The Time Zone Information Format (TZif)
draft-murchison-tzdist-tzif-12

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Last updated 2018-08-08
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Independent Submission                                          A. Olson
Internet-Draft
Intended status: Standards Track                               P. Eggert
Expires: February 9, 2019                                           UCLA
                                                            K. Murchison
                                                                FastMail
                                                          August 8, 2018

                The Time Zone Information Format (TZif)
                     draft-murchison-tzdist-tzif-12

Abstract

   This document defines 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.

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 February 9, 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
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
   3.  The Time Zone Information Format (TZif) . . . . . . . . . . .   4
     3.1.  TZif Header . . . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  TZif Data Block . . . . . . . . . . . . . . . . . . . . .   7
     3.3.  TZif Footer . . . . . . . . . . . . . . . . . . . . . . .  10
       3.3.1.  TZ String Extensions  . . . . . . . . . . . . . . . .  11
   4.  Interoperability Considerations . . . . . . . . . . . . . . .  11
   5.  Use with the Time Zone Data Distribution Service  . . . . . .  12
     5.1.  Truncating TZif Files . . . . . . . . . . . . . . . . . .  13
     5.2.  Example . . . . . . . . . . . . . . . . . . . . . . . . .  13
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   7.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  15
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
     8.1.  application/tzif  . . . . . . . . . . . . . . . . . . . .  15
     8.2.  application/tzif-leap . . . . . . . . . . . . . . . . . .  16
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  17
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     10.2.  Informative References . . . . . . . . . . . . . . . . .  18
     10.3.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .  18
   Appendix A.  Common Interoperability Issues . . . . . . . . . . .  18
   Appendix B.  Change History (To be removed by RFC Editor before
                publication) . . . . . . . . . . . . . . . . . . . .  21
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  24

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 defines the Time Zone Information Format (TZif).  It is
   a binary format used by most UNIX systems to calculate local time.
   There is a wide variety of interoperable software [tz-link] capable
   of generating and reading files in this format.

   This specification does not define the source of leap second
   information, nor does it define the source the time zone data,
   metadata, identifiers, aliases, localized names, or versions as
   defined in Section 3 of [RFC7808].  One such source is the IANA-
   hosted time zone database [RFC6557].

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