Internet Engineering Task Force (IETF) C. Daboo
Request for Comments: 7809 Apple
Updates: 4791 March 2016
Category: Standards Track
ISSN: 2070-1721
Internet Engineering Task Force (IETF) C. Daboo
Request for Comments: 7809 Apple
Updates: 4791 March 2016
Category: Standards Track
ISSN: 2070-1721
Calendaring Extensions to WebDAV (CalDAV): Time Zones by Reference
WebDAV（CalDAV）的日历扩展：按引用划分的时区
Abstract
摘要
This document defines an update to the Calendaring Extensions to WebDAV (CalDAV) calendar access protocol (RFC 4791) to allow clients and servers to exchange iCalendar data without the need to send full time zone data.
本文档定义了对WebDAV（CalDAV）日历访问协议（RFC 4791）日历扩展的更新，以允许客户端和服务器交换iCalendar数据，而无需发送完整的时区数据。
Status of This Memo
关于下段备忘
This is an Internet Standards Track document.
这是一份互联网标准跟踪文件。
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.
本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。有关互联网标准的更多信息，请参见RFC 5741第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7809.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问http://www.rfc-editor.org/info/rfc7809.
Copyright Notice
版权公告
Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2016 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Time Zones by Reference . . . . . . . . . . . . . . . . . . . 3
3.1. New Server Behavior . . . . . . . . . . . . . . . . . . . 4
4. New Client Behavior . . . . . . . . . . . . . . . . . . . . . 7
5. New WebDAV Properties . . . . . . . . . . . . . . . . . . . . 8
5.1. CALDAV:timezone-service-set . . . . . . . . . . . . . . . 8
5.2. CALDAV:calendar-timezone-id . . . . . . . . . . . . . . . 9
6. XML Element Definitions . . . . . . . . . . . . . . . . . . . 9
6.1. CALDAV:calendar-query XML Element . . . . . . . . . . . . 9
6.2. CALDAV:timezone-id XML Element . . . . . . . . . . . . . 10
7. Additional Message Header Fields . . . . . . . . . . . . . . 10
7.1. CalDAV-Timezones Request Header Field . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 11
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10.1. CalDAV-Timezones . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . 12
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 13
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Time Zones by Reference . . . . . . . . . . . . . . . . . . . 3
3.1. New Server Behavior . . . . . . . . . . . . . . . . . . . 4
4. New Client Behavior . . . . . . . . . . . . . . . . . . . . . 7
5. New WebDAV Properties . . . . . . . . . . . . . . . . . . . . 8
5.1. CALDAV:timezone-service-set . . . . . . . . . . . . . . . 8
5.2. CALDAV:calendar-timezone-id . . . . . . . . . . . . . . . 9
6. XML Element Definitions . . . . . . . . . . . . . . . . . . . 9
6.1. CALDAV:calendar-query XML Element . . . . . . . . . . . . 9
6.2. CALDAV:timezone-id XML Element . . . . . . . . . . . . . 10
7. Additional Message Header Fields . . . . . . . . . . . . . . 10
7.1. CalDAV-Timezones Request Header Field . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 11
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10.1. CalDAV-Timezones . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . 12
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 13
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13
The CalDAV [RFC4791] calendar access protocol allows clients to access calendar data stored on a server in the iCalendar [RFC5545] data format. In iCalendar, calendar data that uses local time in any of its date and/or time values is specified as a date-time value in combination with a time zone identifier ("TZID" property parameter). The time zone identifier refers to a time zone definition (a "VTIMEZONE" component) that has all of the rules required to determine local-time UTC offsets for the corresponding time zone. In many cases, these "VTIMEZONE" components can be larger, octet-wise, than the events or tasks that make use of them. However, iCalendar currently requires all iCalendar objects ("VCALENDAR" components) that refer to a time zone via its identifier to also include the corresponding "VTIMEZONE" component. This leads to inefficiencies in the CalDAV protocol because large amounts of "VTIMEZONE" data are continuously being exchanged, and for the most part these time zone definitions are unchanging. This is particularly problematic for mobile or limited devices, with limited network bandwidth, CPU, and energy resources.
CalDAV[RFC4791]日历访问协议允许客户端访问以iCalendar[RFC5545]数据格式存储在服务器上的日历数据。在iCalendar中，在任何日期和/或时间值中使用本地时间的日历数据被指定为与时区标识符（“TZID”属性参数）组合的日期时间值。时区标识符指的是一个时区定义（“VTIMEZONE”组件），它具有确定相应时区的本地UTC时间偏移量所需的所有规则。在许多情况下，这些“VTIMEZONE”组件可能比使用它们的事件或任务更大（八位字节）。但是，iCalendar当前要求通过其标识符引用时区的所有iCalendar对象（“VCALENDAR”组件）也包括相应的“VTIMEZONE”组件。这导致CalDAV协议的效率低下，因为大量的“VTIMEZONE”数据正在不断地交换，并且这些时区定义在很大程度上是不变的。这对于网络带宽、CPU和能源资源有限的移动设备或有限设备来说尤其成问题。
A set of standard time zone definitions are available at the IANA-hosted time zone database [RFC6557]. That database provides the "raw" data for time zone definitions, and those can be converted into iCalendar "VTIMEZONE" components for use in iCalendar applications, as well as converted into other formats for use by other applications (e.g., "zoneinfo" files often found on Unix-based operating systems). A new time zone data distribution service protocol [RFC7808] is available that allows iCalendar applications to retrieve these standard time zone definitions in a timely and accurate fashion, instead of relying on possibly infrequent system updates of time zone data that frequently result in mismatched calendar data and thus missed meetings between calendar users. Another benefit of the time zone data distribution service is that it provides a single "reference" for standard time zone data that CalDAV clients and servers can make use of to "agree" on standard time zone definitions, and thus eliminate the need to exchange the data for those.
IANA托管的时区数据库[RFC6557]中提供了一组标准时区定义。该数据库为时区定义提供“原始”数据，这些数据可以转换为iCalendar“VTIMEZONE”组件，用于iCalendar应用程序，也可以转换为其他应用程序使用的其他格式（例如，在基于Unix的操作系统上常见的“zoneinfo”文件）。新的时区数据分发服务协议[RFC7808]可用，允许iCalendar应用程序及时准确地检索这些标准时区定义，而不是依赖可能不频繁的时区数据系统更新，这常常会导致日历数据不匹配，从而错过日历用户之间的会议。时区数据分发服务的另一个好处是，它为标准时区数据提供了一个“参考”，CalDAV客户端和服务器可以利用该“参考”来“商定”标准时区定义，从而消除了为标准时区定义交换数据的需要。
This specification defines a new mode of operation for CalDAV clients and servers that allows them to exchange iCalendar data without the need to send "VTIMEZONE" components for known, standard time zone definitions. This can significantly reduce the amount of data that needs to be sent between client and server, giving rise to performance and efficiency improvements for each of them.
本规范为CalDAV客户端和服务器定义了一种新的操作模式，允许它们交换iCalendar数据，而无需为已知的标准时区定义发送“VTIMEZONE”组件。这可以显著减少客户端和服务器之间需要发送的数据量，从而提高每个客户端和服务器的性能和效率。
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
本文件中的关键词“必须”、“不得”、“必需”、“应”、“不应”、“建议”、“不建议”、“可”和“可选”应按照[RFC2119]中的说明进行解释。
Other notations used in this memo are as in [RFC4791].
本备忘录中使用的其他符号如[RFC4791]所示。
Note that this specification only defines changes to iCalendar data sent or received via the CalDAV protocol (both [RFC4791] and [RFC6638], and extensions). These changes do not apply to other means of exchanging calendar data, such as scheduling mechanisms based on the iCalendar Transport-Independent Interoperability Protocol (iTIP) [RFC5546], e.g., the iCalendar Message-Based Interoperability Protocol (iMIP) [RFC6047], or other methods.
请注意，本规范仅定义了通过CalDAV协议（包括[RFC4791]和[RFC6638]以及扩展）发送或接收的iCalendar数据的更改。这些更改不适用于交换日历数据的其他方式，例如基于iCalendar传输独立互操作性协议（iTIP）[RFC5546]的调度机制，例如基于iCalendar消息的互操作性协议（iMIP）[RFC6047]或其他方法。
A server that supports this specification MUST include "calendar-no-timezone" as a field in the DAV response header field from an "OPTIONS" request on a calendar home collection (see Section 6.2.1 of [RFC4791]) or calendar collection (see Section 4.2 of [RFC4791]). Clients MUST check for the presence of that field in the DAV response header field before changing their behavior as per Section 4.
支持本规范的服务器必须将“日历无时区”作为来自日历主集合（请参见[RFC4791]第6.2.1节）或日历集合（请参见[RFC4791]第4.2节）的“选项”请求的DAV响应标头字段。在按照第4节更改其行为之前，客户端必须检查DAV响应头字段中是否存在该字段。
A CalDAV server supporting this specification MUST have one or more associated time zone distribution services [RFC7808] that provide data for the set of time zones known to the server and expected to be used by clients. A CalDAV server advertises the set of time zone distribution services it makes use of via a CALDAV:timezone-service-set WebDAV property (see Section 5.1) defined on calendar home collections. Clients can use the time zone data distribution services listed in this property to fetch current time zone definitions for the time zone identifiers in iCalendar data retrieved from the server. This allows clients to keep their "built-in" time zone definitions up to date. It also allows clients to use an "on-demand" model for populating their local time zone definition cache, only fetching a time zone definition when it is first seen in calendar data, potentially allowing for savings on storage space by eliminating the need to store time zone data that is not currently being used.
支持此规范的CalDAV服务器必须具有一个或多个关联的时区分发服务[RFC7808]，这些服务为服务器已知并预期由客户端使用的一组时区提供数据。CalDAV服务器通过日历主集合上定义的CalDAV:timezone service set WebDAV属性（请参见第5.1节）公布其使用的时区分发服务集。客户端可以使用此属性中列出的时区数据分发服务获取从服务器检索的iCalendar数据中的时区标识符的当前时区定义。这允许客户端保持其“内置”时区定义为最新。它还允许客户端使用“按需”模型来填充其本地时区定义缓存，仅在第一次在日历数据中看到时区定义时才获取该定义，从而无需存储当前未使用的时区数据，从而有可能节省存储空间。
When making use of the time zone data distribution services advertised by a CalDAV server, clients MUST follow all the requirements of the time zone data distribution service protocol [RFC7808], taking care to refresh time zone data in a timely fashion.
使用CalDAV服务器公布的时区数据分发服务时，客户端必须遵守时区数据分发服务协议[RFC7808]的所有要求，注意及时刷新时区数据。
Servers MUST support the HTTP "CalDAV-Timezones" request header field (see Section 7.1). If the "CalDAV-Timezones" request header field has the value "T" on any HTTP request that returns iCalendar data, then the server MUST include all the appropriate "VTIMEZONE" components in the iCalendar data (all the ones that are referenced by "TZID" property parameters). If the "CalDAV-Timezones" request header field has the value "F" on any HTTP request that returns iCalendar data, then the server MUST NOT return any "VTIMEZONE" components if the time zone identifier matches one provided by any of the advertised time zone distribution servers (see Section 3.1.2). However, the server MUST return the appropriate "VTIMEZONE" component
服务器必须支持HTTP“CalDAV时区”请求头字段（参见第7.1节）。如果在返回iCalendar数据的任何HTTP请求上，“CalDAV Timezones”请求头字段的值为“T”，则服务器必须在iCalendar数据中包含所有适当的“VTIMEZONE”组件（所有由“TZID”属性参数引用的组件）。如果在返回iCalendar数据的任何HTTP请求上，“CalDAV Timezones”请求头字段的值为“F”，则如果时区标识符与任何播发的时区分发服务器提供的标识符匹配，则服务器不得返回任何“VTIMEZONE”组件（见第3.1.2节）。但是，服务器必须返回相应的“VTIMEZONE”组件
for each time zone with an identifier not available on the advertised time zone distribution servers. This behavior applies to all HTTP requests on CalDAV resources that return iCalendar data either directly (such as a "GET" request on a calendar object resource), or embedded in a "structured" response such as a DAV:multistatus returned by a "REPORT" or "PROPFIND" request.
对于每个时区，其标识符在播发的时区分发服务器上不可用。此行为适用于CalDAV资源上的所有HTTP请求，这些请求直接返回iCalendar数据（如日历对象资源上的“GET”请求），或嵌入“结构化”响应中，如“REPORT”或“PROPFIND”请求返回的DAV:multistatus。
Observation and experiments have shown that, in the vast majority of cases, CalDAV clients have typically ignored time zone definitions in data received from servers, and instead make use of their own "built-in" definitions for the corresponding time zone identifier. This means that it is reasonable for CalDAV servers to unilaterally decide not to send "VTIMEZONE" components for standard time zones that clients are expected to have "built-in" (i.e., IANA time zones). Thus, in the absence of a "CalDAV-Timezones" request header field, servers advertising the "calendar-no-timezone" capability MAY opt to not send standard "VTIMEZONE" components. Servers that do that will need to provide an administrator configuration setting to override the new default behavior based on client "User-Agent" request header field values, or other suitable means of identifying the client software in use.
观察和实验表明，在绝大多数情况下，CalDAV客户端通常会忽略从服务器接收的数据中的时区定义，而是使用其自己的“内置”定义来定义相应的时区标识符。这意味着CalDAV服务器可以单方面决定不发送标准时区的“VTIMEZONE”组件，因为客户机需要“内置”（即IANA时区）。因此，在没有“CalDAV时区”请求头字段的情况下，宣传“日历无时区”功能的服务器可能会选择不发送标准的“VTIMEZONE”组件。执行此操作的服务器将需要提供管理员配置设置，以根据客户端“用户代理”请求标头字段值或识别正在使用的客户端软件的其他适当方式覆盖新的默认行为。
In addition to servers not sending time zone definitions to clients in iCalendar data, this specification also allows clients to not include time zone definitions when sending iCalendar data to the server, as per Section 4. This behavior applies to all HTTP requests on CalDAV resources that include iCalendar data either directly in the request body (such as a "PUT" request on a calendar object resource) or embedded in a "structured" request body such as a one used by a "PROPPATCH" request.
除了服务器不向iCalendar数据中的客户端发送时区定义外，根据第4节，本规范还允许客户端在向服务器发送iCalendar数据时不包含时区定义。此行为适用于CalDAV资源上的所有HTTP请求，这些请求包括直接在请求正文中的iCalendar数据（如日历对象资源上的“PUT”请求）或嵌入在“结构化”请求正文中的iCalendar数据，如“PROPPATCH”请求使用的数据。
Note that, as per Section 4, clients might send time zone definitions for time zones that are not advertised by any of the time zone services associated with the server. In that case, servers have various choices:
请注意，根据第4节，客户机可能会发送与服务器关联的任何时区服务未公布的时区的时区定义。在这种情况下，服务器有多种选择：
1. Servers can preserve the original time zone definitions in the iCalendar data sent by the client, so that those can be returned to that client or other clients who subsequently request iCalendar data.
1. 服务器可以在客户端发送的iCalendar数据中保留原始时区定义，以便将这些定义返回给该客户端或随后请求iCalendar数据的其他客户端。
2. Servers can refuse to accept any unknown/nonstandard time zones -- in which case, they MUST reject the HTTP request containing such data using a WebDAV precondition code of CALDAV:valid-timezone.
2. 服务器可以拒绝接受任何未知/非标准时区——在这种情况下，它们必须使用CALDAV:valid timezone的WebDAV前提条件代码拒绝包含此类数据的HTTP请求。
3. Servers can, with appropriate knowledge, map the unknown/ nonstandard time zone to a standard time zone definition that accurately matches the one supplied by the client. In doing so, servers will need to rewrite the iCalendar data to make use of the new standard time zone identifier chosen by the mapping procedure. Any subsequent request to fetch the calendar data would see the new time zone identifier in the calendar data. Note there is one important situation where this remapping is not appropriate: an attendee's copy of an event. In that case, the original time zone definition needs to be preserved as the organizer's calendar user agent will expect to see that in any iTIP [RFC5546] replies sent by the attendee.
3. 服务器可以在具备适当知识的情况下，将未知/非标准时区映射到与客户端提供的时区定义精确匹配的标准时区定义。在此过程中，服务器需要重写iCalendar数据，以使用映射过程选择的新标准时区标识符。获取日历数据的任何后续请求都会在日历数据中看到新的时区标识符。注意，有一种重要的情况下，这种重新映射是不合适的：与会者的活动副本。在这种情况下，需要保留原始时区定义，因为组织者的日历用户代理希望在与会者发送的任何iTIP[RFC5546]回复中看到该定义。
CalDAV defines a CALDAV:calendar-timezone WebDAV property that is used by clients to set a default time zone for the server to use when doing time-based queries on calendar data (see Section 5.3.2 of [RFC4791]). The content of that WebDAV property is an iCalendar "VTIMEZONE" component. This specification defines a new CALDAV:calendar-timezone-id WebDAV property that allows the default time zone to be set via its time zone identifier, rather than providing the full "VTIMEZONE" component (see Section 5.2). This WebDAV property MUST be present on all resources that also support the CALDAV:calendar-timezone WebDAV property. Its value MUST match the value of the "TZID" iCalendar property in the "VTIMEZONE" component in the CALDAV:calendar-timezone WebDAV property on the same resource. The server MUST accept clients that set either the CALDAV:calendar-timezone or the CALDAV:calendar-timezone-id, and it MUST adjust the value of the alternate property to reflect any changes. That is, if a client sets the CALDAV:calendar-timezone-id WebDAV property value to "America/New_York", then the server will return the full "VTIMEZONE" data for that time zone in the CALDAV:calendar-timezone WebDAV property.
CalDAV定义CalDAV:calendar timezone WebDAV属性，客户端使用该属性设置服务器在对日历数据执行基于时间的查询时使用的默认时区（请参见[RFC4791]第5.3.2节）。WebDAV属性的内容是iCalendar“VTIMEZONE”组件。本规范定义了一个新的CALDAV:calendar timezone id WebDAV属性，该属性允许通过其时区标识符设置默认时区，而不是提供完整的“VTIMEZONE”组件（参见第5.2节）。此WebDAV属性必须存在于同时支持CALDAV:calendar timezone WebDAV属性的所有资源上。其值必须与同一资源上CALDAV:calendar timezone WebDAV属性中“VTIMEZONE”组件中的“TZID”iCalendar属性的值匹配。服务器必须接受设置CALDAV:calendar时区或CALDAV:calendar时区id的客户端，并且必须调整alternate属性的值以反映任何更改。也就是说，如果客户端将CALDAV:calendar timezone id WebDAV属性值设置为“America/New_York”，则服务器将在CALDAV:calendar timezone WebDAV属性中返回该时区的完整“VTIMEZONE”数据。
If a client attempts to update the CALDAV:calendar-timezone-id with a value that does not correspond to a time zone that is known to the server, the server MUST reject the property update using a CALDAV:valid-timezone pre-condition error. In such cases, clients MAY repeat the request using the CALDAV:calendar-timezone instead, and provide the full iCalendar data for the time zone being set.
如果客户端尝试使用与服务器已知的时区不对应的值更新CALDAV:calendar时区id，则服务器必须使用CALDAV:valid timezone前置条件错误拒绝属性更新。在这种情况下，客户机可以使用CALDAV:calendar时区重复请求，并提供所设置时区的完整iCalendar数据。
CalDAV calendar query reports support a CALDAV:timezone XML element that is used by clients to set a specific time zone for the server to use when doing time-based queries on calendar data (see Sections 7.3 and 9.8 of [RFC4791]). The content of that XML element is an
CalDAV日历查询报告支持CalDAV:timezone XML元素，客户端使用该元素设置服务器在对日历数据执行基于时间的查询时要使用的特定时区（请参见[RFC4791]第7.3节和第9.8节）。该XML元素的内容是
iCalendar "VTIMEZONE" component. This specification defines a new CALDAV:timezone-id XML element that can be used as an alternative to the CALDAV:timezone XML element; it allows a specific time zone to be set via its time zone identifier, rather than providing the full "VTIMEZONE" component (see Section 6.2). Servers MUST support a client's ability to provide a time zone identifier for use in a calendar query "REPORT" using this new element.
iCalendar“VTIMEZONE”组件。该规范定义了一个新的CALDAV:timezone id XML元素，可以用作CALDAV:timezone XML元素的替代品；它允许通过时区标识符设置特定的时区，而不是提供完整的“VTIMEZONE”组件（见第6.2节）。服务器必须支持客户端提供时区标识符的能力，以便在使用此新元素的日历查询“报告”中使用。
If a client attempts use of a CALDAV:timezone-id XML element with a value that does not correspond to a time zone that is known to the server, the server MUST reject the request with a CALDAV:valid-timezone precondition error. In such cases, clients MAY repeat the request using the CALDAV:timezone XML element instead, and provide the full iCalendar data for the time zone being used.
如果客户端尝试使用CALDAV:timezone id XML元素，但该元素的值与服务器已知的时区不一致，则服务器必须以CALDAV:valid timezone前提条件错误拒绝该请求。在这种情况下，客户端可以使用CALDAV:timezone XML元素来重复请求，并为所使用的时区提供完整的iCalendar数据。
When a server advertises the "calendar-no-timezone" field in a DAV response header field (as per Section 3.1.1):
当服务器在DAV响应标头字段中播发“日历无时区”字段时（根据第3.1.1节）：
1. Clients SHOULD include an HTTP "CalDAV-Timezones" request header field with a value of "F" to ensure that the CalDAV server does not include "VTIMEZONE" components in any iCalendar data returned in a response (see Section 3.1.3), for those time zones whose identifier is one provided by any of the advertised time zone distribution servers (see Section 3.1.2). In this case, clients will have to retrieve the missing standard time zone definitions either from their own cache of standard time zones or from the set of time zone distribution servers advertised by the CalDAV server (see Section 3.1.2).
1. 客户端应包含一个HTTP“CalDAV Timezones”请求标头字段，该字段的值为“F”，以确保CalDAV服务器在响应中返回的任何iCalendar数据（请参阅第3.1.3节）中不包含“VTIMEZONE”组件，这些时区的标识符由任何播发的时区分发服务器提供（参见第3.1.2节）。在这种情况下，客户端必须从其自己的标准时区缓存或CalDAV服务器公布的一组时区分发服务器中检索缺少的标准时区定义（参见第3.1.2节）。
2. Clients can include an HTTP "CalDAV-Timezones" request header field with a value of "T" to ensure that the CalDAV server does include all "VTIMEZONE" components in any iCalendar data returned in a response (see Section 3.1.3).
2. 客户端可以包含一个值为“T”的HTTP“CalDAV Timezones”请求标头字段，以确保CalDAV服务器在响应中返回的任何iCalendar数据中包含所有“VTIMEZONE”组件（请参阅第3.1.3节）。
3. Clients can expect servers not to include standard time zone definitions in any iCalendar data they receive from the server, if there is no "CalDAV-Timezones" request header field in the HTTP request. Clients MUST retrieve standard time zone definitions either from its own cache of standard time zones or from the set of time zone distribution servers advertised by the CalDAV server (see Section 3.1.2).
3. 如果HTTP请求中没有“CalDAV Timezones”请求头字段，客户端可以期望服务器在从服务器接收的任何iCalendar数据中不包含标准时区定义。客户端必须从其自身的标准时区缓存或CalDAV服务器公布的一组时区分发服务器中检索标准时区定义（参见第3.1.2节）。
4. Clients SHOULD remove standard time zone definitions from iCalendar data they send to the server, provided the corresponding time zone identifier is one available on any of the server's advertised time zone distribution servers (see Section 3.1.2).
4. 如果相应的时区标识符在服务器的任何播发时区分发服务器上可用，则客户端应从发送到服务器的iCalendar数据中删除标准时区定义（请参见第3.1.2节）。
5. Clients MUST send time zone definitions in iCalendar data for any time zone identifiers not available via any of the server's advertised time zone distribution servers. Clients MUST be prepared for the server to reject such data or map the time zone to one in the set of standard time zones provided by the server's associated time zone services (as per Section 3.1.4).
5. 客户端必须在iCalendar数据中发送任何时区标识符的时区定义，这些时区标识符不能通过服务器的任何播发时区分发服务器使用。客户端必须为服务器拒绝此类数据或将时区映射到服务器相关时区服务提供的标准时区集中的一个时区做好准备（根据第3.1.4节）。
6. Clients SHOULD make use of the CALDAV:calendar-timezone-id WebDAV property (see Section 3.1.5) and CalDAV:timezone-id XML element (see Section 3.1.6) for specifying default and specific time zones to use in calendar queries executed by the server.
6. 客户端应使用CALDAV:calendar timezone id WebDAV属性（请参见第3.1.5节）和CALDAV:timezone id XML元素（请参见第3.1.6节）指定服务器执行的日历查询中使用的默认时区和特定时区。
Name: timezone-service-set
名称：时区服务集
Namespace: urn:ietf:params:xml:ns:caldav
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies one or more time zone data distribution servers being used by the CalDAV server to provide standard time zone data.
目的：指定CalDAV服务器用于提供标准时区数据的一个或多个时区数据分发服务器。
Conformance: This property SHOULD be defined on CalDAV calendar home collection resources. If defined, it SHOULD NOT be returned by a "PROPFIND" DAV:allprop request (as defined in Section 14.2 of [RFC4918]).
一致性：应在CalDAV日历主集合资源上定义此属性。如果已定义，则不应通过“PROPFIND”DAV:allprop请求返回（如[RFC4918]第14.2节所定义）。
Description: The CALDAV:timezone-service-set property lists one or more time zone data distribution servers that the CalDAV server is using to provide its set of time zone data. See Section 3.1.2 for more details.
描述：CALDAV:timezone服务集属性列出CALDAV服务器用于提供其时区数据集的一个或多个时区数据分发服务器。详见第3.1.2节。
Definition:
定义：
<!ELEMENT timezone-service-set (DAV:href+)> DAV:href value: URI of a time zone data distribution service as defined by this specification.
<!元素时区服务集（DAV:href+）>DAV:href值：此规范定义的时区数据分发服务的URI。
Example:
例子：
<C:timezone-service-set
xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:href>https://timezones.example.com</D:href>
</C:timezone-service-set>
<C:timezone-service-set
xmlns:D="DAV:"
xmlns:C="urn:ietf:params:xml:ns:caldav">
<D:href>https://timezones.example.com</D:href>
</C:timezone-service-set>
Name: calendar-timezone-id
名称：日历时区id
Namespace: urn:ietf:params:xml:ns:caldav
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies a time zone identifier for a calendar collection.
目的：指定日历集合的时区标识符。
Conformance: This property SHOULD be defined on all resources where the CALDAV:calendar-timezone property is also defined. If defined, it SHOULD NOT be returned by a "PROPFIND" DAV:allprop request (as defined in Section 14.2 of [RFC4918]).
一致性：应该在所有还定义了CALDAV:calendar时区属性的资源上定义此属性。如果已定义，则不应通过“PROPFIND”DAV:allprop请求返回（如[RFC4918]第14.2节所定义）。
Description: The CALDAV:calendar-timezone-id property is used as an alternative to the CALDAV:calendar-timezone property (see Section 5.3.2 of [RFC4791]). It allows clients to set the default time zone using only a time zone identifier. It also indicates to the client the time zone identifier of the current default time zone. See Section 3.1.5 for more details.
说明：CALDAV:calendar时区id属性用作CALDAV:calendar时区属性的替代项（请参见[RFC4791]第5.3.2节）。它允许客户端仅使用时区标识符设置默认时区。它还向客户端指示当前默认时区的时区标识符。详见第3.1.5节。
Definition:
定义：
<!ELEMENT calendar-timezone-id (#PCDATA)> PCDATA value: a time zone identifier.
<!元素日历时区id（#PCDATA）>PCDATA值：时区标识符。
Example:
例子：
<C:calendar-timezone-id
xmlns:C="urn:ietf:params:xml:ns:caldav">US-Eastern<
/C:calendar-timezone-id>
<C:calendar-timezone-id
xmlns:C="urn:ietf:params:xml:ns:caldav">US-Eastern<
/C:calendar-timezone-id>
The CALDAV:calendar-query XML element, defined in Section 9.5 of [RFC4791], is modified to allow use of the CALDAV:timezone-id XML element as follows.
[RFC4791]第9.5节中定义的CALDAV:calendar query XML元素经过修改，允许使用CALDAV:timezone id XML元素，如下所示。
Definition:
定义：
<!ELEMENT calendar-query ((DAV:allprop |
DAV:propname |
DAV:prop)?, filter,
(timezone | timezone-id)?)>
<!ELEMENT calendar-query ((DAV:allprop |
DAV:propname |
DAV:prop)?, filter,
(timezone | timezone-id)?)>
Name: timezone-id
名称：时区id
Namespace: urn:ietf:params:xml:ns:caldav
Namespace: urn:ietf:params:xml:ns:caldav
Purpose: Specifies the time zone identifier for a time zone component to use when determining the results of a report.
目的：指定时区组件在确定报告结果时要使用的时区标识符。
Description: The CALDAV:timezone-id XML element is used as an alternative to the CALDAV:timezone XML element (see Section 9.8 of [RFC4791]) in calendar query reports, to allow a client to specify a time zone using a time zone identifier rather than providing the full iCalendar time zone data. See Section 3.1.6 for more details.
描述：CALDAV:timezone id XML元素用作日历查询报告中CALDAV:timezone XML元素（请参阅[RFC4791]第9.8节）的替代元素，以允许客户端使用时区标识符指定时区，而不是提供完整的iCalendar时区数据。详见第3.1.6节。
Definition:
定义：
<!ELEMENT timezone-id (#PCDATA)> PCDATA value: a time zone identifier.
<!元素时区id（#PCDATA）>PCDATA值：时区标识符。
The "CalDAV-Timezones" request header field provides a way for a client to indicate to the server whether it wants "VTIMEZONE" components returned in any iCalendar data that is part of the HTTP response. The value "T" indicates that the client wants time zone data returned; the value "F" indicates that it does not.
“CalDAV Timezones”请求标头字段为客户端提供了一种向服务器指示其是否希望在作为HTTP响应一部分的任何iCalendar数据中返回“VTIMEZONE”组件的方法。值“T”表示客户端希望返回时区数据；值“F”表示它不存在。
CalDAV-Timezones = "T" / "F"
CalDAV-Timezones = "T" / "F"
Example:
例子：
CalDAV-Timezones: F
CalDAV时区：F
This specifications adds time zone data distribution service [RFC7808] servers into the overall calendaring and scheduling client/ server architecture, as a critical component, and thus adds a new vector of attack against such systems. As such, administrators of CalDAV servers SHOULD ensure that any advertised time zone distribution servers are protected by a level of security commensurate with all the other components in the system.
该规范将时区数据分发服务[RFC7808]服务器作为关键组件添加到整个日历和调度客户机/服务器体系结构中，从而增加了针对此类系统的新攻击向量。因此，CalDAV服务器的管理员应确保任何公布的时区分发服务器受到与系统中所有其他组件相称的安全级别的保护。
Besides the above point, this specification does not introduce any new security concerns beyond those addressed in CalDAV [RFC4791], iCalendar [RFC5545], and the time zone data distribution service [RFC7808].
除上述问题外，本规范未引入任何新的安全问题，这些问题超出了CalDAV[RFC4791]、iCalendar[RFC5545]和时区数据分发服务[RFC7808]中所述的问题。
The privacy recommendations in Section 9 of the time zone data distribution service specification [RFC7808] SHOULD be used to ensure that details of clients' interactions with CalDAV servers are not exposed to potential network observers. Note that since events can be delivered to a calendar user from an outside source (e.g., using iTIP [RFC5546]), and an attacker could create a calendar event with, e.g., a time zone identifier that is fake or rarely used and that could be used to monitor the calendar user's activity and interaction with others, this specification increases the importance of using the mitigations of privacy issues discussed in [RFC7808].
时区数据分发服务规范[RFC7808]第9节中的隐私建议应用于确保客户端与CalDAV服务器交互的细节不会暴露给潜在的网络观察员。请注意，由于事件可以从外部来源（例如，使用iTIP[RFC5546]）传递给日历用户，并且攻击者可以创建一个日历事件，例如，时区标识符是假的或很少使用，可用于监视日历用户的活动和与其他人的交互，本规范增加了使用[RFC7808]中讨论的隐私问题缓解措施的重要性。
The message header field below has been added to the Permanent Message Header Field Registry (see [RFC3864]).
下面的消息头字段已添加到永久消息头字段注册表中（请参阅[RFC3864]）。
Header field name: CalDAV-Timezones
标题字段名称：CalDAV时区
Applicable protocol: http
适用协议：http
Status: standard
状态：标准
Author/Change controller: IETF
作者/变更控制员：IETF
Specification document(s): this document (Section 7.1)
规范文件：本文件（第7.1节）
Related information: none
相关信息：无
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，DOI 10.17487/RFC2119，1997年3月<http://www.rfc-editor.org/info/rfc2119>.
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration Procedures for Message Header Fields", BCP 90, RFC 3864, DOI 10.17487/RFC3864, September 2004, <http://www.rfc-editor.org/info/rfc3864>.
[RFC3864]Klyne，G.，Nottingham，M.和J.Mogul，“消息头字段的注册程序”，BCP 90，RFC 3864，DOI 10.17487/RFC3864，2004年9月<http://www.rfc-editor.org/info/rfc3864>.
[RFC4791] Daboo, C., Desruisseaux, B., and L. Dusseault, "Calendaring Extensions to WebDAV (CalDAV)", RFC 4791, DOI 10.17487/RFC4791, March 2007, <http://www.rfc-editor.org/info/rfc4791>.
[RFC4791]Daboo，C.，Desruisseaux，B.，和L.Dusseault，“WebDAV（CalDAV）日历扩展”，RFC 4791，DOI 10.17487/RFC47912007年3月<http://www.rfc-editor.org/info/rfc4791>.
[RFC4918] Dusseault, L., Ed., "HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)", RFC 4918, DOI 10.17487/RFC4918, June 2007, <http://www.rfc-editor.org/info/rfc4918>.
[RFC4918]Dusseault，L.，Ed.“Web分布式创作和版本控制（WebDAV）的HTTP扩展”，RFC 4918，DOI 10.17487/RFC4918，2007年6月<http://www.rfc-editor.org/info/rfc4918>.
[RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and Scheduling Core Object Specification (iCalendar)", RFC 5545, DOI 10.17487/RFC5545, September 2009, <http://www.rfc-editor.org/info/rfc5545>.
[RFC5545]Desruisseaux，B.，Ed.“互联网日历和调度核心对象规范（iCalendar）”，RFC 5545，DOI 10.17487/RFC5545，2009年9月<http://www.rfc-editor.org/info/rfc5545>.
[RFC6638] Daboo, C. and B. Desruisseaux, "Scheduling Extensions to CalDAV", RFC 6638, DOI 10.17487/RFC6638, June 2012, <http://www.rfc-editor.org/info/rfc6638>.
[RFC6638]Daboo，C.和B.Desruisseaux，“CalDAV的计划扩展”，RFC 6638，DOI 10.17487/RFC6638，2012年6月<http://www.rfc-editor.org/info/rfc6638>.
[RFC7808] Douglass, M. and C. Daboo, "Time Zone Data Distribution Service", RFC 7808, DOI 10.17487/RFC7808, March 2016, <http://www.rfc-editor.org/info/rfc7808>.
[RFC7808]Douglass，M.和C.Daboo，“时区数据分发服务”，RFC 7808，DOI 10.17487/RFC78082016年3月<http://www.rfc-editor.org/info/rfc7808>.
[RFC5546] Daboo, C., Ed., "iCalendar Transport-Independent Interoperability Protocol (iTIP)", RFC 5546, DOI 10.17487/RFC5546, December 2009, <http://www.rfc-editor.org/info/rfc5546>.
[RFC5546]Daboo，C.，Ed.“iCalendar传输独立互操作性协议（iTIP）”，RFC 5546，DOI 10.17487/RFC5546，2009年12月<http://www.rfc-editor.org/info/rfc5546>.
[RFC6047] Melnikov, A., Ed., "iCalendar Message-Based Interoperability Protocol (iMIP)", RFC 6047, DOI 10.17487/RFC6047, December 2010, <http://www.rfc-editor.org/info/rfc6047>.
[RFC6047]Melnikov，A.，Ed.“基于iCalendar消息的互操作性协议（iMIP）”，RFC 6047，DOI 10.17487/RFC6047，2010年12月<http://www.rfc-editor.org/info/rfc6047>.
[RFC6557] Lear, E. and P. Eggert, "Procedures for Maintaining the Time Zone Database", BCP 175, RFC 6557, DOI 10.17487/RFC6557, February 2012, <http://www.rfc-editor.org/info/rfc6557>.
[RFC6557]Lear，E.和P.Eggert，“时区数据库维护程序”，BCP 175，RFC 6557，DOI 10.17487/RFC6557，2012年2月<http://www.rfc-editor.org/info/rfc6557>.
Acknowledgments
致谢
Thanks to Mike Douglass, Andrew McMillan, and Ken Murchison. This specification came about via discussions at the Calendaring and Scheduling Consortium.
感谢迈克·道格拉斯、安德鲁·麦克米兰和肯·默奇森。该规范是通过日历和日程安排联盟的讨论制定的。
Author's Address
作者地址
Cyrus Daboo Apple Inc. 1 Infinite Loop Cupertino, CA 95014 United States
Cyrus Daboo苹果公司，美国加利福尼亚州库比蒂诺市无限环路1号，邮编95014
Email: cyrus@daboo.name
URI: http://www.apple.com/
Email: cyrus@daboo.name
URI: http://www.apple.com/