted in
 the same way.
           +-----------+--------------+--------------------+
           | Component | XML element  | XML Definition     |
           +-----------+--------------+--------------------+
           | VEVENT    | IC:vevent    | Appendix A # 3.6.1 |
           | VTODO     | IC:vtodo     | Appendix A # 3.6.2 |
           | VJOURNAL  | IC:vjournal  | Appendix A # 3.6.3 |
           | VFREEBUSY | IC:vfreebusy | Appendix A # 3.6.4 |
           | VTIMEZONE | IC:vtimezone | Appendix A # 3.6.5 |
           | STANDARD  | IC:standard  | Appendix A # 3.6.5 |
           | DAYLIGHT  | IC:daylight  | Appendix A # 3.6.5 |
           | VALARM    | IC:valarm    | Appendix A # 3.6.6 |
           +-----------+--------------+--------------------+

3.4. Properties (RFC 5545, Sections 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 xCal format.

Daboo, et al. Standards Track [Page 6] RFC 6321 xCal August 2011

 iCalendar properties are enclosed in the XML element IC:properties.
 Each individual iCalendar property is represented in xCal by an
 element of the same name as the iCalendar property, but in lowercase.
 For example, the "CALSCALE" property is represented in xCal by the
 IC:calscale element.
 Example:
 <?xml version="1.0" encoding="utf-8"?>
 <icalendar xmlns="urn:ietf:params:xml:ns:icalendar-2.0">
   <vcalendar>
     <properties>
       <calscale>...</calscale>
       <version>...</version>
       <prodid>...</prodid>
     </properties>
     <components>
     ...
     </components>
   </vcalendar>
 </icalendar>
 Each property can contain an IC:parameters XML element encapsulating
 any iCalendar property parameters associated with the iCalendar
 property.
 Each property will contain one or more "value" XML elements as
 described below representing the value of the iCalendar property.
 As an example, the table below shows iCalendar-to-xCal mappings for
 current iCalendar properties.  Any new iCalendar properties added in
 the future will be converted in the same way.
  +------------------+---------------------+-----------------------+
  | Property         | XML element         | XML Definition        |
  +------------------+---------------------+-----------------------+
  | CALSCALE         | IC:calscale         | Appendix A # 3.7.1    |
  | METHOD           | IC:method           | Appendix A # 3.7.2    |
  | PRODID           | IC:prodid           | Appendix A # 3.7.3    |
  | VERSION          | IC:version          | Appendix A # 3.7.4    |
  | ATTACH           | IC:attach           | Appendix A # 3.8.1.1  |
  | CATEGORIES       | IC:categories       | Appendix A # 3.8.1.2  |
  | CLASS            | IC:class            | Appendix A # 3.8.1.3  |
  | COMMENT          | IC:comment          | Appendix A # 3.8.1.4  |
  | DESCRIPTION      | IC:description      | Appendix A # 3.8.1.5  |
  | GEO              | IC:geo              | Appendix A # 3.8.1.6  |
  | LOCATION         | IC:location         | Appendix A # 3.8.1.7  |

Daboo, et al. Standards Track [Page 7] RFC 6321 xCal August 2011

  | PERCENT-COMPLETE | IC:percent-complete | Appendix A # 3.8.1.8  |
  | PRIORITY         | IC:priority         | Appendix A # 3.8.1.9  |
  | RESOURCES        | IC:resources        | Appendix A # 3.8.1.10 |
  | STATUS           | IC:status           | Appendix A # 3.8.1.11 |
  | SUMMARY          | IC:summary          | Appendix A # 3.8.1.12 |
  | COMPLETED        | IC:completed        | Appendix A # 3.8.2.1  |
  | DTEND            | IC:dtend            | Appendix A # 3.8.2.2  |
  | DUE              | IC:due              | Appendix A # 3.8.2.3  |
  | DTSTART          | IC:dtstart          | Appendix A # 3.8.2.4  |
  | DURATION         | IC:duration         | Appendix A # 3.8.2.5  |
  | FREEBUSY         | IC:freebusy         | Appendix A # 3.8.2.6  |
  | TRANSP           | IC:transp           | Appendix A # 3.8.2.7  |
  | TZID             | IC:tzid             | Appendix A # 3.8.3.1  |
  | TZNAME           | IC:tzname           | Appendix A # 3.8.3.2  |
  | TZOFFSETFROM     | IC:tzoffsetfrom     | Appendix A # 3.8.3.3  |
  | TZOFFSETTO       | IC:tzoffsetto       | Appendix A # 3.8.3.4  |
  | TZURL            | IC:tzurl            | Appendix A # 3.8.3.5  |
  | ATTENDEE         | IC:attendee         | Appendix A # 3.8.4.1  |
  | CONTACT          | IC:contact          | Appendix A # 3.8.4.2  |
  | ORGANIZER        | IC:organizer        | Appendix A # 3.8.4.3  |
  | RECURRENCE-ID    | IC:recurrence-id    | Appendix A # 3.8.4.4  |
  | RELATED-TO       | IC:related-to       | Appendix A # 3.8.4.5  |
  | URL              | IC:url              | Appendix A # 3.8.4.6  |
  | UID              | IC:uid              | Appendix A # 3.8.4.7  |
  | EXDATE           | IC:exdate           | Appendix A # 3.8.5.1  |
  | RDATE            | IC:rdate            | Appendix A # 3.8.5.2  |
  | RRULE            | IC:rrule            | Appendix A # 3.8.5.3  |
  | ACTION           | IC:action           | Appendix A # 3.8.6.1  |
  | REPEAT           | IC:repeat           | Appendix A # 3.8.6.2  |
  | TRIGGER          | IC:trigger          | Appendix A # 3.8.6.3  |
  | CREATED          | IC:created          | Appendix A # 3.8.7.1  |
  | DTSTAMP          | IC:dtstamp          | Appendix A # 3.8.7.2  |
  | LAST-MODIFIED    | IC:last-modified    | Appendix A # 3.8.7.3  |
  | SEQUENCE         | IC:sequence         | Appendix A # 3.8.7.4  |
  | REQUEST-STATUS   | IC:request-status   | Appendix A # 3.8.8.3  |
  +------------------+---------------------+-----------------------+

3.4.1. Special Cases for Properties

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

3.4.1.1. Multi-Valued Properties

 The following iCalendar properties can have values that consist of a
 list of "standard" iCalendar values separated by a specific
 delimiter.  In xCal, these properties are represented by an XML
 element that contains multiple "value" elements (Section 3.6).

Daboo, et al. Standards Track [Page 8] RFC 6321 xCal August 2011

        +------------+---------------+-----------------------+
        | Property   | XML element   | XML Definition        |
        +------------+---------------+-----------------------+
        | CATEGORIES | IC:categories | Appendix A # 3.8.1.2  |
        | RESOURCES  | IC:resources  | Appendix A # 3.8.1.10 |
        | FREEBUSY   | IC:freebusy   | Appendix A # 3.8.2.6  |
        | EXDATE     | IC:exdate     | Appendix A # 3.8.5.1  |
        | RDATE      | IC:rdate      | Appendix A # 3.8.5.2  |
        +------------+---------------+-----------------------+

3.4.1.2. GEO Property

 In iCalendar, the "GEO" property value is defined as a semicolon-
 separated list of two "FLOAT" values; the first representing latitude
 and the second longitude.
 In xCal, the value for the IC:geo element is represented by two XML
 elements.  These are an IC:latitude element and an IC:longitude
 element, each of which contains float values.  See Appendix A #
 3.8.1.6.
 Example:
 <?xml version="1.0" encoding="utf-8"?>
 <icalendar xmlns="urn:ietf:params:xml:ns:icalendar-2.0">
   ...
   <geo>
     <latitude>37.386013</latitude>
     <longitude>-122.082932</longitude>
   </geo>
   ...
 </icalendar>

3.4.1.3. REQUEST-STATUS Property

 In iCalendar, the "REQUEST-STATUS" property value is defined as a
 semicolon-separated list of two or three "TEXT" values.  The first
 represents a code, the second a description, and the third any
 additional data.
 In xCal, the value for the IC:request-status element is represented
 by two or three XML elements.  These are an IC:code element, an IC:
 description element, and an IC:data element, each of which contains
 the corresponding "TEXT" values.  If there is no additional data in
 the iCalendar value, the IC:data element (which would be empty)
 SHOULD NOT be present.  See Appendix A # 3.8.8.3.

Daboo, et al. Standards Track [Page 9] RFC 6321 xCal August 2011

 Example:
 <?xml version="1.0" encoding="utf-8"?>
 <icalendar xmlns="urn:ietf:params:xml:ns:icalendar-2.0">
   ...
   <request-status>
     <code>2.0</code>
     <description>Success</description>
   </request-status>
   ...
 </icalendar>

3.5. Parameters (RFC 5545, Section 3.2)

 iCalendar property parameters are enclosed in the XML element IC:
 parameters, which occurs in each property XML element.  If there are
 no iCalendar property parameters, the IC:parameters element (which
 would be empty) SHOULD NOT be present.
 Each individual iCalendar property parameter is represented in xCal
 by an element of the same name as the iCalendar property parameter,
 but in lowercase.  For example, the "PARTSTAT" property parameter is
 represented in xCal by the IC:partstat element.
 Example:
 <?xml version="1.0" encoding="utf-8"?>
 <icalendar xmlns="urn:ietf:params:xml:ns:icalendar-2.0">
   <vcalendar>
     ...
     <components>
       ...
       <attendee>
         <parameters>
           <partstat><text>NEEDS-ACTION</text></partstat>
         </parameters>
         ...
       </attendee>
       ...
     </components>
   </vcalendar>
 </icalendar>
 Each XML parameter element contains one or more child XML elements
 representing iCalendar value types.

Daboo, et al. Standards Track [Page 10] RFC 6321 xCal August 2011

 As an example, the table below shows iCalendar-to-xCal mappings for
 current iCalendar parameters.  Any new iCalendar parameters added in
 the future will be converted in the same way.
     +----------------+-------------------+---------------------+
     | Parameter      | XML element       | XML Definition      |
     +----------------+-------------------+---------------------+
     | ALTREP         | IC:altrep         | Appendix A # 3.2.1  |
     | CN             | IC:cn             | Appendix A # 3.2.2  |
     | CUTYPE         | IC:cutype         | Appendix A # 3.2.3  |
     | DELEGATED-FROM | IC:delegated-from | Appendix A # 3.2.4  |
     | DELEGATED-TO   | IC:delegated-to   | Appendix A # 3.2.5  |
     | DIR            | IC:dir            | Appendix A # 3.2.6  |
     | ENCODING       | IC:encoding       | Appendix A # 3.2.7  |
     | FMTTYPE        | IC:fmttype        | Appendix A # 3.2.8  |
     | FBTYPE         | IC:fbtype         | Appendix A # 3.2.9  |
     | LANGUAGE       | IC:language       | Appendix A # 3.2.10 |
     | MEMBER         | IC:member         | Appendix A # 3.2.11 |
     | PARTSTAT       | IC:partstat       | Appendix A # 3.2.12 |
     | RANGE          | IC:range          | Appendix A # 3.2.13 |
     | RELATED        | IC:related        | Appendix A # 3.2.14 |
     | RELTYPE        | IC:reltype        | Appendix A # 3.2.15 |
     | ROLE           | IC:role           | Appendix A # 3.2.16 |
     | RSVP           | IC:rsvp           | Appendix A # 3.2.17 |
     | SENT-BY        | IC:sent-by        | Appendix A # 3.2.18 |
     | TZID           | IC:tzid           | Appendix A # 3.2.19 |
     +----------------+-------------------+---------------------+

3.5.1. VALUE Parameter

 iCalendar defines a "VALUE" property parameter (Section 3.2.20 of
 [RFC5545]).  This property parameter is not mapped to an xCal XML
 element.  Instead, the value type is handled by having different XML
 elements for each value, and these appear inside of property
 elements.  Thus, when converting from iCalendar to xCal, any "VALUE"
 property parameters are skipped.  When converting from xCal into
 iCalendar, the appropriate "VALUE" property parameter MUST be
 included in the iCalendar property if the value type is not the
 default value type for that property.

3.6. Values (RFC 5545, Section 3.3)

 In the typical case, iCalendar value types are mapped into XML
 elements with a matching name in all lowercase.  In the case of the
 value for a recurrence rule (see below), iCalendar defines
 "structured" values, and these are mapped into separate child
 elements for each value element.

Daboo, et al. Standards Track [Page 11] RFC 6321 xCal August 2011

3.6.1. Binary (RFC 5545, Section 3.3.1)

 Description:  iCalendar "BINARY" property values are represented by
    the IC:binary XML element.  The content of the element is base64
    encoded data, conforming to Section 4 of [RFC4648], which is the
    base64 method used in [RFC5545].  Whitespace MAY be inserted into
    the data at any point to "wrap" the data to reasonable line
    lengths.  When converting back to iCalendar, the whitespace MUST
    first be removed.
 XML Definition:  Appendix A # 3.3.1
 Example:
 <binary>SGVsbG8gV29ybGQh</binary>

3.6.2. Boolean (RFC 5545, Section 3.3.2)

 Description:  iCalendar "BOOLEAN" property values are represented by
    the IC:boolean XML element.  The content of the element is a
    boolean value.
 XML Definition:  Appendix A # 3.3.2
 Example:
 <boolean>true</boolean>

3.6.3. Calendar User Address (RFC 5545, Section 3.3.3)

 Description:  iCalendar "CAL-ADDRESS" property values are represented
    by the IC:cal-address XML element.  The content of the element is
    a URI.
 XML Definition:  Appendix A # 3.3.3
 Example:
 <cal-address>mailto:cyrus@example.com</cal-address>

3.6.4. Date (RFC 5545, Section 3.3.4)

 Description:  iCalendar "DATE" property values are represented by the
    IC:date XML element.  The content of the element is the same date
    value specified by [RFC5545], with the exception that the date
    components are separated by "-" characters, for consistency with
    [W3C.REC-xmlschema-2-20041028].

Daboo, et al. Standards Track [Page 12] RFC 6321 xCal August 2011

 XML Definition:  Appendix A # 3.3.4
 Example:
 <date>2011-05-17</date>

3.6.5. Date-Time (RFC 5545, Section 3.3.5)

 Description:  iCalendar "DATE-TIME" property values are represented
    by the IC:date-time XML element.  The content of the element is
    the same date-time value specified by [RFC5545], with the
    exception that the date components are separated by "-"
    characters, and the time components are separated by ":"
    characters, for consistency with [W3C.REC-xmlschema-2-20041028].
    Note that while [W3C.REC-xmlschema-2-20041028] allows for a UTC
    offset to be included in date/time values, xCal does not use that,
    and instead follows the iCalendar behavior of using time zone
    definitions via the "TZID" property parameter.
 XML Definition:  Appendix A # 3.3.5
 Example:
 <date-time>2011-05-17T12:00:00</date-time>

3.6.6. Duration (RFC 5545, Section 3.3.6)

 Description:  iCalendar "DURATION" property values are represented by
    the IC:duration XML element.  The content of the element is the
    same duration value specified by [RFC5545].
 XML Definition:  Appendix A # 3.3.6
 Example:
 <duration>P1D</duration>

3.6.7. Float (RFC 5545, Section 3.3.7)

 Description:  iCalendar "FLOAT" property values are represented by
    the IC:float XML element.  The content of the element is a text
    representation of a floating point number.
 XML Definition:  Appendix A # 3.3.7
 Example:
 <float>0.5</float>

Daboo, et al. Standards Track [Page 13] RFC 6321 xCal August 2011

3.6.8. Integer (RFC 5545, Section 3.3.8)

 Description:  iCalendar "INTEGER" property values are represented by
    the IC:integer XML element.  The content of the element is a text
    representation of an integer number.
 XML Definition:  Appendix A # 3.3.8
 Examples:
 <integer>50</integer>
 <integer>-100</integer>

3.6.9. Period of Time (RFC 5545, Section 3.3.9)

 Description:  iCalendar "PERIOD" property values are represented by
    the IC:period XML element.  The content of the element is child
    elements representing the start, end, or duration components of
    the period.
 XML Definition:  Appendix A # 3.3.9
 Example:
 <period>
   <start>2011-05-17T12:00:00</start>
   <duration>P1H</duration>
 </period>

3.6.10. Recurrence Rule (RFC 5545, Section 3.3.10)

 Description:  iCalendar "RECUR" property values are represented by
    the IC:recur XML element.  The content of the element is child
    elements representing the various components of a recurrence rule.
 XML Definition:  Appendix A # 3.3.10
 Example:
 <recur>
   <freq>YEARLY</freq>
   <count>5</count>
   <byday>-1SU</byday>
   <bymonth>10</bymonth>
 </recur>

Daboo, et al. Standards Track [Page 14] RFC 6321 xCal August 2011

3.6.11. Text (RFC 5545, Section 3.3.11)

 Description:  iCalendar "TEXT" property values are represented by the
    IC:text XML element.  The content of the element is simple text.
 XML Definition:  Appendix A # 3.3.11
 Example:
 <text>Hello World!</text>

3.6.12. Time (RFC 5545, Section 3.3.12)

 Description:  iCalendar "TIME" property values are represented by the
    IC:time XML element.  The content of the element is the same time
    value specified by [RFC5545], with the exception that the time
    components are separated by ":" characters, for consistency with
    [W3C.REC-xmlschema-2-20041028].  Note that while
    [W3C.REC-xmlschema-2-20041028] allows for a UTC offset to be
    included in date/time values, xCal does not use that, and instead
    follows the iCalendar behavior of using time zone definitions via
    the "TZID" property parameter.
 XML Definition:  Appendix A # 3.3.12
 Example:
 <time>12:00:00</time>

3.6.13. URI (RFC 5545, Section 3.3.13)

 Description:  iCalendar "URI" property values are represented by the
    IC:uri XML element.  The content of the element is a URI.
 XML Definition:  Appendix A # 3.3.13
 Example:
 <uri>http://calendar.example.com</uri>

Daboo, et al. Standards Track [Page 15] RFC 6321 xCal August 2011

3.6.14. UTC Offset (RFC 5545, Section 3.3.14)

 Description:  iCalendar "UTC-OFFSET" property values are represented
    by the IC:utc-offset XML element.  The content of the element is
    the same UTC offset value specified by [RFC5545], with the
    exception that the hour, minute, and second components are
    separated by a ":" character, for consistency with
    [W3C.REC-xmlschema-2-20041028].
 XML Definition:  Appendix A # 3.3.14
 Example:
 <utc-offset>-05:00</utc-offset>

3.7. Extensions

 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 or property
 parameter is represented by an XML element with the same name, but in
 lowercase, e.g., the "X-FOO" property in iCalendar turns into the IC:
 x-foo element in xCal.  However, see Section 5 for how to deal with
 default values for unrecognized extension properties or property
 parameters.

4. Converting from xCal 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].
 BACKSLASH character encoding and line folding MUST be applied to the
 resulting iCalendar data as required by [RFC5545].
 Non-binary value types MUST NOT be base64 encoded.

4.1. Converting XML Extensions into iCalendar

 XML extensions are converted back to iCalendar in one of two ways,
 depending on whether the extensions are in the iCalendar XML
 namespace or in an external namespace.
 Extensions that are part of the iCalendar XML namespace MUST have
 element names that begin with "x-", and will be converted back to the
 equivalent extension property in iCalendar.  For example, the "x-foo"
 element will convert to the "X-FOO" iCalendar property.

Daboo, et al. Standards Track [Page 16] RFC 6321 xCal August 2011

 Extensions that are in a namespace other than the iCalendar XML
 namespace SHOULD be preserved in the iCalendar representation using
 the "XML" iCalendar property described in Section 4.2.  Only those
 extension elements that are immediate child elements of the IC:
 properties element are converted, any others are ignored.

4.2. The XML Property for iCalendar

 This section describes an extension property for iCalendar, as
 covered in Section 8.2.3 of [RFC5545].
 Property name: XML
 Purpose: To embed extended XML-encoded iCalendar data in the
 iCalendar format.
 Value type: The default value type is "TEXT".  The value type can
 also be set to "BINARY" to indicate base64 encoded content.
 Property parameters: IANA, non-standard, inline encoding, and value
 data type property parameters can be specified on this property.
 Conformance: The property can be specified multiple times in any
 calendar component.
 Description: The value of this property is a single XML 1.0
 [W3C.REC-xml-20081126] element.  The "XML" property MUST NOT be used
 to contain properties that are already defined in iCalendar.  Since
 all elements in the urn:ietf:params:xml:ns:icalendar-2.0 namespace
 convert to a well-defined iCalendar object, the elements in this
 property MUST NOT be in the urn:ietf:params:xml:ns:icalendar-2.0
 namespace.  The XML element that is the value of this property MUST
 have an XML namespace declaration.
 The default value type for this property is "TEXT", and normal
 BACKSLASH character encoding rules for that value MUST be applied.
 Note that the source XML can contain characters not allowed in "TEXT"
 property values.  If this is the case, then the XML data MUST be
 base64 encoded.  As required by [RFC5545], the "ENCODING" property
 parameter MUST be present and set to "BASE64", and the "VALUE"
 property parameter MUST be present and set to "BINARY".
 The ordering of "XML" properties is not preserved in the conversion
 between xCal and iCalendar.
 Format definition: This property is defined by the following
 notation:

Daboo, et al. Standards Track [Page 17] RFC 6321 xCal August 2011

 xml      = "XML" xmlparam ( ":" text ) /
              (
                ";" "ENCODING" "=" "BASE64"
                ";" "VALUE" "=" "BINARY"
                ":" binary
              )
              CRLF
 xmlparam     = *(";" other-param)
 Example: The following is an example of a location embedded in KML
 markup inside the "XML" property.
 XML:<kml xmlns="http://www.opengis.net/kml/2.2">\n
    <Document>\n
      <name>KML Sample</name>\n
      <open>1</open>\n
      <description>An incomplete example of a KML docum
  ent - used as an example!</description>\n
    </Document>\n
  </kml>

5. Handling Unrecognized Properties or Parameters

 In iCalendar, properties have a default value type specified by their
 definition, e.g., "SUMMARY"'s value type is "TEXT" and "DURATION"'s
 is "DURATION".  When a property uses its default value type, the
 "VALUE" property parameter does not need to be specified on the
 property.
 When new properties are defined or "X-" properties are used, an
 iCalendar<->xCal converter might not recognize them, and 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.  As a result, the following rules are applied
 when dealing with unrecognized properties and property parameters:
 o  When converting iCalendar into xCal:
  • Any property that does not include a "VALUE" property parameter

and whose default value type is not known MUST be converted

       using the value type XML element IC:unknown.  The content of
       that element is the unprocessed value text.
  • Any unrecognized property parameter MUST be converted using the

value type XML element IC:unknown, with its content set to the

       property parameter value text, treated as if it were a "TEXT"
       value or list of "TEXT" values.

Daboo, et al. Standards Track [Page 18] RFC 6321 xCal August 2011

 o  When converting xCal into iCalendar:
  • Any IC:unknown property value XML elements are converted

directly into iCalendar values. The containing property MUST

       NOT have a "VALUE" property parameter.
  • Any IC:unknown parameter value XML elements are converted as if

they were IC:text value type XML elements.

 Example: The following is an example of an unrecognized iCalendar
 property (that uses a "DATE-TIME" value as its default) and the
 equivalent xCal representation of that property.
 iCalendar:
 X-PROPERTY:20110512T120000Z
 xCal:
 <x-property>
   <unknown>20110512T120000Z</unknown>
 </x-property>
 Example: The following is an example of an unrecognized iCalendar
 property parameter (that uses a "DURATION" value as its default)
 specified on a recognized iCalendar property, and the equivalent xCal
 representation of that property and property parameter.
 iCalendar:
 DTSTART;X-PARAM=PT30M:20110512T130000Z
 xCal:
 <dtstart>
   <parameters>
     <x-param><unknown>PT30M</unknown></x-param>
   </parameters>
   <date-time>2011-05-12T13:00:00Z</date-time>
 </dtstart>

6. Security Considerations

 For security considerations specific to calendar data, see Section 7
 of [RFC5545].  Since this specification is a mapping from iCalendar,
 no new security concerns are introduced related to calendar data.

Daboo, et al. Standards Track [Page 19] RFC 6321 xCal August 2011

 The use of XML as a format does have security risks.  Section 7 of
 [RFC3470] discusses these risks.  See also the security discussion
 for the application/xml type in [RFC3023].

7. IANA Considerations

 This document defines a new URN to identify a new XML namespace for
 iCalendar data.  The URN conforms to a registry mechanism described
 in [RFC3688].
 This document defines a new media type.  The registration is in
 Section 7.2.
 This document defines a new property for iCalendar.  The registration
 is in Section 7.3.

7.1. Namespace Registration

 Registration request for the iCalendar namespace:
 URI: urn:ietf:params:xml:ns:icalendar-2.0
 Registrant Contact: See the "Authors' Addresses" section of this
 document.
 XML: None.  Namespace URIs do not represent an XML specification.

7.2. Media Type

 This section defines the MIME media type for use with iCalendar in
 XML data.
 Type name:  application
 Subtype name:  calendar+xml
 Required parameters:  None
 Optional parameters:  method, component, and optinfo as defined for
    the text/calendar media type in [RFC5545]; charset as defined for
    application/xml in [RFC3023]; per [RFC3023], use of the charset
    property parameter with the value "utf-8" is STRONGLY RECOMMENDED.
 Encoding considerations:  Same as encoding considerations of
    application/xml as specified in [RFC3023].

Daboo, et al. Standards Track [Page 20] RFC 6321 xCal August 2011

 Security considerations:  See Section 6.
 Interoperability considerations:  This media type provides an
    alternative format for iCalendar data based on XML.
 Published specification:  This specification.
 Applications that use this media type:  Applications that currently
    make use of the text/calendar media type can use this as an
    alternative.
 Additional information:
    Magic number(s):  None
    File extension(s):  xcs
    Macintosh file type code(s):  None specified.
 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 "Authors' Addresses" section of this document.
 Change controller:  IETF

7.3. iCalendar Property Registrations

 This document defines the following new iCalendar property to be
 added to the registry defined in Section 8.2.3 of [RFC5545]:
            +----------+---------+-----------------------+
            | Property | Status  | Reference             |
            +----------+---------+-----------------------+
            | XML      | Current | RFC 6321, Section 4.2 |
            +----------+---------+-----------------------+

Daboo, et al. Standards Track [Page 21] RFC 6321 xCal August 2011

8. Acknowledgments

 The authors would like to thank the following for their valuable
 contributions: Toby Considine, Bernard Desruisseaux, Keith Moore,
 Filip Navara, Simon Perreault, Arnaud Quillaud, Peter Saint-Andre,
 and Dave Thewlis.  This specification originated from the work of the
 XML technical committee of 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.
 [RFC3023]  Murata, M., St. Laurent, S., and D. Kohn, "XML Media
            Types", RFC 3023, January 2001.
 [RFC3470]  Hollenbeck, S., Rose, M., and L. Masinter, "Guidelines for
            the Use of Extensible Markup Language (XML)
            within IETF Protocols", BCP 70, RFC 3470, January 2003.
 [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
            January 2004.
 [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
            Encodings", RFC 4648, October 2006.
 [RFC5545]  Desruisseaux, B., "Internet Calendaring and Scheduling
            Core Object Specification (iCalendar)", RFC 5545,
            September 2009.
 [W3C.REC-xml-20081126]
            Sperberg-McQueen, C., Yergeau, F., Bray, T., Paoli, J.,
            and E. Maler, "Extensible Markup Language (XML) 1.0 (Fifth
            Edition)", World Wide Web Consortium Recommendation REC-
            xml-20081126, November 2008,
            <http://www.w3.org/TR/2008/REC-xml-20081126>.

9.2. Informative References

 [W3C.REC-xmlschema-2-20041028]
            Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes
            Second Edition", World Wide Web Consortium
            Recommendation REC-xmlschema-2-20041028, October 2004,
            <http://www.w3.org/TR/2004/REC-xmlschema-2-20041028>.

Daboo, et al. Standards Track [Page 22] RFC 6321 xCal August 2011

Appendix A. RELAX NG Schema

 Below is a RELAX NG schema for iCalendar in XML.  The schema is non-
 normative and given for reference only.
 This schema uses the compact notation of RELAX NG.  The numeric
 section numbers given in the comments refer to sections in [RFC5545].
 The ordering of elements follows the section ordering of [RFC5545].
 The RELAX NG compact notation "?" operator is used to indicate an
 unordered list of items.  However, that operator, as defined, allows
 "mixing" each element that it operates on at any depth within the
 other elements, rather than just allowing "mixing" of siblings only.
 As a result, the schema provided allows certain constructs that are
 not allowed in iCalendar.  Given that there is no sibling-only
 unordered list operator in RELAX NG, this is the best representation
 that can be given.
 Patterns for date/time, duration, and UTC offset values are given
 because those differ from the values used in iCalendar.  More
 restrictive schema with patterns and numerical limits could be
 derived from the example schema here if more comprehensive schema
 validation is required.
 # RELAX NG Schema for iCalendar in XML
 default namespace = "urn:ietf:params:xml:ns:icalendar-2.0"
 # 3.2 Property Parameters
 # 3.2.1 Alternate Text Representation
 altrepparam = element altrep {
     value-uri
 }
 # 3.2.2 Common Name
 cnparam = element cn {
     value-text
 }

Daboo, et al. Standards Track [Page 23] RFC 6321 xCal August 2011

 # 3.2.3 Calendar User Type
 cutypeparam = element cutype {
     element text {
         "INDIVIDUAL" |
         "GROUP" |
         "RESOURCE" |
         "ROOM" |
         "UNKNOWN"
     }
 }
 # 3.2.4 Delegators
 delfromparam = element delegated-from {
     value-cal-address+
 }
 # 3.2.5 Delegatees
 deltoparam = element delegated-to {
     value-cal-address+
 }
 # 3.2.6 Directory Entry Reference
 dirparam = element dir {
     value-uri
 }
 # 3.2.7 Inline Encoding
 encodingparam = element encoding {
     element text {
         "8BIT" |
         "BASE64"
     }
 }
 # 3.2.8 Format Type
 fmttypeparam = element fmttype {
     value-text
 }

Daboo, et al. Standards Track [Page 24] RFC 6321 xCal August 2011

 # 3.2.9 Free/Busy Time Type
 fbtypeparam = element fbtype {
     element text {
         "FREE" |
         "BUSY" |
         "BUSY-UNAVAILABLE" |
         "BUSY-TENTATIVE"
     }
 }
 # 3.2.10 Language
 languageparam = element language {
     value-text
 }
 # 3.2.11 Group or List Membership
 memberparam = element member {
     value-cal-address+
 }
 # 3.2.12 Participation Status
 partstatparam = element partstat {
     type-partstat-event |
     type-partstat-todo |
     type-partstat-jour
 }
 type-partstat-event = (
     element text {
         "NEEDS-ACTION" |
         "ACCEPTED" |
         "DECLINED" |
         "TENTATIVE" |
         "DELEGATED"
     }
 )

Daboo, et al. Standards Track [Page 25] RFC 6321 xCal August 2011

 type-partstat-todo = (
     element text {
         "NEEDS-ACTION" |
         "ACCEPTED" |
         "DECLINED" |
         "TENTATIVE" |
         "DELEGATED" |
         "COMPLETED" |
         "IN-PROCESS"
     }
 )
 type-partstat-jour = (
     element text {
         "NEEDS-ACTION" |
         "ACCEPTED" |
         "DECLINED"
     }
 )
 # 3.2.13 Recurrence Identifier Range
 rangeparam = element range {
     element text {
         "THISANDFUTURE"
     }
 }
 # 3.2.14 Alarm Trigger Relationship
 trigrelparam = element related {
     element text {
         "START" |
         "END"
     }
 }
 # 3.2.15 Relationship Type
 reltypeparam = element reltype {
     element text {
         "PARENT" |
         "CHILD" |
         "SIBLING"
     }
 }

Daboo, et al. Standards Track [Page 26] RFC 6321 xCal August 2011

 # 3.2.16 Participation Role
 roleparam = element role {
     element text {
         "CHAIR" |
         "REQ-PARTICIPANT" |
         "OPT-PARTICIPANT" |
         "NON-PARTICIPANT"
     }
 }
 # 3.2.17 RSVP Expectation
 rsvpparam = element rsvp {
     value-boolean
 }
 # 3.2.18 Sent By
 sentbyparam = element sent-by {
     value-cal-address
 }
 # 3.2.19 Time Zone Identifier
 tzidparam = element tzid {
     value-text
 }
 # 3.3 Property Value Data Types
 # 3.3.1 BINARY
 value-binary =  element binary {
     xsd:string
 }
 # 3.3.2 BOOLEAN
 value-boolean = element boolean {
     xsd:boolean
 }
 # 3.3.3 CAL-ADDRESS
 value-cal-address = element cal-address {
     xsd:anyURI
 }

Daboo, et al. Standards Track [Page 27] RFC 6321 xCal August 2011

 # 3.3.4 DATE
 pattern-date = xsd:string {
     pattern = "\d\d\d\d-\d\d-\d\d"
 }
 value-date = element date {
     pattern-date
 }
 # 3.3.5 DATE-TIME
 pattern-date-time = xsd:string {
     pattern = "\d\d\d\d-\d\d-\d\dT\d\d:\d\d:\d\dZ?"
 }
 value-date-time = element date-time {
     pattern-date-time
 }
 # 3.3.6 DURATION
 pattern-duration = xsd:string {
     pattern = "(+|-)?P(\d+W)|(\d+D)?"
             ~ "(T(\d+H(\d+M)?(\d+S)?)|"
             ~   "(\d+M(\d+S)?)|"
             ~   "(\d+S))?"
 }
 value-duration = element duration {
     pattern-duration
 }
 # 3.3.7 FLOAT
 value-float = element float {
     xsd:float
 }
 # 3.3.8 INTEGER
 value-integer = element integer {
     xsd:integer
 }

Daboo, et al. Standards Track [Page 28] RFC 6321 xCal August 2011

 # 3.3.9 PERIOD
 value-period = element period {
     element start {
         pattern-date-time
     },
     (
         element end {
             pattern-date-time
         } |
         element duration {
             pattern-duration
         }
     )
 }
 # 3.3.10 RECUR
 value-recur = element recur {
     type-freq,
     (type-until | type-count)?,
     element interval {
         xsd:positiveInteger
     }?,
     type-bysecond*,
     type-byminute*,
     type-byhour*,
     type-byday*,
     type-bymonthday*,
     type-byyearday*,
     type-byweekno*,
     type-bymonth*,
     type-bysetpos*,
     element wkst { type-weekday }?
 }
 type-freq = element freq {
     "SECONDLY" |
     "MINUTELY" |
     "HOURLY"   |
     "DAILY"    |
     "WEEKLY"   |
     "MONTHLY"  |
     "YEARLY"
 }

Daboo, et al. Standards Track [Page 29] RFC 6321 xCal August 2011

 type-until = element until {
     type-date |
     type-date-time
 }
 type-count = element count {
     xsd:positiveInteger
 }
 type-bysecond = element bysecond {
     xsd:positiveInteger
 }
 type-byminute = element byminute {
     xsd:positiveInteger
 }
 type-byhour = element byhour {
     xsd:positiveInteger
 }
 type-weekday = (
     "SU" |
     "MO" |
     "TU" |
     "WE" |
     "TH" |
     "FR" |
     "SA"
 )
 type-byday = element byday {
     xsd:integer?,
     type-weekday
 }
 type-bymonthday = element bymonthday {
     xsd:integer
 }
 type-byyearday = element byyearday {
     xsd:integer
 }
 type-byweekno = element byweekno {
     xsd:integer
 }

Daboo, et al. Standards Track [Page 30] RFC 6321 xCal August 2011

 type-bymonth = element bymonth {
     xsd:positiveInteger
 }
 type-bysetpos = element bysetpos {
     xsd:integer
 }
 # 3.3.11 TEXT
 value-text = element text {
     xsd:string
 }
 # 3.3.12 TIME
 pattern-time = xsd:string {
     pattern = "\d\d:\d\d:\d\dZ?"
 }
 value-time = element time {
     pattern-time
 }
 # 3.3.13 URI
 value-uri = element uri {
     xsd:anyURI
 }
 # 3.3.14 UTC-OFFSET
 value-utc-offset = element utc-offset {
     xsd:string { pattern = "(+|-)\d\d:\d\d(:\d\d)?" }
 }
 # UNKNOWN
 value-unknown = element unknown {
     xsd:string
 }
 # 3.4 iCalendar Stream
 start = element icalendar {
     vcalendar+
 }

Daboo, et al. Standards Track [Page 31] RFC 6321 xCal August 2011

 # 3.6 Calendar Components
 vcalendar = element vcalendar {
     type-calprops,
     type-component
 }
 type-calprops = element properties {
     property-prodid &
     property-version &
     property-calscale? &
     property-method?
 }
 type-component = element components {
     (
         component-vevent |
         component-vtodo |
         component-vjournal |
         component-vfreebusy |
         component-vtimezone
     )*
 }
 # 3.6.1 Event Component
 component-vevent = element vevent {
     type-eventprop,
     element components {
         component-valarm+
     }?
 }
 type-eventprop = element properties {
     property-dtstamp &
     property-dtstart &
     property-uid &
     property-class? &
     property-created? &
     property-description? &
     property-geo? &
     property-last-mod? &
     property-location? &
     property-organizer? &
     property-priority? &
     property-seq? &
     property-status-event? &

Daboo, et al. Standards Track [Page 32] RFC 6321 xCal August 2011

     property-summary? &
     property-transp? &
     property-url? &
     property-recurid? &
     property-rrule? &
     (property-dtend | property-duration)? &
     property-attach* &
     property-attendee* &
     property-categories* &
     property-comment* &
     property-contact* &
     property-exdate* &
     property-rstatus* &
     property-related* &
     property-resources* &
     property-rdate*
 }
 # 3.6.2 To-do Component
 component-vtodo = element vtodo {
     type-todoprop,
     element components {
         component-valarm+
     }?
 }
 type-todoprop = element properties {
     property-dtstamp &
     property-uid &
     property-class? &
     property-completed? &
     property-created? &
     property-description? &
     property-geo? &
     property-last-mod? &
     property-location? &
     property-organizer? &
     property-percent? &
     property-priority? &
     property-recurid? &
     property-seq? &
     property-status-todo? &
     property-summary? &

Daboo, et al. Standards Track [Page 33] RFC 6321 xCal August 2011

     property-url? &
     property-rrule? &
     (
         (property-dtstart?, property-dtend? ) |
         (property-dtstart, property-duration)?
     ) &
     property-attach* &
     property-attendee* &
     property-categories* &
     property-comment* &
     property-contact* &
     property-exdate* &
     property-rstatus* &
     property-related* &
     property-resources* &
     property-rdate*
 }
 # 3.6.3 Journal Component
 component-vjournal = element vjournal {
     type-jourprop
 }
 type-jourprop = element properties {
     property-dtstamp &
     property-uid &
     property-class? &
     property-created? &
     property-dtstart? &
     property-last-mod? &
     property-organizer? &
     property-recurid? &
     property-seq? &
     property-status-jour? &
     property-summary? &
     property-url? &
     property-rrule? &
     property-attach* &
     property-attendee* &
     property-categories* &
     property-comment* &

Daboo, et al. Standards Track [Page 34] RFC 6321 xCal August 2011

     property-contact* &
     property-description? &
     property-exdate* &
     property-related* &
     property-rdate* &
     property-rstatus*
 }
 # 3.6.4 Free/Busy Component
 component-vfreebusy = element vfreebusy {
     type-fbprop
 }
 type-fbprop = element properties {
     property-dtstamp &
     property-uid &
     property-contact? &
     property-dtstart? &
     property-dtend? &
     property-duration? &
     property-organizer? &
     property-url? &
     property-attendee* &
     property-comment* &
     property-freebusy* &
     property-rstatus*
 }
 # 3.6.5 Time Zone Component
 component-vtimezone = element vtimezone {
     element properties {
         property-tzid &
         property-last-mod? &
         property-tzuurl?
     },
     element components {
         (component-standard | component-daylight) &
         component-standard* &
         component-daylight*
     }
 }

Daboo, et al. Standards Track [Page 35] RFC 6321 xCal August 2011

 component-standard = element standard {
     type-tzprop
 }
 component-daylight = element daylight {
     type-tzprop
 }
 type-tzprop = element properties {
     property-dtstart &
     property-tzoffsetto &
     property-tzoffsetfrom &
     property-rrule? &
     property-comment* &
     property-rdate* &
     property-tzname*
 }
 # 3.6.6 Alarm Component
 component-valarm = element valarm {
     audioprop | dispprop | emailprop
 }
 type-audioprop = element properties {
     property-action &
     property-trigger &
     (property-duration, property-repeat)? &
     property-attach?
 }
 type-dispprop = element properties {
     property-action &
     property-description &
     property-trigger &
     property-summary &
     property-attendee+ &
     (property-duration, property-repeat)? &
     property-attach*
 }

Daboo, et al. Standards Track [Page 36] RFC 6321 xCal August 2011

 type-emailprop = element properties {
     property-action &
     property-description &
     property-trigger &
     (property-duration, property-repeat)?
 }
 # 3.7 Calendar Properties
 # 3.7.1 Calendar Scale
 property-calscale = element calscale {
     element parameters { empty }?,
     element text { "GREGORIAN" }
 }
 # 3.7.2 Method
 property-method = element method {
     element parameters { empty }?,
     value-text
 }
 # 3.7.3 Product Identifier
 property-prodid = element prodid {
     element parameters { empty }?,
     value-text
 }
 # 3.7.4 Version
 property-version = element version {
     element parameters { empty }?,
     element text { "2.0" }
 }

Daboo, et al. Standards Track [Page 37] RFC 6321 xCal August 2011

 # 3.8 Component Properties
 # 3.8.1 Descriptive Component Properties
 # 3.8.1.1 Attachment
 property-attach = element attach {
     element parameters {
         fmttypeparam? &
         encodingparam?
     }?,
     value-uri | value-binary
 }
 # 3.8.1.2 Categories
 property-categories = element categories {
     element parameters {
         languageparam? &
     }?,
     value-text+
 }
 # 3.8.1.3 Classification
 property-class = element class {
     element parameters { empty }?,
     element text {
         "PUBLIC" |
         "PRIVATE" |
         "CONFIDENTIAL"
     }
 }
 # 3.8.1.4 Comment
 property-comment = element comment {
     element parameters {
         altrepparam? &
         languageparam?
     }?,

Daboo, et al. Standards Track [Page 38] RFC 6321 xCal August 2011

     value-text
 }
 # 3.8.1.5 Description
 property-description = element description {
     element parameters {
         altrepparam? &
         languageparam?
     }?,
     value-text
 }
 # 3.8.1.6 Geographic Position
 property-geo = element geo {
     element parameters { empty }?,
     element latitude  { xsd:float },
     element longitude { xsd:float }
 }
 # 3.8.1.7 Location
 property-location = element location {
     element parameters {
         altrepparam? &
         languageparam?
     }?,
     value-text
 }
 # 3.8.1.8 Percent Complete
 property-percent = element percent-complete {
     element parameters { empty }?,
     value-integer
 }

Daboo, et al. Standards Track [Page 39] RFC 6321 xCal August 2011

 # 3.8.1.9 Priority
 property-priority = element priority {
     element parameters { empty }?,
     value-integer
 }
 # 3.8.1.10 Resources
 property-resources = element resources {
     element parameters {
         altrepparam? &
         languageparam?
     }?,
     value-text+
 }
 # 3.8.1.11 Status
 property-status-event = element status {
     element parameters { empty }?,
     element text {
         "TENTATIVE" |
         "CONFIRMED" |
         "CANCELLED"
     }
 }
 property-status-todo = element status {
     element parameters { empty }?,
     element text {
         "NEEDS-ACTION" |
         "COMPLETED" |
         "IN-PROCESS" |
         "CANCELLED"
     }
 }

Daboo, et al. Standards Track [Page 40] RFC 6321 xCal August 2011

 property-status-jour = element status {
     element parameters { empty }?,
     element text {
         "DRAFT" |
         "FINAL" |
         "CANCELLED"
     }
 }
 # 3.8.1.12 Summary
 property-summary = element summary {
     element parameters {
         altrepparam? &
         languageparam?
     }?,
     value-text
 }
 # 3.8.2 Date and Time Component Properties
 # 3.8.2.1 Date/Time Completed
 property-completed = element completed {
     element parameters { empty }?,
     value-date-time
 }
 # 3.8.2.2 Date/Time End
 property-dtend = element dtend {
     element parameters {
         tzidparam?
     }?,
     value-date-time |
     value-date
 }

Daboo, et al. Standards Track [Page 41] RFC 6321 xCal August 2011

 # 3.8.2.3 Date/Time Due
 property-due = element due {
     element parameters {
         tzidparam?
     }?,
     value-date-time |
     value-date
 }
 # 3.8.2.4 Date/Time Start
 property-dtstart = element dtstart {
     element parameters {
         tzidparam?
     }?,
     value-date-time |
     value-date
 }
 # 3.8.2.5 Duration
 property-duration = element duration {
     element parameters { empty }?,
     value-duration
 }
 # 3.8.2.6 Free/Busy Time
 property-freebusy = element freebusy {
     element parameters {
         fbtypeparam?
     }?,
     value-period+
 }
 # 3.8.2.7 Time Transparency
 property-transp = element transp {

Daboo, et al. Standards Track [Page 42] RFC 6321 xCal August 2011

     element parameters { empty }?,
     element text {
         "OPAQUE" |
         "TRANSPARENT"
     }
 }
 # 3.8.3 Time Zone Component Properties
 # 3.8.3.1 Time Zone Identifier
 property-tzid = element tzid {
     element parameters { empty }?,
     value-text
 }
 # 3.8.3.2 Time Zone Name
 property-tzname = element tzname {
     element parameters {
         languageparam?
     }?,
     value-text
 }
 # 3.8.3.3 Time Zone Offset From
 property-tzoffsetfrom = element tzoffsetfrom {
     element parameters { empty }?,
     value-utc-offset
 }
 # 3.8.3.4 Time Zone Offset To
 property-tzoffsetto = element tzoffsetto {
     element parameters { empty }?,
     value-utc-offset
 }

Daboo, et al. Standards Track [Page 43] RFC 6321 xCal August 2011

 # 3.8.3.5 Time Zone URL
 property-tzurl = element tzurl {
     element parameters { empty }?,
     value-uri
 }
 # 3.8.4 Relationship Component Properties
 # 3.8.4.1 Attendee
 property-attendee = element attendee {
     element parameters {
         cutypeparam? &
         memberparam? &
         roleparam? &
         partstatparam? &
         rsvpparam? &
         deltoparam? &
         delfromparam? &
         sentbyparam? &
         cnparam? &
         dirparam? &
         languageparam?
     }?,
     value-cal-address
 }
 # 3.8.4.2 Contact
 property-contact = element contact {
     element parameters {
         altrepparam? &
         languageparam?
     }?,
     value-text
 }
 # 3.8.4.3 Organizer
 property-organizer = element organizer {

Daboo, et al. Standards Track [Page 44] RFC 6321 xCal August 2011

     element parameters {
         cnparam? &
         dirparam? &
         sentbyparam? &
         languageparam?
     }?,
     value-cal-address
 }
 # 3.8.4.4 Recurrence ID
 property-recurid = element recurrence-id {
     element parameters {
         tzidparam? &
         rangeparam?
     }?,
     value-date-time |
     value-date
 }
 # 3.8.4.5 Related-To
 property-related = element related-to {
     element parameters {
         reltypeparam?
     }?,
     value-text
 }
 # 3.8.4.6 Uniform Resource Locator
 property-url = element url {
     element parameters { empty }?,
     value-uri
 }
 # 3.8.4.7 Unique Identifier
 property-uid = element uid {
     element parameters { empty }?,

Daboo, et al. Standards Track [Page 45] RFC 6321 xCal August 2011

     value-text
 }
 # 3.8.5 Recurrence Component Properties
 # 3.8.5.1 Exception Date/Times
 property-exdate = element exdate {
     element parameters {
         tzidparam?
     }?,
     value-date-time+ |
     value-date+
 }
 # 3.8.5.2 Recurrence Date/Times
 property-rdate = element rdate {
     element parameters {
         tzidparam?
     }?,
     value-date-time+ |
     value-date+ |
     value-period+
 }
 # 3.8.5.3 Recurrence Rule
 property-rrule = element rrule {
     element parameters { empty }?,
     value-recur
 }
 # 3.8.6 Alarm Component Properties
 # 3.8.6.1 Action
 property-action = element action {
     element parameters { empty }?,

Daboo, et al. Standards Track [Page 46] RFC 6321 xCal August 2011

     element text {
         "AUDIO" |
         "DISPLAY" |
         "EMAIL"
     }
 }
 # 3.8.6.2 Repeat Count
 property-repeat = element repeat {
     element parameters { empty }?,
     value-integer
 }
 # 3.8.6.3 Trigger
 property-trigger = element trigger {
     (
         element parameters {
             trigrelparam?
         }?,
         value-duration
     ) |
     (
         element parameters { empty }?,
         value-date-time
     )
 }
 # 3.8.7 Change Management Component Properties
 # 3.8.7.1 Date/Time Created
 property-created = element created {
     element parameters { empty }?,
     value-date-time
 }
 # 3.8.7.2 Date/Time Stamp
 property-dtstamp = element dtstamp {

Daboo, et al. Standards Track [Page 47] RFC 6321 xCal August 2011

     element parameters { empty }?,
     value-date-time
 }
 # 3.8.7.3 Last Modified
 property-last-mod = element last-modified {
     element parameters { empty }?,
     value-date-time
 }
 # 3.8.7.4 Sequence Number
 property-seq = element sequence {
     element parameters { empty }?,
     value-integer
 }
 # 3.8.8 Miscellaneous Component Properties
 # 3.8.8.3 Request Status
 property-rstatus = element request-status {
     element parameters {
         languageparam?
     }?,
     element code { xsd:string },
     element description { xsd:string },
     element data { xsd:string }?
 }

Daboo, et al. Standards Track [Page 48] RFC 6321 xCal August 2011

Appendix B. Examples

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

B.1. Example 1

B.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

B.1.2. XML Data

 <?xml version="1.0" encoding="utf-8"?>
 <icalendar xmlns="urn:ietf:params:xml:ns:icalendar-2.0">
  <vcalendar>
   <properties>
    <calscale>
      <text>GREGORIAN</text>
    </calscale>
    <prodid>
     <text>-//Example Inc.//Example Calendar//EN</text>
    </prodid>
    <version>
      <text>2.0</text>
    </version>
   </properties>
   <components>
    <vevent>
     <properties>
      <dtstamp>
        <date-time>2008-02-05T19:12:24Z</date-time>
      </dtstamp>
      <dtstart>
        <date>2008-10-06</date>
      </dtstart>
      <summary>
       <text>Planning meeting</text>

Daboo, et al. Standards Track [Page 49] RFC 6321 xCal August 2011

      </summary>
      <uid>
       <text>4088E990AD89CB3DBB484909</text>
      </uid>
     </properties>
    </vevent>
   </components>
  </vcalendar>
 </icalendar>

B.2. Example 2

B.2.1. iCalendar Data

 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.
 UID:00959BC664CA650E933C892C@example.com
 END:VEVENT
 BEGIN:VEVENT

Daboo, et al. Standards Track [Page 50] RFC 6321 xCal August 2011

 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

B.2.2. XML Data

 <?xml version="1.0" encoding="utf-8" ?>
 <icalendar xmlns="urn:ietf:params:xml:ns:icalendar-2.0">
   <vcalendar>
     <properties>
       <prodid>
         <text>-//Example Inc.//Example Client//EN</text>
       </prodid>
       <version>
         <text>2.0</text>
       </version>
     </properties>
     <components>
       <vtimezone>
         <properties>
           <last-modified>
             <date-time>2004-01-10T03:28:45Z</date-time>
           </last-modified>
           <tzid>US/Eastern</tzid>
         </properties>
         <components>
           <daylight>
             <properties>
               <dtstart>
                 <date-time>2000-04-04T02:00:00</date-time>
               </dtstart>
               <rrule>
                 <recur>
                   <freq>YEARLY</freq>
                   <byday>1SU</byday>
                   <bymonth>4</bymonth>
                 </recur>
               </rrule>
               <tzname>
                 <text>EDT</text>
               </tzname>
               <tzoffsetfrom>
                 <utc-offset>-05:00</utc-offset>

Daboo, et al. Standards Track [Page 51] RFC 6321 xCal August 2011

               </tzoffsetfrom>
               <tzoffsetto>
                 <utc-offset>-04:00</utc-offset>
               </tzoffsetto>
             </properties>
           </daylight>
           <standard>
             <properties>
               <dtstart>
                 <date-time>2000-10-26T02:00:00</date-time>
               </dtstart>
               <rrule>
                 <recur>
                   <freq>YEARLY</freq>
                   <byday>-1SU</byday>
                   <bymonth>10</bymonth>
                 </recur>
               </rrule>
               <tzname>
                 <text>EST</text>
               </tzname>
               <tzoffsetfrom>
                 <utc-offset>-04:00</utc-offset>
               </tzoffsetfrom>
               <tzoffsetto>
                 <utc-offset>-05:00</utc-offset>
               </tzoffsetto>
             </properties>
           </standard>
         </components>
       </vtimezone>
       <vevent>
         <properties>
           <dtstamp>
             <date-time>2006-02-06T00:11:21Z</date-time>
           </dtstamp>
           <dtstart>
             <parameters>
               <tzid><text>US/Eastern</text></tzid>
             </parameters>
             <date-time>2006-01-02T12:00:00</date-time>
           </dtstart>
           <duration>
             <duration>PT1H</duration>
           </duration>
           <rrule>
             <recur>
               <freq>DAILY</freq>

Daboo, et al. Standards Track [Page 52] RFC 6321 xCal August 2011

               <count>5</count>
             </recur>
           </rrule>
           <rdate>
             <parameters>
               <tzid><text>US/Eastern</text></tzid>
             </parameters>
             <period>
               <start>2006-01-02T15:00:00</start>
               <duration>PT2H</duration>
             </period>
           </rdate>
           <summary>
             <text>Event #2</text>
           </summary>
           <description>
             <text>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.&#x0a;Please bring your own lunch for the 12 pm
 meetings.</text>
           </description>
           <uid>
             <text>00959BC664CA650E933C892C@example.com</text>
           </uid>
         </properties>
       </vevent>
       <vevent>
         <properties>
           <dtstamp>
             <date-time>2006-02-06T00:11:21Z</date-time>
           </dtstamp>
           <dtstart>
             <parameters>
               <tzid><text>US/Eastern</text></tzid>
             </parameters>
             <date-time>2006-01-04T14:00:00</date-time>
           </dtstart>
           <duration>
             <duration>PT1H</duration>
           </duration>
           <recurrence-id>
             <parameters>
               <tzid><text>US/Eastern</text></tzid>
             </parameters>
             <date-time>2006-01-04T12:00:00</date-time>
           </recurrence-id>
           <summary>
             <text>Event #2 bis</text>

Daboo, et al. Standards Track [Page 53] RFC 6321 xCal August 2011

           </summary>
           <uid>
             <text>00959BC664CA650E933C892C@example.com</text>
           </uid>
         </properties>
       </vevent>
     </components>
   </vcalendar>
 </icalendar>

Authors' Addresses

 Cyrus Daboo
 Apple Inc.
 1 Infinite Loop
 Cupertino, CA  95014
 USA
 EMail: cyrus@daboo.name
 URI:   http://www.apple.com/
 Mike Douglass
 Rensselaer Polytechnic Institute
 110 8th Street
 Troy, NY  12180
 USA
 EMail: douglm@rpi.edu
 URI:   http://www.rpi.edu/
 Steven Lees
 Microsoft Corporation
 One Microsoft Way
 Redmond, WA  98052
 USA
 EMail: steven.lees@microsoft.com
 URI:   http://www.microsoft.com/

Daboo, et al. Standards Track [Page 54]

/data/webs/external/dokuwiki/data/pages/rfc/rfc6321.txt · Last modified: 2011/08/08 18:54 (external edit)