Entity Time This specification defines an XMPP protocol extension for communicating the local time of an entity, including the time in UTC according to the entity as well as the offset from UTC. The time format itself conforms to the dateTime profile of ISO 8601 defined in XEP-0082. This XMPP Extension Protocol is copyright © 1999 – 2024 by the XMPP Standards Foundation (XSF). Permission is hereby granted, free of charge, to any person obtaining a copy of this specification (the "Specification"), to make use of the Specification without restriction, including without limitation the rights to implement the Specification in a software program, deploy the Specification in a network service, and copy, modify, merge, publish, translate, distribute, sublicense, or sell copies of the Specification, and to permit persons to whom the Specification is furnished to do so, subject to the condition that the foregoing copyright notice and this permission notice shall be included in all copies or substantial portions of the Specification. Unless separate permission is granted, modified works that are redistributed shall not contain misleading information regarding the authors, title, number, or publisher of the Specification, and shall not claim endorsement of the modified works by the authors, any organization or project to which the authors belong, or the XMPP Standards Foundation. ## NOTE WELL: This Specification is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. ## In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages. This XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which can be found at <https://xmpp.org/about/xsf/ipr-policy> or obtained by writing to XMPP Standards Foundation, P.O. Box 787, Parker, CO 80134 USA). 0202 Final Standards Track Standards Council XMPP Core XEP-0082 XEP-0090 time http://www.xmpp.org/schemas/time.xsd Peter Saint-Andre stpeter@stpeter.im stpeter@jabber.org https://stpeter.im/ Maciej Niedzielski machekku@uaznia.net machekku@uaznia.net 2.0 2009-09-11 psa

Per a vote of the XMPP Council, advanced specification from Draft to Final.

 1.0 2007-03-28 psa

Per a vote of the XMPP Council, advanced from Experimental to Draft.

 0.2 2007-03-19 psa

Added service discovery section.

 0.1 2006-12-20 psa

Initial version; further specified security considerations; per Council feedback, removed tz and display elements.

 0.0.2 2006-12-19 psa

Clarified text; adjusted protocol definition; corrected schema.

 0.0.1 2006-12-05 mn

First draft.

Although the XMPP protocol extension defined in Legacy Entity Time (XEP-0090) XEP-0090: Legacy Entity Time <https://xmpp.org/extensions/xep-0090.html>. provides a way to discover the time at another entity, it has several limitations:

To overcome these limitations, this document defines a replacement for Legacy Entity Time (XEP-0090) XEP-0090: Legacy Entity Time <https://xmpp.org/extensions/xep-0090.html>. which enables communication of an entity's UTC time and numeric time zone offset while adhering to XEP-0082.

The protocol defined herein provides a standard way for XMPP entities to exchange information about the local time. The information is communicated in a request/response pair using an <iq/> element that contains a <time/> element qualified by the 'urn:xmpp:time' namespace. The following children of the <time/> element are defined for use in IQ stanzas of type 'result':

Element Definition Inclusion
<tzo/> The entity's numeric time zone offset from UTC. The format MUST conform to the Time Zone Definition (TZD) specified in XMPP Date and Time Profiles (XEP-0082) XEP-0082: XMPP Date and Time Profiles <https://xmpp.org/extensions/xep-0082.html>.. REQUIRED
<utc/> The UTC time according to the responding entity. The format MUST conform to the dateTime profile specified in XMPP Date and Time Profiles (XEP-0082) XEP-0082: XMPP Date and Time Profiles <https://xmpp.org/extensions/xep-0082.html>. and MUST be expressed in UTC. REQUIRED
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The standard error conditions described in Error Condition Mappings (XEP-0086) XEP-0086: Error Condition Mappings <https://xmpp.org/extensions/xep-0086.html>. apply (e.g., <service-unavailable/> if the entity does not support the namespace).

If an entity supports the Entity Time protocol, it MUST report that by including a service discovery feature of "urn:xmpp:time" in response to a Service Discovery (XEP-0030) XEP-0030: Service Discovery <https://xmpp.org/extensions/xep-0030.html>. information request:

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This protocol was designed in a way that makes migration from Legacy Entity Time (XEP-0090) XEP-0090: Legacy Entity Time <https://xmpp.org/extensions/xep-0090.html>. straightforward. This document specifies a different format for the XML character data of the <utc> element (compliant with XEP-0082) and specifies a new <tzo> element for the numeric offset from UTC, while removing the formerly optional and effectively useless <display/> and <tz/> elements.

Implementations that support Legacy Entity Time (XEP-0090) XEP-0090: Legacy Entity Time <https://xmpp.org/extensions/xep-0090.html>. should support the protocol defined herein as soon as possible, but should continue to support the protocol defined in XEP-0090 for backwards compatibility until the status of that specification is changed to Obsolete.

Revealing an entity's numeric time zone offset may leak limited information about the entity's current location. If the entity's understanding of UTC is far off from actual UTC, revealing that discrepancy may make it possible for an attacker to send XML stanzas that appear to be in the past or future even though they are not; therefore an entity should use the Network Time Protocol (RFC 958 RFC 958: Network Time Protocol (NTP) <http://tools.ietf.org/html/rfc0958>.) or a similar technology to stay synchronized with actual UTC.

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) The Internet Assigned Numbers Authority (IANA) is the central coordinator for the assignment of unique parameter values for Internet protocols, such as port numbers and URI schemes. For further information, see <http://www.iana.org/>..

The XMPP Registrar The XMPP Registrar maintains a list of reserved protocol namespaces as well as registries of parameters used in the context of XMPP extension protocols approved by the XMPP Standards Foundation. For further information, see <https://xmpp.org/registrar/>. includes 'urn:xmpp:time' in its registry of protocol namespaces (see <https://xmpp.org/registrar/namespaces.html>).

 The protocol documented by this schema is defined in XEP-0202: http://www.xmpp.org/extensions/xep-0202.html ]]>