Network Working Group E. Lear
Internet-Draft Cisco Systems GmbH
Intended status: Best Current Practice P. Eggert
Expires: October 13, 2011 UCLA
April 11, 2011

IANA Procedures for Maintaining the Timezone Database


Timezone information serves as a basic protocol element in protocols, such as the calendaring suite and DHCP. The Timezone (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 IANA 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 timezone community. The intent of this memo is, to the extent possible, document existing practice and provide a means to ease succession.

Status of this Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on October 13, 2011.

Copyright Notice

Copyright (c) 2011 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 ( 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 timezone information. Timezone names are used in DHCP to configure devices with correct local time [RFC4833]. Timezone names can appear in the TZID field of VEVENTs [RFC5545]. The normative reference for these values is the TZ Database [TZDB]. Since the early 1980s, that database, which has been in use on nearly all UNIX systems, Java systems, and other sorts of systems has been hosted at the National Institutes of Health. The database consists of both historic and current entries for geographies throughout the world. Associated with the database is a reference implementation of functions that can be used to convert time values.

The database has been maintained by volunteers who participate in a mailing list that is 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 IANA provides registry services to the Internet community. Those registries are coordinated by technical experts who are designated by the Internet Engineering Steering Group (IESG). The IANA is also well suited as a distribution platform for the TZ Database itself.

The IANA has for quite some time had the capability to maintain designated expert mailing lists. The TZ mailing list would fit nicely just as such a list.

1.1. 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 in RFC 2119 [RFC2119].

TZ Database:
The TimeZone 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 maintaining the TZ mailing list. The TZ Coordinator is an IANA Designated Expert, as defined in Section 3.2 of [RFC5226]. 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 work with the IANA 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 for the 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.

2. The TZ Mailing List

For many years the TZ mailing list at the NIH 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 will be transitioned to the IANA mail server. 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 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. 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. The release itself today consists of several archive files that are downloaded from a well known location.

Moving forward, the TZ database and supporting code SHOULD be signed prior to release using a well known key, along with any appropriate supporting information and distributed from a well known location that is advertised by IANA in a manner of its choosing.

The criteria for updates to the database are as follows:

  1. New keys are only to be created when the region a key was envisioned to cover is not accurately reflected by an existing key.
  2. In order to correct historical inaccuracies, a new key MAY be added when it is necessary to indicate what was the consensus view at given time and location. Such keys 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 timezone policy 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:

In any of these cases, members of the community should raise the issue on the TZ list. If a rough consensus can be formed easily, and quickly, then the results should be presented to the IESG for comment and review. The IESG selects the TZ Coordinator(s). The IESG will use rough consensus of the TZ mailing list as their primary guide to further action, when it exists, and whatever other means they have at their disposal, when rough consensus cannot be found.

5. Appealing Database Decisions

The TZ Coordinator makes decisions based on expertise, as well as with guidance from the TZ mailing lists. While individual decisions MAY be appealed to the IESG, the IESG MUST give great deference to the designated expert in its considerations. In particular, apellants MUST show material harm from the decision, and that the decision is materially in error. The IESG is not a normal avenue for appeals of specific decisions of the TZ Coordinator, but rather a last resort when a TZ Coordinator is thought not to be functioning in an appropriate way.

6. Maintenance and Distribution of Reference Code

Currently the maintainer of the TZ database also maintains reference code, most of which is public domain. Several files from this software are currently distributed under license. Where they exist, licenses SHALL NOT be changed. IANA SHALL allow for the downloading of this reference code. The reference implementation shall be distributed along with an associated cryptographic signature of an identity that IANA will publish.

7. Database Ownership

The database itself is public domain. Should claims be made and substantiated against the database, the IANA will act in accordance with all competent court orders. No ownership claims will be made by IANA 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.

8. IANA Considerations

The IANA SHALL assist the IESG, as required, in filling of the TZ Coordinator, based on the procedures set forth above. The IANA SHALL act as 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. The IANA SHALL provide the TZ Coordinator with appropriate access to maintain the database, as well as necessary tooling that may be required, so long as no direct software costs are incurred. Both current and historical versions of the database will be stored and distributed via HTTP/HTTPs. IANA will be operationally responsible for the security of the system upon which the database resides.

The IANA SHALL also maintain a cryptographic identity that is used to sign the database, and that will survive a change of TZ Coordinators.

9. Security Considerations

The distribution of the database is currently not secured. This memo states that moving forward the TZ database SHOULD be distributed with a valid cryptographic signature.

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, Elwin Davies, Alfred Hoenes, and Ted Hardie for the improvements they made to this document. A special acknowledgment should be given to Arthur David Olson for his excellent stewardship.

11. References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4833] Lear, E. and P. Eggert, "Timezone Options for DHCP", RFC 4833, April 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.
[RFC5545] Desruisseaux, B., "Internet Calendaring and Scheduling Core Object Specification (iCalendar)", RFC 5545, September 2009.
[TZDB] Eggert, P and A.D. Olson, "Sources for Time Zone and Daylight Saving Time Data", .

Appendix A. Changes

Authors' Addresses

Eliot Lear Cisco Systems GmbH Richtistrasse 7 Wallisellen, ZH CH-8304 Switzerland Phone: +41 1 878 9200 EMail:
Paul Eggert UCLA Computer Science Department 4532J Boelter Hall Los Angeles, CA 90095 USA Phone: +1 310 267 2254 EMail:

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