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<?rfc toc="yes"?>
<?rfc tocdepth="4"?><!-- default = 3 -->
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<!--<?rfc strict="yes"?> -->
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<?rfc symrefs="yes"?>
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<rfc number="4791" category="std">
<front>
  <title abbrev="CalDAV">Calendaring Extensions to WebDAV (CalDAV)</title>
  <author initials="C." surname="Daboo" fullname="Cyrus Daboo">
    <organization abbrev="Apple Computer">Apple Computer, abbrev="Apple">Apple Inc.</organization>
    <address>
      <postal>
        <street>1 Infinite Loop</street>
        <city>Cupertino</city>
        <region>CA</region>
        <code>95014</code>
        <country>USA</country>
      </postal>
      <email>cyrus@daboo.name</email>
      <uri>http://www.apple.com/</uri>
    </address>
  </author>
  <author initials="B." surname="Desruisseaux"
    fullname="Bernard Desruisseaux">
    <organization abbrev="Oracle">Oracle Corporation</organization>
    <address>
      <postal>
        <street>600 Blvd. de Maisonneuve West</street>
        <street>Suite 1900</street>
        <city>Montreal</city>
        <region>QC</region>
        <code>H3A 3J2</code>
        <country>CANADA</country>
      </postal>
      <email>bernard.desruisseaux@oracle.com</email>
      <uri>http://www.oracle.com/</uri>
    </address>
  </author>
  <author initials="L.M." surname="Dusseault" fullname="Lisa Dusseault">
    <organization abbrev="OSAF">
      Open Source Application Foundation
    </organization> abbrev="CommerceNet">CommerceNet</organization>
    <address>
      <postal>
        <street>2064 Edgewood Dr.</street>
        <street>169 University Ave.</street>
        <city>Palo Alto</city>
        <region>CA</region>
        <code>94303</code>
        <code>94301</code>
        <country>USA</country>
      </postal>
      <email>lisa@osafoundation.org</email>
      <uri>http://www.osafoundation.org/</uri>
      <email>ldusseault@commerce.net</email>
      <uri>http://commerce.net/</uri>
    </address>
  </author>
  <date month="January" year="2007"/>
  <area>Applications</area>
  <keyword>calsched</keyword>
  <keyword>calsch</keyword>
  <keyword>caldav</keyword>
  <keyword>calendar</keyword>
  <keyword>calendaring</keyword>
  <keyword>scheduling</keyword>
  <keyword>webdav</keyword>
  <keyword>iCal</keyword>
  <keyword>iCalendar</keyword>
  <keyword>iTIP</keyword>
  <keyword>text/calendar</keyword>
  <keyword>HTTP</keyword>
  <abstract>
    <t>
      This document specifies a set of methods, headers, message bodies,
      properties, and reports that define calendar access defines extensions to the Web Distributed Authoring
      and Versioning (WebDAV) protocol.
      The new protocol elements are intended to make WebDAV-based specify a standard way of
      accessing, managing and sharing calendaring and scheduling an interoperable standard
      that supports calendar access, calendar management, calendar sharing,
      and calendar publishing.
      information based on the iCalendar format. This document
	  defines the "calendar-access" feature of CalDAV.
    </t>
  </abstract>
</front>

<middle>
<section title="Introduction">
  <t>
    The concept of using <xref target="RFC2616">HTTP</xref> and
    <xref target="RFC2518">WebDAV</xref> as a basis for a calendar
    access protocol is by no means a new concept: it was discussed in
    the IETF CALSCH working group as early as 1997 or 1998. Several
    companies have implemented calendar access protocols using HTTP
    to upload and download <xref target="RFC2445">iCalendar</xref>
    objects, and using WebDAV to get listings of resources.
    However, those implementations do not interoperate because there
    are many small and big decisions to be made in how to model
    calendaring data as WebDAV resources, as well as how to implement
    required features that aren't already part of WebDAV.

    This document proposes a way to model calendar data in WebDAV,
    with additional features to make an interoperable calendar
    access protocol.
  </t>

  <section title="Notational Conventions">
    <t>
      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 <xref target="RFC2119"/>.
    </t>
    <t>
      The term "protected" is used in the Conformance field
      of property definitions as defined in Section 1.4.2 of
      <xref target="RFC3253"/>.
    </t>
    <t>
      When XML element types in the namespaces "DAV:" and
      "urn:ietf:params:xml:ns:caldav" are referenced in this
      document outside of the context of an XML fragment,
      the string "DAV:" and "CALDAV:" will be prefixed to
      the element type names, respectively.
    </t>
  </section><!-- Notational Conventions -->

  <section title="XML Namespaces and Processing">
    <t>
      Definitions of XML elements in this document use XML element
      type declarations (as found in XML Document Type Declarations),
      described in Section 3.2 of <xref target="W3C.REC-xml-20060816"/>.
    </t>
    <t>
      The namespace "urn:ietf:params:xml:ns:caldav" is reserved
      for the XML elements defined in this specification, its
      revisions, and related CalDAV specifications. XML elements
      defined by individual implementations MUST NOT use the
      "urn:ietf:params:xml:ns:caldav" namespace, and instead
      should use a namespace that they control.
    </t>
    <t>
      The XML declarations used in this document do not include
      namespace information. Thus, implementers must not use these
      declarations as the only way to create valid CalDAV properties or
      to validate the CalDAV XML element type. types. Some of the declarations
      refer to XML elements defined by <xref
      target="RFC2518">WebDAV</xref>, which use the
      "DAV:" namespace. Wherever such XML elements appear, they are
      explicitly prefixed with "DAV:" to avoid confusion.
    </t>
    <t>
      Also note that some CalDAV XML element names are identical to
      WebDAV XML element names, though their namespace differs. Care
      must be taken not to confuse the two sets of names.
    </t>
    <t>
      Processing of XML by CalDAV clients and servers MUST follow the
      rules described in <xref target="RFC2518"/>; in particular, Section
      14, and Appendices Appendix 3 and 4 of that specification.
    </t>
  </section><!-- XML Namespace -->

  <section title="Method Preconditions and Postconditions">
    <t>
      A "precondition" of a method describes the state of the
      server that must be true for that method to be performed.
      A "postcondition" of a method describes the state of the
      server that must be true after that method has been completed.
      If a method precondition or postcondition for a request is
      not satisfied, the response status of the request MUST either be
      403 (Forbidden), if the request should not be repeated
      because it will always fail, or 409 (Conflict), if it is
      expected that the user might be able to resolve the conflict
      and resubmit the request.
    </t>
    <t>
      In order to allow better client handling of 403 and 409
      responses, a distinct XML element type is associated with
      each method precondition and postcondition of a request.
      When a particular precondition is not satisfied or a
      particular postcondition cannot be achieved, the appropriate
      XML element MUST be returned as the child of a top-level
      DAV:error element in the response body, unless otherwise
      negotiated by the request.
      <!-- May need to reference 2518bis
      for error elements in multistatus-->
    </t>
  </section><!-- Method Preconditions and Postconditions -->

</section><!-- Introduction -->
<section title="Requirements Overview" anchor="requirements">
<?rfc compact="no" ?>
 <t>
    This section lists what functionality is required of a CalDAV
    server. To advertise support for CalDAV, a server:
    <list style="symbols">
      <t>
        MUST support <xref target="RFC2445">iCalendar</xref> as a
        media type for the calendar object resource format;
      </t>
      <t>
        MUST support <xref target="RFC2518">WebDAV Class 1</xref>
        (note that <xref target="rfc2518bis"/> describes
        clarifications to <xref target="RFC2518"/> that aid interoperability);
      </t>
      <t>
        MUST support <xref target="RFC3744">WebDAV ACL</xref> with
        the additional privilege defined in <xref target="privileges"/>
        of this document;
      </t>
      <t>
        MUST support transport over TLS <xref target="RFC2246"/>
        as defined in <xref target="RFC2818"/> (note that <xref target="RFC2246"/> has been obsoleted by <xref target="RFC4346"/>);
      </t>
      <t>
        MUST support ETags <xref target="RFC2616"/> with additional
        requirements specified in <xref target="calendar-etag"/> of
        this document;
      </t>
      <t>
        MUST support all calendaring REPORTs reports defined in
        <xref target="reports"/> of this document; and
      </t>
      <t>
        MUST advertise support on all calendar collections and
        calendar object resources for the calendaring REPORTs reports
        in the DAV:supported-report-set property, as defined in
        <xref target="RFC3253">Versioning Extensions to WebDAV</xref>.
      </t>
    </list>
  </t>
  <t>In addition, a server:
    <list style="symbols">
      <t>
        SHOULD support the MKCALENDAR method defined in
        <xref target="METHOD_MKCALENDAR"/> of this document.
      </t>
    </list>
  </t>
</section><!-- requirements -->
<?rfc compact="yes" ?>
<section title="Calendaring Data Model" anchor="model">
  <t>
    One of the features that has made WebDAV a successful protocol
    is its firm data model. This makes it a useful framework for
    other applications such as calendaring. This specification
    follows the same pattern by developing all features based
    on a well-described data model.
  </t>
  <t>
    As a brief overview, a CalDAV calendar is modeled as a WebDAV
    collection with a defined structure; each calendar collection contains
    a number of resources representing calendar objects as its direct
    child resource. Each resource representing a calendar object (event,
    to-do, journal entry, or other calendar components) is called
    a "calendar object resource".  Each calendar object resource and each
    calendar collection can be individually locked and have individual
    WebDAV properties.  Requirements derived from this model are provided
    in <xref target="calendar-object-resource-restrictions"/> and
    <xref target="calendar-collection"/>.
  </t>

  <section title="Calendar Server">
    <t>
      A CalDAV server is a calendaring-aware engine combined with
      a WebDAV repository. A WebDAV repository is a set of WebDAV
      collections, containing other WebDAV resources, within a
      unified URL namespace. For example, the repository
      "http://www.example.com/webdav/" may contain WebDAV
      collections and resources, all of which have URLs beginning
      with "http://www.example.com/webdav/". Note that the root
      URL, "http://www.example.com/", may not itself be a WebDAV
      repository (for example, if the WebDAV support is implemented
      through a servlet or other Web server extension).
    </t>
    <t>
      A WebDAV repository MAY include calendar data in some parts
      of its URL namespace, and non-calendaring data in other parts.
    </t>
    <t>
      A WebDAV repository can advertise itself as a CalDAV server
      if it supports the functionality defined in this
      specification at any point within the root of the
      repository. That might mean that calendaring data is spread
      throughout the repository and mixed with non-calendar data
      in nearby collections (e.g., calendar data may be found in
      /home/lisa/calendars/ as well as in /home/bernard/calendars/,
      and non-calendar data in /home/lisa/contacts/). Or, it might
      mean that calendar data can be found only in certain sections of
      the repository (e.g., /calendar/). Calendaring
      features are only required in the repository sections that
      are or contain calendar object resources. Therefore, a repository
      confining calendar data to the /calendar/ collection would
      only need to support the CalDAV required features within
      that collection.
    </t>
    <t>
      The CalDAV server or repository is the canonical location
      for calendar data and state information. Clients may submit requests to change data
      or download data. Clients may store calendar objects
      offline and attempt to synchronize at a later time.
      However, clients MUST be prepared for calendar data on the
      server to change between the time of last synchronization
      and when attempting an update, as calendar collections may
      be shared and accessible via multiple clients. Entity tags
      and other features make this possible.
    </t>
  </section><!-- Calendar Server -->

  <section anchor="recurrence" title="Recurrence and the Data Model">
    <t>
      Recurrence is an important part of the data model because it
      governs how many resources are expected to exist. This
      specification models a recurring calendar component and its
      recurrence exceptions as a single resource. In this model,
      recurrence rules, recurrence dates, exception rules, and
      exception dates are all part of the data in a single
      calendar object resource. This model avoids problems of limiting
      how many recurrence instances to store in the repository, how to
      keep recurrence instances in sync with the recurring calendar
      component,
      and how to link recurrence exceptions with the recurring calendar
      component. It also results in less data to synchronize between
      client and server, and makes it easier to make changes to all
      recurrence instances or to a recurrence rule. It makes it
      easier to create a recurring calendar component and
      to delete all recurrence instances.
    </t>
    <t>
      Clients are not forced to retrieve information about all recurrence
      instances of a recurring component. The CALDAV:calendar-query and
      CALDAV:calendar-multiget REPORTs reports defined in this document allow
      clients to retrieve only recurrence instances that overlap a
      given time range.
    </t>
  </section><!-- Recurrence -->
</section><!-- Model -->
<?rfc needLines="8" ?>
<section title="Calendar Resources">

  <section title="Calendar Object Resources"
            anchor="calendar-object-resource-restrictions">
    <t>
      Calendar object resources contained in calendar collections MUST
      NOT contain more than one type of calendar component (e.g.,
      VEVENT, VTODO, VJOURNAL, VFREEBUSY, etc.) with the exception of
      VTIMEZONE components, which MUST be specified for each unique TZID
      parameter value specified in the iCalendar object. For instance,
      a calendar object resource can contain two one VEVENT components component and
      one VTIMEZONE component, but it cannot contain one VEVENT
      component and one VTODO component. Instead, the VEVENT and VTODO
      components would have to be stored in separate calendar object
      resources in the same collection.
    </t>

    <t>
      Calendar object resources contained in calendar collections MUST
      NOT specify the iCalendar METHOD property.
    </t>

    <t>
      The UID property value of the calendar components contained in a
      calendar object resource MUST be unique in the scope of the
      calendar collection in which they are stored.
    </t>

    <t>
      Calendar components in a calendar collection that have
      different UID property values MUST be stored in separate calendar
      object resources.
    </t>

    <t>
      Calendar components with the same UID property value, in a given
      calendar collection, MUST be contained in the same calendar object
      resource. This ensures that all components in a recurrence "set"
      are contained in the same calendar object resource. It is possible
      for a calendar object resource to just contain components that represent
      "overridden" instances (ones that modify the behavior of a regular
      instance, and thus include a RECURRENCE-ID property)
      without also including the "master" recurring component (the one that
      defines the recurrence "set" and does not contain any "RECURRENCE-ID"
      property).
    </t>
<?rfc needLines="25" ?>
    <t>For example, given the following iCalendar object:
      <figure>
        <artwork><![CDATA[
BEGIN:VCALENDAR
PRODID:-//Example Corp.//CalDAV Client//EN
VERSION:2.0
BEGIN:VEVENT
UID:1@example.com
SUMMARY:One-off Meeting
DTSTAMP:20041210T183904Z
DTSTART:20041207T120000Z
DTEND:20041207T130000Z
END:VEVENT
BEGIN:VEVENT
UID:2@example.com
SUMMARY:Weekly Meeting
DTSTAMP:20041210T183838Z
DTSTART:20041206T120000Z
DTEND:20041206T130000Z
RRULE:FREQ=WEEKLY
END:VEVENT
BEGIN:VEVENT
UID:2@example.com
SUMMARY:Weekly Meeting
RECURRENCE-ID:20041213T120000Z
DTSTAMP:20041210T183838Z
DTSTART:20041213T130000Z
DTEND:20041213T140000Z
END:VEVENT
END:VCALENDAR
        ]]></artwork>
      </figure>
    </t>
    <t>
      The VEVENT component with the UID value "1@example.com" would
      be stored in its own calendar object resource. The two
      VEVENT components with the UID value "2@example.com", which
      represent a recurring event where one recurrence instance has
      been overridden, would be stored in the same calendar object
      resource.
    </t>
  </section>

  <section title="Calendar Collection" anchor="calendar-collection">
    <t>
      A calendar collection contains calendar object resources that
      represent calendar components within a calendar. A calendar
      collection is manifested to clients as a WebDAV resource
      collection identified by a URL. A calendar collection MUST
      report the DAV:collection and CALDAV:calendar XML elements
      in the value of the DAV:resourcetype property. The element
      type declaration for CALDAV:calendar is:
      <figure>
        <artwork><![CDATA[
    <!ELEMENT calendar EMPTY>
        ]]></artwork>
      </figure>
    </t>
    <t>
      A calendar collection can be created through provisioning (i.e.,
      automatically created when a user's account is provisioned),
      or it can be created with the MKCALENDAR method (see
      <xref target="METHOD_MKCALENDAR"/>). This method can be useful
      for a user to create additional calendars (e.g., soccer
      schedule) or for users to share a calendar (e.g., team
      events or conference rooms). However, note that this document
      doesn't define the purpose of extra calendar collections.
      Users must rely on non-standard cues to find out what a
      calendar collection is for, or use the
      CALDAV:calendar-description property defined
      in <xref target='calendar-description'/> to provide such a
      cue.
    </t>
    <t>
      The following restrictions are applied to the resources within a calendar collection:
<?rfc compact="no" ?>
      <list style="letters">
      <t>
        Calendar collections MUST only contain calendar object
        resources and collections that are not calendar collections,
        i.e., the only "top-level" non-collection resources allowed in
        a calendar collection are calendar object resources. This
        ensures that calendar clients do not have to deal with
        non-calendar data in a calendar collection, though they do have
        to distinguish between calendar object resources and
        collections when using standard WebDAV techniques to examine
        the contents of a collection.
      </t>
      <t>
        Collections contained in calendar collections MUST NOT contain
        calendar collections at any depth, i.e., "nesting" of calendar
        collections within other calendar collections at any depth is
        not allowed. This specification does not define how collections
        contained in a calendar collection are used or how they relate to
        any calendar object resources contained in the calendar
        collection.
      </t>
      </list>
<?rfc compact="yes" ?>
    </t>
    <t>
      Multiple calendar collections MAY be children of the same
      collection.
    </t>
  </section><!-- calendar-collection -->

</section><!-- Calendar Resources -->

<section title="Calendar Access Feature">

  <section title="Calendar Access Support">
    <t>
      A server supporting the features described in this document MUST
      include "calendar-access" as a field in the DAV response header
      from an OPTIONS request on any resource that supports any
      calendar properties, reports, method, or privilege. A value of
      "calendar-access" in the DAV response header MUST indicate that
      the server supports all MUST level requirements specified in this
      document.
    </t>
    <section
      title="Example: Using OPTIONS for the Discovery of Calendar Access Support">
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
OPTIONS /home/bernard/calendars/ HTTP/1.1
Host: cal.example.com
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 200 OK
Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE
Allow: PROPFIND, PROPPATCH, LOCK, UNLOCK, REPORT, ACL
DAV: 1, 2, 3, access-control, calendar-access
Date: Fri, Sat, 11 Nov 2005 2006 09:32:12 GMT
Content-Length: 0
        ]]></artwork>
      </figure>
      <t>
        In this example, the OPTIONS method returns the value
        "calendar-access" in the DAV response header to
        indicate that the collection "/home/bernard/calendars/"
        supports the properties, reports, methods, method, or privileges privilege
        defined in this specification.
      </t>
    </section><!-- Example OPTIONS -->
  </section><!-- Calendar Access Support -->

  <section title="Calendar Collection Properties">
    <t>
      This section defines properties that MAY be defined
      on for calendar collections.
    </t>

    <section title="CALDAV:calendar-description Property"
             anchor="calendar-description">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            calendar-description
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Provides a human-readable description of the calendar
            collection.
          </t>
          <t hangText="Conformance:">
            This property MAY be defined on any calendar collection. If
            defined, it MAY be protected and SHOULD NOT be returned by
            a PROPFIND DAV:allprop request (as defined in Section 12.14.1
            of <xref target="RFC2518"/>). An
            xml:lang attribute indicating the human language of the
            description SHOULD be set for this property by clients or
            through server provisioning. Servers MUST return any
            xml:lang attribute if set for the property.
          </t>
          <t hangText="Description:">
            If present, the property contains a description of the
            calendar collection that is suitable for presentation to a
            user. If not present, the client should assume no
            description for the calendar collection.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT calendar-description (#PCDATA)>
      PCDATA value: string
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
      <C:calendar-description xml:lang="fr-CA"
         xmlns:C="urn:ietf:params:xml:ns:caldav"
      >Calendrier de Mathilde Desruisseaux</C:calendar-description>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- calendar-description -->

    <section title="CALDAV:calendar-timezone Property"
            anchor="calendar-timezone">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            calendar-timezone
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Specifies a time zone on a calendar collection.
          </t>
          <t hangText="Conformance:">
            This property SHOULD be defined on all calendar
            collections. If defined, it SHOULD NOT be returned by a
            PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
            <xref target="RFC2518"/>).
          </t>
          <t hangText="Description:">
            The CALDAV:calendar-timezone property is used to specify
            the time zone the server should rely on to resolve "date"
            values and "date with local time" values (i.e., floating
            time) to "date with UTC time" values. The server will
            require this information to determine if a calendar
            component scheduled with "date" values or "date with local
            time" values overlaps a CALDAV:time-range specified in a
            CALDAV:calendar-query REPORT. The server will also require
            this information to compute the proper FREEBUSY time period
            as "date with UTC time" in the VFREEBUSY component returned
            in a response to a CALDAV:free-busy-query REPORT request
            that takes into account calendar components scheduled with
            "date" values or "date with local time" values. In the
            absence of this property, the server MAY rely on the time
            zone of their choice.
          </t>
          <t hangText="Note:">
            The iCalendar data embedded within the CALDAV:calendar-timezone XML
            element MUST follow the standard XML character data encoding rules,
            including use of &amp;lt;, &amp;gt;, &amp;amp; etc. entity encoding
            or the use of a &lt;![CDATA[ ... ]]&gt; construct. In the later case,
            the iCalendar data cannot contain the character sequence "]]&gt;",
            which is the end delimiter for the CDATA section.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT calendar-timezone (#PCDATA)>
      PCDATA value: an iCalendar object with exactly one VTIMEZONE
            component.
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
<C:calendar-timezone
    xmlns:C="urn:ietf:params:xml:ns:caldav">BEGIN:VCALENDAR
PRODID:-//Example Corp.//CalDAV Client//EN
VERSION:2.0
BEGIN:VTIMEZONE
TZID:US-Eastern
LAST-MODIFIED:19870101T000000Z
BEGIN:STANDARD
DTSTART:19671029T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:Eastern Standard Time (US &amp; Canada)
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19870405T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:Eastern Daylight Time (US &amp; Canada)
END:DAYLIGHT
END:VTIMEZONE
END:VCALENDAR
</C:calendar-timezone>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- calendar-timezone-->

    <section title="CALDAV:supported-calendar-component-set Property"
      anchor="supported-calendar-component-set">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            supported-calendar-component-set
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Specifies the calendar component types
            (e.g., VEVENT, VTODO, etc.) that calendar object
            resources can contain in the calendar collection.
          </t>
          <t hangText="Conformance:">
            This property MAY be defined on any calendar collection. If
            defined, it MUST be protected and SHOULD NOT be returned by
            a PROPFIND DAV:allprop request (as defined in Section 12.14.1
            of <xref target="RFC2518"/>).
          </t>
          <t hangText="Description:">
            The CALDAV:supported-calendar-component-set property is
            used to specify restrictions on the calendar component
            types that calendar object resources may contain in a
            calendar collection. Any attempt by the client to store
            calendar object resources with component types not listed
            in this property, if it exists, MUST result in an error,
            with the CALDAV:supported-calendar-component precondition
            (<xref target="putpreconditions"/>) being violated. Since
            this property is protected, it cannot be changed by clients
            using a PROPPATCH request. However, clients can initialize
            the value of this property when creating a new calendar
            collection with MKCALENDAR. The empty-element tag
            &lt;C:comp name="VTIMEZONE"/&gt; MUST only be specified if
            support for calendar object resources that only contain
            VTIMEZONE components is provided or desired. Support for
            VTIMEZONE components in calendar object resources that
            contain VEVENT or VTODO components is always assumed. In
            the absence of this property, the server MUST accept all
            component types, and the client can assume that.
<!-- RFC Editor Comment: suggest adding the following text "all that all
            component types are accepted" to the end of this sentence --> accepted.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT supported-calendar-component-set (comp*)> (comp+)>
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
      <C:supported-calendar-component-set
          xmlns:C="urn:ietf:params:xml:ns:caldav">
        <C:comp name="VEVENT"/>
        <C:comp name="VTODO"/>
      </C:supported-calendar-component-set>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- supported-calendar-component-set -->

    <section title="CALDAV:supported-calendar-data Property"
      anchor="supported-calendar-data">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            supported-calendar-data
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Specifies what media types are allowed for calendar object
            resources in a calendar collection.
          </t>
          <t hangText="Conformance:">
            This property MAY be defined on any calendar collection. If
            defined, it MUST be protected and SHOULD NOT be returned by
            a PROPFIND DAV:allprop request (as defined in Section 12.14.1
            of <xref target="RFC2518"/>).
          </t>
          <t hangText="Description:">
            The CALDAV:supported-calendar-data property is used to
            specify the media type supported for the calendar object
            resources contained in a given calendar collection (e.g.,
            iCalendar version 2.0). Any attempt by the client to store
            calendar object resources with a media type not listed in
            this property MUST result in an error, with the
            CALDAV:supported-calendar-data precondition (<xref
            target="putpreconditions"/>) being violated. In the absence
            of this property, the server MUST only accept data with the media
            type "text/calendar" and iCalendar version 2.0, and clients
            can assume that the server will only accept this data.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT supported-calendar-data (calendar-data*)> (calendar-data+)>
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
      <C:supported-calendar-data
         xmlns:C="urn:ietf:params:xml:ns:caldav">
        <C:calendar-data content-type="text/calendar" version="2.0"/>
      </C:supported-calendar-data>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- supported-calendar-data -->

    <section title="CALDAV:max-resource-size Property"
             anchor="max-resource-size">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            max-resource-size
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Provides a numeric value indicating the maximum size of a
            resource in octets that the server is willing to accept
            when a calendar object resource is stored in a calendar
            collection.
          </t>
          <t hangText="Conformance:">
            This property MAY be defined on any calendar collection. If
            defined, it MUST be protected and SHOULD NOT be returned by
            a PROPFIND DAV:allprop request (as defined in Section 12.14.1
            of <xref target="RFC2518"/>).
          </t>
          <t hangText="Description:">
            The CALDAV:max-resource-size is used to specify a numeric
            value that represents the maximum size in octets that the
            server is willing to accept when a calendar object resource
            is stored in a calendar collection. Any attempt to store a
            calendar object resource exceeding this size MUST result in
            an error, with the CALDAV:max-resource-size precondition
            (<xref target="putpreconditions"/>) being violated. In the
            absence of this property, the client can assume that the
            server will allow storing a resource of any reasonable size.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT max-resource-size (#PCDATA)>
      PCDATA value: a numeric value (positive integer)
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
      <C:max-resource-size xmlns:C="urn:ietf:params:xml:ns:caldav"
      >102400</C:max-resource-size>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- max-resource-size -->

    <section title="CALDAV:min-date-time Property"
             anchor="min-date-time">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            min-date-time
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Provides a date-time DATE-TIME value indicating the earliest date and
            time (in UTC) that the server is willing to accept for any
            date
            DATE or time DATE-TIME value in a calendar object resource stored in
            a calendar collection.
          </t>
          <t hangText="Conformance:">
            This property MAY be defined on any calendar collection. If
            defined, it MUST be protected and SHOULD NOT be returned by a
            PROPFIND DAV:allprop request (as defined in Section 12.14.1 of
            <xref target="RFC2518"/>).
          </t>
          <t hangText="Description:">
            The CALDAV:min-date-time is used to specify an iCalendar
            DATE-TIME value in UTC that indicates the earliest
            inclusive date that the server is willing to accept for any
            explicit date DATE or time DATE-TIME value in a calendar object resource
            stored in a calendar collection. Any attempt to store a
            calendar object resource using a date DATE or time DATE-TIME value earlier
            than this value MUST result in an error, with the
            CALDAV:min-date-time precondition (<xref
            target="putpreconditions"/>) being violated. Note that
            servers MUST accept recurring components that specify
            instances beyond this limit, provided that none of those
            instances have been overridden. In that case, the server
            MAY simply ignore those instances outside of the
            acceptable range when processing reports on the calendar
            object resource. In the absence of this property, the client
            can assume any valid iCalendar date may be used at least up
            to the CALDAV:max-date-time value, if that is defined.
            </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT min-date-time (#PCDATA)>
      PCDATA value: an iCalendar format DATE-TIME value in UTC
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
      <C:min-date-time xmlns:C="urn:ietf:params:xml:ns:caldav"
      >19000101T000000Z</C:min-date-time>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- min-date-time -->

    <section title="CALDAV:max-date-time Property"
             anchor="max-date-time">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            max-date-time
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Provides a date-time DATE-TIME value indicating the latest date and
            time (in UTC) that the server is willing to accept for any
            date
            DATE or time DATE-TIME value in a calendar object resource stored in
            a calendar collection.
          </t>
          <t hangText="Conformance:">
            This property MAY be defined on any calendar collection. If
            defined, it MUST be protected and SHOULD NOT be returned by
            a PROPFIND DAV:allprop request (as defined in Section 12.14.1
            of <xref target="RFC2518"/>).
          </t>
          <t hangText="Description:">
            The CALDAV:max-date-time is used to specify an iCalendar
            DATE-TIME value in UTC that indicates the inclusive latest
            date that the server is willing to accept for any date or
            time value in a calendar object resource stored in a
            calendar collection. Any attempt to store a calendar object
            resource using a date DATE or time DATE-TIME value later than this value
            MUST result in an error, with the CALDAV:max-date-time
            precondition (<xref target="putpreconditions"/>) being
            violated. Note that servers MUST accept recurring
            components that specify instances beyond this limit,
            provided none of those instances have been overridden. In
            that case, the server MAY simply ignore those instances
            outside of the acceptable range when processing reports on
            the calendar object resource. In the absence of this
            property, the client can assume any valid iCalendar date may
            be used at least down to the CALDAV:min-date-time value, if
            that is defined.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT max-date-time (#PCDATA)>
      PCDATA value: an iCalendar format DATE-TIME value in UTC
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
      <C:max-date-time xmlns:C="urn:ietf:params:xml:ns:caldav"
      >20491231T235959Z</C:max-date-time>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- max-date-time -->

    <section title="CALDAV:max-instances Property"
             anchor="max-instances">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            max-instances
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Provides a numeric value indicating the maximum number of
            recurrence instances that a calendar object resource stored
            in a calendar collection can generate.
          </t>
          <t hangText="Conformance:">
            This property MAY be defined on any calendar collection. If
            defined, it MUST be protected and SHOULD NOT be returned by
            a PROPFIND DAV:allprop request (as defined in Section 12.14.1
            of <xref target="RFC2518"/>).
          </t>
          <t hangText="Description:">
            The CALDAV:max-instances is used to specify a numeric
            value that indicates the maximum number of recurrence
            instances that a calendar object resource stored in a
            calendar collection can generate. Any attempt to store a
            calendar object resource with a recurrence pattern that
            generates more instances than this value MUST result in an
            error, with the CALDAV:max-instances precondition (<xref
            target="putpreconditions"/>) being violated. In the absence
            of this property, the client can assume that the server has
            no limits on the number of recurrence instances it can
            handle or expand.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT max-instances (#PCDATA)>
      PCDATA value: a numeric value (integer greater than zero)
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
      <C:max-instances xmlns:C="urn:ietf:params:xml:ns:caldav"
      >100</C:max-instances>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- max-instances -->

    <section title="CALDAV:max-attendees-per-instance Property"
             anchor="max-attendees-per-instance">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            max-attendees-per-instance
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Provides a numeric value indicating the maximum number of
            ATTENDEE properties in any instance of a calendar object
            resource stored in a calendar collection.
          </t>
          <t hangText="Conformance:">
            This property MAY be defined on any calendar collection. If
            defined, it MUST be protected and SHOULD NOT be returned by
            a PROPFIND DAV:allprop request (as defined in Section 12.14.1
            of <xref target="RFC2518"/>).
          </t>
          <t hangText="Description:">
            The CALDAV:max-attendees-per-instance is used to specify a
            numeric value that indicates the maximum number of
            iCalendar ATTENDEE properties on any one instance of a
            calendar object resource stored in a calendar collection.
            Any attempt to store a calendar object resource with more
            ATTENDEE properties per instance than this value MUST
            result in an error, with the
            CALDAV:max-attendees-per-instance precondition (<xref
            target="putpreconditions"/>) being violated. In the absence
            of this property, the client can assume that the server can
            handle any number of ATTENDEE properties in a calendar
            component.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT max-attendees-per-instance (#PCDATA)>
      PCDATA value: a numeric value (integer greater than zero)
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
      <C:max-attendees-per-instance
           xmlns:C="urn:ietf:params:xml:ns:caldav"
      >25</C:max-attendees-per-instance>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- max-attendees-per-instance -->

      <section title="Additional Precondition for PROPPATCH">
      <t>
        This specification requires an additional Precondition for
        the PROPPATCH method. The precondition is:
<?rfc compact="no" ?>
        <list>
          <t>
            (CALDAV:valid-calendar-data): The time zone specified in
            CALDAV:calendar-timezone property MUST be a valid
            iCalendar object containing a single valid VTIMEZONE component.
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
       </section>
  </section><!-- Calendar Collection Properties -->

  <section title="Creating Resources" anchor="creating-resources">
    <t>
      The creation of calendar
      Calendar collections and calendar object resources may be initiated created
      by either a CalDAV client or by the CalDAV server. For
      example, a server might come pre-configured with This
      specification defines restrictions and a user's data model that both
      clients and servers MUST adhere to when manipulating such calendar
      collection, or the CalDAV client might
      data.
    </t>

    <section title="MKCALENDAR Method" anchor="METHOD_MKCALENDAR">
      <t>
        An HTTP request using the server to create MKCALENDAR method creates a new calendar
        collection for a given user. Servers might populate
      events as calendar objects inside a calendar collection, or clients
      might request the server to create events. Either way, both client and
      server MUST comply with the requirements in this document, and MUST
      understand objects appearing in calendar collections or
<!-- RFC Editor Comment: This is not very clear.  If we understand the
intent correctly, we suggest "and MUST understand objects appearing in
calendar collections or MUST understand objects according to the data
model defined here" -->
      according to the data model defined here.
    </t>

    <section title="MKCALENDAR Method" anchor="METHOD_MKCALENDAR">
      <t>
        An HTTP request using the MKCALENDAR method creates a new calendar
        collection resource. A resource. A server MAY restrict calendar collection
        creation to particular collections.
      </t>
      <t>
        Support for MKCALENDAR on the server is only RECOMMENDED and not
        REQUIRED because some calendar stores only support one calendar
        per user (or principal), and those are typically pre-created for
        each account. However, servers and clients are strongly encouraged
        to support MKCALENDAR whenever possible to allow users to create
        multiple calendar collections to help organize their data better.
      </t>
      <t>
        Clients SHOULD use the DAV:displayname property for a
        human-readable name of the calendar. Clients can either
        specify the value of the DAV:displayname property in the
        request body of the MKCALENDAR request, or alternatively
        issue a PROPPATCH request to change the DAV:displayname property
        to the appropriate value immediately after issuing the
        MKCALENDAR request. Clients SHOULD NOT set the DAV:displayname
        property to be the same as any other calendar collection at the same
        URI "level". When displaying calendar collections to users,
        clients SHOULD check the DAV:displayname property and use that
        value as the name of the calendar. In the event that the
        DAV:displayname property is empty, the client MAY use the last
        part of the calendar collection URI as the name; however, that
        path segment may be "opaque" and not represent any meaningful
        human-readable text.
      </t>
      <t>
        If a MKCALENDAR request fails, the server state preceding the
        request MUST be restored.
      </t>
      <t>
        Marshalling:
        <list>
          <t>
            If a request body is included, it MUST be a CALDAV:mkcalendar
            XML element. Instruction processing MUST occur in the order
            instructions are received (i.e., from top to bottom).
            Instructions MUST either all be executed or none executed.
            Thus, if any error occurs during processing, all executed
            instructions MUST be undone and a proper error result
            returned. Instruction processing details can be found in
            the definition of the DAV:set instruction in Section 12.13.2
            of <xref target="RFC2518"/>.
            <figure>
              <artwork><![CDATA[
      <!ELEMENT mkcalendar (DAV:set)>
              ]]></artwork>
            </figure>
          </t>
          <t>
            If a response body for a successful request is included, it MUST
            be a CALDAV:mkcalendar-response XML element.
          <figure>
            <artwork><![CDATA[
      <!ELEMENT mkcalendar-response ANY>
            ]]></artwork>
          </figure>

        </t>
        <t>
          The response MUST include a Cache-Control:no-cache header.
        </t>
        </list>
      </t>
      <t>
        Preconditions:
<?rfc compact="no" ?>
        <list>
          <t>
            (DAV:resource-must-be-null): A resource MUST NOT exist
            at the Request-URI;
          </t>
          <t>
            (CALDAV:calendar-collection-location-ok): The
            Request-URI MUST identify a location where a calendar
            collection can be created;
          </t>
          <t>
            (CALDAV:valid-calendar-data): The time zone specified in
            the CALDAV:calendar-timezone property MUST be a valid
            iCalendar object containing a single valid VTIMEZONE component;
          </t>
          <t>
            (DAV:needs-privilege): The DAV:bind privilege MUST be
            granted to the current user on the parent collection
            of the Request-URI.
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
      <t> Postconditions:
<?rfc compact="no" ?>
        <list>
          <t>
            (CALDAV:initialize-calendar-collection): A new
            calendar collection exists at the Request-URI. The
            DAV:resourcetype of the calendar collection MUST
            contain both DAV:collection and CALDAV:calendar XML
            elements.
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>

      <section title="Status Codes">
        <t>
          The following are examples of response codes one would expect
          to get in a response to a MKCALENDAR request. Note that this
          list is by no means exhaustive.
<?rfc compact="no" ?>
          <list>
            <t>
              201 (Created) - The calendar collection resource was created
              in its entirety;
            </t>
            <t>
              207 (Multi-Status) - The calendar collection resource was
              not created since one or more DAV:set instructions specified
              in the request body could not be processed successfully. The
              following are examples of response codes one would expect
              to be used in a 207 (Multi-Status) response in this situation:
              <list>
                <t>
                  403 (Forbidden) - The client, for reasons the server
                  chooses not to specify, cannot alter one of the properties;
                </t>
                <t>
                  409 (Conflict) - The client has provided a value whose
                  semantics are not appropriate for the property. This
                  includes trying to set read-only properties;
                </t>
                <t>
                  424 (Failed Dependency) - The DAV:set instruction on the
                  specified resource would have succeeded if it were not for
                  the failure of another DAV:set instruction specified in the
                  request body;
                </t>
                <t>
                  423 (Locked) - The specified resource is locked and the
                  client either is not a lock owner or the lock type
                  requires a lock token to be submitted and the client did
                  not submit it; and
                </t>
                <t>
                  507 (Insufficient Storage) - The server did not have
                  sufficient space to record the property;
                </t>
              </list>
            </t>
            <t>
              403 (Forbidden) - This indicates at least one of two
              conditions: 1) the server does not allow the creation of calendar
              collections at the given location in its namespace, or 2) the
              parent collection of the Request-URI exists but cannot accept
              members;
            </t>
            <t>
              409 (Conflict) - A collection cannot be made at the
              Request-URI until one or more intermediate collections have been
              created;
            </t>
            <t>
              415 (Unsupported Media Type) - The server does not support
              the request type of the body; and
            </t>
            <t>
              507 (Insufficient Storage) - The resource does not have
              sufficient space to record the state of the resource after the
              execution of this method.
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- Status Codes -->

      <section title="Example: Successful MKCALENDAR Request">

        <t>
          This example creates a calendar collection called
          /home/lisa/calendars/events/ on the server
          cal.example.com with specific values for the properties
          DAV:displayname, CALDAV:calendar-description,
          CALDAV:supported-calendar-component-set, and
          CALDAV:calendar-timezone.
        </t>

        <figure>
          <preamble>&gt;&gt; Request &lt;&lt;</preamble>
          <artwork><![CDATA[
MKCALENDAR /home/lisa/calendars/events/ HTTP/1.1
Host: cal.example.com
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:mkcalendar xmlns:D="DAV:"
              xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:set>
    <D:prop>
      <D:displayname>Lisa's Events</D:displayname>
      <C:calendar-description xml:lang="en"
>Calendar restricted to events.</C:calendar-description>
      <C:supported-calendar-component-set>
        <C:comp name="VEVENT"/>
      </C:supported-calendar-component-set>
      <C:calendar-timezone>]]>&lt;![CDATA[<![CDATA[BEGIN:VCALENDAR
PRODID:-//Example Corp.//CalDAV Client//EN
VERSION:2.0
BEGIN:VTIMEZONE
TZID:US-Eastern
LAST-MODIFIED:19870101T000000Z
BEGIN:STANDARD
DTSTART:19671029T020000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:Eastern Standard Time (US & Canada)
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:19870405T020000
RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:Eastern Daylight Time (US & Canada)
END:DAYLIGHT
END:VTIMEZONE
END:VCALENDAR
]]>]]&gt;<![CDATA[</C:calendar-timezone>
    </D:prop>
  </D:set>
</C:mkcalendar>
          ]]></artwork>
        </figure>
        <figure>
          <preamble>&gt;&gt; Response &lt;&lt;</preamble>
          <artwork><![CDATA[
HTTP/1.1 201 Created
Cache-Control: no-cache
Date: Fri, Sat, 11 Nov 2005 2006 09:32:12 GMT
Content-Length: 0
          ]]></artwork>
        </figure>
      </section><!-- Example - MKCALENDAR -->

        <!--+++
      <section title="Example: Failed MKCALENDAR request">
      </section>
        -->

    </section><!-- MKCALENDAR Method -->

    <section title="Creating Calendar Object Resources">
      <t>
        Clients populate calendar collections with calendar object
        resources. The URL for each calendar object resource is
        entirely arbitrary and does not need to bear a specific
        relationship to the calendar object resource's iCalendar
        properties or other metadata. New calendar object resources
        MUST be created with a PUT request targeted at an unmapped URI. A PUT
        request targeted at a mapped URI updates an existing calendar
        object resource.
      </t>
      <t>
        When servers create new resources, it's not hard for the server to
        choose an unmapped URI. It's slightly tougher for clients, because a
        client might not want to examine all resources in the collection
        and might not want to lock the entire collection to ensure that a new
        resource isn't created with a name collision. However, there is an HTTP
        feature to mitigate this. If the client intends to create a new
        non-collection resource, such as a new VEVENT, the client SHOULD
        use the HTTP request header "If-None-Match: *" on the PUT request.
        The Request-URI on the PUT request MUST include the target
        collection, where the resource is to be created, plus the name of
        the resource in the last path segment. The "If-None-Match: *" request
        header ensures that the client will not inadvertently overwrite an
        existing resource if the last path segment turned out to already be
        used.
      </t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
PUT /home/lisa/calendars/events/qwue23489.ics HTTP/1.1
If-None-Match: *
Host: cal.example.com
Content-Type: text/calendar
Content-Length: xxxx

BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
UID:20010712T182145Z-123401@example.com
DTSTAMP:20060712T182145Z
DTSTART:20060714T170000Z
DTEND:20060715T040000Z
SUMMARY:Bastille Day Party
END:VEVENT
END:VCALENDAR
]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 201 Created
Content-Length: 0
Date: Fri, Sat, 11 Nov 2005 2006 09:32:12 GMT
ETag: "123456789-000-111"
        ]]></artwork>
      </figure>
      <t>
        The request to change an existing event is the same, but with a
        specific ETag in the "If-Match" header, rather than the
        "If-None-Match" header.
      </t>
      <t>
        As indicated in Section 3.10 of
        <xref target="RFC2445"/>, the URL of calendar
        object resources containing (an arbitrary set of) calendaring
        and scheduling information may be suffixed by ".ics", and the URL
        of calendar object resources containing free or busy time
        information may be suffixed by ".ifb".
      </t>

      <section title="Additional Preconditions for PUT, COPY, and MOVE"
               anchor="putpreconditions">
      <t>
        This specification creates additional Preconditions for
        PUT, COPY, and MOVE methods. These preconditions apply:
        <list>
          <t>When apply
        when a PUT operation of a calendar object resource into
        a calendar collection occurs.</t>
          <t>When occurs, or when a COPY or MOVE
        operation of a calendar object resource into
        a calendar collection occurs.</t>
<!-- RFC Editor Comment: we suggest making the above items complete
sentences -->
        </list> occurs, or when a COPY or MOVE
        operation occurs on a calendar collection.
      </t>
<?rfc needLines="5" ?>
        <t>The new preconditions are:
<?rfc compact="no" ?>
        <list>
          <t>
            (CALDAV:supported-calendar-data): The resource submitted in
            the PUT request, or targeted by a COPY or MOVE request, MUST
            be a supported media type (i.e., iCalendar) for calendar object
            resources;
          </t>
          <t>
            (CALDAV:valid-calendar-data): The resource submitted in the
            PUT request, or targeted by a COPY or MOVE request, MUST be valid
            data for the media type being specified (i.e., MUST contain valid
            iCalendar data);
          </t>
          <t>
            (CALDAV:valid-calendar-object-resource): The resource
            submitted in the PUT request, or targeted by a COPY or MOVE request,
            MUST obey all restrictions specified in
            <xref target="calendar-object-resource-restrictions"/>
            (e.g., calendar object resources MUST NOT contain more
            than one type of calendar component, calendar object
            resources MUST NOT specify the iCalendar METHOD property,
            etc.);
          </t>
          <t>
            (CALDAV:supported-calendar-component): The resource
            submitted in the PUT request, or targeted by a COPY or MOVE request,
            MUST contain a type of calendar component that is supported in the
            targeted calendar collection;
          </t>
           <t>
             (CALDAV:no-uid-conflict): The resource submitted in the
             PUT request, or targeted by a COPY or MOVE request, MUST NOT
             specify an iCalendar UID property
             value already in use in the targeted calendar collection
             or overwrite an existing calendar object resource with
             one that has a different UID
             property value. Servers SHOULD report the URL of the
             resource that is already making use of the same UID
             property value in the DAV:href element;
             <figure>
               <artwork><![CDATA[
             <!ELEMENT no-uid-conflict (DAV:href)>
               ]]></artwork>
             </figure>
           </t>
          <t>
            (CALDAV:calendar-collection-location-ok): In a COPY or
            MOVE request, when the Request-URI is a calendar collection,
            the Destination-URI MUST identify a location where a calendar
            collection can be created;
          </t>
          <t>
            (CALDAV:max-resource-size): The resource submitted in the
             PUT request, or targeted by a COPY or MOVE request, MUST have an octet size less than or equal to the value of the CALDAV:max-resource-size property value (<xref target="max-resource-size"/>) on the calendar collection where the resource will be stored;
          </t>
          <t>
            (CALDAV:min-date-time): The resource submitted in the
             PUT request, or targeted by a COPY or MOVE request, MUST have all of its iCalendar date DATE or time DATE-TIME property values (for each recurring instance) greater than or equal to the value of the CALDAV:min-date-time property value (<xref target="min-date-time"/>) on the calendar collection where the resource will be stored;
          </t>
          <t>
            (CALDAV:max-date-time): The resource submitted in the
             PUT request, or targeted by a COPY or MOVE request, MUST have all of its iCalendar date DATE or time DATE-TIME property values (for each recurring instance) less than the value of the CALDAV:max-date-time property value (<xref target="max-date-time"/>) on the calendar collection where the resource will be stored;
          </t>
          <t>
            (CALDAV:max-instances): The resource submitted in the
             PUT request, or targeted by a COPY or MOVE request, MUST generate a number of recurring instances less than or equal to the value of the CALDAV:max-instances property value (<xref target="max-instances"/>) on the calendar collection where the resource will be stored;
          </t>
          <t>
            (CALDAV:max-attendees-per-instance): The resource submitted in the
             PUT request, or targeted by a COPY or MOVE request, MUST have a number of ATTENDEE properties on any one instance less than or equal to the value of the CALDAV:max-attendees-per-instance property value (<xref target="max-attendees-per-instance"/>) on the calendar collection where the resource will be stored;
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
       </section>
    </section><!-- Creating Calendar Object Resources -->

    <section title="Non-Standard Components, Properties, and Parameters">
       <t>
         iCalendar provides a "standard mechanism for doing non-standard
         things". This extension support allows implementers to make use of
         non-standard components, properties, and parameters whose names are
         prefixed with the text "X-".
       </t>
       <t>
         Servers MUST support the use of non-standard components,
         properties, and parameters in calendar object resources stored
         via the PUT method.
       </t>
       <t>
         Servers may need to enforce rules for their own "private"
         components, properties, or parameters, so servers MAY reject
         any attempt by the client to change those or use values for
         those outside of any restrictions the server may have. Servers
         SHOULD ensure that any "private" components, properties, or
         parameters it uses follow the convention of including a vendor
         id in the "X-" name, as described in Section 4.2 of <xref
         target="RFC2445"/>, e.g., "X-ABC-Private". "X-ABC-PRIVATE".
       </t>
    </section>

    <section title="Calendar Object Resource Entity Tag"
             anchor="calendar-etag">
      <t>
        The DAV:getetag property MUST be defined and set to a strong
        entity tag on all calendar object resources.
      </t>
      <t>
        A response to a GET request targeted at a calendar object
        resource MUST contain an ETag response header field
        indicating the current value of the strong entity tag of
        the calendar object resource.
      </t>
      <t>
        Servers SHOULD return a strong entity tag (ETag header) in a PUT
        response when the stored calendar object resource is equivalent
        by octet equality to the calendar object resource submitted in
        the body of the PUT request. This allows clients to reliably use
        the returned strong entity tag for data synchronization
        purposes. For instance, the client can do a PROPFIND request on
        the stored calendar object resource and have the DAV:getetag
        property returned, and compare that value with the strong entity
        tag it received on the PUT response, and know that if they are
        equal, then the calendar object resource on the server has not
        been changed.
      </t>
      <t>
        In the case where the data stored by a server as a result of a
        PUT request is not equivalent by octet equality to the submitted
        calendar object resource, the behavior of the ETag response
        header is not specified here, with the exception that a strong
        entity tag MUST NOT be returned in the response. As a result,
        clients may need to retrieve the modified calendar object
        resource (and ETag) as a basis for further changes, rather than
        use the calendar object resource it had sent with the PUT
        request.
      </t>
    </section><!-- Calendar Object Resource Entity Tag -->
  </section><!-- Creating Resources -->
</section><!-- Calendar Access Feature -->

<section title="Calendaring Access Control">
  <section anchor="privileges" title="Calendaring Privilege">
    <t>
      CalDAV servers MUST support and adhere to the requirements of
      <xref target="RFC3744">WebDAV ACL</xref>. WebDAV ACL provides
      a framework for an extensible set of privileges that can be
      applied to WebDAV collections and ordinary resources.
      CalDAV servers MUST also support the calendaring privilege
      defined in this section.
    </t>

    <section title="CALDAV:read-free-busy Privilege"
            anchor="PRIVILEGE_read-free-busy">
      <t>
        Calendar users often wish to allow other users to see their
        busy time information, without viewing the other details
        of the calendar components (e.g., location, summary, attendees).
        This allows a significant amount of privacy while still
        allowing other users to schedule meetings at times when
        the user is likely to be free.
      </t>
      <t>
        The CALDAV:read-free-busy privilege controls which calendar
        collections, regular collections, and calendar object resources
        are examined when a CALDAV:free-busy-query REPORT request is
        processed (see <xref target="free-busy-query"/>).  This
        privilege can be granted on calendar collections, regular
        collections, or calendar object resources. Servers MUST support
        this privilege on all calendar collections, regular collections,
        and calendar object resources.
      </t>
      <t>
        <figure>
          <artwork><![CDATA[
        <!ELEMENT read-free-busy EMPTY>
          ]]></artwork>
        </figure>
      </t>
      <t>
        The CALDAV:read-free-busy privilege MUST be aggregated in the
        DAV:read privilege. Servers MUST allow the CALDAV:read-free-busy
        to be granted without the DAV:read privilege being granted.
      </t>
<?rfc needLines="5" ?>
      <t>
        Clients should note that when only the CALDAV:read-free-busy
        privilege has been granted on a resource,
        access to GET, HEAD, OPTIONS, and PROPFIND on the resource is
        not imlied implied (those operations are governed by the DAV:read privilege).
      </t>
    </section><!-- PRIVILEGE_read-free-busy -->
  </section> <!-- privileges -->

  <section anchor="principal.properties"
          title="Additional Principal Property">
    <t>
      This section defines an additional property for WebDAV principal
      resources, as defined in <xref target="RFC3744"/>.
    </t>

    <section anchor="PROPERTY_calendar-home-set"
            title="CALDAV:calendar-home-set Property">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            calendar-home-set
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Identifies the URL of any WebDAV collections that contain
            calendar collections owned by the associated principal
            resource.
          </t>
          <t hangText="Conformance:">
            This property SHOULD be defined on a principal resource. If
            defined, it MAY be protected and SHOULD NOT be returned by
            a PROPFIND DAV:allprop request (as defined in Section 12.14.1
            of <xref target="RFC2518"/>).
          </t>
          <t hangText="Description:">
            The CALDAV:calendar-home-set property is meant to allow
            users to easily find the calendar collections owned by
            the principal. Typically, users will group all the
            calendar collections that they own under a common
            collection. This property specifies the URL of
            collections that are either calendar collections or
            ordinary collections that have child or descendant
            calendar collections owned by the principal.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT calendar-home-set (DAV:href*)>
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
    <C:calendar-home-set xmlns:D="DAV:"
                         xmlns:C="urn:ietf:params:xml:ns:caldav">
      <D:href>http://cal.example.com/home/bernard/calendars/</D:href>
    </C:calendar-home-set>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- PROPERTY_calendar-home-set -->
  </section><!-- principal.properties -->

</section><!-- Calendaring Access Control -->

<section title="Calendaring Reports" anchor="reports">
  <t>
    This section defines the REPORTs reports that CalDAV servers MUST
    support on calendar collections and calendar object resources.
  </t>
  <t>
    CalDAV servers MUST advertise support for these REPORTs reports
    on all calendar collections and calendar object resources
    with the DAV:supported-report-set property, defined in
    Section 3.1.5 of <xref target="RFC3253"/>. CalDAV servers
    MAY also advertise support for these REPORTs reports on ordinary
    collections.
  </t>
  <t>
    Some of these REPORTs reports allow calendar data (from possibly
    multiple resources) to be returned.
  </t>

  <section anchor="METHOD_REPORT" title="REPORT Method">
    <t>
      The REPORT method (defined in Section 3.6 of
      <xref target="RFC3253"/>) provides an
      extensible mechanism for obtaining information about one or
      more resources. Unlike the PROPFIND method, which returns
      the value of one or more named properties, the REPORT method
      can involve more complex processing. REPORT is valuable in
      cases where the server has access to all of the information
      needed to perform the complex request (such as a query), and
      where it would require multiple requests for the client to
      retrieve the information needed to perform the same request.
    </t>
    <t>
      CalDAV servers MUST support the DAV:expand-property REPORT
      defined in Section 3.8 of <xref target="RFC3253"/>.
    </t>
  </section><!-- REPORT Method -->

  <section title="Ordinary Collections">
    <t>
      Servers MAY support the REPORTs reports defined in this document on
      ordinary collections (collections that are not calendar
      collections), in addition to calendar collections or calendar
      object resources. In computing responses to the REPORTs reports on
      ordinary collections, servers MUST only consider calendar object
      resources contained in calendar collections that are targeted by
      the REPORT, REPORT request, based on the value of the Depth request header.
    </t>
  </section><!-- Ordinary collections -->

  <section title="Date and Floating Time">
    <t>
      iCalendar provides a way to specify DATE and DATE-TIME values
      that are not bound to any time zone in particular, hereafter
      called "floating date" and "floating time", respectively. These
      values are used to represent the same day, hour, minute, and
      second value, regardless of which time zone is being observed.
      For instance, the DATE value "20051111", represents November 11,
      2005 in no specific time zone, while the DATE-TIME value
      "20051111T111100" represents November 11, 2005, at 11:11 A.M. in
      no specific time zone.
    </t>
    <t>
      CalDAV servers may need to convert "floating date" and "floating
      time" values in date with UTC time values in the processing
      of calendaring REPORT requests.
    </t>
    <t>
      For the CALDAV:calendar-query REPORT, CalDAV servers MUST rely
      on the value of the CALDAV:timezone XML element, if specified
      as part of the request body, to perform the proper conversion
      of "floating date" and "floating time" values to date with UTC
      time values. If the CALDAV:timezone XML element is not specified
      in the request body, CalDAV servers MUST rely on the value of
      the CALDAV:calendar-timezone property, if defined, or else the
      CalDAV servers MAY rely on the time zone of their choice.
    </t>
    <t>
      For the CALDAV:free-busy-query REPORT, CalDAV servers MUST rely
      on the value of the CALDAV:calendar-timezone property, if defined,
      to compute the proper FREEBUSY time period value as date with UTC
      time for calendar components scheduled with "floating date" or
      "floating time". If the CALDAV:calendar-timezone property is not
      defined, CalDAV servers MAY rely on the time zone of their choice.
    </t>
  </section><!-- Date and floating time -->

  <section title="Time Range Filtering">
    <t>
      Some of the reports defined in this section can include a time
      range filter that is used to restrict the set of calendar object
      resources returned to just those that overlap the specified time
      range. The time range filter can be applied to a calendar
      component as a whole, or to specific calendar component
      properties with date DATE or date-time DATE-TIME value types.
    </t>
    <t>To determine whether a calendar object resource matches the time
    range filter element, the start and end times for the targeted
    component or property are determined and then compared to the
    requested time range. If there is an overlap with the requested
    time range, then the calendar object resource matches the filter
    element. The rules defined in <xref target="RFC2445" /> for
    determining the actual start and end times of calendar components
    MUST be used, and these are fully enumerated in <xref
    target="time_range_element"/>
    of this document. </t>
    <t>
      When such time range filtering is used, special consideration must
      be given to recurring calendar components, such as VEVENT and
      VTODO. The server MUST expand recurring components to
      determine whether any recurrence instances overlap the specified
      time range. If one or more recurrence instances overlap the time
      range, then the calendar object resource matches the filter element.
    </t>
  </section>

  <section title="Searching Text: Collations" anchor="collation">
    <t>
      Some of the reports defined in this section do text matches of
character strings provided by the client and are compared to stored calendar data. Since iCalendar data is, by default, encoded in the UTF-8 charset and may include  characters outside the US-ASCII charset range in some property and parameter values, there is a need to ensure that text matching follows well-defined rules.
    </t>
<?rfc needLines="5" ?>
    <t>
      To deal with this, this specification makes use of the IANA Collation Registry defined in <xref target="RFC4790"/> to specify collations that may be used to carry out the text comparison operations with a well-defined rule.
    </t>
    <t>
      The comparisons used in CalDAV are all "substring" matches, as per <xref target="RFC4790"/>, Section 4.2. Collations supported by the server MUST support "substring" match operations.
    </t>
    <t>
      CalDAV servers are REQUIRED to support the "i;ascii-casemap" and "i;octet" collations, as described in <xref target="RFC4790"/>, and MAY support other collations.
    </t>
    <t>
      Servers MUST advertise the set of collations that they support via the CALDAV:supported-collation-set property defined on any resource that supports reports that use collations.
    </t>
    <t>
      Clients MUST only use collations from the list advertised by the server.
    </t>
    <t>
      In the absence of a collation explicitly specified by the client, or if the client specifies the "default" collation identifier (as defined in <xref target="RFC4790"/>, Section 3.1), the server MUST default to using "i;ascii-casemap" as the collation.
    </t>
    <t>
      Wildcards (as defined in <xref target="RFC4790"/>, Section 3.2) MUST NOT be used in the collation identifier.
    </t>
    <t>
      If the client chooses a collation not supported by the server, the server MUST respond with a CALDAV:supported-collation precondition error response.
    </t>
    <section anchor="PROPERTY_supported-collation-set"
            title="CALDAV:supported-collation-set Property">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            supported-collation-set
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Identifies the set of collations supported by the server for text matching operations.
          </t>
          <t hangText="Conformance:">
            This property MUST be defined on any resource that supports
            a REPORT report that does text matching. If defined, it MUST be
            protected and SHOULD NOT be returned by a PROPFIND
            DAV:allprop request (as defined in Section 12.14.1 of <xref
            target="RFC2518"/>).
          </t>
          <t hangText="Description:">
            The CALDAV:supported-collation-set property contains zero or more CALDAV:supported-collation elements, which specify the collection identifiers of the collations supported by the server.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT supported-collation-set (supported-collation*)>

      <!ELEMENT supported-collation (#PCDATA)>
              ]]></artwork>
            </figure>
          </t>
          <t hangText="Example:">
            <figure>
              <artwork><![CDATA[
    <C:supported-collation-set
        xmlns:C="urn:ietf:params:xml:ns:caldav">
      <C:supported-collation>i;ascii-casemap</C:supported-collation>
      <C:supported-collation>i;octet</C:supported-collation>
    </C:supported-collation-set>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- PROPERTY_supported-collation-set -->
  </section>

  <section title="Partial Retrieval">
    <t>Some calendaring REPORTs reports defined in this document allow partial
    retrieval of calendar object resources. A CalDAV client can specify
    what information to return in the body of a calendaring REPORT
    request.</t>

    <t>A CalDAV client can request particular WebDAV property values,
    all WebDAV property values, or a list of the names of the
    resource's WebDAV properties. A CalDAV client can also request
    calendar data to be returned and specify whether all calendar components
    and properties should be returned, or only particular ones. See
    CALDAV:calendar-data in <xref target="calendar_data_element"/>.</t>

    <t>By default, the returned calendar data will include the
    component that defines the recurrence set, referred to as the
    "master component", as well as the components that define
    exceptions to the recurrence set, referred to as the "overridden
    components".</t>

    <t>A CalDAV client that is only interested in the recurrence instances that
    overlap a specified time range can request to receive only the
    "master component", along with the "overridden components" that
    impact the specified time range, and thus, limit the data returned by
    the server (see CALDAV:limit-recurrence-set in <xref
    target="limit_recurrence_set_element"/>.)
    target="limit_recurrence_set_element"/>). An overridden component
    impacts a time range if its current start and end times overlap the
    time range, or if the original start and end times - -- the ones that
    would have been used if the instance were not overridden - -- overlap
    the time range, or if it affects other instances that overlap
    the time range.</t>

    <t>A CalDAV client with no support for recurrence properties (i.e.,
    EXDATE, EXRULE, RDATE, and RRULE) and possibly VTIMEZONE components,
    or a client unwilling to perform recurrence expansion because
    of limited processing capability, can request to receive only the
    recurrence instances that overlap a specified time range as
    separate calendar components that each define exactly one
    recurrence instance (see CALDAV:expand in <xref
    target="expand_element"/>.)</t>

    <t>Finally, in the case of VFREEBUSY components, a CalDAV client
    can request to receive only the FREEBUSY property values that
    overlap a specified time range (see CALDAV:limit-freebusy-set in
    <xref target="limit_freebusy_set_element"/>.)</t>
  </section><!-- Partial Retrieval -->

    <section title="Non-Standard Components, Properties, and Parameters">
       <t>
         Servers MUST support the use of non-standard component,
         property, or parameter names in the CALDAV:calendar-data XML element
         in calendaring REPORT requests to allow clients to request that
         non-standard components, properties, and parameters be returned
         in the calendar data provided in the response.
       </t>
       <t>
         Servers MAY support the use of non-standard component, property,
         or parameter names in the CALDAV:comp-filter, CALDAV:prop-filter, and
         CALDAV:param-filter XML elements specified in the CALDAV:filter
         XML element of calendaring REPORT requests.
       </t>
       <t>
         Servers MUST fail with the CALDAV:supported-filter precondition if
         a calendaring REPORT request uses a CALDAV:comp-filter,
         CALDAV:prop-filter, or CALDAV:param-filter XML element that makes
         reference to a non-standard component, property, or parameter
	 name on which the server does not support queries.
       </t>
    </section>

  <section anchor="calendar-query" title="CALDAV:calendar-query Report"> REPORT">
    <t>
      The CALDAV:calendar-query REPORT performs a search for all
      calendar object resources that match a specified filter.
      The response of this REPORT report will contain all the WebDAV
      properties and calendar object resource data specified in the
      request. In the case of the CALDAV:calendar-data XML element,
      one can explicitly specify the calendar components and properties
      that should be returned in the calendar object resource data
      that matches the filter.
    </t>
    <t>
      The format of this REPORT report is modeled on the PROPFIND method.
      The request and response bodies of the CALDAV:calendar-query
      REPORT use XML elements that are also used by PROPFIND. In
      particular, the request can include XML elements to request
      WebDAV properties to be returned. When that occurs, the
      response should follow the same behavior as PROPFIND with
      respect to the DAV:multistatus response elements used to
      return specific property results. For instance, a request
      to retrieve the value of a property that does not exist
      is an error and MUST be noted with a response XML element
      that contains a 404 (Not Found) status value.
    </t>
    <t>
      Support for the CALDAV:calendar-query REPORT is REQUIRED.
    </t>
    <t>
      Marshalling:
<?rfc compact="no" ?>
      <list>
        <t>
          The request body MUST be a CALDAV:calendar-query XML
          element, as defined in <xref target='calendar_query_element'/>.
        </t>
        <t>
          The request MAY include a Depth header. If no Depth header
          is included, Depth:0 is assumed.
        </t>
        <t>
          The response body for a successful request MUST be a
          DAV:multistatus XML element (i.e., the response uses the
          same format as the response for PROPFIND). In the case
          where there are no response elements, the returned
          DAV:multistatus XML element is empty.
        </t>
        <t>
          The response body for a successful CALDAV:calendar-query
          REPORT request MUST contain a DAV:response element
          for each iCalendar object that matched the search
          filter. Calendar data is being returned in the
          CALDAV:calendar-data XML element inside the
          DAV:propstat XML element.
        </t>
      </list>
<?rfc compact="yes" ?>
    </t>
    <t>
      Preconditions:
<?rfc compact="no" ?>
      <list>
        <t>
          (CALDAV:supported-calendar-data): The attributes
          "content-type" and "version" of the CALDAV:calendar-data
          XML element (see <xref target="calendar_data_element"/>) specify a media type supported by the server
          for calendar object resources.
        </t>
        <t>
          (CALDAV:valid-filter): The CALDAV:filter XML element (see <xref target="filter_element"/>)
          specified in the REPORT request MUST be valid.
          For instance, a CALDAV:filter cannot nest a
          <![CDATA[<C:comp name="VEVENT">]]> element in a
          <![CDATA[<C:comp name="VTODO">]]> element, and a
          CALDAV:filter cannot nest a
          <![CDATA[<C:time-range start="..." end="...">]]>
          element in a
          <![CDATA[<C:prop name="SUMMARY">]]> element.
        </t>
       <t>
         (CALDAV:supported-filter): The CALDAV:comp-filter (see <xref
         target="comp_filter_element"/>), CALDAV:prop-filter (see <xref
         target="prop_filter_element"/>), and CALDAV:param-filter (see
         <xref target="param_filter_element"/>) XML elements used in
         the CALDAV:filter XML element (see <xref
         target="filter_element"/>) in the REPORT request only make
         reference to components, properties, and parameters for which
         queries are supported by the server, i.e., if the
         CALDAV:filter element attempts to reference an unsupported
         component, property, or parameter, this precondition is
         violated. Servers SHOULD report the CALDAV:comp-filter,
         CALDAV:prop-filter, or CALDAV:param-filter for which it does
         not provide support.
         <figure>
           <artwork><![CDATA[
         <!ELEMENT supported-filter (comp-filter*,
                                     prop-filter*,
                                     param-filter*)>
           ]]></artwork>
         </figure>
       </t>
          <t>
            (CALDAV:valid-calendar-data): The time zone specified in
            the REPORT request MUST be a valid
            iCalendar object containing a single valid VTIMEZONE component.
          </t>
      <t>
        (CALDAV:min-date-time): Any XML element specifying a range of
        time MUST have its start or end date DATE or time DATE-TIME
        values greater than or equal to
        the value of the CALDAV:min-date-time property value
        (<xref target="min-date-time"/>) on the calendar collections
        being targeted by the REPORT; REPORT request;
      </t>
      <t>
        (CALDAV:max-date-time): Any XML element specifying a range of
        time MUST have its start or end date DATE or time DATE-TIME
        values less than or equal to
        the value of the CALDAV:max-date-time property value
        (<xref target="max-date-time"/>) on the calendar collections
        being targeted by the REPORT; REPORT request;
      </t>
      <t>
        (CALDAV:supported-collation): Any XML attribute specifying a collation MUST specify a collation supported by the server as described in <xref target="collation"/>.
      </t>
      </list>
<?rfc compact="yes" ?>
    </t>
    <t>Postconditions:
<?rfc compact="no" ?>
      <list>
        <t>
          (DAV:number-of-matches-within-limits): The number of matching
          calendar object resources must fall within server-specific,
          predefined limits. For example, this condition might be
          triggered if a search specification would cause the return
          of an extremely large number of responses.
        </t>
      </list>
<?rfc compact="yes" ?>
    </t>

    <section title="Example: Partial Retrieval of Events by Time Range">
      <t>
        In this example, the client requests the server to
        return specific components and properties of the VEVENT
        components that overlap the time range from January
        4, 2006, at 00:00:00 A.M. UTC to January 5, 2006, at
        00:00:00 A.M. UTC. In addition, the DAV:getetag
        property is also requested and returned as part of the
        response. Note that the first calendar object returned is a
        recurring event whose first instance lies outside the requested
        time range, but whose third instance does overlap the time range.
        Note that due to the CALDAV:calendar-data element restrictions, the
        DTSTAMP property in VEVENT components has not been returned, and
        the only property returned in the VCALENDAR object is VERSION.
      </t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:D="DAV:"
              xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop>
    <D:getetag/>
    <C:calendar-data>
      <C:comp name="VCALENDAR">
        <C:prop name="VERSION"/>
        <C:comp name="VEVENT">
          <C:prop name="SUMMARY"/>
          <C:prop name="UID"/>
          <C:prop name="DTSTART"/>
          <C:prop name="DTEND"/>
          <C:prop name="DURATION"/>
          <C:prop name="RRULE"/>
          <C:prop name="RDATE"/>
          <C:prop name="EXRULE"/>
          <C:prop name="EXDATE"/>
          <C:prop name="RECURRENCE-ID"/>
        </C:comp>
        <C:comp name="VTIMEZONE"/>
      </C:comp>
    </C:calendar-data>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VEVENT">
        <C:time-range start="20060104T000000Z"
                      end="20060105T000000Z"/>
      </C:comp-filter>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Date: Fri, Sat, 11 Nov 2005 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
           xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd2.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd2"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
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
DTSTART;TZID=US/Eastern:20060102T120000
DURATION:PT1H
RRULE:FREQ=DAILY;COUNT=5
SUMMARY:Event #2
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=US/Eastern:20060104T140000
DURATION:PT1H
RECURRENCE-ID;TZID=US/Eastern:20060104T120000
SUMMARY:Event #2 bis
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=US/Eastern:20060106T140000
DURATION:PT1H
RECURRENCE-ID;TZID=US/Eastern:20060106T120000
SUMMARY:Event #2 bis bis
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd3.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd3"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
</D:multistatus>
  ]]></artwork>
      </figure>
    </section>

    <section title="Example: Partial Retrieval of Recurring Events">
      <t>
        In this example, the client requests the server to
        return VEVENT components that overlap the time range
        from January 3, 2006, at 00:00:00 A.M. UTC to January 5, 2006,
        at 00:00:00 A.M. UTC. Use of the CALDAV:limit-recurrence-set
        element causes the server to only return overridden
        recurrence components that overlap the time range specified
        in that element or that affect other instances that overlap the time
        range (e.g., in the case of a "THISANDFUTURE" behavior). In this example,
        the first overridden component in the matching resource is returned, but
        the second one is not.
      </t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:D="DAV:"
                  xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop>
    <C:calendar-data>
      <C:limit-recurrence-set start="20060103T000000Z"
                              end="20060105T000000Z"/>
    </C:calendar-data>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VEVENT">
        <C:time-range start="20060103T000000Z"
                      end="20060105T000000Z"/>
      </C:comp-filter>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Date: Fri, Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
           xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd2.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd2"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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
SUMMARY:Event #2
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:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd3.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd3"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
</D:multistatus>
        ]]></artwork>
      </figure>
    </section>

    <section title="Example: Expanded Retrieval of Recurring Events">
      <t>
        In this example, the client requests the server to
        return VEVENT components that overlap the time range
        from January 2, 2006, at 00:00:00 A.M. UTC to January 5, 2006,
        at 00:00:00 A.M. UTC and to return recurring calendar
        components expanded into individual recurrence instance
        calendar components. Use of the CALDAV:expand
        element causes the server to only return overridden recurrence
        instances that overlap the time range specified in that element.
      </t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:D="DAV:"
                  xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop>
    <C:calendar-data>
      <C:expand start="20060103T000000Z"
                end="20060105T000000Z"/>
    </C:calendar-data>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VEVENT">
        <C:time-range start="20060103T000000Z"
                      end="20060105T000000Z"/>
      </C:comp-filter>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
  ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Date: Fri, Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
           xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd2.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd2"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
DTSTAMP:20060206T001121Z
DTSTART:20060103T170000
DURATION:PT1H
RECURRENCE-ID:20060103T170000
SUMMARY:Event #2
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20060206T001121Z
DTSTART:20060104T190000
DURATION:PT1H
RECURRENCE-ID:20060104T170000
SUMMARY:Event #2 bis
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd3.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd3"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART:20060104T150000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
</D:multistatus>
        ]]></artwork>
      </figure>
    </section>

    <section title="Example: Partial Retrieval of Stored Free Busy Components">
      <t>
        In this example, the client requests the server to
        return the VFREEBUSY components that have free busy
        information that overlap the time range from January 2,
        2006, at 00:00:00 A.M. UTC (inclusively) to January 3, 2006,
        at 00:00:00 A.M. UTC (exclusively).  Use of the
        CALDAV:limit-freebusy-set element causes the server
        to only return the FREEBUSY property values that
        overlap the time range specified in that element.
        Note that this is not an example of discovering when
        the calendar owner is busy.
      </t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:D="DAV:"
              xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop>
    <C:calendar-data>
      <C:limit-freebusy-set start="20060102T000000Z"
                              end="20060103T000000Z"/>
    </C:calendar-data>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VFREEBUSY">
        <C:time-range start="20060102T000000Z"
                        end="20060103T000000Z"/>
      </C:comp-filter>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Date: Fri, Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
               xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd8.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd8"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VFREEBUSY
ORGANIZER;CN="Bernard Desruisseaux":mailto:bernard@example.com
UID:76ef34-54a3d2@example.com
DTSTAMP:20050530T123421Z
DTSTART:20060101T100000Z
DTEND:20060108T100000Z
FREEBUSY;FBTYPE=BUSY-TENTATIVE:20060102T100000Z/20060102T120000Z
END:VFREEBUSY
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
</D:multistatus>
  ]]></artwork>
      </figure>
    </section><!-- Example: Partial retrieval of busy time -->

    <section title="Example: Retrieval of To-Dos by Alarm Time Range">
      <t> In this example, the client requests the server to
        return the VTODO components that have an alarm trigger
        scheduled in the specified time range. </t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop xmlns:D="DAV:">
    <D:getetag/>
    <C:calendar-data/>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VTODO">
        <C:comp-filter name="VALARM">
          <C:time-range start="20060106T100000Z"
                          end="20060107T100000Z"/>
        </C:comp-filter>
      </C:comp-filter>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Date: Fri, Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
               xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd4.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd4"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235300Z
DUE;TZID=US/Eastern:20060106T120000
LAST-MODIFIED:20060205T235308Z
SEQUENCE:1
STATUS:NEEDS-ACTION
SUMMARY:Task #2
UID:E10BA47467C5C69BB74E8720@example.com
BEGIN:VALARM
ACTION:AUDIO
TRIGGER;RELATED=START:-PT10M
END:VALARM
END:VTODO
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
</D:multistatus>
  ]]></artwork>
      </figure>
    </section>
    <section title="Example: Retrieval of Event by UID">
      <t> In this example, the client requests the server to
        return the VEVENT component that has the UID property
        set to "DC6C50A017428C5216A2F1CD@example.com". </t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop xmlns:D="DAV:">
    <D:getetag/>
    <C:calendar-data/>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VEVENT">
        <C:prop-filter name="UID">
          <C:text-match collation="i;octet"
          >DC6C50A017428C5216A2F1CD@example.com</C:text-match>
        </C:prop-filter>
      </C:comp-filter>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
  ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Date: Fri, Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
               xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd3.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd3"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
</D:multistatus>
  ]]></artwork>
      </figure>
    </section>
    <section
      title="Example: Retrieval of Events by PARTSTAT">
      <t> In this example, the client requests the server to
        return the VEVENT components that have the ATTENDEE
        property with the value "mailto:lisa@example.com" and
        for which the PARTSTAT parameter is set to
        "NEEDS-ACTION". </t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop xmlns:D="DAV:">
    <D:getetag/>
    <C:calendar-data/>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VEVENT">
        <C:prop-filter name="ATTENDEE">
          <C:text-match collation="i;ascii-casemap"
           >mailto:lisa@example.com</C:text-match>
          <C:param-filter name="PARTSTAT">
            <C:text-match collation="i;ascii-casemap"
             >NEEDS-ACTION</C:text-match>
          </C:param-filter>
        </C:prop-filter>
      </C:comp-filter>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Date: Fri, Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
               xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd3.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd3"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
</D:multistatus>
  ]]></artwork>
      </figure>
    </section>
    <section title="Example: Retrieval of Events Only">
      <t> In this example, the client requests the server to
        return all VEVENT components. </t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop xmlns:D="DAV:">
    <D:getetag/>
    <C:calendar-data/>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VEVENT"/>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Date: Fri, Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
               xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd1.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd1"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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:20060206T001102Z
DTSTART;TZID=US/Eastern:20060102T100000
DURATION:PT1H
SUMMARY:Event #1
Description:Go Steelers!
UID:74855313FA803DA593CD579A@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd2.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd2"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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
SUMMARY:Event #2
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
BEGIN:VEVENT
DTSTAMP:20060206T001121Z
DTSTART;TZID=US/Eastern:20060106T140000
DURATION:PT1H
RECURRENCE-ID;TZID=US/Eastern:20060106T120000
SUMMARY:Event #2 bis bis
UID:00959BC664CA650E933C892C@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd3.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd3"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
</D:multistatus>
  ]]></artwork>
      </figure>
    </section>
    <section title="Example: Retrieval of All Pending To-Dos">
      <t>
        In this example, the client requests the server to return all
        VTODO components that do not include a "COMPLETED" property and
        do not have a "STATUS" property value matching "CANCELLED",
        i.e., VTODOs that still need to be worked on.
      </t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop xmlns:D="DAV:">
    <D:getetag/>
    <C:calendar-data/>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VTODO">
        <C:prop-filter name="COMPLETED">
          <C:is-not-defined/>
        </C:prop-filter>
        <C:prop-filter name="STATUS">
          <C:text-match
             negate-condition="yes">CANCELLED</c:text-match>
        </C:prop-filter>
      </C:comp-filter>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Date: Fri, Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
               xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd4.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd4"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235335Z
DUE;VALUE=DATE:20060104
STATUS:NEEDS-ACTION
SUMMARY:Task #1
UID:DDDEEB7915FA61233B861457@example.com
BEGIN:VALARM
ACTION:AUDIO
TRIGGER;RELATED=START:-PT10M
END:VALARM
END:VTODO
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>

  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd5.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd5"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235300Z
DUE;VALUE=DATE:20060106
LAST-MODIFIED:20060205T235308Z
SEQUENCE:1
STATUS:NEEDS-ACTION
SUMMARY:Task #2
UID:E10BA47467C5C69BB74E8720@example.com
BEGIN:VALARM
ACTION:AUDIO
TRIGGER;RELATED=START:-PT10M
END:VALARM
END:VTODO
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
</D:multistatus>
  ]]></artwork>
      </figure>
    </section>
    <section title="Example: Attempt to Query Unsupported Property">
      <t> In this example, the client requests the server to
        return all VEVENT components that include an "X-ABC-GUID" property
        with a value matching "ABC". However, the server does not support
        querying that non-standard property, and instead returns an error
        response.</t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop xmlns:D="DAV:">
    <D:getetag/>
    <C:calendar-data/>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VEVENT">
        <C:prop-filter name="X-ABC-GUID">
          <C:text-match>ABC</C:text-match>
        </C:prop-filter>
      </C:comp-filter>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 403 Forbidden
Date: Fri, Sat, 11 Nov 2005 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:error>
  <C:supported-filter>
    <C:prop-filter name="X-ABC-GUID"/>
  </C:supported-filter>
</D:error>
  ]]></artwork>
      </figure>
    </section>
  </section><!-- calendar-query -->

  <section anchor="calendar-multiget"
    title="CALDAV:calendar-multiget Report"> REPORT">
    <t>
      The CALDAV:calendar-multiget REPORT is used to retrieve specific
      calendar object resources from within a collection, if the
      Request-URI is a collection, or to retrieve a specific
      calendar object resource, if the Request-URI is a calendar
      object resource. This REPORT report is similar to the CALDAV:calendar-query
      REPORT (see <xref target='calendar-query'/>), except that it takes
      a list of DAV:href elements, instead of a CALDAV:filter element, to
      determine which calendar object resources to return.
    </t>
    <t>
      Support for the calendar-multiget CALDAV:calendar-multiget REPORT is REQUIRED.</t>
    <t>
      Marshalling:
<?rfc compact="no" ?>
      <list>
        <t>
          The request body MUST be a CALDAV:calendar-multiget XML
          element (see <xref target='calendar_multiget_element'/>). If
          the Request-URI is a collection resource, then the DAV:href
          elements MUST refer to calendar object resources within that
          collection, and they MAY refer to calendar object resources
          at any depth within the collection. As a result, the "Depth"
          header MUST be ignored by the server and SHOULD NOT be sent
          by the client. If the Request-URI refers to a non-collection
          resource, then there MUST be a single DAV:href element that
          is equivalent to the Request-URI.
        </t>
        <t>
          The response body for a successful request MUST be a
          DAV:multistatus XML element.
        </t>
        <t>
          The response body for a successful CALDAV:calendar-multiget
          REPORT request MUST contain a DAV:response element
          for each calendar object resource referenced by the
          provided set of DAV:href elements. Calendar data is
          being returned in the CALDAV:calendar-data element
          inside the DAV:prop element.
        </t>
        <t>
          In the case of an error accessing any of the provided
          DAV:href resources, the server MUST return the appropriate
          error status code in the DAV:status element of the
          corresponding DAV:response element.
        </t>
<?rfc compact="yes" ?>
      </list>
    </t>
    <t>
      Preconditions:
<?rfc compact="no" ?>
      <list>
        <t>
          (CALDAV:supported-calendar-data): The attributes
          "content-type" and "version" of the CALDAV:calendar-data
          XML elements (see <xref target="calendar_data_element"/>) specify a media type supported by the
          server for calendar object resources.
        </t>
      <t>
        (CALDAV:min-date-time): Any XML element specifying a range of
        time MUST have its start or end date DATE or time DATE-TIME
        values greater than or equal to
        the value of the CALDAV:min-date-time property value
        (<xref target="min-date-time"/>) on the calendar collections
        being targeted by the REPORT; REPORT request;
      </t>
      <t>
        (CALDAV:max-date-time): Any XML element specifying a range of
        time MUST have its start or end date DATE or time DATE-TIME
        values less than or equal to
        the value of the CALDAV:max-date-time property value
        (<xref target="max-date-time"/>) on the calendar collections
        being targeted by the REPORT; REPORT request;
      </t>
      </list>
<?rfc compact="yes" ?>
    </t>
    <t>
      Postconditions:
<?rfc compact="no" ?>
      <list>
        <t>
          None.
        </t>
      </list>
<?rfc compact="yes" ?>
    </t>
    <section title="Example: Successful CALDAV:calendar-multiget Report"> REPORT">
      <t>
        In this example, the client requests the server to
        return specific properties of the VEVENT components
        referenced by specific URIs. In addition, the
        DAV:getetag property is also requested and returned as
        part of the response. Note that in this example, the
        resource at
        http://cal.example.com/bernard/work/mtg1.ics
        does not exist, resulting in an error status response.
      </t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-multiget xmlns:D="DAV:"
                 xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop>
    <D:getetag/>
    <C:calendar-data/>
  </D:prop>
  <D:href>/bernard/work/abcd1.ics</D:href>
  <D:href>/bernard/work/mtg1.ics</D:href>
</C:calendar-multiget>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Date: Fri, Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
               xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd1.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd1"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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:20060206T001102Z
DTSTART;TZID=US/Eastern:20060102T100000
DURATION:PT1H
SUMMARY:Event #1
Description:Go Steelers!
UID:74855313FA803DA593CD579A@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>
  <D:response>
    <D:href>http://cal.example.com/bernard/work/mtg1.ics</D:href>
    <D:status>HTTP/1.1 404 Not Found</D:status>
  </D:response>
</D:multistatus>
  ]]></artwork>
      </figure>
    </section>
  </section><!-- calendar-multiget -->

  <section title="CALDAV:free-busy-query Report" REPORT"
          anchor="free-busy-query">
    <t>
      The CALDAV:free-busy-query REPORT generates a VFREEBUSY
      component containing free busy information for all the
      calendar object resources targeted by the request and
      that have the CALDAV:read-free-busy or DAV:read privilege
      granted to the current user.
    </t>
    <t>
      Only VEVENT components without a TRANSP property or with the
      TRANSP property set to "OPAQUE", and VFREEBUSY components
      SHOULD be considered in generating the free busy time information.
    </t>
    <t>
      In the case of VEVENT components, the free or busy time type
      (FBTYPE) of the FREEBUSY properties in the returned VFREEBUSY
      component SHOULD be derived from the value of the TRANSP and
      STATUS properties, as outlined in the table below:
      <figure>
        <artwork>
      +---------------------------++------------------+
      |          VEVENT           ||    VFREEBUSY     |
      +-------------+-------------++------------------+
      | TRANSP      | STATUS      || FBTYPE           |
      +=============+=============++==================+
      |             | CONFIRMED   || BUSY             |
      |             | (default)   ||                  |
      | OPAQUE      +-------------++------------------+
      | (default)   | CANCELLED   || FREE             |
      |             +-------------++------------------+
      |             | TENTATIVE   || BUSY-TENTATIVE   |
      |             +-------------++------------------+
      |             | x-name      || BUSY or          |
      |             |             || x-name           |
      +-------------+-------------++------------------+
      |             | CONFIRMED   ||                  |
      | TRANSPARENT | CANCELLED   || FREE             |
      |             | TENTATIVE   ||                  |
      |             | x-name      ||                  |
      +-------------+-------------++------------------+
        </artwork>
      </figure>
    </t>
    <t>
      Duplicate busy time periods with the same FBTYPE parameter
      value SHOULD NOT be specified in the returned VFREEBUSY
      component. Servers SHOULD coalesce consecutive or overlapping
      busy time periods of the same type. Busy time periods with
      different FBTYPE parameter values MAY overlap.
    </t>
    <t>
      Support for the CALDAV:free-busy-query REPORT is REQUIRED.
    </t>
    <t>Marshalling:
<?rfc compact="no" ?>
      <list>
        <t>
          The request body MUST be a CALDAV:free-busy-query XML
          element (see <xref target='free_busy_query_element'/>),
          which MUST contain exactly one CALDAV:time-range XML
          element, as defined in <xref target="time_range_element"/>.
        </t>
        <t>
          The request MAY include a Depth header. If no Depth header
          is included, Depth:0 is assumed.
        </t>
        <t>
          The response body for a successful request MUST be an
          iCalendar object that contains exactly one VFREEBUSY
          component that describes the busy time intervals for the
          calendar object resources containing VEVENT, or VFREEBUSY
          components that satisfy the Depth value and for which the
          current user is at least granted the CALDAV:read-free-busy
          privilege. If no calendar object resources are found to
          satisfy these conditions, a VFREEBUSY component with no
          FREEBUSY property MUST be returned. This REPORT report only
          returns busy time information. Free time information can
          be inferred from the returned busy time information.
        </t>
        <t>
          If the current user is not granted the CALDAV:read-free-busy or
          DAV:read privileges on the Request-URI, the CALDAV:free-busy-query
          REPORT request MUST fail and return a 404 (Not Found) status
          value. This restriction will prevent users from discovering
          URLs of resources for which they are only granted the
          CALDAV:read-free-busy privilege.
        </t>
        <t>
          The CALDAV:free-busy-query REPORT request can only be run against
          a collection (either a regular collection or a calendar collection).
          An attempt to run the report on a calendar object resource MUST fail
          and return a 403 (Forbidden) status value.
        </t>
      </list>
<?rfc compact="yes" ?>
    </t>

    <t>Preconditions:
<?rfc compact="no" ?>
      <list>
        <t>
          None.
        </t>
      </list>
<?rfc compact="yes" ?>
    </t>
    <t>Postconditions:
<?rfc compact="no" ?>
      <list>
        <t>
          (DAV:number-of-matches-within-limits): The number of matching
          calendar object resources must fall within server-specific,
          predefined limits. For example, this postcondition might fail
          if the specified CALDAV:time-range would cause an extremely
          large number of calendar object resources to be considered in
          computing the response.
        </t>
      </list>
<?rfc compact="yes" ?>
    </t>

    <section title="Example: Successful CALDAV:free-busy-query Report"> REPORT">
      <t>In this example, the client requests the server to
        return free busy information on the calendar collection
        /bernard/work/, between 9:00 A.M. and 5:00 P.M. EST (2:00 P.M.
        and 10:00 P.M. UTC) on the
        January 4, 2006. The server responds, indicating two
        busy time intervals of one hour, one of which is tentative.</t>
      <t>See <xref target="examples"/> for the calendar data being targeted by this example.</t>
      <figure>
        <preamble>&gt;&gt; Request &lt;&lt;</preamble>
        <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:free-busy-query xmlns:C="urn:ietf:params:xml:ns:caldav">
  <C:time-range start="20060104T140000Z"
                  end="20060105T220000Z"/>
</C:free-busy-query>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 200 OK
Date: Fri, Sat, 11 Nov 2006 09:32:12 GMT
Content-Type: text/calendar
Content-Length: xxxx

BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
BEGIN:VFREEBUSY
DTSTAMP:20050125T090000Z
DTSTART:20060104T140000Z
DTEND:20060105T220000Z
FREEBUSY;FBTYPE=BUSY-TENTATIVE:20060104T150000Z/PT1H
FREEBUSY:20060104T190000Z/PT1H
END:VFREEBUSY
END:VCALENDAR
        ]]></artwork>
      </figure>
    </section><!-- Example: free-busy-query -->
  </section><!-- free-busy-query -->
</section><!-- Calendaring Reports -->

  <section title="Guidelines">

    <section title="Client-to-Client Interoperability">
      <t>
        There are a number of actions clients can take that will be
        legal (the server will not return errors), but that can degrade
        interoperability with other client implementations accessing
        the same data.  For example, a recurrence rule could be replaced
        with a set of recurrence dates, a single recurring event could
        be replaced with a set of independent resources to represent
        each recurrence, or the start/end time values can be translated
        from the original time zone to another time zone.  Although this
        advice amounts to iCalendar interoperability best practices and
        is not limited only to CalDAV usage, interoperability problems are
        likely to be more evident in CalDAV use cases.
      </t>
    </section>

    <section title="Synchronization Operations">
      <t>
        WebDAV already provides functionality required to synchronize a
        collection or set of collections, to make changes offline, and
        provides a simple way to resolve conflicts when reconnected. ETags
        are the key to making this work, but these are not required of
        all WebDAV servers. Since offline functionality is more
        important to calendar applications than to some other WebDAV
        applications, CalDAV servers MUST support ETags, as specified
        in <xref target="calendar-etag"/>.
      </t>
      <section title='Use of Reports'>
        <section title='Restrict the Time Range'>
          <t>
            The REPORTs reports provided in CalDAV can be used by clients to
            optimize their performance in terms of network bandwidth
            usage and resource consumption on the local client machine.
            Both are certainly major considerations for mobile or handheld
            devices with limited capacity, but they are also relevant to
            desktop client applications in cases where the calendar
            collections contain large amounts of data.
          </t>
          <t>
            Typically, clients present calendar data to users in
            views that span a finite time interval, so whenever
            possible, clients should only retrieve calendar components
            from the server using CALDAV:calendar-query REPORT, combined
            with a CALDAV:time-range element, to limit the set of
            returned components to just those needed to populate the
            current view.
          </t>
        </section>
        <section title='Synchronize by Time Range'>
          <t>Typically in a calendar, historical data (events, to-dos,
            etc. that have completed prior to the current date) do
            not change, though they may be deleted. As a result, a
            client can speed up the synchronization process by only
            considering data for the present time and the future
            up to a reasonable limit (e.g., one week, one month). If
            the user then tries to examine a portion of the
            calendar outside the range that has been
            synchronized, the client can perform another
            synchronization operation on the new time interval being
            examined. This "just-in-time" synchronization can
            minimize bandwidth for common user interaction
            behaviors.</t>
        </section>
        <section title='Synchronization Process'>
          <t>
            If a client wants to support calendar data synchronization,
            as opposed to downloading calendar data each time it is needed,
            the client needs to cache the calendar object resource's URI and ETag,
            along with the actual calendar data. While the URI remains
            static for the lifetime of the calendar object resource, the
            ETag will change with each successive change to the calendar
            object resource. Thus, to synchronize a local data cache with
            the server, the client can first fetch the URI/ETag pairs for
            the time interval being considered, and compare those results
            with the cached data. Any cached component whose ETag differs
            from that on the server needs to be refreshed.
          </t>
          <t>
            In order to properly detect the changes between the server and
            client data, the client will need to keep a record of which
            calendar object resources have been created, changed, or deleted
            since the last synchronization operation so that it can reconcile
            those changes with the data on the server.
          </t>
          <t>
            Here's an example of how to do that:
          </t>
          <t>
            The client issues a CALDAV:calendar-query REPORT request
            for a specific time range and asks for only the
            DAV:getetag property to be returned:
            <figure>
              <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:D="DAV:"
                  xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop>
    <D:getetag/>
  </D:prop>
  <C:filter>
    <C:comp-filter name="VCALENDAR">
      <C:comp-filter name="VEVENT">
        <C:time-range start="20040902T000000Z"
                        end="20040903T000000Z"/>
      </C:comp-filter>
    </C:comp-filter>
  </C:filter>
</C:calendar-query>
              ]]></artwork>
            </figure>
          </t>
          <t>
            The client then uses the results to determine which calendar
            object resources have changed, been created, or deleted on
            the server, and how those relate to locally cached calendar
            object resources that may have changed, been created, or
            deleted. If the client determines that there are calendar
            object resources on the server that need to be fetched,
            the client issues a CALDAV:calendar-multiget REPORT request
            to fetch its calendar data:
            <figure>
              <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-multiget xmlns:D="DAV:"
                     xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:prop>
    <D:getetag/>
    <C:calendar-data/>
  </D:prop>
  <D:href>/bernard/work/abcd1.ics</D:href>
  <D:href>/bernard/work/mtg1.ics</D:href>
</C:calendar-multiget>
           ]]></artwork>
         </figure>
       </t>
      </section><!-- Synchronization Process -->
    </section><!-- Use of Reports -->
      <section title='Restrict the Properties Returned'>
        <t>
          A client may not need all the calendar properties of a calendar
          object resource when presenting information to the user. Since
          some calendar property values can be large (e.g., ATTACH or
          ATTENDEE), a client can choose to restrict the
          calendar properties to be returned in a calendaring REPORT
          request to those it knows it will use.
        </t>
        <t>
          However, if a client needs to make a change to a calendar object
          resource, it can only change the entire calendar object resource
          via a PUT request. There is currently no way to incrementally make
          a change to a set of calendar properties of a calendar object
          resource. As a result, the client will have to get the entire
          calendar object resource that is being changed.
        </t>
      </section>
    </section><!-- Synchronization Operations -->

    <section title="Use of Locking">
      <t>
        WebDAV locks can be used to prevent two clients that are modifying the
        same resource from either overwriting each others' changes
        (though that problem can also be solved by using ETags) or
        wasting time making changes that will conflict
        with another set of changes. In a multi-user calendar system,
        an interactive calendar client could lock an event while the user is
        editing the event, and unlock the event when the user finishes
        or cancels.  Locks can also be used to prevent changes while
        data is being reorganized.  For example, a calendar client
        might lock two calendar collections prior to moving a bunch
        of calendar resources from one to another.
      </t>
      <t>
        Clients are responsible for requesting a lock timeout period that
        is appropriate
        to the use case.  When the user explicitly decides to reserve
        a resource and prevent other changes, a long timeout might be
        appropriate, but in cases where the client automatically decides
        to lock the resource, the timeout should be short (and the client
        can always refresh the lock should it need to).  A short lock
        timeout means that if the client is unable to remove the lock,
        the other calendar users aren't prevented from making changes.
      </t>
    </section><!-- Use of Locking -->

    <section title="Finding Calendars">
      <t>
        Much of the time, a calendar client (or agent) will discover
        a new calendar's location by being provided directly with the
        URL.  For example, a user will type his or her own calendar location into
        client configuration information or copy and paste a URL from
        email into the calendar application. The client need only confirm
        that the URL points to a resource that is a calendar collection.
        The client may also be able to browse WebDAV collections to find
        calendar collections.
      </t>
      <t>
        The choice of HTTP URLs means that calendar object resources are
        backward compatible with existing software, but does have the
        disadvantage that existing software does not usually know to look at
        the OPTIONS response to that URL to determine what can be done with it.
        This is somewhat of a barrier for WebDAV usage as well as with CalDAV
        usage. This specification does not offer a way through this other than
        making the information available in the OPTIONS response should this
        be requested.
      </t>
      <t>
        For calendar sharing and scheduling use cases, one might wish to
        find the calendar belonging to another user. If the other user has
        a calendar in the same repository, that calendar can be found by
        using the principal namespace required by WebDAV ACL support.
        For other cases, the authors have no universal solution, but
        implementers can consider whether to use
        <xref target="RFC2426">vCard</xref> or
        <xref target="RFC4511">LDAP</xref> standards together with
        <xref target="RFC2739">calendar attributes</xref>.
      </t>
      <t>
        Because CalDAV requires servers to support <xref target="RFC3744">
        WebDAV ACL</xref>, including principal namespaces, and with the
        addition of the CALDAV:calendar-home-set property, there are a
        couple options for CalDAV clients to find one's own calendar or
        another user's calendar.
      </t>
      <t>
        In this case, a DAV:principal-match REPORT is used to find a named
        property (the CALDAV:calendar-home-set) on the Principal-URL of the
        current user.  Using this, a WebDAV client can learn "who am I" and
        "where are my calendars".  The REPORT request body looks like this:
      </t>
      <figure>
        <artwork><![CDATA[
<?xml version="1.0" encoding="utf-8" ?>
<D:principal-match xmlns:D="DAV:">
  <D:self/>
  <D:prop>
    <C:calendar-home-set
       xmlns:C="urn:ietf:params:xml:ns:caldav"/>
  </D:prop>
</D:principal-match>
        ]]></artwork>
      </figure>

      <t>
        To find other users' calendars, the DAV:principal-property-search
        REPORT can be used to filter on some properties and return
        others. To search for a calendar owned by a user named "Laurie",
        the REPORT request body would look like this:
      </t>

      <figure>
        <artwork><![CDATA[
<?xml version="1.0" encoding="utf-8" ?>
<D:principal-property-search xmlns:D="DAV:">
  <D:property-search>
    <D:prop>
      <D:displayname/>
    </D:prop>
    <D:match>Laurie</D:match>
  </D:property-search>
  <D:prop>
    <C:calendar-home-set
       xmlns:C="urn:ietf:params:xml:ns:caldav"/>
    <D:displayname/>
  </D:prop>
</D:principal-property-search>
        ]]></artwork>
      </figure>

      <t>
        The server performs a case-sensitive or caseless search for a
        matching string subset of "Laurie" within the DAV:displayname
        property.  Thus, the server might return "Laurie Dusseault",
        "Laurier Desruisseaux", or "Wilfrid Laurier" as matching
        DAV:displayname values, and return the calendars for each of these.
      </t>
    </section><!-- Finding calendars -->

    <section title="Storing and Using Attachments">
      <t>
        CalDAV clients MAY create attachments in calendar components either
        as inline or external. This section contains some guidelines for
        creating and managing attachments.
      </t>
      <section title="Inline Attachments">
        <t>
          CalDAV clients MUST support inline attachments as specified in
          <xref target="RFC2445">iCalendar</xref>. CalDAV servers MUST
          support inline attachments, so clients can rely on being able
          to create attachments this way.  On the other hand, inline
          attachments have some drawbacks:
        </t>
        <t>
<?rfc compact="no" ?>
          <list style="symbols">
            <t>
              Servers MAY impose limitations on the size of calendar
              object resources (i.e., refusing PUT requests of very
              large iCalendar objects). Servers that impose such
              limitations MUST use
              the CALDAV:max-resource-size property on a calendar
              collection to inform the client as to what the limitation
              is (see <xref target="max-resource-size"/>).
            </t>
            <t>
              Servers MAY impose storage quota limitations on calendar
              collections (See <xref target="RFC4331"/>).
            </t>
            <t>
              Any change to a calendar object resource containing an
              inline attachment requires the entire inline attachment to be
              re-uploaded.
            </t>
            <t>
              Clients synchronizing a changed calendar object resource
              have to download the entire calendar object resource, even
              if the attachment is unchanged.
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- Inline attachments -->

      <section title="External Attachments">

        <t>
          CalDAV clients SHOULD support downloading of external
          attachments referenced by arbitrary URI schemes, by either
          processing them directly, or by passing the attachment URI to
          a suitable "helper application" for processing, if such an
          application exists. CalDAV clients MUST support downloading of
          external attachments referenced by the "http" or "https" URI schemes.
          An external attachment could be:
        </t>
<?rfc compact="no" ?>
        <t>
          <list style="symbols">
            <t>
              In a collection in the calendar collection containing
              the calendar object resource;
            </t>
            <t>
              Somewhere else in the same repository that hosts the
              calendar collection; or
            </t>
            <t>
              On an HTTP or FTP server elsewhere.
            </t>
<?rfc compact="yes" ?>
          </list>
        </t>

        <t>
          CalDAV servers MAY provide support for child collections in
          calendar collections. CalDAV servers MAY allow the MKCOL
          method to create child collections in calendar collections.
          Child collections of calendar collections MAY contain any
          type of resource except calendar collections that they MUST
          NOT contain. Some CalDAV servers won't allow child collections
          in calendar collections, and it may be possible on such a
          server to discover other locations where attachments can be
          stored.
        </t>
        <t>
          Clients are entirely responsible for maintaining reference
          consistency with calendar components that link to external
          attachments. A client deleting a calendar component with an
          external attachment might therefore also delete the attachment
          if that's appropriate; however, appropriateness can be very hard
          to determine.  A new component might easily reference some
          pre-existing Web resource that is intended to have
          independent existence from the calendar component (the
          "attachment" could be a major proposal to be discussed
          in a meeting, for instance). Best practices will probably
          emerge and should probably be documented, but for now, clients
          should be wary of engaging in aggressive "cleanup" of external
          attachments.  A client could involve the user in making
          decisions about removing unreferenced documents, or a client
          could be conservative in only deleting attachments it had
          created.
        </t>
        <t>
          Also, clients are responsible for consistency of permissions
          when using external attachments.  One reason for servers to
          support the storage of attachments within child collections of
          calendar collections is that ACL inheritance might make it
          easier to grant the same permissions to attachments that are
          granted on the calendar collection. Otherwise, it can be very
          difficult to keep permissions synchronized.  With attachments
          stored on separate repositories, it can be impossible to keep
          permissions consistent -- the two repositories may not support
          the same permissions or have the same set of principals.  Some
          systems have used tickets or other anonymous access control
          mechanisms to provide partially satisfactory solutions to these
          kinds of problems.
        </t>
      </section><!-- External attachments -->
    </section><!-- Storing and Using Attachments -->

    <section title='Storing and Using Alarms'>
      <t>
        Note that all CalDAV calendar collections (including those
        the user might treat as public or group calendars) can
        contain alarm information on events and to-dos.  Users can
        synchronize a calendar between multiple devices and decide
        to have alarms execute on a different device than the device
        that created the alarm.  Not all alarm action types are completely
        interoperable (e.g., those that name a sound file to play).
      </t>
      <t>
        <list>
<?rfc compact="no" ?>
        <list>
          <t>
            When the action is "AUDIO" and the client is configured to
            execute the alarm, the client SHOULD play the suggested
            sound if it's available or play another sound, but SHOULD NOT
            rewrite the alarm just to replace the suggested sound with
            a sound that's locally available.
          </t>
          <t>
            When the action is "DISPLAY" and the client is configured to
            execute the alarm, the client SHOULD execute a display alarm by
            displaying according to the suggested description or
            some reasonable replacement, but SHOULD NOT rewrite the alarm
            for its own convenience.
          </t>
          <t>
            When the action is "EMAIL" and the client is incapable of
            sending email, it SHOULD ignore the alarm, but it MUST continue
            to synchronize the alarm itself.
          </t>
          <t>
            This specification makes no recommendations about executing
            alarms of type PROCEDURE, except to note that clients are
            advised to take care to avoid creating security holes by
            executing these.
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
      <t>
        Non-interoperable alarm information (e.g., should somebody define
        a color to be used in a display alarm) should be put in non-standard
        properties inside the VALARM component in order to keep the basic
        alarm usable on all devices.
      </t>
      <t>
        Clients that allow changes to calendar object resources MUST
        synchronize the alarm data that already exists in the resources.
        Clients MAY execute alarms that are downloaded in this fashion,
        possibly based on user preference.  If a client is only doing
        read operations on a calendar and there is no risk of losing
        alarm information, then the client MAY discard alarm information.
      </t>
      <t>
        This specification makes no attempt to provide multi-user alarms
        on group calendars or to find out for whom an alarm is intended.
        Addressing those issues might require extensions to iCalendar;
        for example, to store alarms per-user, or to indicate for which user a
        VALARM was intended.  In the meantime, clients might maximize
        interoperability by generally not uploading alarm information to
        public, group, or resource calendars.
      </t>
    </section><!-- Storing and Using Alarms -->
  </section>

  <section title='XML Element Definitions'>

    <section anchor="calendar_element"
      title="CALDAV:calendar XML Element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            calendar
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Specifies the resource type of a calendar collection.
          </t>
          <t hangText="Description:">
            See <xref target='calendar-collection'/>.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT calendar EMPTY>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section>

    <section anchor="mkcalendar_element"
      title="CALDAV:mkcalendar XML Element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            mkcalendar
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Specifies a request that includes the WebDAV property values
            to be set for a calendar collection resource when it is created.
          </t>
          <t hangText="Description:">
            See <xref target='METHOD_MKCALENDAR'/>.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT mkcalendar (DAV:set)>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section>

    <section anchor="mkcalendar_response_element"
      title="CALDAV:mkcalendar-response XML Element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            mkcalendar-response
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Specifies a response body for a successful MKCALENDAR request.
          </t>
          <t hangText="Description:">
            See <xref target='METHOD_MKCALENDAR'/>.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT mkcalendar-response ANY>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section>

    <section anchor="ELEMENT_supported-collation"
            title="CALDAV:supported-collation XML Element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            supported-collation
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Identifies a single collation via its collation identifier, as defined by <xref target="RFC4790"/>.
          </t>
          <t hangText="Description:">
            The CALDAV:supported-collation contains the text of a collation identifier, as described in <xref target='PROPERTY_supported-collation-set'/>.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT supported-collation (#PCDATA)>
      PCDATA value: collation identifier
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- ELEMENT_supported-collation -->

    <section anchor="calendar_query_element"
      title="CALDAV:calendar-query XML Element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            calendar-query
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Defines a REPORT report for querying calendar object resources.
          </t>
          <t hangText="Description:">
            See <xref target='calendar-query'/>.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT calendar-query ((DAV:allprop |
                                 DAV:propname |
                                 DAV:prop)?, filter, timezone?)>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section>

    <section anchor="calendar_data_element"
      title="CALDAV:calendar-data XML Element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            calendar-data
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Used to
            (1) specify a
            Specified one of the following:
            <list style="numbers">
              <t>
                A supported media type for
                calendar object resources when nested in the
                CALDAV:supported-calendar-data property;
            (2) specify which
              </t>
              <t>
                The parts of a calendar object resource
                should be returned by a given calendaring REPORT; and
            (3) specify the report;
              </t>
              <t>
                The content of a calendar object resource
                in a response to a calendaring REPORT.
<!-- RFC Editor Comment: should this be displayed as it looks above
or should the text be run together?  The text document produces the
text in paragraph format. --> report.
              </t>
            </list>
          </t>
          <t hangText="Description:">
            When nested in the CALDAV:supported-calendar-data property,
            the CALDAV:calendar-data XML element specifies a media type
            supported by the CalDAV server for calendar object resources.
          </t>
          <t>
            When used in a calendaring REPORT request, the
            CALDAV:calendar-data XML element specifies which parts
            of calendar object resources need to be returned in the
            response. If the CALDAV:calendar-data XML element doesn't
            contain any CALDAV:comp element, calendar object resources
            will be returned in their entirety.
          </t>
          <t>
            Finally, when used in a calendaring REPORT response, the
            CALDAV:calendar-data XML element specifies the content of
            a calendar object resource. Given that XML parsers normalize
            the two-character sequence CRLF (US-ASCII decimal 13 and
            US-ASCII decimal 10) to a single LF character (US-ASCII
            decimal 10), the CR character (US-ASCII decimal 13) MAY be
            omitted in calendar object resources specified in the
            CALDAV:calendar-data XML element. Furthermore, calendar
            object resources specified in the CALDAV:calendar-data XML
            element MAY be invalid per their media type specification
            if the CALDAV:calendar-data XML element part of the
            calendaring REPORT request did not specify required properties
            (e.g., UID, DTSTAMP, etc.), or specified a CALDAV:prop XML
            element with the "novalue" attribute set to "yes".
          </t>
          <t hangText="Note:">
            The CALDAV:calendar-data XML element is specified in
            requests and responses inside the DAV:prop XML element
            as if it were a WebDAV property. However, the
            CALDAV:calendar-data XML element is not a WebDAV
            property and, as such, is not returned in PROPFIND
            responses, nor used in PROPPATCH requests.
          </t>
          <t hangText="Note:">
            The iCalendar data embedded within the CALDAV:calendar-data XML
            element MUST follow the standard XML character data encoding rules,
            including use of &amp;lt;, &amp;gt;, &amp;amp; etc. entity encoding
            or the use of a &lt;![CDATA[ ... ]]&gt; construct. In the later case,
            the iCalendar data cannot contain the character sequence "]]&gt;",
            which is the end delimiter for the CDATA section.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT calendar-data ((comp?, EMPTY>

      when nested in the CALDAV:supported-calendar-data property
      to specify a supported media type for calendar object
      resources;

      <!ELEMENT calendar-data (comp?,
                               (expand | limit-recurrence-set)?,
                                        limit-freebusy-set?) |
                               #PCDATA)?>
                               limit-freebusy-set?)>

      when nested in the DAV:prop XML element in a calendaring
      REPORT request to specify which parts of calendar object
      resources should be returned in the response;

      <!ELEMENT calendar-data (#PCDATA)>
      PCDATA value: iCalendar object

      when nested in the DAV:prop XML element in a calendaring
      REPORT response to specify the content of a returned
      calendar object resource.

      <!ATTLIST calendar-data content-type CDATA "text/calendar"> "text/calendar"
                              version CDATA "2.0">
      content-type value: a MIME media type
      version value: a version string

      attributes can be used on all three variants of the
      CALDAV:calendar-data XML element.
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>

      <section anchor="comp_element" title="CALDAV:comp XML Element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">
              comp
            </t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav
            </t>
            <t hangText="Purpose:">
              Defines which component types to return.
            </t>
            <t hangText="Description:">
              The name value is a calendar component name
              (e.g., "VEVENT").
            </t>
            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT comp ((allprop | prop*), (allcomp | comp*))>

      <!ATTLIST comp name CDATA #REQUIRED>
      name value: a calendar component name
                ]]></artwork>
              </figure>
            </t>
            <t hangText="Note:">
              The CALDAV:prop and CALDAV:allprop elements have
              the same name as the DAV:prop and DAV:allprop
              elements defined in <xref target="RFC2518"/>.
              However, the CALDAV:prop and CALDAV:allprop elements
              are defined in the "urn:ietf:params:xml:ns:caldav"
              namespace instead of the "DAV:" namespace.
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section>

      <section anchor="allcomp_element"
              title="CALDAV:allcomp XML Element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">
              allcomp
            </t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav
            </t>
            <t hangText="Purpose:">
              Specifies that all components shall be returned.
            </t>
            <t hangText="Description:">
              The CALDAV:allcomp XML element can be used when the
              client wants all types of components returned by a
              calendaring REPORT request.
            </t>
            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT allcomp EMPTY>
                ]]></artwork>
              </figure>
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- allcomp -->

      <section anchor="allprop_element"
        title="CALDAV:allprop XML Element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">
              allprop
            </t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav
            </t>
            <t hangText="Purpose:">
              Specifies that all properties shall be returned.</t>
            <t hangText="Description:">
              The CALDAV:allprop XML element can be used when the client
              wants all properties of components returned by a
              calendaring REPORT request.
            </t>
            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT allprop EMPTY>
                ]]></artwork>
              </figure>
            </t>
            <t hangText="Note:">
              The CALDAV:allprop element has the same name as the
              DAV:allprop element defined in <xref target="RFC2518"/>.
              However, the CALDAV:allprop element is defined in the
              "urn:ietf:params:xml:ns:caldav" namespace instead of
              the "DAV:" namespace.
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- allprop -->
      <section anchor="prop_element" title="CALDAV:prop XML Element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">prop</t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav</t>
            <t hangText="Purpose:">Defines which
              properties to return in the
              response.</t>
            <t hangText="Description:">The "name"
              attribute specifies the name of the
              calendar property to return (e.g.,
              "ATTENDEE"). The "novalue" attribute
              can be used by clients to request that
              the actual value of the property not be
              returned (if the "novalue" attribute is
              set to "yes"). In that case, the server
              will return just the iCalendar property
              name and any iCalendar parameters and a
              trailing ":" without the subsequent
              value data.
            </t>
            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT prop EMPTY>

      <!ATTLIST prop name CDATA #REQUIRED
                     novalue (yes | no) "no">
      name value: a calendar property name
      novalue value: "yes" or "no"
                ]]></artwork>
              </figure>
            </t>
            <t hangText="Note:">
              The CALDAV:prop element has the same name as the
              DAV:prop element defined in <xref target="RFC2518"/>.
              However, the CALDAV:prop element is defined in the
              "urn:ietf:params:xml:ns:caldav" namespace instead of
              the "DAV:" namespace.
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- prop -->

      <section anchor="expand_element"
        title="CALDAV:expand XML Element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">
              expand
            </t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav
            </t>
            <t hangText="Purpose:">
              Forces the server to expand recurring components
              into individual recurrence instances.
            </t>
            <t hangText="Description:">
<!-- RFC Editor Comment: it looks like the text is inteded to be
separate paragraphs, but the resulting text creates one extended
paragraph. -->
              The CALDAV:expand XML element specifies that for
              a given calendaring REPORT request, the server MUST
              expand the recurrence set into calendar components
              that define exactly one recurrence instance, and MUST
              return only those whose scheduled time intersect a
              specified time range.
            </t>
            <t>
              The "start" attribute specifies the inclusive start of
              the time range, and the "end" attribute specifies the
              non-inclusive end of the time range. Both attributes are
              specified as date with UTC time value. The value of the
              "end" attribute MUST be greater than the value of the
              "start" attribute.
            </t>
            <t>
              The server MUST use the same logic as defined for
              CALDAV:time-range to determine if a recurrence
              instance intersects the specified time range.
            </t>
            <t>
              Recurring components, other than the initial instance, MUST
              include a RECURRENCE-ID property indicating which instance they
              refer to.
            </t>
            <t>
              The returned calendar components MUST NOT use
              recurrence properties (i.e., EXDATE, EXRULE, RDATE,
              and RRULE) and MUST NOT have reference to or include
              VTIMEZONE components. Date and local time with reference
              to time zone information MUST be converted into date
              with UTC time.
            </t>
            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT expand EMPTY>

      <!ATTLIST expand start CDATA #REQUIRED
                       end   CDATA #REQUIRED>
      start value: an iCalendar "date with UTC time"
      end value: an iCalendar "date with UTC time"
                ]]></artwork>
              </figure>
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- expand -->

      <section anchor="limit_recurrence_set_element"
        title="CALDAV:limit-recurrence-set XML Element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">
              limit-recurrence-set
            </t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav
            </t>
            <t hangText="Purpose:">
              Specifies a time range to limit the set of "overridden
              components" returned by the server.
            </t>
            <t hangText="Description:">
<!-- RFC Editor Comment: same vertical whitespace comment as above -->
              The CALDAV:limit-recurrence-set XML element specifies
              that for a given calendaring REPORT request, the server
              MUST return, in addition to the "master component", only the
              "overridden components" that impact a specified time
              range. An overridden component impacts a time range if
              its current start and end times overlap the time range,
              or if the original start and end times -- the ones that
              would have been used if the instance were not overridden
              -- overlap the time range.
            </t>
            <t>
              The "start" attribute specifies the inclusive start of
              the time range, and the "end" attribute specifies the
              non-inclusive end of the time range. Both attributes are
              specified as date with UTC time value. The value of the
              "end" attribute MUST be greater than the value of the
              "start" attribute.
            </t>
            <t>
              The server MUST use the same logic as defined for
              CALDAV:time-range to determine if the current or
              original scheduled time of an "overridden"
              recurrence instance intersects the specified time
              range.
            </t>
            <t>
              Overridden components that have a RANGE parameter on their
              RECURRENCE-ID property may specify one or more instances
              in the recurrence set, and some of those instances may
              fall within the specified time range or may have
              originally fallen within the specified time range prior
              to being overridden. If that is the case, the overridden
              component MUST be included in the results, as it has a
              direct impact on the interpretation of instances within
              the specified time range.
            </t>
            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT limit-recurrence-set EMPTY>

      <!ATTLIST limit-recurrence-set start CDATA #REQUIRED
                                     end   CDATA #REQUIRED>
      start value: an iCalendar "date with UTC time"
      end value: an iCalendar "date with UTC time"
                ]]></artwork>
              </figure>
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- limit-recurrence-set -->

      <section anchor="limit_freebusy_set_element"
        title="CALDAV:limit-freebusy-set XML Element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">
              limit-freebusy-set
            </t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav
            </t>
            <t hangText="Purpose:">
              Specifies a time range to limit the set of FREEBUSY
              values returned by the server.
            </t>
            <t hangText="Description:">
<!-- RFC Editor Comment: same vertical whitespace comment as above -->
              The CALDAV:limit-freebusy-set XML element specifies
              that for a given calendaring REPORT request, the server
              MUST only return the FREEBUSY property values of a
              VFREEBUSY component that intersects a specified time
              range.
            </t>
            <t>
              The "start" attribute specifies the inclusive start of
              the time range, and the "end" attribute specifies the
              non-inclusive end of the time range. Both attributes are
              specified as "date with UTC time" value. The value of the
              "end" attribute MUST be greater than the value of the
              "start" attribute.
            </t>
            <t>
              The server MUST use the same logic as defined for
              CALDAV:time-range to determine if a FREEBUSY property
              value intersects the specified time range.
            </t>
            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT limit-freebusy-set EMPTY>

      <!ATTLIST limit-freebusy-set start CDATA #REQUIRED
                                   end   CDATA #REQUIRED>
      start value: an iCalendar "date with UTC time"
      end value: an iCalendar "date with UTC time"
                ]]></artwork>
              </figure>
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- limit-freebusy-set -->
    </section><!-- calendar-data -->

    <section anchor="filter_element" title="CALDAV:filter XML Element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            filter
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Specifies a filter to limit the set of calendar
            components returned by the server.
          </t>
          <t hangText="Description:">
            The CALDAV:filter XML element specifies the search
            filter used to limit the calendar components returned
            by a calendaring REPORT request.
          </t>
          <t hangText="Definition:">
           <figure>
             <artwork><![CDATA[
      <!ELEMENT filter (comp-filter)>
             ]]></artwork>
           </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
     <section anchor="comp_filter_element"
              title="CALDAV:comp-filter XML Element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">
              comp-filter
            </t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav
            </t>
            <t hangText="Purpose:">
              Specifies search criteria on calendar components.
            </t>
            <t hangText="Description:">
              The CALDAV:comp-filter XML element specifies the
              queried calendar component type (e.g., "VEVENT").
              A calendar object resource is said to match a
              CALDAV:comp-filter if:
              <list style="symbols">
              <t>A
                <t>
                  The CALDAV:comp-filter element is empty and a
                  component of the type specified by the "name"
                  attribute exists, and exists in the calendar object resource;
                </t>
              </list>
              </t>
              <t>or:
              <list style="symbols">
              <t>
                The CALDAV:comp-filter is empty, or
              it element contains at least one recurrence instance scheduled to
              overlap a given time range if a CALDAV:time-range XML
                CALDAV:is-not-defined element is specified, and that any CALDAV:prop-filter and
              CALDAV:comp-filter child elements also match.</t>
<!-- RFC Editor Comment: This is a bit confusing.  Can this be broken
into a sublist?  For example:

* 1. a no component of
                the type specified by the "name" attribute exists,
  2. exists
                in the calendar object resource;
              </t>
              </list>
              </t>
              <t>or:
              <list style="symbols">
                <t>
                  The CALDAV:comp-filter is empty (or it element contains a
                  CALDAV:time-range XML element and at least one
                  recurrence instance in the calendar object resource
                  is scheduled to overlap a given the specified time range if a
     CALDAV:time-range XML element is specified), range, and
  3.
                  any specified CALDAV:prop-filter and
                  CALDAV:comp-filter child elements also match each other.

If this change is unacceptable, we recommend that the sentence
be reworded.
-->
                  calendar object resource;
                </t>
              </list>
              </t>
              <t>or:
              <list style="symbols">
              <t>A component of the type specified by the "name"
              attribute does not exist
                <t>
                  The CALDAV:comp-filter element only contains
                  CALDAV:prop-filter and CALDAV:comp-filter child elements
                  that all match the CALDAV:is-not-defined
              element is specified.</t> calendar object resource.
                </t>
              </list>
            </t>
            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT comp-filter (is-not-defined | (time-range?,
                             prop-filter*, comp-filter*))>

      <!ATTLIST comp-filter name CDATA #REQUIRED>
      name value: a calendar component name (e.g., "VEVENT")
                ]]></artwork>
              </figure>
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- comp-filter -->
      <section anchor="prop_filter_element"
              title="CALDAV:prop-filter XML Element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">
              prop-filter
            </t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav
            </t>
            <t hangText="Purpose:">
              Specifies search criteria on calendar properties.
            </t>
            <t hangText="Description:">
              The CALDAV:prop-filter XML element specifies a
              search criteria on a specific calendar property
              (e.g., CATEGORIES) in the scope of a given
              CALDAV:comp-filter. A calendar component is said
              to match a CALDAV:prop-filter if:
              <list style="symbols">
              <t>A property of the type specified by the "name"
              attribute exists, and the CALDAV:prop-filter is empty, or
              it matches the CALDAV:time-range XML element or
              CALDAV:text-match conditions if specified, and that any
              CALDAV:param-filter child elements also match.</t>
              </list>
              </t>
              <t>or:
              <list style="symbols">
              <t>A property of the type specified by the "name"
              attribute does not exist, and the CALDAV:is-not-defined
              element is specified.</t>
              </list>
            </t>
            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT prop-filter ((is-not-defined (is-not-defined |
                             ((time-range | text-match)?,
                              param-filter*))>

      <!ATTLIST prop-filter name CDATA #REQUIRED>
      name value: a calendar property name (e.g., "ATTENDEE")
                ]]></artwork>
              </figure>
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- prop-filter -->
      <section title="CALDAV:param-filter XML Element"
               anchor="param_filter_element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">
              param-filter
            </t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav
            </t>
            <t hangText="Purpose:">
              Limits the search to specific parameter values.
            </t>
            <t hangText="Description:">
              The CALDAV:param-filter XML element specifies a
              search criteria on a specific calendar property
              parameter (e.g., PARTSTAT) in the scope of a
              given CALDAV:prop-filter. A calendar property
              is said to match a CALDAV:param-filter if:
              <list style="symbols">
              <t>A parameter of the type specified by the "name"
              attribute exists, and the CALDAV:param-filter is empty, or
              it matches the CALDAV:text-match conditions if specified.</t>
              </list>
              </t>
              <t>or:
              <list style="symbols">
              <t>A parameter of the type specified by the "name"
              attribute does not exist, and the CALDAV:is-not-defined
              element is specified.</t>
              </list>
            </t>
            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT param-filter (is-not-defined | text-match)?> text-match?)>

      <!ATTLIST param-filter name CDATA #REQUIRED>
      name value: a property parameter name (e.g., "PARTSTAT")
                ]]></artwork>
              </figure>
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- param-filter -->
      <section title="CALDAV:is-not-defined XML Element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">is-not-defined</t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav</t>
            <t hangText="Purpose:">Specifies that a match should occur if
            the enclosing component, property, or parameter does not exist.</t>
            <t hangText="Description:">
              The CALDAV:is-not-defined XML element specifies that
              a match occurs if the enclosing component, property, or parameter
              value specified in a calendaring REPORT request does not
              exist in the calendar data being tested.</t>

            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT is-not-defined EMPTY>
                ]]></artwork>
              </figure>
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- is-not-defined -->
      <section title="CALDAV:text-match XML Element" anchor="text_match_element">
        <t>
<?rfc compact="no" ?>
          <list style="hanging">
            <t hangText="Name:">text-match</t>
            <t hangText="Namespace:">
              urn:ietf:params:xml:ns:caldav</t>
            <t hangText="Purpose:">Specifies a substring
              match on a property or parameter value.</t>
            <t hangText="Description:">
              The CALDAV:text-match XML element specifies text used
              for a substring match against the property or parameter
              value specified in a calendaring REPORT request.</t>

              <t>The "collation" attribute is used to select the collation that the server MUST use for character string matching. In the absence of this attribute, the server MUST use the "i;ascii-casemap" collation.</t>

              <t>The "negate-condition" attribute is used to indicate
              that this test returns a match if the text matches when
              the attribute value is set to "no", or return a match if
              the text does not match, if the attribute value is set to
              "yes". For example, this can be used to match components
              with a STATUS property not set to CANCELLED.</t>

            <t hangText="Definition:">
              <figure>
                <artwork><![CDATA[
      <!ELEMENT text-match (#PCDATA)>
      PCDATA value: string

      <!ATTLIST text-match collation        CDATA "i;ascii-casemap"
                           negate-condition (yes | no) "no">
                ]]></artwork>
              </figure>
            </t>
          </list>
<?rfc compact="yes" ?>
        </t>
      </section><!-- text-match -->
    </section><!-- filter -->

    <section title="CALDAV:timezone XML Element"
             anchor="timezone_element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            timezone
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Specifies the time zone component to use when determining the
            results of a report.
          </t>
          <t hangText="Description:">
            The CALDAV:timezone XML element specifies that for a
            given calendaring REPORT request, the server MUST rely
            on the specified VTIMEZONE component instead of the
            CALDAV:calendar-timezone property of the calendar
            collection, in which the calendar object resource is
            contained to resolve "date" values and "date with local
            time" values (i.e., floating time) to "date with UTC time"
            values. The server will require this information to
            determine if a calendar component scheduled with "date"
            values or "date with local time" values intersects a
            CALDAV:time-range specified in a CALDAV:calendar-query
            REPORT.
          </t>
          <t hangText="Note:">
            The iCalendar data embedded within the CALDAV:timezone XML
            element MUST follow the standard XML character data encoding rules,
            including use of &amp;lt;, &amp;gt;, &amp;amp; etc. entity encoding
            or the use of a &lt;![CDATA[ ... ]]&gt; construct. In the later case,
            the iCalendar data cannot contain the character sequence "]]&gt;",
            which is the end delimiter for the CDATA section.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT timezone (#PCDATA)>
      PCDATA value: an iCalendar object with exactly one VTIMEZONE
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- timezone -->

    <section title="CALDAV:time-range XML Element"
             anchor="time_range_element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            time-range
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            Specifies a time range to limit the set of calendar
            components returned by the server.
          </t>
          <t hangText="Description:">
<!-- RFC Editor Comment: same vertical whitespace comment as above -->
            The CALDAV:time-range XML element specifies that for a
            given calendaring REPORT request, the server MUST only
            return the calendar object resources that, depending on the
            context, have a component or property whose value intersects
            a specified time range.
          </t>
          <t>
            The "start" attribute specifies the inclusive start of the
            time range, and the "end" attribute specifies the
            non-inclusive end of the time range. Both attributes MUST be
            specified as "date with UTC time" value. Time ranges open
            at one end can be specified by including only one
            attribute; however, at least one attribute MUST always be
            present in the CALDAV:time-range element. If either the
            "start" or "end" attribute is not specified in the
            CALDAV:time-range XML element, assume "-infinity" and
            "+infinity" as their value, respectively. If both "start"
            and "end" are present, the value of the "end" attribute
            MUST be greater than the value of the "start" attribute.
          </t>
          <t>
            Time range tests MUST consider every recurrence instance
            when testing the time range condition; if any one instance
            matches, then the test returns true. Testing recurrence
            instances requires the server to infer an effective value
            for DTSTART, DTEND, DURATION, and DUE properties for an
            instance based on the recurrence patterns and any overrides.
          </t>
          <t>
            A VEVENT component overlaps a given time range if the
            condition for the corresponding component state specified in
            the table below is satisfied. Note that, as specified in
            <xref target="RFC2445"/>, the DTSTART property is REQUIRED in
            the VEVENT component. The conditions depend on the presence
            of the DTEND and DURATION properties in the VEVENT
            component. Furthermore, the value of the DTEND property MUST
            be later in time than the value of the DTSTART property. The
            duration of a VEVENT component with no DTEND and DURATION
            properties is 1 day (+P1D) when the DTSTART is a DATE value,
            and 0 seconds when the DTSTART is a DATE-TIME value.
            <figure>
              <artwork><![CDATA[
   +---------------------------------------------------------------+
   | VEVENT has the DTEND property?                                |
   |   +-----------------------------------------------------------+
   |   | VEVENT has the DURATION property?                         |
   |   |   +-------------------------------------------------------+
   |   |   | DURATION property value is greater than 0 seconds?    |
   |   |   |   +---------------------------------------------------+
   |   |   |   | DTSTART property is a DATE-TIME value value?            |
   |   |   |   |   +-----------------------------------------------+
   |   |   |   |   | Condition to evaluate                         |
   +---+---+---+---+-----------------------------------------------+
   | Y | N | N | * | (start <  DTEND AND end > DTSTART)            |
   +---+---+---+---+-----------------------------------------------+
   | N | Y | Y | * | (start <  DTSTART+DURATION AND end > DTSTART) |
   |   |   +---+---+-----------------------------------------------+
   |   |   | N | * | (start <= DTSTART AND end > DTSTART)          |
   +---+---+---+---+-----------------------------------------------+
   | N | N | N | Y | (start <= DTSTART AND end > DTSTART)          |
   +---+---+---+---+-----------------------------------------------+
   | N | N | N | N | (start <  DTSTART+P1D AND end > DTSTART)      |
   +---+---+---+---+-----------------------------------------------+
              ]]></artwork>
            </figure>
          </t>
          <t>
            A VTODO component is said to overlap a given time range if
            the condition for the corresponding component state
            specified in the table below is satisfied. The conditions
            depend on the presence of the DTSTART, DURATION, DUE,
            COMPLETED, and CREATED properties in the VTODO component.
            Note that, as specified in <xref target="RFC2445"/>, the DUE
            value MUST be a DATE-TIME value equal to or after the DTSTART
            value if specified.
            <figure>
              <artwork><![CDATA[
+-------------------------------------------------------------------+
| VTODO has the DTSTART property?                                   |
|   +---------------------------------------------------------------+
|   |   VTODO has the DURATION property?                            |
|   |   +-----------------------------------------------------------+
|   |   | VTODO has the DUE property?                               |
|   |   |   +-------------------------------------------------------+
|   |   |   | VTODO has the COMPLETED property?                     |
|   |   |   |   +---------------------------------------------------+
|   |   |   |   | VTODO has the CREATED property?                   |
|   |   |   |   |   +-----------------------------------------------+
|   |   |   |   |   | Condition to evaluate                         |
+---+---+---+---+---+-----------------------------------------------+
| Y | Y | N | * | * | (start  <= DTSTART+DURATION)  AND             |
|   |   |   |   |   | ((end   >  DTSTART)  OR                       |
|   |   |   |   |   |  (end   >= DTSTART+DURATION))                 |
+---+---+---+---+---+-----------------------------------------------+
| Y | N | Y | * | * | ((start <  DUE)      OR  (start <= DTSTART))  |
|   |   |   |   |   | AND                                           |
|   |   |   |   |   | ((end   >  DTSTART)  OR  (end   >= DUE))      |
+---+---+---+---+---+-----------------------------------------------+
| Y | N | N | * | * | (start  <= DTSTART)  AND (end >  DTSTART)     |
+---+---+---+---+---+-----------------------------------------------+
| N | N | Y | * | * | (start  <  DUE)      AND (end >= DUE)         |
+---+---+---+---+---+-----------------------------------------------+
| N | N | N | Y | Y | ((start <= CREATED)  OR  (start <= COMPLETED))|
|   |   |   |   |   | AND                                           |
|   |   |   |   |   | ((end   >= CREATED)  OR  (end   >= COMPLETED))|
+---+---+---+---+---+-----------------------------------------------+
| N | N | N | Y | N | (start  <= COMPLETED) AND (end  >= COMPLETED) |
+---+---+---+---+---+-----------------------------------------------+
| N | N | N | N | Y | (end    >  CREATED)                           |
+---+---+---+---+---+-----------------------------------------------+
| N | N | N | N | N | TRUE                                          |
+---+---+---+---+---+-----------------------------------------------+
              ]]></artwork>
            </figure>
          </t>
          <t>
            A VJOURNAL component overlaps a given time range if the
            condition for the corresponding component state specified in
            the table below is satisfied. The conditions depend on the
            presence of the DTSTART property in the VJOURNAL component
            and on whether the DTSTART is a DATE-TIME or DATE value. The
            effective "duration" of a VJOURNAL component is 1 day (+P1D)
            when the DTSTART is a DATE value, and 0 seconds when the
            DTSTART is a DATE-TIME value.
            <figure>
              <artwork><![CDATA[
   +----------------------------------------------------+
   | VJOURNAL has the DTSTART property?                 |
   |   +------------------------------------------------+
   |   | DTSTART property is a DATE-TIME value value?         |
   |   |   +--------------------------------------------+
   |   |   | Condition to evaluate                      |
   +---+---+--------------------------------------------+
   | Y | Y | (start <= DTSTART)     AND (end > DTSTART) |
   +---+---+--------------------------------------------+
   | Y | N | (start <  DTSTART+P1D) AND (end > DTSTART) |
   +---+---+--------------------------------------------+
   | N | * | FALSE                                      |
   +---+---+--------------------------------------------+
              ]]></artwork>
            </figure>
          </t>
          <t>
            A VFREEBUSY component overlaps a given time range if the
            condition for the corresponding component state specified
            in the table below is satisfied. The conditions depend on
            the presence in the VFREEBUSY component of the DTSTART and
            DTEND properties, and any FREEBUSY properties in the absence
            of DTSTART and DTEND. Any DURATION property
            is ignored, as it has a special meaning when used in a
            VFREEBUSY component.
          </t>
          <t>
            When only FREEBUSY properties are used, each period in each
            FREEBUSY property is compared against the time range,
            irrespective of the type of free busy information (free,
            busy, busy-tentative, busy-unavailable) represented by the
            property.
          </t>
          <t>
            <figure>
              <artwork><![CDATA[
   +------------------------------------------------------+
   | VFREEBUSY has both the DTSTART and DTEND properties? |
   |   +--------------------------------------------------+
   |   | VFREEBUSY has the FREEBUSY property?             |
   |   |   +----------------------------------------------+
   |   |   | Condition to evaluate                        |
   +---+---+----------------------------------------------+
   | Y | * | (start <= DTEND) AND (end > DTSTART)         |
   +---+---+----------------------------------------------+
   | N | Y | (start <  freebusy-period-end) AND           |
   |   |   | (end   >  freebusy-period-start)             |
   +---+---+----------------------------------------------+
   | N | N | FALSE                                        |
   +---+---+----------------------------------------------+
              ]]></artwork>
            </figure>
          </t>
          <t>
           A VALARM component is said to overlap a given time range if
           the following condition holds:
            <figure>
              <artwork><![CDATA[
      (start <= trigger-time) AND (end > trigger-time)
              ]]></artwork>
            </figure>
            A VALARM component can be defined such that it
            triggers repeatedly. Such a VALARM component is
            said to overlap a given time range if at least
            one of its triggers overlaps the time range.
          </t>
          <t>
            The calendar properties COMPLETED, CREATED, DTEND, DTSTAMP,
            DTSTART, DUE, and LAST-MODIFIED overlap a given time range if
            the following condition holds:
            <figure>
              <artwork><![CDATA[
       (start <= date-time) AND (end > date-time)
              ]]></artwork>
            </figure>
            Note that if DTEND is not present in a VEVENT, but DURATION is, then the test should instead operate on the 'effective' DTEND, i.e., DTSTART+DURATION. Similarly, if DUE is not present in a VTODO, but DTSTART and DURATION are, then the test should instead operate on the 'effective' DUE, i.e., DTSTART+DURATION.
          </t>
          <t>
            The semantic of CALDAV:time-range is not defined
            for any other calendar properties.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT time-range EMPTY>

      <!ATTLIST time-range start CDATA #IMPLIED
                           end   CDATA #IMPLIED>
      start value: an iCalendar "date with UTC time"
      end value: an iCalendar "date with UTC time"
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- time-range -->

    <section anchor="calendar_multiget_element"
      title="CALDAV:calendar-multiget XML Element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            calendar-multiget
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            CalDAV REPORT report used to retrieve specific calendar
            object resources.
          </t>
          <t hangText="Description:">
            See <xref target='calendar-multiget'/>.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT calendar-multiget ((DAV:allprop |
                                   DAV:propname |
                                   DAV:prop)?, DAV:href+)>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- calendar-multiget -->

    <section anchor="free_busy_query_element"
            title="CALDAV:free-busy-query XML Element">
      <t>
<?rfc compact="no" ?>
        <list style="hanging">
          <t hangText="Name:">
            free-busy-query
          </t>
          <t hangText="Namespace:">
            urn:ietf:params:xml:ns:caldav
          </t>
          <t hangText="Purpose:">
            CalDAV REPORT report used to generate a
            VFREEBUSY to determine busy time over a specific
            time range.
          </t>
          <t hangText="Description:">
            See <xref target="free-busy-query"/>.
          </t>
          <t hangText="Definition:">
            <figure>
              <artwork><![CDATA[
      <!ELEMENT free-busy-query (time-range)>
              ]]></artwork>
            </figure>
          </t>
        </list>
<?rfc compact="yes" ?>
      </t>
    </section><!-- free-busy-query -->
  </section><!-- XML Element Definitions -->

  <section title='Internationalization Considerations'>
    <t>
      CalDAV allows internationalized strings to be stored and
      retrieved for the description of calendar collections
      (see <xref target="calendar-description"/>).
    </t>
    <t>
      The CALDAV:calendar-query report REPORT (<xref target="calendar-query"/>)
      includes a text searching option controlled by the
      CALDAV:text-match element, and details of character handling are
      covered in the description of that element (see <xref
      target="text_match_element"/>).
    </t>
  </section>

  <section title="Security Considerations">
    <t>
      HTTP protocol transactions are sent in the clear over the
      network unless protection from snooping is negotiated. This
      can be accomplished by use of TLS, as defined in
      <xref target="RFC2818"/>.
      In particular, HTTP Basic authentication MUST NOT be used
      unless TLS is in effect.
    </t>
    <t>
      Servers MUST take adequate precautions to ensure that malicious
      clients cannot consume excessive server resources (CPU, memory,
      disk, etc.) through carefully crafted reports. For example, a
      client could upload an event with a recurrence rule that
      specifies a recurring event occurring every second for the next
      100 years, which would result in approximately 3 x 10^9
      instances! A REPORT report that asks for recurrences to be expanded
      over that range would likely constitute a denial-of-service
      attack on the server.
    </t>
    <t>
      When creating new resources (including calendar collections), clients
      MUST ensure that the resource name (the last path segment of the resource
      URI) assigned to the new resource does not
      expose any data from within the iCalendar resource itself or information
      about the nature of a calendar collection. This is required to ensure that
      the presence of a specific iCalendar component or nature of components in
      a collection cannot be inferred based on the name of a resource.
    </t>
    <t>
      When rolling up free-busy information, more information about a
      user's events is exposed if busy periods overlap or are adjacent
      (this tells the client requesting the free-busy information that
      the calendar owner has at least two events, rather than knowing
      only that the calendar owner has one or more events during the
      busy period). Thus, a conservative approach to calendar data
      privacy would have servers always coalesce such busy periods when
      they are the same type.
    </t>
    <t>
      Procedure alarms are a known security risk for either clients or
      servers to handle, particularly when the alarm was created by
      another agent. Clients and servers are not required to execute
      such procedure alarms.
    </t>

    <t>
      Security considerations described in
      <xref target="RFC2445">iCalendar</xref> and
      <xref target="RFC2446">iTIP</xref> are also applicable to CalDAV.
    </t>
    <t>
      Beyond these, CalDAV does not raise any security considerations
      that are not present in <xref target="RFC2616">HTTP</xref> and
      WebDAV <xref target="RFC2518"/>, <xref target="RFC3253"/>,
      <xref target="RFC3744"/>.
    </t>
  </section><!-- Security Considerations -->

  <section title='IANA Considerations' anchor='IANA'>
    <t>
      This document uses one new URN to identify a new XML namespace.
      The URN conforms to a registry mechanism described in
      <xref target="RFC3688"/>.
    </t>
    <section title='Namespace Registration' anchor='ns.registration'>
      <t>Registration request for the CalDAV namespace: </t>
      <t>URI: urn:ietf:params:xml:ns:caldav </t>
      <t>Registrant Contact: See the "Authors' Addresses" section of
        this document. </t>
      <t>XML: None. Namespace URIs do not represent an XML
        specification. </t>
    </section><!-- ns.registration -->
  </section><!-- IANA -->

  <section title="Acknowledgements">
    <t>
      The authors would like to thank the following individuals for
      contributing their ideas and support for writing this
      specification: Michael Arick, Mario Bonin, Chris Bryant, Scott
      Carr, Andre Courtemanche, Marten den Haring, Mike Douglass, Ted
      Hardie, Jeffrey Harris, Sam Hartman, Helge Hess, Jeff McCullough,
      Alexey Melnikov, Dan Mosedale, Brian Moseley, Francois Perrault,
      Kervin L. Pierre, Julian F. Reschke, Wilfredo Sanchez Vega, Mike
      Shaver, Jari Urpalainen, Simon Vaillancourt, Jim Whitehead.
    </t>
    <t>
      The authors would also like to thank the Calendaring and
      Scheduling Consortium for advice with this specification,
      and for organizing interoperability testing events to help
      refine it.
    </t>
  </section>
</middle>

<back>
  <references title='Normative References'>
    &rfc2119;
    &rfc2246;
    &rfc2445;
    &rfc2446;
    &rfc2518;
    &rfc2616;
    &rfc2818;
    &rfc3253;
    &rfc3688;
    &rfc3744;
    &rfc4346;
    &W3C.REC-xml-20060816;
<?rfc linefile="5323:/tmp/CGI21168.2"?>
    <?rfc linefile="1:http://xml.resource.org/public/rfc/bibxml3/reference.I-D.newman-i18n-comparator.xml"?>

<reference anchor='RFC4790'>
<front>
<title>Internet Application Protocol Collation Registry</title>

<author initials='C' surname='Newman' fullname='Chris Newman'>
    <organization />
</author>

<date month='January' day='19' year='2007' />

<abstract><t>Many Internet application protocols include string-based
lookup, searching, or sorting operations. However the problem space
for searching and sorting international strings is large, not fully
explored, and is outside the area of expertise for the Internet
Engineering Task Force (IETF). Rather than attempt to solve such a
large problem, this specification creates an abstraction framework so
that application protocols can precisely identify a comparison
function and the repertoire of comparison functions can be extended
in the future.</t></abstract>

</front>

<seriesInfo name='RFC'
value='4790' />
<format type='TXT'
        target='http://www.ietf.org/internet-drafts/draft-newman-i18n-comparator-14.txt' />
</reference>
<?rfc linefile="5324:/tmp/CGI21168.2"?>
  </references>

  <references title="Informative References">
    &rfc2426;
    &rfc2739;
    &rfc4331;
    &rfc4511;
<?rfc linefile="5331:/tmp/CGI21168.2"?>
    <?rfc linefile="1:http://xml.resource.org/public/rfc/bibxml3/reference.I-D.ietf-webdav-rfc2518bis.xml"?>

<reference anchor='rfc2518bis'>
<front>
<title>HTTP Extensions for Distributed Authoring - WebDAV</title>

<author initials='L' surname='Dusseault' fullname='Lisa Dusseault'>
    <organization />
</author>

<date month='December' day='5' year='2006' />

<abstract><t>WebDAV consists of a set of methods, headers, and
content-types ancillary to HTTP/1.1 for the management of resource
properties, creation and management of resource collections, URL
namespace manipulation, and resource locking (collision
avoidance). RFC2518 was published in February 1999, and this
specification makes minor revisions mostly due to interoperability
experience.</t></abstract>

</front>

<seriesInfo name='Work in'
value='Progress' />
<format type='TXT'
        target='http://www.ietf.org/internet-drafts/draft-ietf-webdav-rfc2518bis-17.txt' />
</reference>
  </references>

  <section title="CalDAV Method Privilege Table (Normative)">
    <t>
      The following table extends the WebDAV Method Privilege
      Table specified in Appendix B of <xref target="RFC3744"/>.
    </t>
    <texttable>
      <ttcol>METHOD</ttcol><ttcol>PRIVILEGES</ttcol>
      <c>MKCALENDAR</c><c>DAV:bind</c>
      <c>REPORT</c><c>DAV:read or CALDAV:read-free-busy
        (on all referenced resources)</c>
    </texttable>
  </section>

  <section title="Calendar Collections Used in the Examples"
           anchor="examples">
    <t>
      This appendix shows the calendar object resources contained in
      the calendar collection queried in the examples throughout
      this document.
    </t>
    <t>
      The content of the calendar collection is being shown as if it
      were returned by a CALDAV:calendar-query REPORT request
      designed to return all the calendar data in the collection:
    </t>
    <t>
            <figure>
            <preamble>&gt;&gt; Request &lt;&lt;</preamble>
              <artwork><![CDATA[
REPORT /bernard/work/ HTTP/1.1
Host: cal.example.com
Depth: 1
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-query xmlns:D="DAV:"
                 xmlns:C="urn:ietf:params:xml:ns:caldav">
 <D:prop>
   <D:getetag/>
   <C:calendar-data/>
 </D:prop>
 <C:filter>
   <C:comp-filter name="VCALENDAR">
     <C:allprop/>
     <C:allcomp/>
   </C:comp-filter> name="VCALENDAR"/>
 </C:filter>
</C:calendar-query>
        ]]></artwork>
      </figure>
      <figure>
        <preamble>&gt;&gt; Response &lt;&lt;</preamble>
        <artwork><![CDATA[
HTTP/1.1 207 Multi-Status
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx

<?xml version="1.0" encoding="utf-8" ?>
<D:multistatus xmlns:D="DAV:"
              xmlns:C="urn:ietf:params:xml:ns:caldav">

  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd1.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd1"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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:20060206T001102Z
DTSTART;TZID=US/Eastern:20060102T100000
DURATION:PT1H
SUMMARY:Event #1
Description:Go Steelers!
UID:74855313FA803DA593CD579A@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>

  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd2.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd2"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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
SUMMARY:Event #2
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:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>

  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd3.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd3"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV 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
ATTENDEE;PARTSTAT=ACCEPTED;ROLE=CHAIR:mailto:cyrus@example.com
ATTENDEE;PARTSTAT=NEEDS-ACTION:mailto:lisa@example.com
DTSTAMP:20060206T001220Z
DTSTART;TZID=US/Eastern:20060104T100000
DURATION:PT1H
LAST-MODIFIED:20060206T001330Z
ORGANIZER:mailto:cyrus@example.com
SEQUENCE:1
STATUS:TENTATIVE
SUMMARY:Event #3
UID:DC6C50A017428C5216A2F1CD@example.com
END:VEVENT
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>

  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd4.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd4"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235335Z
DUE;VALUE=DATE:20060104
STATUS:NEEDS-ACTION
SUMMARY:Task #1
UID:DDDEEB7915FA61233B861457@example.com
BEGIN:VALARM
ACTION:AUDIO
TRIGGER;RELATED=START:-PT10M
END:VALARM
END:VTODO
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>

  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd5.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd5"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235300Z
DUE;VALUE=DATE:20060106
LAST-MODIFIED:20060205T235308Z
SEQUENCE:1
STATUS:NEEDS-ACTION
SUMMARY:Task #2
UID:E10BA47467C5C69BB74E8720@example.com
BEGIN:VALARM
ACTION:AUDIO
TRIGGER;RELATED=START:-PT10M
END:VALARM
END:VTODO
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>

  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd6.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd6"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
COMPLETED:20051223T122322Z
DTSTAMP:20060205T235400Z
DUE;VALUE=DATE:20051225
LAST-MODIFIED:20060205T235308Z
SEQUENCE:1
STATUS:COMPLETED
SUMMARY:Task #3
UID:E10BA47467C5C69BB74E8722@example.com
END:VTODO
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>

  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd7.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd7"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VTODO
DTSTAMP:20060205T235600Z
DUE;VALUE=DATE:20060101
LAST-MODIFIED:20060205T235308Z
SEQUENCE:1
STATUS:CANCELLED
SUMMARY:Task #4
UID:E10BA47467C5C69BB74E8725@example.com
END:VTODO
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>

  <D:response>
    <D:href>http://cal.example.com/bernard/work/abcd8.ics</D:href>
    <D:propstat>
      <D:prop>
        <D:getetag>"fffff-abcd8"</D:getetag>
        <C:calendar-data>BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VFREEBUSY
ORGANIZER;CN="Bernard Desruisseaux":mailto:bernard@example.com
UID:76ef34-54a3d2@example.com
DTSTAMP:20050530T123421Z
DTSTART:20060101T000000Z
DTEND:20060108T000000Z
FREEBUSY:20050531T230000Z/20050601T010000Z
FREEBUSY;FBTYPE=BUSY-TENTATIVE:20060102T100000Z/20060102T120000Z
FREEBUSY:20060103T100000Z/20060103T120000Z
FREEBUSY:20060104T100000Z/20060104T120000Z
FREEBUSY;FBTYPE=BUSY-UNAVAILABLE:20060105T100000Z/20060105T120000Z
FREEBUSY:20060106T100000Z/20060106T120000Z
END:VFREEBUSY
END:VCALENDAR
</C:calendar-data>
      </D:prop>
      <D:status>HTTP/1.1 200 OK</D:status>
    </D:propstat>
  </D:response>

</D:multistatus>
              ]]></artwork>
            </figure>
    </t>
  <!-- Example calendar collections -->
  </section>
</back>
</rfc>