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+Network Working Group                                           C. Daboo
+Request for Comments: 4791                                         Apple
+Category: Standards Track                                B. Desruisseaux
+                                                                  Oracle
+                                                            L. Dusseault
+                                                             CommerceNet
+                                                              March 2007
+
+
+               Calendaring Extensions to WebDAV (CalDAV)
+
+Status of This Memo
+
+   This document specifies an Internet standards track protocol for the
+   Internet community, and requests discussion and suggestions for
+   improvements.  Please refer to the current edition of the "Internet
+   Official Protocol Standards" (STD 1) for the standardization state
+   and status of this protocol.  Distribution of this memo is unlimited.
+
+Copyright Notice
+
+   Copyright (C) The IETF Trust (2007).
+
+Abstract
+
+   This document defines extensions to the Web Distributed Authoring and
+   Versioning (WebDAV) protocol to specify a standard way of accessing,
+   managing, and sharing calendaring and scheduling information based on
+   the iCalendar format.  This document defines the "calendar-access"
+   feature of CalDAV.
+
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+Daboo, et al.               Standards Track                     [Page 1]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+Table of Contents
+
+   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
+     1.1.  Notational Conventions . . . . . . . . . . . . . . . . . .  5
+     1.2.  XML Namespaces and Processing  . . . . . . . . . . . . . .  5
+     1.3.  Method Preconditions and Postconditions  . . . . . . . . .  6
+   2.  Requirements Overview  . . . . . . . . . . . . . . . . . . . .  6
+   3.  Calendaring Data Model . . . . . . . . . . . . . . . . . . . .  7
+     3.1.  Calendar Server  . . . . . . . . . . . . . . . . . . . . .  7
+     3.2.  Recurrence and the Data Model  . . . . . . . . . . . . . .  8
+   4.  Calendar Resources . . . . . . . . . . . . . . . . . . . . . .  9
+     4.1.  Calendar Object Resources  . . . . . . . . . . . . . . . .  9
+     4.2.  Calendar Collection  . . . . . . . . . . . . . . . . . . . 10
+   5.  Calendar Access Feature  . . . . . . . . . . . . . . . . . . . 11
+     5.1.  Calendar Access Support  . . . . . . . . . . . . . . . . . 11
+       5.1.1.  Example: Using OPTIONS for the Discovery of
+               Calendar Access Support  . . . . . . . . . . . . . . . 12
+     5.2.  Calendar Collection Properties . . . . . . . . . . . . . . 12
+       5.2.1.  CALDAV:calendar-description Property . . . . . . . . . 12
+       5.2.2.  CALDAV:calendar-timezone Property  . . . . . . . . . . 13
+       5.2.3.  CALDAV:supported-calendar-component-set Property . . . 14
+       5.2.4.  CALDAV:supported-calendar-data Property  . . . . . . . 15
+       5.2.5.  CALDAV:max-resource-size Property  . . . . . . . . . . 16
+       5.2.6.  CALDAV:min-date-time Property  . . . . . . . . . . . . 17
+       5.2.7.  CALDAV:max-date-time Property  . . . . . . . . . . . . 18
+       5.2.8.  CALDAV:max-instances Property  . . . . . . . . . . . . 19
+       5.2.9.  CALDAV:max-attendees-per-instance Property . . . . . . 19
+       5.2.10. Additional Precondition for PROPPATCH  . . . . . . . . 20
+     5.3.  Creating Resources . . . . . . . . . . . . . . . . . . . . 20
+       5.3.1.  MKCALENDAR Method  . . . . . . . . . . . . . . . . . . 20
+         5.3.1.1.  Status Codes . . . . . . . . . . . . . . . . . . . 22
+         5.3.1.2.  Example: Successful MKCALENDAR Request . . . . . . 23
+       5.3.2.  Creating Calendar Object Resources . . . . . . . . . . 25
+         5.3.2.1.  Additional Preconditions for PUT, COPY, and
+                   MOVE . . . . . . . . . . . . . . . . . . . . . . . 26
+       5.3.3.  Non-Standard Components, Properties, and Parameters  . 28
+       5.3.4.  Calendar Object Resource Entity Tag  . . . . . . . . . 28
+   6.  Calendaring Access Control . . . . . . . . . . . . . . . . . . 29
+     6.1.  Calendaring Privilege  . . . . . . . . . . . . . . . . . . 29
+       6.1.1.  CALDAV:read-free-busy Privilege  . . . . . . . . . . . 29
+     6.2.  Additional Principal Property  . . . . . . . . . . . . . . 30
+       6.2.1.  CALDAV:calendar-home-set Property  . . . . . . . . . . 30
+   7.  Calendaring Reports  . . . . . . . . . . . . . . . . . . . . . 31
+     7.1.  REPORT Method  . . . . . . . . . . . . . . . . . . . . . . 31
+     7.2.  Ordinary Collections . . . . . . . . . . . . . . . . . . . 31
+     7.3.  Date and Floating Time . . . . . . . . . . . . . . . . . . 32
+     7.4.  Time Range Filtering . . . . . . . . . . . . . . . . . . . 32
+     7.5.  Searching Text: Collations . . . . . . . . . . . . . . . . 33
+
+
+
+Daboo, et al.               Standards Track                     [Page 2]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+       7.5.1.  CALDAV:supported-collation-set Property  . . . . . . . 34
+     7.6.  Partial Retrieval  . . . . . . . . . . . . . . . . . . . . 34
+     7.7.  Non-Standard Components, Properties, and Parameters  . . . 35
+     7.8.  CALDAV:calendar-query REPORT . . . . . . . . . . . . . . . 36
+       7.8.1.  Example: Partial Retrieval of Events by Time Range . . 38
+       7.8.2.  Example: Partial Retrieval of Recurring Events . . . . 42
+       7.8.3.  Example: Expanded Retrieval of Recurring Events  . . . 45
+       7.8.4.  Example: Partial Retrieval of Stored Free Busy
+               Components . . . . . . . . . . . . . . . . . . . . . . 48
+       7.8.5.  Example: Retrieval of To-Dos by Alarm Time Range . . . 50
+       7.8.6.  Example: Retrieval of Event by UID . . . . . . . . . . 51
+       7.8.7.  Example: Retrieval of Events by PARTSTAT . . . . . . . 53
+       7.8.8.  Example: Retrieval of Events Only  . . . . . . . . . . 55
+       7.8.9.  Example: Retrieval of All Pending To-Dos . . . . . . . 59
+       7.8.10. Example: Attempt to Query Unsupported Property . . . . 62
+     7.9.  CALDAV:calendar-multiget REPORT  . . . . . . . . . . . . . 63
+       7.9.1.  Example: Successful CALDAV:calendar-multiget REPORT  . 64
+     7.10. CALDAV:free-busy-query REPORT  . . . . . . . . . . . . . . 66
+       7.10.1. Example: Successful CALDAV:free-busy-query REPORT  . . 68
+   8.  Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . 69
+     8.1.  Client-to-Client Interoperability  . . . . . . . . . . . . 69
+     8.2.  Synchronization Operations . . . . . . . . . . . . . . . . 69
+       8.2.1.  Use of Reports . . . . . . . . . . . . . . . . . . . . 69
+         8.2.1.1.  Restrict the Time Range  . . . . . . . . . . . . . 69
+         8.2.1.2.  Synchronize by Time Range  . . . . . . . . . . . . 70
+         8.2.1.3.  Synchronization Process  . . . . . . . . . . . . . 70
+       8.2.2.  Restrict the Properties Returned . . . . . . . . . . . 72
+     8.3.  Use of Locking . . . . . . . . . . . . . . . . . . . . . . 72
+     8.4.  Finding Calendars  . . . . . . . . . . . . . . . . . . . . 72
+     8.5.  Storing and Using Attachments  . . . . . . . . . . . . . . 74
+       8.5.1.  Inline Attachments . . . . . . . . . . . . . . . . . . 74
+       8.5.2.  External Attachments . . . . . . . . . . . . . . . . . 75
+     8.6.  Storing and Using Alarms . . . . . . . . . . . . . . . . . 76
+   9.  XML Element Definitions  . . . . . . . . . . . . . . . . . . . 77
+     9.1.  CALDAV:calendar XML Element  . . . . . . . . . . . . . . . 77
+     9.2.  CALDAV:mkcalendar XML Element  . . . . . . . . . . . . . . 77
+     9.3.  CALDAV:mkcalendar-response XML Element . . . . . . . . . . 78
+     9.4.  CALDAV:supported-collation XML Element . . . . . . . . . . 78
+     9.5.  CALDAV:calendar-query XML Element  . . . . . . . . . . . . 78
+     9.6.  CALDAV:calendar-data XML Element . . . . . . . . . . . . . 79
+       9.6.1.  CALDAV:comp XML Element  . . . . . . . . . . . . . . . 80
+       9.6.2.  CALDAV:allcomp XML Element . . . . . . . . . . . . . . 81
+       9.6.3.  CALDAV:allprop XML Element . . . . . . . . . . . . . . 81
+       9.6.4.  CALDAV:prop XML Element  . . . . . . . . . . . . . . . 82
+       9.6.5.  CALDAV:expand XML Element  . . . . . . . . . . . . . . 82
+       9.6.6.  CALDAV:limit-recurrence-set XML Element  . . . . . . . 83
+       9.6.7.  CALDAV:limit-freebusy-set XML Element  . . . . . . . . 84
+     9.7.  CALDAV:filter XML Element  . . . . . . . . . . . . . . . . 85
+
+
+
+Daboo, et al.               Standards Track                     [Page 3]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+       9.7.1.  CALDAV:comp-filter XML Element . . . . . . . . . . . . 85
+       9.7.2.  CALDAV:prop-filter XML Element . . . . . . . . . . . . 86
+       9.7.3.  CALDAV:param-filter XML Element  . . . . . . . . . . . 87
+       9.7.4.  CALDAV:is-not-defined XML Element  . . . . . . . . . . 88
+       9.7.5.  CALDAV:text-match XML Element  . . . . . . . . . . . . 88
+     9.8.  CALDAV:timezone XML Element  . . . . . . . . . . . . . . . 89
+     9.9.  CALDAV:time-range XML Element  . . . . . . . . . . . . . . 90
+     9.10. CALDAV:calendar-multiget XML Element . . . . . . . . . . . 94
+     9.11. CALDAV:free-busy-query XML Element . . . . . . . . . . . . 95
+   10. Internationalization Considerations  . . . . . . . . . . . . . 95
+   11. Security Considerations  . . . . . . . . . . . . . . . . . . . 95
+   12. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 96
+     12.1. Namespace Registration . . . . . . . . . . . . . . . . . . 96
+   13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 96
+   14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 97
+     14.1. Normative References . . . . . . . . . . . . . . . . . . . 97
+     14.2. Informative References . . . . . . . . . . . . . . . . . . 98
+   Appendix A.  CalDAV Method Privilege Table (Normative) . . . . . . 99
+   Appendix B.  Calendar Collections Used in the Examples . . . . . . 99
+
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+Daboo, et al.               Standards Track                     [Page 4]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+1.  Introduction
+
+   The concept of using HTTP [RFC2616] and WebDAV [RFC2518] 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 iCalendar [RFC2445] 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.
+
+1.1.  Notational Conventions
+
+   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
+   document are to be interpreted as described in [RFC2119].
+
+   The term "protected" is used in the Conformance field of property
+   definitions as defined in Section 1.4.2 of [RFC3253].
+
+   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.
+
+1.2.  XML Namespaces and Processing
+
+   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 [W3C.REC-xml-20060816].
+
+   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.
+
+   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 CalDAV
+   XML element types.  Some of the declarations refer to XML elements
+   defined by WebDAV [RFC2518], which use the "DAV:" namespace.
+   Wherever such XML elements appear, they are explicitly prefixed with
+   "DAV:" to avoid confusion.
+
+
+
+Daboo, et al.               Standards Track                     [Page 5]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+   Processing of XML by CalDAV clients and servers MUST follow the rules
+   described in [RFC2518]; in particular, Section 14, and Appendix 3 of
+   that specification.
+
+1.3.  Method Preconditions and Postconditions
+
+   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.
+
+   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.
+
+2.  Requirements Overview
+
+   This section lists what functionality is required of a CalDAV server.
+   To advertise support for CalDAV, a server:
+
+   o  MUST support iCalendar [RFC2445] as a media type for the calendar
+      object resource format;
+
+   o  MUST support WebDAV Class 1 [RFC2518] (note that [rfc2518bis]
+      describes clarifications to [RFC2518] that aid interoperability);
+
+   o  MUST support WebDAV ACL [RFC3744] with the additional privilege
+      defined in Section 6.1 of this document;
+
+   o  MUST support transport over TLS [RFC2246] as defined in [RFC2818]
+      (note that [RFC2246] has been obsoleted by [RFC4346]);
+
+   o  MUST support ETags [RFC2616] with additional requirements
+      specified in Section 5.3.4 of this document;
+
+
+
+
+Daboo, et al.               Standards Track                     [Page 6]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   o  MUST support all calendaring reports defined in Section 7 of this
+      document; and
+
+   o  MUST advertise support on all calendar collections and calendar
+      object resources for the calendaring reports in the DAV:supported-
+      report-set property, as defined in Versioning Extensions to WebDAV
+      [RFC3253].
+
+   In addition, a server:
+
+   o  SHOULD support the MKCALENDAR method defined in Section 5.3.1 of
+      this document.
+
+3.  Calendaring Data Model
+
+   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.
+
+   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 Section 4.1 and Section 4.2.
+
+3.1.  Calendar Server
+
+   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).
+
+   A WebDAV repository MAY include calendar data in some parts of its
+   URL namespace, and non-calendaring data in other parts.
+
+   A WebDAV repository can advertise itself as a CalDAV server if it
+   supports the functionality defined in this specification at any point
+
+
+
+Daboo, et al.               Standards Track                     [Page 7]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+   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.
+
+3.2.  Recurrence and the Data Model
+
+   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.
+
+   Clients are not forced to retrieve information about all recurrence
+   instances of a recurring component.  The CALDAV:calendar-query and
+   CALDAV:calendar-multiget reports defined in this document allow
+   clients to retrieve only recurrence instances that overlap a given
+   time range.
+
+
+
+
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+
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+Daboo, et al.               Standards Track                     [Page 8]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+4.  Calendar Resources
+
+4.1.  Calendar Object Resources
+
+   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 one VEVENT 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.
+
+   Calendar object resources contained in calendar collections MUST NOT
+   specify the iCalendar METHOD property.
+
+   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.
+
+   Calendar components in a calendar collection that have different UID
+   property values MUST be stored in separate calendar object resources.
+
+   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).
+
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+Daboo, et al.               Standards Track                     [Page 9]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   For example, given the following iCalendar object:
+
+   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
+
+   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.
+
+4.2.  Calendar Collection
+
+   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:
+
+       <!ELEMENT calendar EMPTY>
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 10]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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 Section 5.3.1).  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 Section 5.2.1
+   to provide such a cue.
+
+   The following restrictions are applied to the resources within a
+   calendar collection:
+
+   a.  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.
+
+   b.  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.
+
+   Multiple calendar collections MAY be children of the same collection.
+
+5.  Calendar Access Feature
+
+5.1.  Calendar Access Support
+
+   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.
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 11]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+5.1.1.  Example: Using OPTIONS for the Discovery of Calendar Access
+        Support
+
+   >> Request <<
+
+   OPTIONS /home/bernard/calendars/ HTTP/1.1
+   Host: cal.example.com
+
+   >> Response <<
+
+   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, access-control, calendar-access
+   Date: Sat, 11 Nov 2006 09:32:12 GMT
+   Content-Length: 0
+
+   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, method,
+   or privilege defined in this specification.
+
+5.2.  Calendar Collection Properties
+
+   This section defines properties for calendar collections.
+
+5.2.1.  CALDAV:calendar-description Property
+
+   Name:  calendar-description
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Provides a human-readable description of the calendar
+      collection.
+
+   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 [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.
+
+   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.
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 12]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   Definition:
+
+         <!ELEMENT calendar-description (#PCDATA)>
+         PCDATA value: string
+
+   Example:
+
+         <C:calendar-description xml:lang="fr-CA"
+            xmlns:C="urn:ietf:params:xml:ns:caldav"
+         >Calendrier de Mathilde Desruisseaux</C:calendar-description>
+
+5.2.2.  CALDAV:calendar-timezone Property
+
+   Name:  calendar-timezone
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies a time zone on a calendar collection.
+
+   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 [RFC2518]).
+
+   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.
+
+   Note:  The iCalendar data embedded within the CALDAV:calendar-
+      timezone XML element MUST follow the standard XML character data
+      encoding rules, including use of &lt;, &gt;, &amp; etc. entity
+      encoding or the use of a <![CDATA[ ... ]]> construct.  In the
+      later case, the iCalendar data cannot contain the character
+      sequence "]]>", which is the end delimiter for the CDATA section.
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 13]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   Definition:
+
+         <!ELEMENT calendar-timezone (#PCDATA)>
+         PCDATA value: an iCalendar object with exactly one VTIMEZONE
+               component.
+
+   Example:
+
+   <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>
+
+5.2.3.  CALDAV:supported-calendar-component-set Property
+
+   Name:  supported-calendar-component-set
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies the calendar component types (e.g., VEVENT,
+      VTODO, etc.) that calendar object resources can contain in the
+      calendar collection.
+
+   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 [RFC2518]).
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 14]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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 (Section 5.3.2.1) 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 <C:comp name="VTIMEZONE"/> 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 all component types are accepted.
+
+   Definition:
+
+         <!ELEMENT supported-calendar-component-set (comp+)>
+
+   Example:
+
+         <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>
+
+5.2.4.  CALDAV:supported-calendar-data Property
+
+   Name:  supported-calendar-data
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies what media types are allowed for calendar object
+      resources in a calendar collection.
+
+   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 [RFC2518]).
+
+   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
+
+
+
+Daboo, et al.               Standards Track                    [Page 15]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      resources with a media type not listed in this property MUST
+      result in an error, with the CALDAV:supported-calendar-data
+      precondition (Section 5.3.2.1) 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.
+
+   Definition:
+
+         <!ELEMENT supported-calendar-data (calendar-data+)>
+
+   Example:
+
+         <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>
+
+5.2.5.  CALDAV:max-resource-size Property
+
+   Name:  max-resource-size
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   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.
+
+   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 [RFC2518]).
+
+   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 (Section 5.3.2.1) being
+      violated.  In the absence of this property, the client can assume
+      that the server will allow storing a resource of any reasonable
+      size.
+
+   Definition:
+
+         <!ELEMENT max-resource-size (#PCDATA)>
+         PCDATA value: a numeric value (positive integer)
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 16]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   Example:
+
+         <C:max-resource-size xmlns:C="urn:ietf:params:xml:ns:caldav"
+         >102400</C:max-resource-size>
+
+5.2.6.  CALDAV:min-date-time Property
+
+   Name:  min-date-time
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Provides a DATE-TIME value indicating the earliest date and
+      time (in UTC) that the server is willing to accept for any DATE or
+      DATE-TIME value in a calendar object resource stored in a calendar
+      collection.
+
+   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 [RFC2518]).
+
+   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 or DATE-TIME value in a calendar object resource
+      stored in a calendar collection.  Any attempt to store a calendar
+      object resource using a DATE or DATE-TIME value earlier than this
+      value MUST result in an error, with the CALDAV:min-date-time
+      precondition (Section 5.3.2.1) 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 up to the
+      CALDAV:max-date-time value, if that is defined.
+
+   Definition:
+
+         <!ELEMENT min-date-time (#PCDATA)>
+         PCDATA value: an iCalendar format DATE-TIME value in UTC
+
+   Example:
+
+         <C:min-date-time xmlns:C="urn:ietf:params:xml:ns:caldav"
+         >19000101T000000Z</C:min-date-time>
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 17]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+5.2.7.  CALDAV:max-date-time Property
+
+   Name:  max-date-time
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Provides a DATE-TIME value indicating the latest date and
+      time (in UTC) that the server is willing to accept for any DATE or
+      DATE-TIME value in a calendar object resource stored in a calendar
+      collection.
+
+   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 [RFC2518]).
+
+   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 or DATE-TIME value later than this value MUST result in an
+      error, with the CALDAV:max-date-time precondition
+      (Section 5.3.2.1) 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.
+
+   Definition:
+
+         <!ELEMENT max-date-time (#PCDATA)>
+         PCDATA value: an iCalendar format DATE-TIME value in UTC
+
+   Example:
+
+         <C:max-date-time xmlns:C="urn:ietf:params:xml:ns:caldav"
+         >20491231T235959Z</C:max-date-time>
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 18]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+5.2.8.  CALDAV:max-instances Property
+
+   Name:  max-instances
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Provides a numeric value indicating the maximum number of
+      recurrence instances that a calendar object resource stored in a
+      calendar collection can generate.
+
+   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 [RFC2518]).
+
+   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 (Section 5.3.2.1) 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.
+
+   Definition:
+
+         <!ELEMENT max-instances (#PCDATA)>
+         PCDATA value: a numeric value (integer greater than zero)
+
+   Example:
+
+         <C:max-instances xmlns:C="urn:ietf:params:xml:ns:caldav"
+         >100</C:max-instances>
+
+5.2.9.  CALDAV:max-attendees-per-instance Property
+
+   Name:  max-attendees-per-instance
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   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.
+
+   Conformance:  This property MAY be defined on any calendar
+      collection.  If defined, it MUST be protected and SHOULD NOT be
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 19]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      returned by a PROPFIND DAV:allprop request (as defined in Section
+      12.14.1 of [RFC2518]).
+
+   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 (Section 5.3.2.1) 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.
+
+   Definition:
+
+         <!ELEMENT max-attendees-per-instance (#PCDATA)>
+         PCDATA value: a numeric value (integer greater than zero)
+
+   Example:
+
+         <C:max-attendees-per-instance
+              xmlns:C="urn:ietf:params:xml:ns:caldav"
+         >25</C:max-attendees-per-instance>
+
+5.2.10.  Additional Precondition for PROPPATCH
+
+   This specification requires an additional Precondition for the
+   PROPPATCH method.  The precondition is:
+
+      (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.
+
+5.3.  Creating Resources
+
+   Calendar collections and calendar object resources may be created by
+   either a CalDAV client or by the CalDAV server.  This specification
+   defines restrictions and a data model that both clients and servers
+   MUST adhere to when manipulating such calendar data.
+
+5.3.1.  MKCALENDAR Method
+
+   An HTTP request using the MKCALENDAR method creates a new calendar
+   collection resource.  A server MAY restrict calendar collection
+   creation to particular collections.
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 20]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+   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.
+
+   If a MKCALENDAR request fails, the server state preceding the request
+   MUST be restored.
+
+   Marshalling:
+      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 [RFC2518].
+
+         <!ELEMENT mkcalendar (DAV:set)>
+
+      If a response body for a successful request is included, it MUST
+      be a CALDAV:mkcalendar-response XML element.
+
+         <!ELEMENT mkcalendar-response ANY>
+
+      The response MUST include a Cache-Control:no-cache header.
+
+   Preconditions:
+
+      (DAV:resource-must-be-null): A resource MUST NOT exist at the
+      Request-URI;
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 21]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      (CALDAV:calendar-collection-location-ok): The Request-URI MUST
+      identify a location where a calendar collection can be created;
+
+      (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;
+
+      (DAV:needs-privilege): The DAV:bind privilege MUST be granted to
+      the current user on the parent collection of the Request-URI.
+
+   Postconditions:
+
+      (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.
+
+5.3.1.1.  Status Codes
+
+   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.
+
+      201 (Created) - The calendar collection resource was created in
+      its entirety;
+
+      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:
+
+         403 (Forbidden) - The client, for reasons the server chooses
+         not to specify, cannot alter one of the properties;
+
+         409 (Conflict) - The client has provided a value whose
+         semantics are not appropriate for the property.  This includes
+         trying to set read-only properties;
+
+         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;
+
+         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
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 22]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+         507 (Insufficient Storage) - The server did not have sufficient
+         space to record the property;
+
+      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;
+
+      409 (Conflict) - A collection cannot be made at the Request-URI
+      until one or more intermediate collections have been created;
+
+      415 (Unsupported Media Type) - The server does not support the
+      request type of the body; and
+
+      507 (Insufficient Storage) - The resource does not have sufficient
+      space to record the state of the resource after the execution of
+      this method.
+
+5.3.1.2.  Example: Successful MKCALENDAR Request
+
+   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.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 23]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   >> Request <<
+
+   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><![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
+   ]]></C:calendar-timezone>
+       </D:prop>
+     </D:set>
+   </C:mkcalendar>
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 24]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   >> Response <<
+
+   HTTP/1.1 201 Created
+   Cache-Control: no-cache
+   Date: Sat, 11 Nov 2006 09:32:12 GMT
+   Content-Length: 0
+
+5.3.2.  Creating Calendar Object Resources
+
+   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.
+
+   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.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 25]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   >> Request <<
+
+   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
+
+   >> Response <<
+
+   HTTP/1.1 201 Created
+   Content-Length: 0
+   Date: Sat, 11 Nov 2006 09:32:12 GMT
+   ETag: "123456789-000-111"
+
+   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.
+
+   As indicated in Section 3.10 of [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".
+
+5.3.2.1.  Additional Preconditions for PUT, COPY, and MOVE
+
+   This specification creates additional Preconditions for PUT, COPY,
+   and MOVE methods.  These preconditions apply when a PUT operation of
+   a calendar object resource into a calendar collection occurs, or when
+   a COPY or MOVE operation of a calendar object resource into a
+   calendar collection occurs, or when a COPY or MOVE operation occurs
+   on a calendar collection.
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 26]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   The new preconditions are:
+
+      (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;
+
+      (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);
+
+      (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 Section 4.1 (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.);
+
+      (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;
+
+      (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;
+
+                <!ELEMENT no-uid-conflict (DAV:href)>
+
+      (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;
+
+      (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 (Section 5.2.5) on the calendar collection
+      where the resource will be stored;
+
+      (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 or DATE-TIME property values (for each recurring
+
+
+
+Daboo, et al.               Standards Track                    [Page 27]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      instance) greater than or equal to the value of the CALDAV:min-
+      date-time property value (Section 5.2.6) on the calendar
+      collection where the resource will be stored;
+
+      (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 or DATE-TIME property values (for each recurring
+      instance) less than the value of the CALDAV:max-date-time property
+      value (Section 5.2.7) on the calendar collection where the
+      resource will be stored;
+
+      (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 (Section 5.2.8) on the calendar
+      collection where the resource will be stored;
+
+      (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 (Section 5.2.9) on the calendar collection where
+      the resource will be stored;
+
+5.3.3.  Non-Standard Components, Properties, and Parameters
+
+   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-".
+
+   Servers MUST support the use of non-standard components, properties,
+   and parameters in calendar object resources stored via the PUT
+   method.
+
+   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 [RFC2445], e.g., "X-ABC-PRIVATE".
+
+5.3.4.  Calendar Object Resource Entity Tag
+
+   The DAV:getetag property MUST be defined and set to a strong entity
+   tag on all calendar object resources.
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 28]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+   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.
+
+   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.
+
+6.  Calendaring Access Control
+
+6.1.  Calendaring Privilege
+
+   CalDAV servers MUST support and adhere to the requirements of WebDAV
+   ACL [RFC3744].  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.
+
+6.1.1.  CALDAV:read-free-busy Privilege
+
+   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.
+
+   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 Section 7.10).  This privilege can be granted on calendar
+   collections, regular collections, or calendar object resources.
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 29]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   Servers MUST support this privilege on all calendar collections,
+   regular collections, and calendar object resources.
+
+
+           <!ELEMENT read-free-busy EMPTY>
+
+   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.
+
+   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 implied (those
+   operations are governed by the DAV:read privilege).
+
+6.2.  Additional Principal Property
+
+   This section defines an additional property for WebDAV principal
+   resources, as defined in [RFC3744].
+
+6.2.1.  CALDAV:calendar-home-set Property
+
+   Name:  calendar-home-set
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Identifies the URL of any WebDAV collections that contain
+      calendar collections owned by the associated principal resource.
+
+   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 [RFC2518]).
+
+   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.
+
+   Definition:
+
+         <!ELEMENT calendar-home-set (DAV:href*)>
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 30]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   Example:
+
+       <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>
+
+7.  Calendaring Reports
+
+   This section defines the reports that CalDAV servers MUST support on
+   calendar collections and calendar object resources.
+
+   CalDAV servers MUST advertise support for these reports on all
+   calendar collections and calendar object resources with the DAV:
+   supported-report-set property, defined in Section 3.1.5 of [RFC3253].
+   CalDAV servers MAY also advertise support for these reports on
+   ordinary collections.
+
+   Some of these reports allow calendar data (from possibly multiple
+   resources) to be returned.
+
+7.1.  REPORT Method
+
+   The REPORT method (defined in Section 3.6 of [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.
+
+   CalDAV servers MUST support the DAV:expand-property REPORT defined in
+   Section 3.8 of [RFC3253].
+
+7.2.  Ordinary Collections
+
+   Servers MAY support the 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 on ordinary collections, servers
+   MUST only consider calendar object resources contained in calendar
+   collections that are targeted by the REPORT request, based on the
+   value of the Depth request header.
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 31]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+7.3.  Date and Floating Time
+
+   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.
+
+   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.
+
+   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.
+
+   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.
+
+7.4.  Time Range Filtering
+
+   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 or DATE-TIME
+   value types.
+
+   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 [RFC2445] for determining the actual start and
+   end times of calendar components MUST be used, and these are fully
+   enumerated in Section 9.9 of this document.
+
+
+
+Daboo, et al.               Standards Track                    [Page 32]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+7.5.  Searching Text: Collations
+
+   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.
+
+   To deal with this, this specification makes use of the IANA Collation
+   Registry defined in [RFC4790] to specify collations that may be used
+   to carry out the text comparison operations with a well-defined rule.
+
+   The comparisons used in CalDAV are all "substring" matches, as per
+   [RFC4790], Section 4.2.  Collations supported by the server MUST
+   support "substring" match operations.
+
+   CalDAV servers are REQUIRED to support the "i;ascii-casemap" and
+   "i;octet" collations, as described in [RFC4790], and MAY support
+   other collations.
+
+   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.
+
+   Clients MUST only use collations from the list advertised by the
+   server.
+
+   In the absence of a collation explicitly specified by the client, or
+   if the client specifies the "default" collation identifier (as
+   defined in [RFC4790], Section 3.1), the server MUST default to using
+   "i;ascii-casemap" as the collation.
+
+   Wildcards (as defined in [RFC4790], Section 3.2) MUST NOT be used in
+   the collation identifier.
+
+   If the client chooses a collation not supported by the server, the
+   server MUST respond with a CALDAV:supported-collation precondition
+   error response.
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 33]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+7.5.1.  CALDAV:supported-collation-set Property
+
+   Name:  supported-collation-set
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Identifies the set of collations supported by the server
+      for text matching operations.
+
+   Conformance:  This property MUST be defined on any resource that
+      supports a 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 [RFC2518]).
+
+   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.
+
+   Definition:
+
+         <!ELEMENT supported-collation-set (supported-collation*)>
+
+         <!ELEMENT supported-collation (#PCDATA)>
+
+   Example:
+
+       <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>
+
+7.6.  Partial Retrieval
+
+   Some calendaring 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.
+
+   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 Section 9.6.
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 34]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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".
+
+   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 Section 9.6.6).  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.
+
+   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 Section 9.6.5.)
+
+   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
+   Section 9.6.7.)
+
+7.7.  Non-Standard Components, Properties, and Parameters
+
+   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.
+
+   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.
+
+   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.
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 35]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+7.8.  CALDAV:calendar-query REPORT
+
+   The CALDAV:calendar-query REPORT performs a search for all calendar
+   object resources that match a specified filter.  The response of this
+   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.
+
+   The format of this 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.
+
+   Support for the CALDAV:calendar-query REPORT is REQUIRED.
+
+   Marshalling:
+
+      The request body MUST be a CALDAV:calendar-query XML element, as
+      defined in Section 9.5.
+
+      The request MAY include a Depth header.  If no Depth header is
+      included, Depth:0 is assumed.
+
+      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.
+
+      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.
+
+   Preconditions:
+
+      (CALDAV:supported-calendar-data): The attributes "content-type"
+      and "version" of the CALDAV:calendar-data XML element (see
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 36]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      Section 9.6) specify a media type supported by the server for
+      calendar object resources.
+
+      (CALDAV:valid-filter): The CALDAV:filter XML element (see
+      Section 9.7) specified in the REPORT request MUST be valid.  For
+      instance, a CALDAV:filter cannot nest a <C:comp name="VEVENT">
+      element in a <C:comp name="VTODO"> element, and a CALDAV:filter
+      cannot nest a <C:time-range start="..." end="..."> element in a
+      <C:prop name="SUMMARY"> element.
+
+      (CALDAV:supported-filter): The CALDAV:comp-filter (see
+      Section 9.7.1), CALDAV:prop-filter (see Section 9.7.2), and
+      CALDAV:param-filter (see Section 9.7.3) XML elements used in the
+      CALDAV:filter XML element (see Section 9.7) 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.
+
+            <!ELEMENT supported-filter (comp-filter*,
+                                        prop-filter*,
+                                        param-filter*)>
+
+      (CALDAV:valid-calendar-data): The time zone specified in the
+      REPORT request MUST be a valid iCalendar object containing a
+      single valid VTIMEZONE component.
+
+      (CALDAV:min-date-time): Any XML element specifying a range of time
+      MUST have its start or end DATE or DATE-TIME values greater than
+      or equal to the value of the CALDAV:min-date-time property value
+      (Section 5.2.6) on the calendar collections being targeted by the
+      REPORT request;
+
+      (CALDAV:max-date-time): Any XML element specifying a range of time
+      MUST have its start or end DATE or DATE-TIME values less than or
+      equal to the value of the CALDAV:max-date-time property value
+      (Section 5.2.7) on the calendar collections being targeted by the
+      REPORT request;
+
+      (CALDAV:supported-collation): Any XML attribute specifying a
+      collation MUST specify a collation supported by the server as
+      described in Section 7.5.
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 37]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   Postconditions:
+
+      (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.
+
+7.8.1.  Example: Partial Retrieval of Events by Time Range
+
+   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.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 38]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   >> Request <<
+
+   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>
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Date: Sat, 11 Nov 2006 09:32:12 GMT
+   Content-Type: application/xml; charset="utf-8"
+   Content-Length: xxxx
+
+
+
+Daboo, et al.               Standards Track                    [Page 39]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   <?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
+
+
+
+Daboo, et al.               Standards Track                    [Page 40]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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>
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 41]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+7.8.2.  Example: Partial Retrieval of Recurring Events
+
+   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.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+   >> Request <<
+
+   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>
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Date: Sat, 11 Nov 2006 09:32:12 GMT
+   Content-Type: application/xml; charset="utf-8"
+   Content-Length: xxxx
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 42]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   <?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>
+
+
+
+Daboo, et al.               Standards Track                    [Page 43]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+         <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>
+
+
+
+Daboo, et al.               Standards Track                    [Page 44]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+     </D:response>
+   </D:multistatus>
+
+7.8.3.  Example: Expanded Retrieval of Recurring Events
+
+   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.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+   >> Request <<
+
+   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>
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Date: Sat, 11 Nov 2006 09:32:12 GMT
+   Content-Type: application/xml; charset="utf-8"
+   Content-Length: xxxx
+
+
+
+Daboo, et al.               Standards Track                    [Page 45]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   <?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
+
+
+
+Daboo, et al.               Standards Track                    [Page 46]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 47]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+7.8.4.  Example: Partial Retrieval of Stored Free Busy Components
+
+   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.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+   >> Request <<
+
+   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>
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 48]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Date: 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>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 49]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+7.8.5.  Example: Retrieval of To-Dos by Alarm Time Range
+
+   In this example, the client requests the server to return the VTODO
+   components that have an alarm trigger scheduled in the specified time
+   range.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+   >> Request <<
+
+   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>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 50]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Date: 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>
+
+7.8.6.  Example: Retrieval of Event by UID
+
+   In this example, the client requests the server to return the VEVENT
+   component that has the UID property set to
+   "DC6C50A017428C5216A2F1CD@example.com".
+
+   See Appendix B for the calendar data being targeted by this example.
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 51]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   >> Request <<
+
+   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>
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Date: 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
+
+
+
+Daboo, et al.               Standards Track                    [Page 52]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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>
+
+7.8.7.  Example: Retrieval of Events by PARTSTAT
+
+   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.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 53]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   >> Request <<
+
+   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>
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Date: 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
+
+
+
+Daboo, et al.               Standards Track                    [Page 54]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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>
+
+7.8.8.  Example: Retrieval of Events Only
+
+   In this example, the client requests the server to return all VEVENT
+   components.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 55]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   >> Request <<
+
+   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>
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Date: 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
+
+
+
+Daboo, et al.               Standards Track                    [Page 56]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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
+
+
+
+Daboo, et al.               Standards Track                    [Page 57]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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
+
+
+
+Daboo, et al.               Standards Track                    [Page 58]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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>
+
+7.8.9.  Example: Retrieval of All Pending To-Dos
+
+   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.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 59]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   >> Request <<
+
+   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>
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Date: 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
+
+
+
+Daboo, et al.               Standards Track                    [Page 60]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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>
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 61]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+7.8.10.  Example: Attempt to Query Unsupported Property
+
+   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.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+   >> Request <<
+
+   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>
+
+   >> Response <<
+
+   HTTP/1.1 403 Forbidden
+   Date: 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>
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 62]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+7.9.  CALDAV:calendar-multiget REPORT
+
+   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 is similar to the CALDAV:calendar-query REPORT (see
+   Section 7.8), except that it takes a list of DAV:href elements,
+   instead of a CALDAV:filter element, to determine which calendar
+   object resources to return.
+
+   Support for the CALDAV:calendar-multiget REPORT is REQUIRED.
+
+   Marshalling:
+
+      The request body MUST be a CALDAV:calendar-multiget XML element
+      (see Section 9.10).  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.
+
+      The response body for a successful request MUST be a DAV:
+      multistatus XML element.
+
+      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.
+
+      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.
+
+   Preconditions:
+
+      (CALDAV:supported-calendar-data): The attributes "content-type"
+      and "version" of the CALDAV:calendar-data XML elements (see
+      Section 9.6) specify a media type supported by the server for
+      calendar object resources.
+
+      (CALDAV:min-date-time): Any XML element specifying a range of time
+      MUST have its start or end DATE or DATE-TIME values greater than
+
+
+
+Daboo, et al.               Standards Track                    [Page 63]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      or equal to the value of the CALDAV:min-date-time property value
+      (Section 5.2.6) on the calendar collections being targeted by the
+      REPORT request;
+
+      (CALDAV:max-date-time): Any XML element specifying a range of time
+      MUST have its start or end DATE or DATE-TIME values less than or
+      equal to the value of the CALDAV:max-date-time property value
+      (Section 5.2.7) on the calendar collections being targeted by the
+      REPORT request;
+
+   Postconditions:
+
+      None.
+
+7.9.1.  Example: Successful CALDAV:calendar-multiget REPORT
+
+   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.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+   >> Request <<
+
+   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>
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Date: Sat, 11 Nov 2006 09:32:12 GMT
+   Content-Type: application/xml; charset="utf-8"
+
+
+
+Daboo, et al.               Standards Track                    [Page 64]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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>
+
+
+
+Daboo, et al.               Standards Track                    [Page 65]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+     </D:response>
+   </D:multistatus>
+
+7.10.  CALDAV:free-busy-query REPORT
+
+   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.
+
+   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.
+
+   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:
+
+         +---------------------------++------------------+
+         |          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      ||                  |
+         +-------------+-------------++------------------+
+
+   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.
+
+   Support for the CALDAV:free-busy-query REPORT is REQUIRED.
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 66]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   Marshalling:
+
+      The request body MUST be a CALDAV:free-busy-query XML element (see
+      Section 9.11), which MUST contain exactly one CALDAV:time-range
+      XML element, as defined in Section 9.9.
+
+      The request MAY include a Depth header.  If no Depth header is
+      included, Depth:0 is assumed.
+
+      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
+      only returns busy time information.  Free time information can be
+      inferred from the returned busy time information.
+
+      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.
+
+      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.
+
+   Preconditions:
+
+      None.
+
+   Postconditions:
+
+      (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.
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 67]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+7.10.1.  Example: Successful CALDAV:free-busy-query REPORT
+
+   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.
+
+   See Appendix B for the calendar data being targeted by this example.
+
+   >> Request <<
+
+   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>
+
+   >> Response <<
+
+   HTTP/1.1 200 OK
+   Date: 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
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 68]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+8.  Guidelines
+
+8.1.  Client-to-Client Interoperability
+
+   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.
+
+8.2.  Synchronization Operations
+
+   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 Section 5.3.4.
+
+8.2.1.  Use of Reports
+
+8.2.1.1.  Restrict the Time Range
+
+   The 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.
+
+   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.
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 69]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+8.2.1.2.  Synchronize by Time Range
+
+   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.
+
+8.2.1.3.  Synchronization Process
+
+   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.
+
+   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.
+
+   Here's an example of how to do that:
+
+   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:
+
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 70]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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>
+
+   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:
+
+   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>
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 71]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+8.2.2.  Restrict the Properties Returned
+
+   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.
+
+   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.
+
+8.3.  Use of Locking
+
+   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.
+
+   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.
+
+8.4.  Finding Calendars
+
+   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.
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 72]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+   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 vCard [RFC2426] or LDAP [RFC4511] standards
+   together with calendar attributes [RFC2739].
+
+   Because CalDAV requires servers to support WebDAV ACL [RFC3744],
+   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.
+
+   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:
+
+   <?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>
+
+   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:
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 73]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   <?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>
+
+   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.
+
+8.5.  Storing and Using Attachments
+
+   CalDAV clients MAY create attachments in calendar components either
+   as inline or external.  This section contains some guidelines for
+   creating and managing attachments.
+
+8.5.1.  Inline Attachments
+
+   CalDAV clients MUST support inline attachments as specified in
+   iCalendar [RFC2445].  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:
+
+   o  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
+      Section 5.2.5).
+
+   o  Servers MAY impose storage quota limitations on calendar
+      collections (See [RFC4331]).
+
+   o  Any change to a calendar object resource containing an inline
+      attachment requires the entire inline attachment to be re-
+      uploaded.
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 74]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   o  Clients synchronizing a changed calendar object resource have to
+      download the entire calendar object resource, even if the
+      attachment is unchanged.
+
+8.5.2.  External Attachments
+
+   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:
+
+   o  In a collection in the calendar collection containing the calendar
+      object resource;
+
+   o  Somewhere else in the same repository that hosts the calendar
+      collection; or
+
+   o  On an HTTP or FTP server elsewhere.
+
+   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.
+
+   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.
+
+   Also, clients are responsible for consistency of permissions when
+   using external attachments.  One reason for servers to support the
+
+
+
+Daboo, et al.               Standards Track                    [Page 75]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+8.6.  Storing and Using Alarms
+
+   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).
+
+      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.
+
+      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.
+
+      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.
+
+      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.
+
+   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.
+
+   Clients that allow changes to calendar object resources MUST
+   synchronize the alarm data that already exists in the resources.
+
+
+
+Daboo, et al.               Standards Track                    [Page 76]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+   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.
+
+9.  XML Element Definitions
+
+9.1.  CALDAV:calendar XML Element
+
+   Name:  calendar
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies the resource type of a calendar collection.
+
+   Description:  See Section 4.2.
+
+   Definition:
+
+         <!ELEMENT calendar EMPTY>
+
+9.2.  CALDAV:mkcalendar XML Element
+
+   Name:  mkcalendar
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies a request that includes the WebDAV property
+      values to be set for a calendar collection resource when it is
+      created.
+
+   Description:  See Section 5.3.1.
+
+   Definition:
+
+         <!ELEMENT mkcalendar (DAV:set)>
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 77]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+9.3.  CALDAV:mkcalendar-response XML Element
+
+   Name:  mkcalendar-response
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies a response body for a successful MKCALENDAR
+      request.
+
+   Description:  See Section 5.3.1.
+
+   Definition:
+
+         <!ELEMENT mkcalendar-response ANY>
+
+9.4.  CALDAV:supported-collation XML Element
+
+   Name:  supported-collation
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Identifies a single collation via its collation identifier,
+      as defined by [RFC4790].
+
+   Description:  The CALDAV:supported-collation contains the text of a
+      collation identifier, as described in Section 7.5.1.
+
+   Definition:
+
+         <!ELEMENT supported-collation (#PCDATA)>
+         PCDATA value: collation identifier
+
+9.5.  CALDAV:calendar-query XML Element
+
+   Name:  calendar-query
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Defines a report for querying calendar object resources.
+
+   Description:  See Section 7.8.
+
+   Definition:
+
+         <!ELEMENT calendar-query ((DAV:allprop |
+                                    DAV:propname |
+                                    DAV:prop)?, filter, timezone?)>
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 78]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+9.6.  CALDAV:calendar-data XML Element
+
+   Name:  calendar-data
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specified one of the following:
+
+      1.  A supported media type for calendar object resources when
+          nested in the CALDAV:supported-calendar-data property;
+
+      2.  The parts of a calendar object resource should be returned by
+          a calendaring report;
+
+      3.  The content of a calendar object resource in a response to a
+          calendaring report.
+
+   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.
+
+      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.
+
+      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".
+
+   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.
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 79]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   Note:  The iCalendar data embedded within the CALDAV:calendar-data
+      XML element MUST follow the standard XML character data encoding
+      rules, including use of &lt;, &gt;, &amp; etc. entity encoding or
+      the use of a <![CDATA[ ... ]]> construct.  In the later case, the
+      iCalendar data cannot contain the character sequence "]]>", which
+      is the end delimiter for the CDATA section.
+
+   Definition:
+
+         <!ELEMENT calendar-data 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?)>
+
+         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"
+                                 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.
+
+9.6.1.  CALDAV:comp XML Element
+
+   Name:  comp
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Defines which component types to return.
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 80]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   Description:  The name value is a calendar component name (e.g.,
+      VEVENT).
+
+   Definition:
+
+         <!ELEMENT comp ((allprop | prop*), (allcomp | comp*))>
+
+         <!ATTLIST comp name CDATA #REQUIRED>
+         name value: a calendar component name
+
+   Note:  The CALDAV:prop and CALDAV:allprop elements have the same name
+      as the DAV:prop and DAV:allprop elements defined in [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.
+
+9.6.2.  CALDAV:allcomp XML Element
+
+   Name:  allcomp
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies that all components shall be returned.
+
+   Description:  The CALDAV:allcomp XML element can be used when the
+      client wants all types of components returned by a calendaring
+      REPORT request.
+
+   Definition:
+
+         <!ELEMENT allcomp EMPTY>
+
+9.6.3.  CALDAV:allprop XML Element
+
+   Name:  allprop
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies that all properties shall be returned.
+
+   Description:  The CALDAV:allprop XML element can be used when the
+      client wants all properties of components returned by a
+      calendaring REPORT request.
+
+   Definition:
+
+         <!ELEMENT allprop EMPTY>
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 81]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   Note:  The CALDAV:allprop element has the same name as the DAV:
+      allprop element defined in [RFC2518].  However, the CALDAV:allprop
+      element is defined in the "urn:ietf:params:xml:ns:caldav"
+      namespace instead of the "DAV:" namespace.
+
+9.6.4.  CALDAV:prop XML Element
+
+   Name:  prop
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Defines which properties to return in the response.
+
+   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.
+
+   Definition:
+
+         <!ELEMENT prop EMPTY>
+
+         <!ATTLIST prop name CDATA #REQUIRED
+                        novalue (yes | no) "no">
+         name value: a calendar property name
+         novalue value: "yes" or "no"
+
+   Note:  The CALDAV:prop element has the same name as the DAV:prop
+      element defined in [RFC2518].  However, the CALDAV:prop element is
+      defined in the "urn:ietf:params:xml:ns:caldav" namespace instead
+      of the "DAV:" namespace.
+
+9.6.5.  CALDAV:expand XML Element
+
+   Name:  expand
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Forces the server to expand recurring components into
+      individual recurrence instances.
+
+   Description:  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
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 82]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      recurrence instance, and MUST return only those whose scheduled
+      time intersect a specified time range.
+
+      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.
+
+      The server MUST use the same logic as defined for CALDAV:time-
+      range to determine if a recurrence instance intersects the
+      specified time range.
+
+      Recurring components, other than the initial instance, MUST
+      include a RECURRENCE-ID property indicating which instance they
+      refer to.
+
+      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.
+
+   Definition:
+
+         <!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"
+
+9.6.6.  CALDAV:limit-recurrence-set XML Element
+
+   Name:  limit-recurrence-set
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies a time range to limit the set of "overridden
+      components" returned by the server.
+
+   Description:  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
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 83]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      times -- the ones that would have been used if the instance were
+      not overridden -- overlap the time range.
+
+      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.
+
+      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.
+
+      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.
+
+   Definition:
+
+         <!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"
+
+9.6.7.  CALDAV:limit-freebusy-set XML Element
+
+   Name:  limit-freebusy-set
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies a time range to limit the set of FREEBUSY values
+      returned by the server.
+
+   Description:  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.
+
+      The "start" attribute specifies the inclusive start of the time
+      range, and the "end" attribute specifies the non-inclusive end of
+
+
+
+Daboo, et al.               Standards Track                    [Page 84]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      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.
+
+      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.
+
+   Definition:
+
+         <!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"
+
+9.7.  CALDAV:filter XML Element
+
+   Name:  filter
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies a filter to limit the set of calendar components
+      returned by the server.
+
+   Description:  The CALDAV:filter XML element specifies the search
+      filter used to limit the calendar components returned by a
+      calendaring REPORT request.
+
+   Definition:
+
+         <!ELEMENT filter (comp-filter)>
+
+9.7.1.  CALDAV:comp-filter XML Element
+
+   Name:  comp-filter
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies search criteria on calendar components.
+
+   Description:  The CALDAV:comp-filter XML element specifies a query
+      targeted at the calendar object (i.e., VCALENDAR) or at a specific
+      calendar component type (e.g., VEVENT).  The scope of the
+      CALDAV:comp-filter XML element is the calendar object when used as
+      a child of the CALDAV:filter XML element.  The scope of the
+      CALDAV:comp-filter XML element is the enclosing calendar component
+
+
+
+Daboo, et al.               Standards Track                    [Page 85]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      when used as a child of another CALDAV:comp-filter XML element.  A
+      CALDAV:comp-filter is said to match if:
+
+      *  The CALDAV:comp-filter XML element is empty and the calendar
+         object or calendar component type specified by the "name"
+         attribute exists in the current scope;
+
+      or:
+
+      *  The CALDAV:comp-filter XML element contains a CALDAV:is-not-
+         defined XML element and the calendar object or calendar
+         component type specified by the "name" attribute does not exist
+         in the current scope;
+
+      or:
+
+      *  The CALDAV:comp-filter XML element contains a CALDAV:time-range
+         XML element and at least one recurrence instance in the
+         targeted calendar component is scheduled to overlap the
+         specified time range, and all specified CALDAV:prop-filter and
+         CALDAV:comp-filter child XML elements also match the targeted
+         calendar component;
+
+      or:
+
+      *  The CALDAV:comp-filter XML element only contains CALDAV:prop-
+         filter and CALDAV:comp-filter child XML elements that all match
+         the targeted calendar component.
+
+   Definition:
+
+         <!ELEMENT comp-filter (is-not-defined | (time-range?,
+                                prop-filter*, comp-filter*))>
+
+         <!ATTLIST comp-filter name CDATA #REQUIRED>
+         name value: a calendar object or calendar component
+                     type (e.g., VEVENT)
+
+9.7.2.  CALDAV:prop-filter XML Element
+
+   Name:  prop-filter
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies search criteria on calendar properties.
+
+   Description:  The CALDAV:prop-filter XML element specifies a query
+      targeted at a specific calendar property (e.g., CATEGORIES) in the
+
+
+
+Daboo, et al.               Standards Track                    [Page 86]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      scope of the enclosing calendar component.  A calendar property is
+      said to match a CALDAV:prop-filter if:
+
+      *  The CALDAV:prop-filter XML element is empty and a property of
+         the type specified by the "name" attribute exists in the
+         enclosing calendar component;
+
+      or:
+
+      *  The CALDAV:prop-filter XML element contains a CALDAV:is-not-
+         defined XML element and no property of the type specified by
+         the "name" attribute exists in the enclosing calendar
+         component;
+
+      or:
+
+      *  The CALDAV:prop-filter XML element contains a CALDAV:time-range
+         XML element and the property value overlaps the specified time
+         range, and all specified CALDAV:param-filter child XML elements
+         also match the targeted property;
+
+      or:
+
+      *  The CALDAV:prop-filter XML element contains a CALDAV:text-match
+         XML element and the property value matches it, and all
+         specified CALDAV:param-filter child XML elements also match the
+         targeted property;
+
+   Definition:
+
+         <!ELEMENT prop-filter (is-not-defined |
+                                ((time-range | text-match)?,
+                                 param-filter*))>
+
+         <!ATTLIST prop-filter name CDATA #REQUIRED>
+         name value: a calendar property name (e.g., ATTENDEE)
+
+9.7.3.  CALDAV:param-filter XML Element
+
+   Name:  param-filter
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Limits the search to specific parameter values.
+
+   Description:  The CALDAV:param-filter XML element specifies a query
+      targeted at a specific calendar property parameter (e.g.,
+      PARTSTAT) in the scope of the calendar property on which it is
+
+
+
+Daboo, et al.               Standards Track                    [Page 87]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      defined.  A calendar property parameter is said to match a CALDAV:
+      param-filter if:
+
+      *  The CALDAV:param-filter XML element is empty and a parameter of
+         the type specified by the "name" attribute exists on the
+         calendar property being examined;
+
+      or:
+
+      *  The CALDAV:param-filter XML element contains a CALDAV:is-not-
+         defined XML element and no parameter of the type specified by
+         the "name" attribute exists on the calendar property being
+         examined;
+
+   Definition:
+
+         <!ELEMENT param-filter (is-not-defined | text-match?)>
+
+         <!ATTLIST param-filter name CDATA #REQUIRED>
+         name value: a property parameter name (e.g., PARTSTAT)
+
+9.7.4.  CALDAV:is-not-defined XML Element
+
+   Name:  is-not-defined
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies that a match should occur if the enclosing
+      component, property, or parameter does not exist.
+
+   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.
+
+   Definition:
+
+         <!ELEMENT is-not-defined EMPTY>
+
+9.7.5.  CALDAV:text-match XML Element
+
+   Name:  text-match
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies a substring match on a property or parameter
+      value.
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 88]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+      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.
+
+      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.
+
+   Definition:
+
+         <!ELEMENT text-match (#PCDATA)>
+         PCDATA value: string
+
+         <!ATTLIST text-match collation        CDATA "i;ascii-casemap"
+                              negate-condition (yes | no) "no">
+
+9.8.  CALDAV:timezone XML Element
+
+   Name:  timezone
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies the time zone component to use when determining
+      the results of a report.
+
+   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.
+
+   Note:  The iCalendar data embedded within the CALDAV:timezone XML
+      element MUST follow the standard XML character data encoding
+      rules, including use of &lt;, &gt;, &amp; etc. entity encoding or
+      the use of a <![CDATA[ ... ]]> construct.  In the later case, the
+
+
+
+Daboo, et al.               Standards Track                    [Page 89]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      iCalendar data cannot contain the character sequence "]]>", which
+      is the end delimiter for the CDATA section.
+
+   Definition:
+
+         <!ELEMENT timezone (#PCDATA)>
+         PCDATA value: an iCalendar object with exactly one VTIMEZONE
+
+9.9.  CALDAV:time-range XML Element
+
+   Name:  time-range
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  Specifies a time range to limit the set of calendar
+      components returned by the server.
+
+   Description:  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.
+
+      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.
+
+      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.
+
+      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 [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
+
+
+
+Daboo, et al.               Standards Track                    [Page 90]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      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.
+
+      +---------------------------------------------------------------+
+      | 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?            |
+      |   |   |   |   +-----------------------------------------------+
+      |   |   |   |   | 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)      |
+      +---+---+---+---+-----------------------------------------------+
+
+      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 [RFC2445], the
+      DUE value MUST be a DATE-TIME value equal to or after the DTSTART
+      value if specified.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 91]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   +-------------------------------------------------------------------+
+   | 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                                          |
+   +---+---+---+---+---+-----------------------------------------------+
+
+      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.
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 92]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+      +----------------------------------------------------+
+      | VJOURNAL has the DTSTART property?                 |
+      |   +------------------------------------------------+
+      |   | DTSTART property is a DATE-TIME value?         |
+      |   |   +--------------------------------------------+
+      |   |   | Condition to evaluate                      |
+      +---+---+--------------------------------------------+
+      | Y | Y | (start <= DTSTART)     AND (end > DTSTART) |
+      +---+---+--------------------------------------------+
+      | Y | N | (start <  DTSTART+P1D) AND (end > DTSTART) |
+      +---+---+--------------------------------------------+
+      | N | * | FALSE                                      |
+      +---+---+--------------------------------------------+
+
+      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.
+
+      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.
+
+
+      +------------------------------------------------------+
+      | 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                                        |
+      +---+---+----------------------------------------------+
+
+      A VALARM component is said to overlap a given time range if the
+      following condition holds:
+
+         (start <= trigger-time) AND (end > trigger-time)
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 93]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+      The calendar properties COMPLETED, CREATED, DTEND, DTSTAMP,
+      DTSTART, DUE, and LAST-MODIFIED overlap a given time range if the
+      following condition holds:
+
+          (start <= date-time) AND (end > date-time)
+
+   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.
+
+      The semantic of CALDAV:time-range is not defined for any other
+      calendar components and properties.
+
+   Definition:
+
+         <!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"
+
+9.10.  CALDAV:calendar-multiget XML Element
+
+   Name:  calendar-multiget
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  CalDAV report used to retrieve specific calendar object
+      resources.
+
+   Description:  See Section 7.9.
+
+   Definition:
+
+         <!ELEMENT calendar-multiget ((DAV:allprop |
+                                      DAV:propname |
+                                      DAV:prop)?, DAV:href+)>
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 94]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+9.11.  CALDAV:free-busy-query XML Element
+
+   Name:  free-busy-query
+
+   Namespace:  urn:ietf:params:xml:ns:caldav
+
+   Purpose:  CalDAV report used to generate a VFREEBUSY to determine
+      busy time over a specific time range.
+
+   Description:  See Section 7.10.
+
+   Definition:
+
+         <!ELEMENT free-busy-query (time-range)>
+
+10.  Internationalization Considerations
+
+   CalDAV allows internationalized strings to be stored and retrieved
+   for the description of calendar collections (see Section 5.2.1).
+
+   The CALDAV:calendar-query REPORT (Section 7.8) 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 Section 9.7.5).
+
+11.  Security Considerations
+
+   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 [RFC2818].  In particular,
+   HTTP Basic authentication MUST NOT be used unless TLS is in effect.
+
+   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 that asks for
+   recurrences to be expanded over that range would likely constitute a
+   denial-of-service attack on the server.
+
+   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.
+
+
+
+Daboo, et al.               Standards Track                    [Page 95]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+   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.
+
+   Security considerations described in iCalendar [RFC2445] and iTIP
+   [RFC2446] are also applicable to CalDAV.
+
+   Beyond these, CalDAV does not raise any security considerations that
+   are not present in HTTP [RFC2616] and WebDAV [RFC2518], [RFC3253],
+   [RFC3744].
+
+12.  IANA Considerations
+
+   This document uses one new URN to identify a new XML namespace.  The
+   URN conforms to a registry mechanism described in [RFC3688].
+
+12.1.  Namespace Registration
+
+   Registration request for the CalDAV namespace:
+
+   URI: urn:ietf:params:xml:ns:caldav
+
+   Registrant Contact: See the "Authors' Addresses" section of this
+   document.
+
+   XML: None.  Namespace URIs do not represent an XML specification.
+
+13.  Acknowledgements
+
+   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, Mike Douglass, Ted Hardie, Marten den Haring, 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, and Jim Whitehead.
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 96]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   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.
+
+14.  References
+
+14.1.  Normative References
+
+   [RFC2119]               Bradner, S., "Key words for use in RFCs to
+                           Indicate Requirement Levels", BCP 14,
+                           RFC 2119, March 1997.
+
+   [RFC2246]               Dierks, T. and C. Allen, "The TLS Protocol
+                           Version 1.0", RFC 2246, January 1999.
+
+   [RFC2445]               Dawson, F. and Stenerson, D., "Internet
+                           Calendaring and Scheduling Core Object
+                           Specification (iCalendar)", RFC 2445,
+                           November 1998.
+
+   [RFC2446]               Silverberg, S., Mansour, S., Dawson, F., and
+                           R. Hopson, "iCalendar Transport-Independent
+                           Interoperability Protocol (iTIP) Scheduling
+                           Events, BusyTime, To-dos and Journal
+                           Entries", RFC 2446, November 1998.
+
+   [RFC2518]               Goland, Y., Whitehead, E., Faizi, A., Carter,
+                           S., and D. Jensen, "HTTP Extensions for
+                           Distributed Authoring -- WEBDAV", RFC 2518,
+                           February 1999.
+
+   [RFC2616]               Fielding, R., Gettys, J., Mogul, J., Frystyk,
+                           H., Masinter, L., Leach, P., and T. Berners-
+                           Lee, "Hypertext Transfer Protocol --
+                           HTTP/1.1", RFC 2616, June 1999.
+
+   [RFC2818]               Rescorla, E., "HTTP Over TLS", RFC 2818,
+                           May 2000.
+
+   [RFC3253]               Clemm, G., Amsden, J., Ellison, T., Kaler,
+                           C., and J. Whitehead, "Versioning Extensions
+                           to WebDAV (Web Distributed Authoring and
+                           Versioning)", RFC 3253, March 2002.
+
+   [RFC3688]               Mealling, M., "The IETF XML Registry",
+                           BCP 81, RFC 3688, January 2004.
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 97]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   [RFC3744]               Clemm, G., Reschke, J., Sedlar, E., and J.
+                           Whitehead, "Web Distributed Authoring and
+                           Versioning (WebDAV) Access Control Protocol",
+                           RFC 3744, May 2004.
+
+   [RFC4346]               Dierks, T. and E. Rescorla, "The Transport
+                           Layer Security (TLS) Protocol Version 1.1",
+                           RFC 4346, April 2006.
+
+   [RFC4790]               Newman, C., Duerst, M., and A. Gulbrandsen,
+                           "Internet Application Protocol Collation
+                           Registry", RFC 4790, March 2007.
+
+   [W3C.REC-xml-20060816]  Paoli, J., Maler, E., Yergeau, F., Sperberg-
+                           McQueen, C., and T. Bray, "Extensible Markup
+                           Language (XML) 1.0 (Fourth Edition)", World
+                           Wide Web Consortium Recommendation REC-xml-
+                           20060816, August 2006,
+                           <http://www.w3.org/TR/2006/REC-xml-20060816>.
+
+14.2.  Informative References
+
+   [RFC2426]               Dawson, F. and T. Howes, "vCard MIME
+                           Directory Profile", RFC 2426, September 1998.
+
+   [RFC2739]               Small, T., Hennessy, D., and F. Dawson,
+                           "Calendar Attributes for vCard and LDAP",
+                           RFC 2739, January 2000.
+
+   [RFC4331]               Korver, B. and L. Dusseault, "Quota and Size
+                           Properties for Distributed Authoring and
+                           Versioning (DAV) Collections", RFC 4331,
+                           February 2006.
+
+   [RFC4511]               Sermersheim, J., "Lightweight Directory
+                           Access Protocol (LDAP): The Protocol",
+                           RFC 4511, June 2006.
+
+   [rfc2518bis]            Dusseault, L., "HTTP Extensions for
+                           Distributed Authoring - WebDAV", Work
+                           in Progress, December 2006.
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 98]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+Appendix A.  CalDAV Method Privilege Table (Normative)
+
+   The following table extends the WebDAV Method Privilege Table
+   specified in Appendix B of [RFC3744].
+
+   +------------+------------------------------------------------------+
+   | METHOD     | PRIVILEGES                                           |
+   +------------+------------------------------------------------------+
+   | MKCALENDAR | DAV:bind                                             |
+   | REPORT     | DAV:read or CALDAV:read-free-busy (on all referenced |
+   |            | resources)                                           |
+   +------------+------------------------------------------------------+
+
+Appendix B.  Calendar Collections Used in the Examples
+
+   This appendix shows the calendar object resources contained in the
+   calendar collection queried in the examples throughout this document.
+
+   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:
+
+   >> Request <<
+
+   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:filter>
+   </C:calendar-query>
+
+   >> Response <<
+
+   HTTP/1.1 207 Multi-Status
+   Content-Type: application/xml; charset="utf-8"
+   Content-Length: xxxx
+
+
+
+
+Daboo, et al.               Standards Track                    [Page 99]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+   <?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>
+
+
+
+Daboo, et al.               Standards Track                   [Page 100]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+         <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>
+
+
+
+Daboo, et al.               Standards Track                   [Page 101]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+       <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>
+
+
+
+Daboo, et al.               Standards Track                   [Page 102]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+           <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>
+
+
+
+Daboo, et al.               Standards Track                   [Page 103]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+     </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>
+
+
+
+Daboo, et al.               Standards Track                   [Page 104]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+       </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>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                   [Page 105]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+Authors' Addresses
+
+   Cyrus Daboo
+   Apple Inc.
+   1 Infinite Loop
+   Cupertino, CA  95014
+   USA
+
+   EMail: cyrus@daboo.name
+   URI:   http://www.apple.com/
+
+
+   Bernard Desruisseaux
+   Oracle Corporation
+   600 Blvd. de Maisonneuve West
+   Suite 1900
+   Montreal, QC  H3A 3J2
+   CANADA
+
+   EMail: bernard.desruisseaux@oracle.com
+   URI:   http://www.oracle.com/
+
+
+   Lisa Dusseault
+   CommerceNet
+   169 University Ave.
+   Palo Alto, CA  94301
+   USA
+
+   EMail: ldusseault@commerce.net
+   URI:   http://commerce.net/
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                   [Page 106]
+
+RFC 4791                         CalDAV                       March 2007
+
+
+Full Copyright Statement
+
+   Copyright (C) The IETF Trust (2007).
+
+   This document is subject to the rights, licenses and restrictions
+   contained in BCP 78, and except as set forth therein, the authors
+   retain all their rights.
+
+   This document and the information contained herein are provided on an
+   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
+   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
+   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
+   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
+   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
+   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+
+Intellectual Property
+
+   The IETF takes no position regarding the validity or scope of any
+   Intellectual Property Rights or other rights that might be claimed to
+   pertain to the implementation or use of the technology described in
+   this document or the extent to which any license under such rights
+   might or might not be available; nor does it represent that it has
+   made any independent effort to identify any such rights.  Information
+   on the procedures with respect to rights in RFC documents can be
+   found in BCP 78 and BCP 79.
+
+   Copies of IPR disclosures made to the IETF Secretariat and any
+   assurances of licenses to be made available, or the result of an
+   attempt made to obtain a general license or permission for the use of
+   such proprietary rights by implementers or users of this
+   specification can be obtained from the IETF on-line IPR repository at
+   http://www.ietf.org/ipr.
+
+   The IETF invites any interested party to bring to its attention any
+   copyrights, patents or patent applications, or other proprietary
+   rights that may cover technology that may be required to implement
+   this standard.  Please address the information to the IETF at
+   ietf-ipr@ietf.org.
+
+Acknowledgement
+
+   Funding for the RFC Editor function is currently provided by the
+   Internet Society.
+
+
+
+
+
+
+
+Daboo, et al.               Standards Track                   [Page 107]
+