1. RFC 6557
Internet Engineering Task Force (IETF)                           E. Lear
Request for Comments: 6557                            Cisco Systems GmbH
BCP: 175                                                       P. Eggert
Category: Best Current Practice                                     UCLA
ISSN: 2070-1721                                            February 2012

           Procedures for Maintaining the Time Zone Database


   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

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 in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at

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RFC 6557           Maintaining the Time Zone Database      February 2012

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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.

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

   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.

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1.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 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 in Section 3.2 of [RFC5226], except
      as regards to appeals, as discussed in Section 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.

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2.  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

   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

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   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

   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

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   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.

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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.  References

11.1.  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.

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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,

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.

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Authors' Addresses

   Eliot Lear
   Cisco Systems GmbH
   Richtistrasse 7
   CH-8304  Wallisellen

   Phone: +41 1 878 9200
   EMail: lear@cisco.com

   Paul Eggert
   Computer Science Department
   4532J Boelter Hall
   Los Angeles, CA  90095

   Phone: +1 310 267 2254
   EMail: eggert@cs.ucla.edu

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  1. RFC 6557