The Time Zone Information Format (TZif)
draft-murchison-tzdist-tzif-16

Document Type Active Internet-Draft (individual in art area)
Last updated 2018-12-07 (latest revision 2018-12-05)
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Independent Submission                                          A. Olson
Internet-Draft
Intended status: Standards Track                               P. Eggert
Expires: June 8, 2019                                               UCLA
                                                            K. Murchison
                                                                FastMail
                                                        December 5, 2018

                The Time Zone Information Format (TZif)
                     draft-murchison-tzdist-tzif-16

Abstract

   This document specifies the Time Zone Information Format (TZif) for
   representing and exchanging time zone information, independent of any
   particular service or protocol.  Two MIME media types for this format
   are also defined.

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   This Internet-Draft will expire on June 8, 2019.

Copyright Notice

   Copyright (c) 2018 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
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   (https://trustee.ietf.org/license-info) in effect on the date of
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Olson, et al.             Expires June 8, 2019                  [Page 1]
Internet-Draft                    TZif                     December 2018

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
   3.  The Time Zone Information Format (TZif) . . . . . . . . . . .   5
     3.1.  TZif Header . . . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  TZif Data Block . . . . . . . . . . . . . . . . . . . . .   8
     3.3.  TZif Footer . . . . . . . . . . . . . . . . . . . . . . .  11
       3.3.1.  TZ String Extensions  . . . . . . . . . . . . . . . .  12
   4.  Interoperability Considerations . . . . . . . . . . . . . . .  13
   5.  Use with the Time Zone Data Distribution Service  . . . . . .  14
     5.1.  Truncating TZif Files . . . . . . . . . . . . . . . . . .  14
     5.2.  Example TZDIST Request for TZif Data  . . . . . . . . . .  15
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  17
   7.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  17
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  17
     8.1.  application/tzif  . . . . . . . . . . . . . . . . . . . .  17
     8.2.  application/tzif-leap . . . . . . . . . . . . . . . . . .  18
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  19
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  19
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  19
     10.2.  Informative References . . . . . . . . . . . . . . . . .  20
     10.3.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .  21
   Appendix A.  Common Interoperability Issues . . . . . . . . . . .  21
   Appendix B.  Example TZif Files . . . . . . . . . . . . . . . . .  24
     B.1.  Version 1 File Representing UTC (with Leap Seconds) . . .  24
     B.2.  Version 2 File Representing Pacific/Honolulu  . . . . . .  28
     B.3.  Truncated Version 3 File Representing Asia/Jerusalem  . .  32
   Appendix C.  Change History (To be removed by RFC Editor before
                publication) . . . . . . . . . . . . . . . . . . . .  34
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  37

1.  Introduction

   Time zone data typically consists of offsets from Universal Time
   (UT), daylight saving transition rules, one or more local time
   designations (acronyms or abbreviations), and optional leap second
   adjustments.  One such format for conveying this information is
   iCalendar [RFC5545].  It is a text-based format used by calendaring
   and scheduling systems.

   This document specifies the widely deployed Time Zone Information
   Format (TZif).  It is a binary format used by most UNIX systems to
   calculate local time.  This format was introduced in the 1980s and
   has evolved since then into multiple upward-compatible versions.
   There is a wide variety of interoperable software [tz-link] capable
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