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Internet Engineering Task Force (IETF)                           E. LearRequest for Comments: 6557                            Cisco Systems GmbHBCP: 175                                                       P. EggertCategory: Best Current Practice                                     UCLAISSN: 2070-1721                                            February 2012Procedures for Maintaining the Time Zone DatabaseAbstract   Time zone information serves as a basic protocol element in   protocols, such as the calendaring suite and DHCP.  The Time Zone   (TZ) Database specifies the indices used in various protocols, as   well as their semantic meanings, for all localities throughout the   world.  This database has been meticulously maintained and   distributed free of charge by a group of volunteers, coordinated by a   single volunteer who is now planning to retire.  This memo specifies   procedures involved with maintenance of the TZ database and   associated code, including how to submit proposed updates, how   decisions for inclusion of those updates are made, and the selection   of a designated expert by and for the time zone community.  The   intent of this memo is, to the extent possible, to document existing   practice and provide a means to ease succession of the database   maintainers.Status of This Memo   This memo documents an Internet Best Current Practice.   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   BCPs is available inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc6557.Lear & Eggert             Best Current Practice                 [Page 1]

RFC 6557           Maintaining the Time Zone Database      February 2012Copyright Notice   Copyright (c) 2012 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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.1.  Introduction   The IETF has specified several standards that make use of time zone   information.  Time zone names are used in DHCP to configure devices   with correct local time [RFC4833].  Time zone names can appear in the   TZID field of calendaring VEVENTs [RFC5545].  The normative reference   for these values is the TZ Database [TZDB].  From the early 1980s   through 2011, that database, which has been in use on nearly all UNIX   systems, Java systems, and other sorts of systems, was hosted at the   U.S. National Institutes of Health (NIH).  The database consists of   both historic and current entries for geographies throughout the   world.  Associated with the database is a reference implementation of   ISO/IEC 9899 C [ISO9899C] and IEEE 1003.1 [IEEE1003.1] POSIX time   functions that can be used to convert time values.   The database was previously maintained by volunteers who participated   in the <tz@elsie.nci.nih.gov> mailing list that was also hosted at   the NIH.  The database itself is updated approximately twenty times   per year, depending on the year, based on information these experts   provide to the maintainer.  Arthur David Olson has maintained the   database, coordinated the mailing list, and provided a release   platform since the database's inception.  With his retirement now   approaching, it is necessary to provide a means for this good work to   continue.   The time zone community has requested that the IETF adopt the ongoing   maintenance of the Time Zone Database.  The time zone community would   like the IETF to maintain it in a consistent fashion to its   administration of the Internet protocol parameters and values.Lear & Eggert             Best Current Practice                 [Page 2]

RFC 6557           Maintaining the Time Zone Database      February 20121.1.  Terminology   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 inRFC 2119 [RFC2119].   IANA (Internet Assigned Numbers Authority):  For purposes of this      RFC, IANA is a role, not an organization.  The IANA Considerations      defined in this RFC will be provided by the Internet Corporation      for Assigned Names and Numbers (ICANN) in accordance with the      IETF-ICANN "Memorandum of Understanding Concerning Technical Work      of the Internet Assigned Numbers Authority", which was signed and      ratified in March of 2000[RFC2860].   TZ Database:  The Time Zone Database, sometimes referred to as the      "Olson Database".  This database consists of information about      offsets from UTC for different localities, including daylight      saving time (DST) transition information.   TZ Coordinator:  The person or people who maintain and manage release      of the TZ Database.  The TZ Coordinator also has responsibility      for managing the TZ mailing list.  The TZ Coordinator is an IANA      Designated Expert, as defined inSection 3.2 of [RFC5226], except      as regards to appeals, as discussed inSection 5 of this document.      Roughly speaking, this means that the IESG will choose one or more      experts to manage the TZ database, code, and mailing list.  The TZ      Coordinator will also lead work to develop appropriate service      metrics.  There SHALL be a single lead individual and at least one      backup individual for this function.   TZ mailing list:  The forum where matters relating to the TZ database      and supporting code are discussed.   The rest of this document specifies the following:   1.  Transferring and maintenance of the TZ mailing list;   2.  Procedures for selecting a technical expert who will play the       role of TZ Coordinator and release manager for the TZ database;   3.  Procedures for updating the TZ database;   4.  Maintenance and ownership of reference code; and   5.  Ownership of the database.Lear & Eggert             Best Current Practice                 [Page 3]

RFC 6557           Maintaining the Time Zone Database      February 20122.  The TZ Mailing List   For many years, the TZ mailing list has been the forum where   discussion of changes to the TZ database and support files would take   place.  In addition, the TZ mailing list is used to announce releases   of the database.  Currently, the TZ mailing list is administered by   the TZ Coordinator.   This list membership, formerly at the NIH, has been transitioned to   the IANA mail server.  Its address, moving forward, is <tz@iana.org>.   Subscriptions are processed at   <https://mm.icann.org/mailman/listinfo/tz/>.  The TZ Coordinator will   continue to manage the list.  While the TZ Coordinator may establish   other rules of governance for the list, members of that list will be   informed that a condition of participating on the list is that all   contributions to the list are released to the public domain, and that   by placing their contribution in the public domain, contributors   waive forever any intellectual property claims.   The list will be used just as it has been: to learn of, discuss, and   confirm TZ definition changes, as well as to serve as an announcement   list for new versions of the database.3.  Making Updates to the TZ Database   Updates to the TZ database are made by the TZ Coordinator in   consultation with the TZ mailing list.  The TZ Coordinator is   empowered to decide, as the designated expert, appropriate changes,   but SHOULD take into account views expressed on the mailing list.   The TZ Coordinator will also decide the timing of database releases.   Today, the release itself consists of several archive files that are   downloaded from a well-known location.   Moving forward, the TZ database, supporting code, and any appropriate   supporting information SHOULD be cryptographically signed prior to   release using well known public keys, along with any appropriate   supporting information and distributed from   <http://www.iana.org/time-zones>.   The criteria for updates to the database include the following:   1.  New TZ names (e.g., locations) are only to be created when the       scope of the region a name was envisioned to cover is no longer       accurate.Lear & Eggert             Best Current Practice                 [Page 4]

RFC 6557           Maintaining the Time Zone Database      February 2012   2.  In order to correct historical inaccuracies, a new TZ name MAY be       added when it is necessary to indicate what was the consensus       view at a given time and location.  Such TZ names are usually not       added when the inaccuracy was prior to 1970.   3.  Changes to existing entries SHALL reflect the consensus on the       ground in the region covered by that entry.   To be clear, the TZ Coordinator SHALL NOT set time zone policy for a   region but use judgment and whatever available sources exist to   assess what the average person on street would think the time   actually is, or in case of historical corrections, was.4.  Selecting or Replacing a TZ Coordinator   From time to time it will be necessary to appoint a new TZ   Coordinator.  This could occur for a number of reasons:   o  The TZ Coordinator is retiring (as Arthur David Olson is) or has      announced that he or she will be unable to continue to perform the      function;   o  The TZ Coordinator is missing, has become incapacitated, or has      died; or   o  The TZ Coordinator is not performing the function in accordance      with community wishes.   In any of these cases, members of the community should raise the   issue on the TZ mailing list and attempt to reach consensus on a new   candidate to fulfill the role of TZ Coordinator.  If rough consensus   cannot be reached easily, the Area Directors of the IETF Applications   Area should attempt to guide the members of the community to rough   consensus.  The candidate that is agreed upon by the community   through rough consensus shall be presented to the IESG for   confirmation.  If rough consensus cannot be reached, even with   guidance from the Applications Area Directors, the IESG shall use   whatever means it has at its disposal to choose a candidate who in   its best judgment will be able to fulfill the role of TZ Coordinator.5.  Appealing Database Decisions   The TZ Coordinator makes decisions based on expertise, as well as   with guidance from the TZ mailing list.  If a member of the community   has a concern with an individual decision made by the TZ Coordinator   with regard to the TZ database, the individual shall proceed as   follows:Lear & Eggert             Best Current Practice                 [Page 5]

RFC 6557           Maintaining the Time Zone Database      February 2012   1.  Attempt to resolve the concern directly with the TZ Coordinator.   2.  If a resolution cannot be reached directly with the TZ       Coordinator, express the concern to the community and attempt to       achieve rough consensus regarding a resolution on the TZ mailing       list.  The Area Directors of the IETF Applications Area may at       their discretion attempt to guide the members of the community to       rough consensus.   3.  As a last resort, if a resolution cannot be reached on the TZ       mailing list, appeal to the IESG for a resolution.  The appellant       must show that the decision made by the TZ Coordinator (a) was       materially in error and (b) has caused material harm.  In its       deliberations regarding an appeal, the IESG shall weigh all the       evidence presented to it and use its best judgment in determining       a resolution.6.  Maintenance and Distribution of Reference Code   Currently, the maintainer of the TZ database also maintains reference   code, most of which is public domain.  The reference implementation   shall be distributed along with an associated cryptographic signature   verifiable by a public key.  Several files from this software are   currently distributed under license.  Where they exist, licenses   SHALL NOT be changed.7.  Database Ownership   The TZ database itself is not an IETF Contribution or an IETF   document.  Rather it is a pre-existing and regularly updated work   that is in the public domain, and is intended to remain in the public   domain.  Therefore, BCPs 78 [RFC5378] and 79 [RFC3979] do not apply   to the TZ Database or contributions that individuals make to it.   Should any claims be made and substantiated against the TZ Database,   the organization that is providing the IANA Considerations defined in   this RFC, under the memorandum of understanding with the IETF,   currently ICANN, may act in accordance with all competent court   orders.  No ownership claims will be made by ICANN or the IETF Trust   on the database or the code.  Any person making a contribution to the   database or code waives all rights to future claims in that   contribution or in the TZ Database.8.  IANA Considerations   This section documents the following IANA actions:   o  Assistance on request of the IESG in selection of the TZ      Coordinator, based on the procedures set forth above.Lear & Eggert             Best Current Practice                 [Page 6]

RFC 6557           Maintaining the Time Zone Database      February 2012   o  Maintenance of a repository for the TZ database and associated      reference code.  The TZ Coordinator SHALL be named by the IESG as      described above, and will act as the maintainer of the database      and code, as described above.   o  Creation of appropriate access for the TZ Coordinator to maintain      the database, as well as necessary tooling that may be required,      so long as no direct software costs are incurred.   o  Establishment of security of the system upon which the database      resides.  Both current and historical versions of the database      will be stored and distributed via HTTP/HTTPS.   o  Maintenance of a cryptographic private key that is used to sign      the database and that will survive a change of TZ Coordinator.9.  Security Considerations   The distribution of the database is currently not secured.  This memo   states that the TZ database SHOULD be distributed with a valid   cryptographic signature moving forward.10.  Acknowledgments   The authors would like to thank the TZ mailing list for their   remarkable achievements over the many years.  Thanks also to Marshall   Eubanks, S. Moonesamy, Peter Saint-Andre, Alexey Melenkov, Tony   Finch, Elwyn Davies, Alfred Hoenes, Ted Hardie, Barry Leiba, Russ   Housley, Pete Resnick, and Elise Gerich for the improvements they   made to this document.  A special acknowledgment should be given to   Arthur David Olson for his excellent stewardship, to Rob Elz for   continuing that stewardship, and to the team at ICANN for their good   efforts, moving forward.11.  References11.1.  Normative References   [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate                Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC2860]    Carpenter, B., Baker, F., and M. Roberts, "Memorandum of                Understanding Concerning the Technical Work of the                Internet Assigned Numbers Authority",RFC 2860,                June 2000.Lear & Eggert             Best Current Practice                 [Page 7]

RFC 6557           Maintaining the Time Zone Database      February 2012   [RFC5226]    Narten, T. and H. Alvestrand, "Guidelines for Writing an                IANA Considerations Section in RFCs",BCP 26,RFC 5226,                May 2008.   [TZDB]       Eggert, P. and A. Olson, "Sources for Time Zone and                Daylight Saving Time Data", 1987,                <ftp://ftp.iana.org/tz/code/tz-link.htm>.11.2.  Informational References   [IEEE1003.1] Institute of Electrical and Electronics Engineers,                "Standard for Information Technology - Portable                Operating System Interface (POSIX) - Base Definitions",                IEEE Standard 1003.1-2008, December 2008.   [ISO9899C]   International Standards Organization, "Information                technology -- Programming languages -- C", ISO/                IEC Standard 9899:2011, December 2011.   [RFC3979]    Bradner, S., "Intellectual Property Rights in IETF                Technology",BCP 79,RFC 3979, March 2005.   [RFC4833]    Lear, E. and P. Eggert, "Timezone Options for DHCP",RFC 4833, April 2007.   [RFC5378]    Bradner, S. and J. Contreras, "Rights Contributors                Provide to the IETF Trust",BCP 78,RFC 5378,                November 2008.   [RFC5545]    Desruisseaux, B., "Internet Calendaring and Scheduling                Core Object Specification (iCalendar)",RFC 5545,                September 2009.Lear & Eggert             Best Current Practice                 [Page 8]

RFC 6557           Maintaining the Time Zone Database      February 2012Authors' Addresses   Eliot Lear   Cisco Systems GmbH   Richtistrasse 7   CH-8304  Wallisellen   Switzerland   Phone: +41 1 878 9200   EMail: lear@cisco.com   Paul Eggert   UCLA   Computer Science Department   4532J Boelter Hall   Los Angeles, CA  90095   USA   Phone: +1 310 267 2254   EMail: eggert@cs.ucla.eduLear & Eggert             Best Current Practice                 [Page 9]