rfc9636.original   rfc9636.txt 
Internet Engineering Task Force (IETF) A.D. Olson Internet Engineering Task Force (IETF) A. Olson
Internet-Draft Request for Comments: 9636
Obsoletes: 8536 (if approved) P. Eggert Obsoletes: 8536 P. Eggert
Intended status: Standards Track UCLA Category: Standards Track UCLA
Expires: 9 November 2024 K. Murchison ISSN: 2070-1721 K. Murchison
Fastmail Fastmail
8 May 2024 October 2024
The Time Zone Information Format (TZif) The Time Zone Information Format (TZif)
draft-murchison-rfc8536bis-15
Abstract Abstract
This document specifies the Time Zone Information Format (TZif) for This document specifies the Time Zone Information Format (TZif) for
representing and exchanging time zone information, independent of any representing and exchanging time zone information, independent of any
particular service or protocol. Two media types for this format are particular service or protocol. Two media types for this format are
also defined. also defined.
This document replaces and obsoletes RFC 8536. This document replaces and obsoletes RFC 8536.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 9 November 2024. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9636.
Copyright Notice Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the Copyright (c) 2024 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Conventions Used in This Document . . . . . . . . . . . . . . 3 2. Conventions Used in This Document
3. The Time Zone Information Format (TZif) . . . . . . . . . . . 5 3. The Time Zone Information Format (TZif)
3.1. TZif Header . . . . . . . . . . . . . . . . . . . . . . . 6 3.1. TZif Header
3.2. TZif Data Block . . . . . . . . . . . . . . . . . . . . . 8 3.2. TZif Data Block
3.3. TZif Footer . . . . . . . . . . . . . . . . . . . . . . . 12 3.3. TZif Footer
3.3.1. All-Year Daylight Saving Time . . . . . . . . . . . . 13 3.3.1. All-Year Daylight Saving Time
3.3.2. TZ String Extension . . . . . . . . . . . . . . . . . 14 3.3.2. TZ String Extension
4. Interoperability Considerations . . . . . . . . . . . . . . . 14 4. Interoperability Considerations
5. Internationalization Considerations . . . . . . . . . . . . . 16 5. Internationalization Considerations
6. Use with the Time Zone Data Distribution Service . . . . . . 16 6. Use with the Time Zone Data Distribution Service
6.1. Truncating TZif Files . . . . . . . . . . . . . . . . . . 17 6.1. Truncating TZif Files
6.2. Example TZDIST Request for TZif Data . . . . . . . . . . 17 6.2. Example TZDIST Request for TZif Data
7. Security Considerations . . . . . . . . . . . . . . . . . . . 19 7. Security Considerations
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 19 8. Privacy Considerations
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 9. IANA Considerations
9.1. application/tzif . . . . . . . . . . . . . . . . . . . . 20 9.1. application/tzif
9.2. application/tzif-leap . . . . . . . . . . . . . . . . . . 21 9.2. application/tzif-leap
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 10. References
10.1. Normative References . . . . . . . . . . . . . . . . . . 22 10.1. Normative References
10.2. Informative References . . . . . . . . . . . . . . . . . 23 10.2. Informative References
Appendix A. Common Interoperability Issues . . . . . . . . . . . 24 Appendix A. Common Interoperability Issues
Appendix B. Example TZif Files . . . . . . . . . . . . . . . . . 27 Appendix B. Example TZif Files
B.1. Version 1 File Representing UTC (with Leap Seconds) . . . 27 B.1. Version 1 File Representing UTC (with Leap Seconds)
B.2. Version 2 File Representing Pacific/Honolulu . . . . . . 33 B.2. Version 2 File Representing Pacific/Honolulu
B.3. Truncated Version 2 File Representing Pacific/Johnston . 40 B.3. Truncated Version 2 File Representing Pacific/Johnston
B.4. Truncated Version 3 File Representing Asia/Jerusalem . . 45 B.4. Truncated Version 3 File Representing Asia/Jerusalem
B.5. Truncated Version 4 File Representing Europe/London . . . 47 B.5. Truncated Version 4 File Representing Europe/London
Appendix C. Changes from RFC 8536 . . . . . . . . . . . . . . . 50 Appendix C. Changes from RFC 8536
Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 51 Acknowledgments
D.1. Since rfc8536bis-14 . . . . . . . . . . . . . . . . . . . 51 Authors' Addresses
D.2. Since rfc8536bis-13 . . . . . . . . . . . . . . . . . . . 51
D.3. Since rfc8536bis-12 . . . . . . . . . . . . . . . . . . . 51
D.4. Since rfc8536bis-11 . . . . . . . . . . . . . . . . . . . 52
D.5. Since rfc8536bis-10 . . . . . . . . . . . . . . . . . . . 52
D.6. Since rfc8536bis-09 . . . . . . . . . . . . . . . . . . . 52
D.7. Since rfc8536bis-08 . . . . . . . . . . . . . . . . . . . 52
D.8. Since rfc8536bis-07 . . . . . . . . . . . . . . . . . . . 52
D.9. Since rfc8536bis-06 . . . . . . . . . . . . . . . . . . . 52
D.10. Since rfc8536bis-05 . . . . . . . . . . . . . . . . . . . 53
D.11. Since rfc8536bis-04 . . . . . . . . . . . . . . . . . . . 53
D.12. Since rfc8536bis-03 . . . . . . . . . . . . . . . . . . . 53
D.13. Since rfc8536bis-02 . . . . . . . . . . . . . . . . . . . 53
D.14. Since rfc8536bis-01 . . . . . . . . . . . . . . . . . . . 53
D.15. Since rfc8536bis-00 . . . . . . . . . . . . . . . . . . . 53
D.16. Since RFC 8536 . . . . . . . . . . . . . . . . . . . . . 54
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 54
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54
1. Introduction 1. Introduction
Time zone data typically consists of offsets from universal time Time zone data typically consists of offsets from universal time
(UT), daylight saving transition rules, one or more local time (UT), daylight saving transition rules, one or more local time
designations (acronyms or abbreviations), and optional leap-second designations (acronyms or abbreviations), and optional leap-second
adjustments. One such format for conveying this information is adjustments. One such format for conveying this information is
iCalendar [RFC5545]. It is a text-based format used by calendaring iCalendar [RFC5545]. It is a text-based format used by calendaring
and scheduling systems. and scheduling systems.
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Format (TZif). It is a binary format used by most UNIX systems to Format (TZif). It is a binary format used by most UNIX systems to
calculate local time. This format was introduced in the 1980s and calculate local time. This format was introduced in the 1980s and
has evolved since then into multiple upward-compatible versions. has evolved since then into multiple upward-compatible versions.
There is a wide variety of interoperable software capable of There is a wide variety of interoperable software capable of
generating and reading files in this format [tz-link]. generating and reading files in this format [tz-link].
This specification does not define the source of the data assembled This specification does not define the source of the data assembled
into a TZif file. One such source is the IANA-hosted time zone into a TZif file. One such source is the IANA-hosted time zone
database [RFC6557]. database [RFC6557].
This document obsoletes RFC 8536, providing editorial improvements, This document obsoletes [RFC8536], providing editorial improvements,
new details, and errata fixes while keeping full compatibility with new details, and errata fixes while keeping full compatibility with
the interchange format of RFC 8536. Additionally, a new version of the interchange format of [RFC8536]. Additionally, a new version of
the format is defined. The changes from RFC 8536 are summarized in the format is defined. The changes from [RFC8536] are summarized in
Appendix C. Appendix C.
2. Conventions Used in This Document 2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
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International Atomic Time (TAI): The time standard based on atomic International Atomic Time (TAI): The time standard based on atomic
clocks since 1972. It is equal to UTC but without leap-second clocks since 1972. It is equal to UTC but without leap-second
adjustments. adjustments.
Leap Second: A one-second adjustment to keep UTC close to mean solar Leap Second: A one-second adjustment to keep UTC close to mean solar
time at the prime meridian (see [ITU-R-TF.460]). Each inserted or time at the prime meridian (see [ITU-R-TF.460]). Each inserted or
deleted leap second occurs at the end of a UTC month, that is, a deleted leap second occurs at the end of a UTC month, that is, a
month using the Gregorian calendar and the UTC timescale. month using the Gregorian calendar and the UTC timescale.
Leap-Second Correction (LEAPCORR): The value of TAI - UTC - 10 for Leap-Second Correction (LEAPCORR): The value of "TAI - UTC - 10" for
timestamps after the first leap second, and zero for timestamps timestamps after the first leap second, and zero for timestamps
before that. The expression "TAI - UTC - 10" comes from the fact before that. The expression "TAI - UTC - 10" comes from the fact
that TAI - UTC was defined to be 10 just prior to the first leap that TAI - UTC was defined to be 10 just prior to the first leap
second in 1972, so clocks with leap seconds have a zero LEAPCORR second in 1972, so clocks with leap seconds have a zero LEAPCORR
before the first leap second. before the first leap second.
Local Time: Civil time for a particular location. Its offset from Local Time: Civil time for a particular location. Its offset from
universal time can depend on the date and time of day. universal time can depend on the date and time of day.
POSIX Epoch: 1970-01-01 00:00:00 UTC, the basis for absolute POSIX Epoch: 1970-01-01 00:00:00 UTC, the basis for absolute
timestamps in this document. timestamps in this document.
Standard Time: The time according to a location's law or practice, Standard Time: The time according to a location's law or practice,
unadjusted for Daylight Saving Time. unadjusted for daylight saving time.
Time Change: A change to civil timekeeping practice. It occurs when Time Change: A change to civil timekeeping practice. It occurs when
one or more of the following happen simultaneously: one or more of the following happen simultaneously:
1. a change in UT offset 1. a change in UT offset
2. a change in whether daylight saving time is in effect 2. a change in whether daylight saving time is in effect
3. a change in time zone abbreviation 3. a change in time zone abbreviation
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1. a change in UT offset 1. a change in UT offset
2. a change in whether daylight saving time is in effect 2. a change in whether daylight saving time is in effect
3. a change in time zone abbreviation 3. a change in time zone abbreviation
4. a leap second (i.e., a change in LEAPCORR) 4. a leap second (i.e., a change in LEAPCORR)
Time Zone Data: The Time Zone Data Distribution Service (TZDIST) Time Zone Data: The Time Zone Data Distribution Service (TZDIST)
[RFC7808] defines "Time zone data" as "data that defines a single [RFC7808] defines "Time zone data" as "data that defines a single
time zone, including an identifier, UTC offset values, DST rules, time zone, including an identifier, UTC offset values, DST rules,
and other information such as time zone abbreviations." The and other information such as time zone abbreviations". The
interchange format defined in this document is one such form of interchange format defined in this document is one such form of
time zone data. time zone data.
Transition Time: The moment of occurrence of a time change that is Transition Time: The moment of occurrence of a time change that is
not a leap second. It is identified with a signed integer count not a leap second. It is identified with a signed integer count
of UNIX leap time seconds since the POSIX epoch. of UNIX leap time seconds since the POSIX epoch.
Universal Time (UT): The basis of civil time. This is the principal Universal Time (UT): The basis of civil time. This is the principal
form of the mean solar time at the prime meridian (0 degrees form of the mean solar time at the prime meridian (0 degrees
longitude) for timestamps before UTC was introduced in 1960 and is longitude) for timestamps before UTC was introduced in 1960 and is
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time. time.
Wall Time: Another name for local time; short for "wall-clock time". Wall Time: Another name for local time; short for "wall-clock time".
3. The Time Zone Information Format (TZif) 3. The Time Zone Information Format (TZif)
The Time Zone Information Format begins with a fixed 44-octet version The Time Zone Information Format begins with a fixed 44-octet version
1 header (Section 3.1) containing a field that specifies the version 1 header (Section 3.1) containing a field that specifies the version
of the file's format. Readers designed for version N can read of the file's format. Readers designed for version N can read
version N+1 files without too much trouble; data specific to version version N+1 files without too much trouble; data specific to version
N+1 either appears after version N data so that earlier-version N+1 either appears after version N data so that earlier version
readers can easily ignore later-version data they are not designed readers can easily ignore later version data they are not designed
for, or it appears as a minor extension to version N that version N for, or it appears as a minor extension to version N that version N
readers are likely to tolerate well. readers are likely to tolerate well.
The version 1 header is followed by a variable-length version 1 data The version 1 header is followed by a variable-length version 1 data
block (Section 3.2) containing four-octet (32-bit) transition times block (Section 3.2) containing four-octet (32-bit) transition times
and leap-second occurrences. These 32-bit values are limited to and leap-second occurrences. These 32-bit values are limited to
representing time changes from 1901-12-13 20:45:52 through 2038-01-19 representing time changes from 1901-12-13 20:45:52 through 2038-01-19
03:14:07 UT, and the version 1 header and data block are present only 03:14:07 UT, and the version 1 header and data block are present only
for backward compatibility with obsolescent readers, as discussed in for backward compatibility with obsolescent readers, as discussed in
Common Interoperability Issues (Appendix A). "Common Interoperability Issues" (Appendix A).
Version 1 files terminate after the version 1 data block. Files from Version 1 files terminate after the version 1 data block. Files from
versions 2 and higher extend the format by appending a second versions 2 and higher extend the format by appending a second
44-octet version 2+ header, a variable-length version 2+ data block 44-octet version 2+ header, a variable-length version 2+ data block
containing eight-octet (64-bit) transition times and leap-second containing eight-octet (64-bit) transition times and leap-second
occurrences, and a variable-length footer (Section 3.3). These occurrences, and a variable-length footer (Section 3.3). These
64-bit values can represent times approximately 292 billion years 64-bit values can represent times approximately 292 billion years
into the past or future. into the past or future.
NOTE: All multi-octet integer values MUST be stored in network octet NOTE: All multi-octet integer values MUST be stored in network octet
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The fields of the header are defined as follows: The fields of the header are defined as follows:
magic: The four-octet ASCII [RFC20] sequence "TZif" (0x54 0x5A 0x69 magic: The four-octet ASCII [RFC20] sequence "TZif" (0x54 0x5A 0x69
0x66), which identifies the file as utilizing the Time Zone 0x66), which identifies the file as utilizing the Time Zone
Information Format. Information Format.
ver(sion): An octet identifying the version of the file's format. ver(sion): An octet identifying the version of the file's format.
The value MUST be one of the following: The value MUST be one of the following:
NUL (0x00) Version 1 - The file contains only the version 1 * NUL (0x00) Version 1 - The file contains only the version 1
header and data block. Version 1 files MUST NOT contain a header and data block. Version 1 files MUST NOT contain a
version 2+ header, data block, or footer. version 2+ header, data block, or footer.
'2' (0x32) Version 2 - The file MUST contain the version 1 header * '2' (0x32) Version 2 - The file MUST contain the version 1
and data block, a version 2+ header and data block, and a header and data block, a version 2+ header and data block, and
footer. The TZ string in the footer (Section 3.3), if a footer. The TZ string in the footer (Section 3.3), if non-
nonempty, MUST strictly adhere to the requirements for the TZ empty, MUST strictly adhere to the requirements for the TZ
environment variable as defined in Section 8.3 of the "Base environment variable as defined in Section 8.3 of the "Base
Definitions" volume of [POSIX] and MUST encode the POSIX Definitions" volume of [POSIX] and MUST encode the POSIX
portable character set as ASCII. The leap-second records MUST portable character set as ASCII. The leap-second records MUST
NOT be truncated at the start (Section 6.1), and MUST NOT NOT be truncated at the start (Section 6.1) and MUST NOT
contain an expiration time. contain an expiration time.
'3' (0x33) Version 3 - The file MUST conform to all version 2 * '3' (0x33) Version 3 - The file MUST conform to all version 2
requirements, except that any TZ string in the footer requirements, except that any TZ string in the footer
(Section 3.3) MAY use the TZ string extension described below (Section 3.3) MAY use the TZ string extension described below
(Section 3.3.2). (Section 3.3.2).
'4' (0x34) Version 4 - The file MUST conform to all version 3 * '4' (0x34) Version 4 - The file MUST conform to all version 3
requirements, except that the leap-second records MAY be requirements, except that the leap-second records MAY be
truncated at the start, and MAY contain an expiration time. truncated at the start, and MAY contain an expiration time.
isutcnt: A four-octet unsigned integer specifying the number of UT/ isutcnt: A four-octet unsigned integer specifying the number of UT/
local indicators contained in the data block -- MUST either be local indicators contained in the data block -- MUST either be
zero or equal to "typecnt". zero or equal to "typecnt".
isstdcnt: A four-octet unsigned integer specifying the number of isstdcnt: A four-octet unsigned integer specifying the number of
standard/wall indicators contained in the data block -- MUST standard/wall indicators contained in the data block -- MUST
either be zero or equal to "typecnt". either be zero or equal to "typecnt".
leapcnt: A four-octet unsigned integer specifying the number of leapcnt: A four-octet unsigned integer specifying the number of
leap-second records contained in the data block. leap-second records contained in the data block.
timecnt: A four-octet unsigned integer specifying the number of timecnt: A four-octet unsigned integer specifying the number of
transition times contained in the data block. transition times contained in the data block.
typecnt: A four-octet unsigned integer specifying the number of typecnt: A four-octet unsigned integer specifying the number of
local time type records contained in the data block -- MUST NOT be local time type records contained in the data block -- MUST NOT be
zero. (Although local time type records convey no useful zero. (Although local time type records convey no useful
information in files that have nonempty TZ strings but no information in files that have non-empty TZ strings but no
transitions, at least one such record is nevertheless required transitions, at least one such record is nevertheless required
because many TZif readers reject files that have zero time types.) because many TZif readers reject files that have zero time types.)
charcnt: A four-octet unsigned integer specifying the total number charcnt: A four-octet unsigned integer specifying the total number
of octets used by the set of time zone designations contained in of octets used by the set of time zone designations contained in
the data block - MUST NOT be zero. The count includes the the data block -- MUST NOT be zero. The count includes the
trailing NUL (0x00) octet at the end of the last time zone trailing NUL (0x00) octet at the end of the last time zone
designation. designation.
Although the version 1 and 2+ headers have the same format, magic Although the version 1 and 2+ headers have the same format, magic
number, and version fields, their count fields may differ, because number, and version fields, their count fields may differ, because
the version 1 data can be a subset of the version 2+ data. the version 1 data can be a subset of the version 2+ data.
3.2. TZif Data Block 3.2. TZif Data Block
A TZif data block consists of seven variable-length elements, each of A TZif data block consists of seven variable-length elements, each of
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+---------------------------------------------------------+ +---------------------------------------------------------+
Figure 3: TZif Data Block Figure 3: TZif Data Block
The elements of the data block are defined as follows: The elements of the data block are defined as follows:
transition times: A series of four- or eight-octet UNIX leap time transition times: A series of four- or eight-octet UNIX leap time
values sorted in strictly ascending order. Each value is used as values sorted in strictly ascending order. Each value is used as
a transition time at which the rules for computing local time may a transition time at which the rules for computing local time may
change. The number of time values is specified by the "timecnt" change. The number of time values is specified by the "timecnt"
field in the header. Each time value SHOULD be at least -2**59. field in the header. Each time value SHOULD be at least -2^59.
(-2**59 is the greatest negated power of 2 that predates the Big (-2^59 is the greatest negated power of 2 that predates the Big
Bang, and avoiding earlier timestamps works around known TZif Bang, and avoiding earlier timestamps works around known TZif
reader bugs relating to outlandishly negative timestamps.) reader bugs relating to outlandishly negative timestamps.)
transition types: A series of one-octet unsigned integers specifying transition types: A series of one-octet unsigned integers specifying
the type of local time of the corresponding transition time. the type of local time of the corresponding transition time.
These values serve as zero-based indices into the array of local These values serve as zero-based indices into the array of local
time type records. The number of type indices is specified by the time type records. The number of type indices is specified by the
"timecnt" field in the header. Each type index MUST be in the "timecnt" field in the header. Each type index MUST be in the
range [0, "typecnt" - 1]. range [0, "typecnt" - 1].
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"typecnt" field in the header. Each record has the following "typecnt" field in the header. Each record has the following
format (the lengths of multi-octet fields are shown in format (the lengths of multi-octet fields are shown in
parentheses): parentheses):
+---------------+---+---+ +---------------+---+---+
| utoff (4) |dst|idx| | utoff (4) |dst|idx|
+---------------+---+---+ +---------------+---+---+
utoff: A four-octet signed integer specifying the number of utoff: A four-octet signed integer specifying the number of
seconds to be added to UT in order to determine local time. seconds to be added to UT in order to determine local time.
The value MUST NOT be -2**31 and SHOULD be in the range The value MUST NOT be -2^31 and SHOULD be in the range [-89999,
[-89999, 93599] (i.e., its value SHOULD be more than -25 hours 93599] (i.e., its value SHOULD be more than -25 hours and less
and less than 26 hours). Avoiding -2**31 allows 32-bit clients than 26 hours). Avoiding -2^31 allows 32-bit clients to negate
to negate the value without overflow. Restricting it to the value without overflow. Restricting it to [-89999, 93599]
[-89999, 93599] allows easy support by implementations that allows easy support by implementations that already support the
already support the POSIX-required range [-24:59:59, 25:59:59]. POSIX-required range [-24:59:59, 25:59:59].
(is)dst: A one-octet value indicating whether local time should (is)dst: A one-octet value indicating whether local time should
be considered Daylight Saving Time (DST). The value MUST be 0 be considered Daylight Saving Time (DST). The value MUST be 0
or 1. A value of one (1) indicates that this type of time is or 1. A value of one (1) indicates that this type of time is
DST. A value of zero (0) indicates that this time type is DST. A value of zero (0) indicates that this time type is
standard time. standard time.
(desig)idx: A one-octet unsigned integer specifying a zero-based (desig)idx: A one-octet unsigned integer specifying a zero-based
index into the series of time zone designation octets, thereby index into the series of time zone designation octets, thereby
selecting a particular designation string. Each index MUST be selecting a particular designation string. Each index MUST be
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+---------------+---------------+ +---------------+---------------+
version 2+ Data Block: version 2+ Data Block:
+---------------+---------------+---------------+ +---------------+---------------+---------------+
| occur (8) | corr (4) | | occur (8) | corr (4) |
+---------------+---------------+---------------+ +---------------+---------------+---------------+
occur(rence): A four- or eight-octet UNIX leap time value occur(rence): A four- or eight-octet UNIX leap time value
specifying the time at which a leap-second correction occurs or specifying the time at which a leap-second correction occurs or
at which the leap-second table expires. The first value, if at which the leap-second table expires. The first value, if
present, MUST be nonnegative, and each leap second MUST occur present, MUST be non-negative, and each leap second MUST occur
at the end of a UTC month. at the end of a UTC month.
corr(ection): A four-octet signed integer specifying the value of corr(ection): A four-octet signed integer specifying the value of
LEAPCORR on or after the occurrence. If "leapcnt" is zero, LEAPCORR on or after the occurrence. If "leapcnt" is zero,
LEAPCORR is zero for all timestamps; otherwise, for timestamps LEAPCORR is zero for all timestamps; otherwise, for timestamps
before the first occurrence time, LEAPCORR is zero if the first before the first occurrence time, LEAPCORR is zero if the first
correction is one (1) or minus one (-1), and is unspecified correction is one (1) or minus one (-1) and is unspecified
otherwise (which can happen only in files truncated at the otherwise (which can happen only in files truncated at the
start (Section 6.1)). start (Section 6.1)).
The first leap second is a positive leap second if and only if The first leap second is a positive leap second if and only if
its correction is positive. Each correction after the first its correction is positive. Each correction after the first
MUST differ from the previous correction by either one (1) for MUST differ from the previous correction by either one (1) for
a positive leap second or minus one (-1) for a negative leap a positive leap second or minus one (-1) for a negative leap
second, except that in version 4 files with two or more leap- second, except that in version 4 files with two or more leap-
second records, the correction value of the last two records second records, the correction value of the last two records
MAY be the same, with the occurrence of last record indicating MAY be the same, with the occurrence of last record indicating
the expiration time of the leap-second table. the expiration time of the leap-second table.
The leap-second table expiration time is the time at which the The leap-second table expiration time is the time at which the
table no longer records the presence or absence of future leap- table no longer records the presence or absence of future leap-
second corrections, and post-expiration timestamps can not be second corrections, and post-expiration timestamps cannot be
accurately calculated. For example, a leap-second table accurately calculated. For example, a leap-second table
published in January, which predicts the presence or absence of published in January, which predicts the presence or absence of
a leap second at June's end, might expire in mid-December a leap second at June's end, might expire in mid-December
because it is not known when the next leap second will occur. because it is not known when the next leap second will occur.
If leap seconds become permanently discontinued, as requested If leap seconds become permanently discontinued, as requested
by the General Conference on Weights and Measures by the General Conference on Weights and Measures
[CGPM-2022-R4], leap-second tables published after the [CGPM-2022-R4], leap-second tables published after the
discontinuation time SHOULD NOT expire, since they will not be discontinuation time SHOULD NOT expire, since they will not be
updated in the foreseeable future. updated in the foreseeable future.
skipping to change at page 12, line 25 skipping to change at line 520
"isutcnt" field in the header. If "isutcnt" is zero (0), all "isutcnt" field in the header. If "isutcnt" is zero (0), all
transition times associated with local time types are assumed to transition times associated with local time types are assumed to
be specified as local time. be specified as local time.
The type corresponding to a transition time specifies local time for The type corresponding to a transition time specifies local time for
timestamps starting at the given transition time and continuing up timestamps starting at the given transition time and continuing up
to, but not including, the next transition time. Local time for to, but not including, the next transition time. Local time for
timestamps before the first transition is specified by the first time timestamps before the first transition is specified by the first time
type (time type 0). Local time for timestamps on or after the last type (time type 0). Local time for timestamps on or after the last
transition is specified by the TZ string in the footer (Section 3.3) transition is specified by the TZ string in the footer (Section 3.3)
if present and nonempty; otherwise, it is unspecified. If there are if present and non-empty; otherwise, it is unspecified. If there are
no transitions, local time for all timestamps is specified by the TZ no transitions, local time for all timestamps is specified by the TZ
string in the footer if present and nonempty; otherwise, it is string in the footer if present and non-empty; otherwise, it is
specified by time type 0. A time type with a designation string of specified by time type 0. A time type with a designation string of
"-00" represents an unspecified local time. "-00" represents an unspecified local time.
A given pair of standard/wall and UT/local indicators is used to A given pair of standard/wall and UT/local indicators is used to
designate whether the corresponding transition time was specified as designate whether the corresponding transition time was specified as
UT, standard time, or wall-clock time. There are only three UT, standard time, or wall-clock time. There are only three
combinations of the two indicators, given that the standard/wall combinations of the two indicators, given that the standard/wall
value MUST be one (1) if the UT/local value is one (1). This value MUST be one (1) if the UT/local value is one (1). This
information can be useful if the transition times in a TZif file need information can be useful if the transition times in a TZif file need
to be transformed into transitions appropriate for another time zone to be transformed into transitions appropriate for another time zone
(e.g. when calculating transition times for a simple POSIX-like TZ (e.g., when calculating transition times for a simple POSIX-like TZ
string such as "AKST9AKDT"). string such as "AKST9AKDT").
In order to eliminate unused space in a TZif file, every nonzero In order to eliminate unused space in a TZif file, every nonzero
local time type index SHOULD appear at least once in the transition local time type index SHOULD appear at least once in the transition
type array. Likewise, every octet in the time zone designations type array. Likewise, every octet in the time zone designations
array SHOULD be used by at least one time type record. array SHOULD be used by at least one time type record.
3.3. TZif Footer 3.3. TZif Footer
The TZif footer is structured as follows (the lengths of multi-octet The TZif footer is structured as follows (the lengths of multi-octet
skipping to change at page 13, line 22 skipping to change at line 563
NL: An ASCII new line character (0x0A). NL: An ASCII new line character (0x0A).
TZ string: A rule for computing local time changes after the last TZ string: A rule for computing local time changes after the last
transition time stored in the version 2+ data block. The string transition time stored in the version 2+ data block. The string
is either empty or uses the expanded format of the "TZ" is either empty or uses the expanded format of the "TZ"
environment variable as defined in Section 8.3 of the "Base environment variable as defined in Section 8.3 of the "Base
Definitions" volume of [POSIX] with ASCII encoding, possibly Definitions" volume of [POSIX] with ASCII encoding, possibly
utilizing the extension described below (Section 3.3.2) in version utilizing the extension described below (Section 3.3.2) in version
3 and higher files. If the string is empty, the corresponding 3 and higher files. If the string is empty, the corresponding
information is not available. If the string is nonempty and one information is not available. If the string is non-empty and one
or more transitions appear in the version 2+ data, the string MUST or more transitions appear in the version 2+ data, the string MUST
be consistent with the last version 2+ transition. In other be consistent with the last version 2+ transition. In other
words, evaluating the TZ string at the time of the last transition words, evaluating the TZ string at the time of the last transition
should yield the same time type as was specified in the last should yield the same time type as was specified in the last
transition. The string MUST NOT contain NUL octets or be transition. The string MUST NOT contain NUL octets or be
NUL-terminated, and it SHOULD NOT begin with the ':' (colon) NUL-terminated, and it SHOULD NOT begin with the ":" (colon)
character. character.
The TZif footer is present only in version 2 and higher files, as the The TZif footer is present only in version 2 and higher files, as the
obsolescent version 1 format was designed before the need for a obsolescent version 1 format was designed before the need for a
footer was apparent. footer was apparent.
3.3.1. All-Year Daylight Saving Time 3.3.1. All-Year Daylight Saving Time
DST is considered to be in effect all year if its UT offset is less DST is considered to be in effect all year if its UT offset is less
than (i.e., west of) that of standard time, and it starts January 1 than (i.e., west of) that of standard time, and it starts January 1
at 00:00 and ends December 31 at 24:00 minus the difference between at 00:00 and ends December 31 at 24:00 minus the difference between
standard and daylight saving time, leaving no room for standard time standard and daylight saving time, leaving no room for standard time
in the calendar. [POSIX] implies, but does not explicitly state in the calendar. [POSIX] implies but does not explicitly state this,
this, so it is spelled out here for clarity. so it is spelled out here for clarity.
Example: XXX3EDT4,0/0,J365/23 Example: XXX3EDT4,0/0,J365/23
This represents a time zone that is perpetually 4 hours west of UT This represents a time zone that is perpetually 4 hours west of UT
and is abbreviated "EDT". The "XXX" is ignored. and is abbreviated "EDT". The "XXX" is ignored.
3.3.2. TZ String Extension 3.3.2. TZ String Extension
The TZ string in a version 3 or higher TZif file MAY use the The TZ string in a version 3 or higher TZif file MAY use the
following extension to POSIX TZ strings. This extension is described following extension to POSIX TZ strings. This extension is described
using the terminology of Section 8.3 of the "Base Definitions" volume using the terminology of Section 8.3 of the "Base Definitions" volume
of [POSIX]. of [POSIX].
* The hours part of the transition times may be signed and range The hours part of the transition times may be signed and range from
from -167 through 167 (-167 <= hh <= 167) instead of the POSIX- -167 through 167 (-167 <= hh <= 167) instead of the POSIX-required
required unsigned values from 0 through 24. unsigned values from 0 through 24.
Example: <-03>3<-02>,M3.5.0/-2,M10.5.0/-1 Example: <-03>3<-02>,M3.5.0/-2,M10.5.0/-1
This represents a time zone that observes daylight saving time This represents a time zone that observes daylight saving time
from 22:00 on the day before March's last Sunday until 23:00 on from 22:00 on the day before March's last Sunday until 23:00 on
the day before October's last Sunday. Standard time is 3 hours the day before October's last Sunday. Standard time is 3 hours
west of UT and is abbreviated "-03"; daylight saving time is 2 west of UT and is abbreviated "-03"; daylight saving time is 2
hours west of UT and is abbreviated "-02". hours west of UT and is abbreviated "-02".
A TZif file that uses the above extension MUST be designated as A TZif file that uses the above extension MUST be designated as
version 3 (or higher), even if a future version of POSIX adopts this version 3 (or higher), even if a future version of POSIX adopts this
extension. extension.
4. Interoperability Considerations 4. Interoperability Considerations
The following practices help ensure the interoperability of TZif The following practices help ensure the interoperability of TZif
applications. applications.
skipping to change at page 15, line 8 skipping to change at line 640
* To save space, writers of version 2+ files MAY output a * To save space, writers of version 2+ files MAY output a
placeholder version 1 data block with all counts zero except that placeholder version 1 data block with all counts zero except that
"typecnt" and "charcnt" are both one (1). If this is done, "typecnt" and "charcnt" are both one (1). If this is done,
obsolescent version-1-only readers MUST interpret these files as obsolescent version-1-only readers MUST interpret these files as
lacking time changes and time zone abbreviations. lacking time changes and time zone abbreviations.
* Unless the version 1 data block is a placeholder, the sequence of * Unless the version 1 data block is a placeholder, the sequence of
timestamps defined by the version 1 header and data block SHOULD timestamps defined by the version 1 header and data block SHOULD
be a contiguous sub-sequence of the timestamps defined by the be a contiguous sub-sequence of the timestamps defined by the
version 2+ header and data block, and by the footer. This version 2+ header and data block and by the footer. This
guideline helps obsolescent version 1 readers agree with current guideline helps obsolescent version 1 readers agree with current
readers about timestamps within the contiguous sub-sequence. readers about timestamps within the contiguous sub-sequence.
* When a TZif file contains a leap-second table expiration time, * When a TZif file contains a leap-second table expiration time,
TZif readers SHOULD either refuse to process post-expiration TZif readers SHOULD either refuse to process post-expiration
timestamps, or process them as if the expiration time did not timestamps or process them as if the expiration time did not exist
exist (possibly with an error indication). This lessens (possibly with an error indication). This lessens disagreement
disagreement among implementations when processing far-future among implementations when processing far-future timestamps that
timestamps that cannot yet be handled exactly. cannot yet be handled exactly.
* Time zone designations MUST consist of at least three (3) and no * Time zone designations MUST consist of at least three (3) and no
more than six (6) ASCII characters from the set of alphanumerics, more than six (6) ASCII characters from the set of alphanumerics,
'-', and '+'. This is compatible with POSIX requirements for time "-", and "+". This is compatible with POSIX requirements for time
zone abbreviations. zone abbreviations.
* A reader that encounters a time zone designation containing bytes * A reader that encounters a time zone designation containing bytes
other than ASCII alphanumerics, '-', and '+' SHOULD act if the other than ASCII alphanumerics, "-", and "+" SHOULD act if the
designation instead contained a signed numeric string derived from designation instead contained a signed numeric string derived from
the UT offset, for example, "-10" and "+0530" to indicate 10 hours the UT offset, for example, "-10" and "+0530" to indicate 10 hours
west and 5.5 hours east of Greenwich, respectively. west and 5.5 hours east of Greenwich, respectively.
* When reading a version 2 or higher file, readers SHOULD ignore the * When reading a version 2 or higher file, readers SHOULD ignore the
version 1 header and data block except for the purpose of skipping version 1 header and data block except for the purpose of skipping
over them. This improves compatibility among readers of over them. This improves compatibility among readers of non-
nonconforming files where version 2+ data is not upward compatible conforming files where version 2+ data is not upward compatible
with version 1. with version 1.
* Readers SHOULD calculate the total lengths of the headers and data * Readers SHOULD calculate the total lengths of the headers and data
blocks and check that they all fit within the actual file size, as blocks and check that they all fit within the actual file size, as
part of a validity check for the file. part of a validity check for the file.
* When a TZif file is used in a MIME message entity, it SHOULD be * When a TZif file is used in a MIME message entity, it SHOULD be
indicated by one of the following media types: indicated by one of the following media types:
- "application/tzif-leap" (Section 9.2) to indicate that leap- - "application/tzif-leap" (Section 9.2) to indicate that leap-
skipping to change at page 16, line 12 skipping to change at line 691
records are not included in the TZif data; "leapcnt" in the records are not included in the TZif data; "leapcnt" in the
header(s) MUST be zero (0). header(s) MUST be zero (0).
* Common interoperability issues and possible workarounds are * Common interoperability issues and possible workarounds are
described in Appendix A. described in Appendix A.
5. Internationalization Considerations 5. Internationalization Considerations
TZif time zone designations contain only ASCII alphanumerics, "-", TZif time zone designations contain only ASCII alphanumerics, "-",
and "+". Commonly used designations include numeric strings like and "+". Commonly used designations include numeric strings like
"-10" and "+0530" for UT offsets, and English-language abbreviations "-10" and "+0530" for UT offsets and English language abbreviations
like "CEST" for Central European Summer Time and "GMT" for Greenwich like "CEST" for Central European Summer Time and "GMT" for Greenwich
Mean Time. It is the TZif reader's responsibility to substitute Mean Time. It is the TZif reader's responsibility to substitute
different abbreviations when needed for internationalization, such as different abbreviations when needed for internationalization, such as
substituting "HNC" (l'heure normale du Centre) for "CST" (Central substituting "HNC" (l'heure normale du Centre) for "CST" (Central
Standard Time) in French-speaking regions. This substitution can be Standard Time) in French-speaking regions. This substitution can be
problematic, as abbreviations can be ambiguous: for example, "CST" problematic, as abbreviations can be ambiguous; for example, "CST"
commonly stands for China Standard Time and Cuba Standard Time as commonly stands for China Standard Time and Cuba Standard Time as
well as Central Standard Time. One approach for addressing this well as Central Standard Time. One approach for addressing this
issue can be found in the timezone charts of the Unicode Common issue can be found in the time zone charts of the Unicode Common
Locale Data Repository (CLDR) Project. [CLDR] Locale Data Repository (CLDR) Project [CLDR].
Although the original TZif design allowed for any nonzero octets in Although the original TZif design allowed for any nonzero octets in
time zone designations and it was common practice until the mid-1990s time zone designations, and it was common practice until the mid-
for designations to contain ASCII spaces, designations are now 1990s for designations to contain ASCII spaces, designations are now
limited to ASCII alphanumerics, "-", and "+" to avoid confusion and limited to ASCII alphanumerics, "-", and "+" to avoid confusion and
to encourage portability to a wide variety of locales. to encourage portability to a wide variety of locales.
6. Use with the Time Zone Data Distribution Service 6. Use with the Time Zone Data Distribution Service
The Time Zone Data Distribution Service (TZDIST) [RFC7808] is a The Time Zone Data Distribution Service (TZDIST) [RFC7808] is a
service that allows reliable, secure, and fast delivery of time zone service that allows reliable, secure, and fast delivery of time zone
data and leap-second rules to client systems such as calendaring and data and leap-second rules to client systems such as calendaring and
scheduling applications or operating systems. scheduling applications or operating systems.
A TZDIST service MAY supply time zone data to clients in the Time A TZDIST service MAY supply time zone data to clients in the Time
Zone Information Format. Such a service MUST indicate that it Zone Information Format. Such a service MUST indicate that it
supports this format by including the media type "application/tzif" supports this format by including the media type "application/tzif"
(Section 9.1) in its "capabilities" response (Section 5.1 of (Section 9.1) in its "capabilities" response (Section 5.1 of
[RFC7808]). A TZDIST service MAY also include the media type [RFC7808]). A TZDIST service MAY also include the media type
"application/tzif-leap" (Section 9.2) in its "capabilities" response "application/tzif-leap" (Section 9.2) in its "capabilities" response
if it is able to generate TZif files containing leap-second records. if it is able to generate TZif files containing leap-second records.
A TZDIST service MUST NOT advertise the "application/tzif-leap" media A TZDIST service MUST NOT advertise the "application/tzif-leap" media
type without also advertising "application/tzif". type without also advertising "application/tzif".
TZDIST clients MUST use the HTTP "Accept" header field [RFC9110], TZDIST clients MUST use the HTTP "Accept" header field ([RFC9110],
Section 12.5.1 to indicate their preference to receive data in the Section 12.5.1) to indicate their preference to receive data in the
"application/tzif" and/or "application/tzif-leap" formats. "application/tzif" and/or "application/tzif-leap" formats.
6.1. Truncating TZif Files 6.1. Truncating TZif Files
As described in Section 3.9 of [RFC7808], a TZDIST service MAY As described in Section 3.9 of [RFC7808], a TZDIST service MAY
truncate time zone transition data. A truncated TZif file is valid truncate time zone transition data. A truncated TZif file is valid
from its first and up to, but not including, its last version 2+ from its first and up to, but not including, its last version 2+
transition time, if present. transition time, if present.
When truncating the start of a TZif file, the service MUST supply in When truncating the start of a TZif file, the service MUST supply in
skipping to change at page 17, line 25 skipping to change at line 750
indicates local time immediately before the start point, and the time indicates local time immediately before the start point, and the time
type of the first transition indicates local time thereafter. Time type of the first transition indicates local time thereafter. Time
type 0 MUST be a placeholder indicating that local time is type 0 MUST be a placeholder indicating that local time is
unspecified, so that the reader is unambiguously informed of unspecified, so that the reader is unambiguously informed of
truncation at the start. truncation at the start.
When truncating the start of a TZif file containing leap-second When truncating the start of a TZif file containing leap-second
records, the service MUST keep all leap-second records governing records, the service MUST keep all leap-second records governing
timestamps within the truncation range, even if the first such record timestamps within the truncation range, even if the first such record
precedes the start point of the truncation range. If the truncated precedes the start point of the truncation range. If the truncated
leap-second table is nonempty, its first record MUST have a positive leap-second table is non-empty, its first record MUST have a positive
correction if and only if it represents a positive leap second. correction if and only if it represents a positive leap second.
When truncating the end of a TZif file, the service MUST supply in When truncating the end of a TZif file, the service MUST supply in
the version 2+ data a last transition time that is the end point of the version 2+ data a last transition time that is the end point of
the truncation range and MUST supply an empty TZ string. As with the truncation range and MUST supply an empty TZ string. As with
untruncated TZif files with empty TZ strings, a truncated TZif file untruncated TZif files with empty TZ strings, a truncated TZif file
does not indicate local time after the last transition. To this end, does not indicate local time after the last transition. To this end,
the time type of the last transition MUST be a placeholder indicating the time type of the last transition MUST be a placeholder indicating
that local time is unspecified. that local time is unspecified.
skipping to change at page 19, line 43 skipping to change at line 859
As discussed in Section 9 of [RFC7808], transmission of time zone As discussed in Section 9 of [RFC7808], transmission of time zone
data over an insecure communications channel could leak the past, data over an insecure communications channel could leak the past,
current, or future location of a device or user. As such, TZif data current, or future location of a device or user. As such, TZif data
transmitted over a public communications channel MUST be protected transmitted over a public communications channel MUST be protected
with a confidentiality layer such as that provided by Transport Layer with a confidentiality layer such as that provided by Transport Layer
Security (TLS) [RFC8446]. Security (TLS) [RFC8446].
9. IANA Considerations 9. IANA Considerations
The IANA is requested to update the Media Types Registry IANA has updated the "Media Types" registry
(https://www.iana.org/assignments/media-types/media-types.xhtml) as (https://www.iana.org/assignments/media-types) as follows.
follows:
This document defines two media types [RFC6838] for the exchange of This document defines two media types [RFC6838] for the exchange of
data utilizing the Time Zone Information Format. data utilizing the Time Zone Information Format.
9.1. application/tzif 9.1. application/tzif
Type name: Type name: application
application
Subtype name: Subtype name: tzif
tzif
Required parameters: Required parameters: N/A
N/A
Optional parameters: Optional parameters: N/A
N/A
Encoding considerations: Encoding considerations: binary
binary
Security considerations: Security considerations: See Section 7 of RFC 9636.
See Section 7 of This Document.
Interoperability considerations: Interoperability considerations: See Section 4 of RFC 9636.
See Section 4 of This Document.
Published specification: Published specification: RFC 9636.
This specification.
Applications that use this media type: Applications that use this media type: This media type is designed
This media type is designed for widespread use by applications for widespread use by applications that need to use or exchange
that need to use or exchange time zone information relative to time zone information relative to UNIX time, such as the Time Zone
UNIX Time, such as the Time Zone Information Compiler (zic) [ZIC] Information Compiler (zic) [ZIC] and the GNU C Library [GNU-C].
and the GNU C Library [GNU-C]. The Time Zone Distribution Service The Time Zone Distribution Service [RFC7808] can directly use this
[RFC7808] can directly use this media type. media type.
Fragment identifier considerations: Fragment identifier considerations: N/A
N/A
Additional information: Additional information:
Magic number(s): The first 4 octets are 0x54, 0x5A, 0x69, 0x66
Magic number(s): The first 4 octets are 0x54, 0x5A, 0x69, 0x66
File extensions(s): N/A File extensions(s): N/A
Macintosh file type code(s): N/A Macintosh file type code(s): N/A
Person & email address to contact for further information: Person & email address to contact for further information: Time Zone
Time Zone Database mailing list <tz@iana.org> Database mailing list <tz@iana.org>
Intended usage: Intended usage: COMMON
COMMON
Restrictions on usage: Restrictions on usage: N/A
N/A
Author: Author: See the "Authors' Addresses" section of RFC 9636.
See the "Authors' Addresses" section of This Document.
Change controller: Change controller: IETF
IETF
9.2. application/tzif-leap 9.2. application/tzif-leap
Type name: Type name: application
application
Subtype name: Subtype name: tzif-leap
tzif-leap
Required parameters: Required parameters: none
none
Optional parameters: Optional parameters: none
none
Encoding considerations: Encoding considerations: binary
binary
Security considerations: Security considerations: See Section 7 of RFC 9636.
See Section 7 of This Document.
Interoperability considerations: Interoperability considerations: See Section 4 of RFC 9636.
See Section 4 of This Document.
Published specification: Published specification: RFC 9636.
This specification.
Applications that use this media type: Applications that use this media type: This media type is designed
This media type is designed for widespread use by applications for widespread use by applications that need to use or exchange
that need to use or exchange time zone information relative to time zone information relative to UNIX leap time, such as the Time
UNIX Leap Time, such as the Time Zone Information Compiler (zic) Zone Information Compiler (zic) [ZIC] and the GNU C Library
[ZIC] and the GNU C Library [GNU-C]. The Time Zone Distribution [GNU-C]. The Time Zone Distribution Service [RFC7808] can
Service [RFC7808] can directly use this media type. directly use this media type.
Fragment identifier considerations: Fragment identifier considerations: N/A
N/A
Additional information: Additional information:
Magic number(s): The first 4 octets are 0x54, 0x5A, 0x69, 0x66 Magic number(s): The first 4 octets are 0x54, 0x5A, 0x69, 0x66
File extensions(s): N/A File extensions(s): N/A
Macintosh file type code(s): N/A Macintosh file type code(s): N/A
Person & email address to contact for further information: Person & email address to contact for further information: Time Zone
Time Zone Database mailing list <tz@iana.org> Database mailing list <tz@iana.org>
Intended usage: Intended usage: COMMON
COMMON
Restrictions on usage: Restrictions on usage: N/A
N/A
Author: Author: See the "Authors' Addresses" section of RFC 9636.
See the "Authors' Addresses" section of This Document.
Change controller: Change controller: IETF
IETF
10. References 10. References
10.1. Normative References 10.1. Normative References
[GNU-C] "The GNU C Library (glibc)", [GNU-C] Free Software Foundation, "The GNU C Library",
<https://www.gnu.org/software/libc/>. <https://www.gnu.org/software/libc/>.
[ITU-R-TF.460] [ITU-R-TF.460]
International Telecommunications Union, "Standard- International Telecommunication Union, "Standard-frequency
frequency and time-signal emissions", ITU-R Recommendation and time-signal emissions", ITU-R Recommendation TF.460,
TF.460, February 2002, February 2002, <https://www.itu.int/rec/R-REC-TF.460/en>.
<https://www.itu.int/rec/R-REC-TF.460/en>.
[POSIX] IEEE, "Standard for Information Technology--Portable [POSIX] IEEE, "IEEE Standard for Information Technology--Portable
Operating System Interface (POSIX(R)) Base Specifications, Operating System Interface (POSIX(TM)) Base
Issue 7", IEEE 1003.1-2017, Specifications, Issue 7", POSIX.1-2017, IEEE
DOI 10.1109/IEEESTD.2018.8277153, 31 January 2018, Std 1003.1-2017, DOI 10.1109/IEEESTD.2018.8277153, January
<https://pubs.opengroup.org/onlinepubs/9699919799/>. 2018, <https://pubs.opengroup.org/onlinepubs/9699919799/>.
[RFC20] Cerf, V., "ASCII format for network interchange", STD 80, [RFC20] Cerf, V., "ASCII format for network interchange", STD 80,
RFC 20, DOI 10.17487/RFC0020, October 1969, RFC 20, DOI 10.17487/RFC0020, October 1969,
<https://www.rfc-editor.org/info/rfc20>. <https://www.rfc-editor.org/info/rfc20>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 23, line 23 skipping to change at line 998
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110, Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022, DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/info/rfc9110>. <https://www.rfc-editor.org/info/rfc9110>.
[ZIC] Kerrisk, M., "ZIC(8)", [ZIC] Kerrisk, M., "zic(8) - Linux manual page",
<http://man7.org/linux/man-pages/man8/zic.8.html>. <http://man7.org/linux/man-pages/man8/zic.8.html>.
10.2. Informative References 10.2. Informative References
[CGPM-2022-R4] [CGPM-2022-R4]
General Conference on Weights and Measures, "Resolution 4 General Conference on Weights and Measures, "Resolution 4
of the 27th CGPM (2022)", November 2022, of the 27th CGPM (2022)", DOI 10.59161/CGPM2022RES4E,
November 2022,
<https://www.bipm.org/en/cgpm-2022/resolution-4>. <https://www.bipm.org/en/cgpm-2022/resolution-4>.
[CLDR] Unicode, Inc., "Unicode CLDR Project", 2024, [CLDR] Unicode, Inc., "Unicode CLDR Project",
<https://cldr.unicode.org/>. <https://cldr.unicode.org/>.
[EGGERT-TZ] [EGGERT-TZ]
"History for tz", "History for tz", commit b5318b5, June 2024,
<https://github.com/eggert/tz/commits/main/tzfile.5>. <https://github.com/eggert/tz/commits/main/tzfile.5>.
[Err6426] RFC Errata, "Erratum ID 6426", RFC 8536, [Err6426] RFC Errata, "Erratum ID 6426", RFC 8536,
<https://www.rfc-editor.org/errata/eid6426>. <https://www.rfc-editor.org/errata/eid6426>.
[Err6435] RFC Errata, "Erratum ID 6435", RFC 8536, [Err6435] RFC Errata, "Erratum ID 6435", RFC 8536,
<https://www.rfc-editor.org/errata/eid6435>. <https://www.rfc-editor.org/errata/eid6435>.
[Err6757] RFC Errata, "Erratum ID 6757", RFC 8536, [Err6757] RFC Errata, "Erratum ID 6757", RFC 8536,
<https://www.rfc-editor.org/errata/eid6757>. <https://www.rfc-editor.org/errata/eid6757>.
skipping to change at page 24, line 19 skipping to change at line 1044
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
[RFC8536] Olson, A., Eggert, P., and K. Murchison, "The Time Zone [RFC8536] Olson, A., Eggert, P., and K. Murchison, "The Time Zone
Information Format (TZif)", RFC 8536, Information Format (TZif)", RFC 8536,
DOI 10.17487/RFC8536, February 2019, DOI 10.17487/RFC8536, February 2019,
<https://www.rfc-editor.org/info/rfc8536>. <https://www.rfc-editor.org/info/rfc8536>.
[tz-link] Eggert, P. and A.D. Olson, "Time zone and daylight saving [tz-link] Eggert, P. and A. Olson, "Time zone and daylight saving
time data", time data",
<https://www.iana.org/time-zones/repository/tz-link.html>. <https://www.iana.org/time-zones/repository/tz-link.html>.
Appendix A. Common Interoperability Issues Appendix A. Common Interoperability Issues
This section documents common problems in implementing this This section documents common problems in implementing this
specification. Most of these are problems in generating TZif files specification. Most of these are problems in generating TZif files
for use by readers conforming to predecessors of this specification for use by readers conforming to predecessors of this specification
[EGGERT-TZ]. The goals of this section are: [EGGERT-TZ]. The goals of this section are to help:
1. to help TZif writers output files that avoid common pitfalls in 1. TZif writers output files that avoid common pitfalls in older or
older or buggy TZif readers, buggy TZif readers,
2. to help TZif readers avoid common pitfalls when reading files 2. TZif readers avoid common pitfalls when reading files generated
generated by future TZif writers, and by future TZif writers, and
3. to help any future specification authors see what sort of 3. any future specification authors see what sort of problems arise
problems arise when the TZif format is changed. when the TZif format is changed.
When new versions of the TZif format have been defined, a design goal When new versions of the TZif format have been defined, a design goal
has been that a reader can successfully use a TZif file even if the has been that a reader can successfully use a TZif file even if the
file is of a later TZif version than what the reader was designed file is of a later TZif version than what the reader was designed
for. When complete compatibility was not achieved, an attempt was for. When complete compatibility was not achieved, an attempt was
made to limit glitches to rarely used timestamps and allow simple made to limit glitches to rarely used timestamps and allow simple
partial workarounds in writers designed to generate new-version data partial workarounds in writers designed to generate newer-version
useful even for older-version readers. This section attempts to data useful even for older-version readers. This section attempts to
document these compatibility issues and workarounds, as well as document these compatibility issues and workarounds as well as other
documenting other common bugs in readers. common bugs in readers.
Interoperability problems with TZif include the following: Interoperability problems with TZif include the following:
* Some readers examine only version 1 data. As a partial * Some readers examine only version 1 data. As a partial
workaround, a writer can output as much version 1 data as workaround, a writer can output as much version 1 data as
possible. However, a reader should ignore version 1 data and use possible. However, a reader should ignore version 1 data and use
version 2+ data, even if the reader's timestamps have only 32 version 2+ data, even if the reader's timestamps have only 32
bits. bits.
* Some readers designed for version 2 might mishandle timestamps * Some readers designed for version 2 might mishandle timestamps
skipping to change at page 25, line 25 skipping to change at line 1096
necessary, so that only far-future timestamps are mishandled by necessary, so that only far-future timestamps are mishandled by
version 2 readers. version 2 readers.
* Some readers designed for version 2 do not support permanent * Some readers designed for version 2 do not support permanent
daylight saving time with transitions after 24:00 -- e.g., a TZ daylight saving time with transitions after 24:00 -- e.g., a TZ
string "EST5EDT,0/0,J365/25" denoting permanent Eastern Daylight string "EST5EDT,0/0,J365/25" denoting permanent Eastern Daylight
Time (-04). As a workaround, a writer can substitute standard Time (-04). As a workaround, a writer can substitute standard
time for two time zones east, e.g., "XXX3EDT4,0/0,J365/23" for a time for two time zones east, e.g., "XXX3EDT4,0/0,J365/23" for a
time zone with a never-used standard time (XXX, -03) and negative time zone with a never-used standard time (XXX, -03) and negative
daylight saving time (EDT, -04) all year. Alternatively, as a daylight saving time (EDT, -04) all year. Alternatively, as a
partial workaround a writer can substitute standard time for the partial workaround, a writer can substitute standard time for the
next time zone east -- e.g., "AST4" for permanent Atlantic next time zone east -- e.g., "AST4" for permanent Atlantic
Standard Time (-04). Standard Time (-04).
* Some readers designed for version 2 or 3, and that require strict * Some readers designed for version 2 or 3 and that require strict
conformance to RFC 8536, reject version 4 files whose leap-second conformance to [RFC8536] reject version 4 files whose leap-second
tables are truncated at the start or that end in expiration times. tables are truncated at the start or end in expiration times.
* Some readers ignore the footer and instead predict future * Some readers ignore the footer and instead predict future
timestamps from the time type of the last transition. As a timestamps from the time type of the last transition. As a
partial workaround, a writer can output more transitions than partial workaround, a writer can output more transitions than
necessary. necessary.
* Some readers do not use time type 0 for timestamps before the * Some readers do not use time type 0 for timestamps before the
first transition, in that they infer a time type using a heuristic first transition, in that they infer a time type using a heuristic
that does not always select time type 0. As a partial workaround, that does not always select time type 0. As a partial workaround,
a writer can output a placeholder (no-op) first transition at an a writer can output a placeholder (no-op) first transition at an
early time. early time.
* Some readers mishandle timestamps before the first transition that * Some readers mishandle timestamps before the first transition that
has a timestamp not less than -2**31. Readers that support only has a timestamp that is not less than -2^31. Readers that support
32-bit timestamps are likely to be more prone to this problem, for only 32-bit timestamps are likely to be more prone to this
example, when they process 64-bit transitions, only some of which problem, for example, when they process 64-bit transitions, only
are representable in 32 bits. As a partial workaround, a writer some of which are representable in 32 bits. As a partial
can output a placeholder transition at timestamp -2**31. workaround, a writer can output a placeholder transition at
timestamp -2^31.
* Some readers mishandle a transition if its timestamp has the * Some readers mishandle a transition if its timestamp has the
minimum possible signed 64-bit value. Timestamps less than -2**59 minimum possible signed 64-bit value. Timestamps less than -2^59
are not recommended. are not recommended.
* Some readers mishandle POSIX-style TZ strings that contain "<" or * Some readers mishandle POSIX-style TZ strings that contain "<" or
">". As a partial workaround, a writer can avoid using '<' or '>' ">". As a partial workaround, a writer can avoid using "<" or ">"
for time zone abbreviations containing only alphabetic characters. for time zone abbreviations containing only alphabetic characters.
* Many readers mishandle time zone abbreviations that contain non- * Many readers mishandle time zone abbreviations that contain non-
ASCII characters. These characters are not recommended. ASCII characters. These characters are not recommended.
* Some readers may mishandle time zone abbreviations that contain * Some readers may mishandle time zone abbreviations that contain
fewer than 3 or more than 6 characters, or that contain ASCII fewer than 3 or more than 6 characters or that contain ASCII
characters other than alphanumerics, '-', and '+'. These characters other than alphanumerics, "-", and "+". These
abbreviations are not recommended. abbreviations are not recommended.
* This specification does not dictate how readers should deal with * This specification does not dictate how readers should deal with
timestamps when local time is unspecified. Common practice is for timestamps when local time is unspecified. Common practice is for
readers to report UT with designation string "-00". A reader readers to report UT with designation string "-00". A reader
could return an error indication instead. could return an error indication instead.
* Some readers mishandle TZif files that specify daylight saving * Some readers mishandle TZif files that specify daylight saving
time UT offsets that are less than the UT offsets for the time UT offsets that are less than the UT offsets for the
corresponding standard time. These readers do not support corresponding standard time. These readers do not support
skipping to change at page 26, line 40 skipping to change at line 1158
string "IST-1GMT0,M10.5.0,M3.5.0/1", observing standard time (IST, string "IST-1GMT0,M10.5.0,M3.5.0/1", observing standard time (IST,
+01) in summer and daylight saving time (GMT, +00) in winter. As +01) in summer and daylight saving time (GMT, +00) in winter. As
a partial workaround, a writer can output data for the equivalent a partial workaround, a writer can output data for the equivalent
of the POSIX TZ string "GMT0IST,M3.5.0/1,M10.5.0", thus swapping of the POSIX TZ string "GMT0IST,M3.5.0/1,M10.5.0", thus swapping
standard and daylight saving time. Although this workaround standard and daylight saving time. Although this workaround
misidentifies which part of the year uses daylight saving time, it misidentifies which part of the year uses daylight saving time, it
records UT offsets and time zone abbreviations correctly. records UT offsets and time zone abbreviations correctly.
* Some readers generate ambiguous timestamps for positive leap * Some readers generate ambiguous timestamps for positive leap
seconds that occur when the UTC offset is not a multiple of 60 seconds that occur when the UTC offset is not a multiple of 60
seconds. For example, in a timezone with UTC offset +01:23:45 and seconds. For example, in a time zone with UTC offset +01:23:45
with a positive leap second 78796801 (1972-06-30 23:59:60 UTC), and with a positive leap second 78796801 (1972-06-30 23:59:60
some readers will map both 78796800 and 78796801 to 01:23:45 local UTC), some readers will map both 78796800 and 78796801 to 01:23:45
time the next day instead of mapping the latter to 01:23:46, and local time the next day instead of mapping the latter to 01:23:46,
they will map 78796815 to 01:23:59 instead of to 01:23:60. This and they will map 78796815 to 01:23:59 instead of to 01:23:60.
has not yet been a practical problem, since no civil authority has This has not yet been a practical problem, since no civil
observed such UTC offsets since leap seconds were introduced in authority has observed such UTC offsets since leap seconds were
1972. introduced in 1972.
Some interoperability problems are reader bugs that are listed here Some interoperability problems are reader bugs that are listed here
mostly as warnings to developers of readers. mostly as warnings to developers of readers.
* Some readers do not support negative timestamps. Developers of * Some readers do not support negative timestamps. Developers of
distributed applications should keep this in mind if they need to distributed applications should keep this in mind if they need to
deal with pre-1970 data. deal with pre-1970 data.
* Some readers mishandle timestamps before the first transition that * Some readers mishandle timestamps before the first transition that
has a nonnegative timestamp. Readers that do not support negative has a non-negative timestamp. Readers that do not support
timestamps are likely to be more prone to this problem. negative timestamps are likely to be more prone to this problem.
* Some readers mishandle time zone abbreviations like "-08" that * Some readers mishandle time zone abbreviations like "-08" that
contain '+', '-', or digits. contain "+", "-", or digits.
* Some readers mishandle UT offsets that are out of the conventional * Some readers mishandle UT offsets that are out of the conventional
range of -12 through +12 hours and so do not support locations range of -12 through +12 hours and so do not support locations
like Kiritimati that are outside this range. like Kiritimati that are outside this range.
* Some readers mishandle UT offsets in the range [-3599, -1] seconds * Some readers mishandle UT offsets in the range [-3599, -1] seconds
from UT, because they integer-divide the offset by 3600 to get 0 from UT because they integer-divide the offset by 3600 to get 0
and then display the hour part as "+00". and then display the hour part as "+00".
* Some readers mishandle UT offsets that are not a multiple of one * Some readers mishandle UT offsets that are not a multiple of one
hour, 15 minutes, or 1 minute. hour, 15 minutes, or 1 minute.
Appendix B. Example TZif Files Appendix B. Example TZif Files
The following sections contain annotated hexadecimal dumps of example The following sections contain annotated hexadecimal dumps of example
TZif files. TZif files.
skipping to change at page 27, line 47 skipping to change at line 1212
B.1. Version 1 File Representing UTC (with Leap Seconds) B.1. Version 1 File Representing UTC (with Leap Seconds)
+========+=============+==================+========================+ +========+=============+==================+========================+
| File | Hexadecimal | Record Name / | Field Value | | File | Hexadecimal | Record Name / | Field Value |
| Offset | Octets | Field Name | | | Offset | Octets | Field Name | |
+========+=============+==================+========================+ +========+=============+==================+========================+
| 000 | 54 5a 69 66 | magic | "TZif" | | 000 | 54 5a 69 66 | magic | "TZif" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 004 | 00 | version | 0 (1) | | 004 | 00 | version | 0 (1) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 005 | 00 00 00 00 | | | | 005 | 00 00 00 00 | |
| | 00 00 00 00 | | | | | 00 00 00 00 | |
| | 00 00 00 00 | | | | | 00 00 00 00 | |
| | 00 00 00 | | | | | 00 00 00 | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 020 | 00 00 00 01 | isutcnt | 1 | | 020 | 00 00 00 01 | isutcnt | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 024 | 00 00 00 01 | isstdcnt | 1 | | 024 | 00 00 00 01 | isstdcnt | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 028 | 00 00 00 1b | leapcnt | 27 | | 028 | 00 00 00 1b | leapcnt | 27 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 032 | 00 00 00 00 | timecnt | 0 | | 032 | 00 00 00 00 | timecnt | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 036 | 00 00 00 01 | typecnt | 1 | | 036 | 00 00 00 01 | typecnt | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 040 | 00 00 00 04 | charcnt | 4 | | 040 | 00 00 00 04 | charcnt | 4 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[0] | |
| | | localtimetype[0] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 044 | 00 00 00 00 | utoff | 0 (+00:00) | | 044 | 00 00 00 00 | utoff | 0 (+00:00) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 048 | 00 | isdst | 0 (no) | | 048 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 049 | 00 | desigidx | 0 | | 049 | 00 | desigidx | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 050 | 55 54 43 00 | designations[0] | "UTC\0" | | 050 | 55 54 43 00 | designations[0] | "UTC\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[0] | |
| | | leapsecond[0] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 054 | 04 b2 58 00 | occurrence | 78796800 | | 054 | 04 b2 58 00 | occurrence | 78796800 |
| | | | (1972-06-30T23:59:60Z) | | | | | (1972-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 058 | 00 00 00 01 | correction | 1 | | 058 | 00 00 00 01 | correction | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[1] | |
| | | leapsecond[1] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 062 | 05 a4 ec 01 | occurrence | 94694401 | | 062 | 05 a4 ec 01 | occurrence | 94694401 |
| | | | (1972-12-31T23:59:60Z) | | | | | (1972-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 066 | 00 00 00 02 | correction | 2 | | 066 | 00 00 00 02 | correction | 2 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[2] | |
| | | leapsecond[2] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 070 | 07 86 1f 82 | occurrence | 126230402 | | 070 | 07 86 1f 82 | occurrence | 126230402 |
| | | | (1973-12-31T23:59:60Z) | | | | | (1973-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 074 | 00 00 00 03 | correction | 3 | | 074 | 00 00 00 03 | correction | 3 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[3] | |
| | | leapsecond[3] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 078 | 09 67 53 03 | occurrence | 157766403 | | 078 | 09 67 53 03 | occurrence | 157766403 |
| | | | (1974-12-31T23:59:60Z) | | | | | (1974-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 082 | 00 00 00 04 | correction | 4 | | 082 | 00 00 00 04 | correction | 4 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[4] | |
| | | leapsecond[4] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 086 | 0b 48 86 84 | occurrence | 189302404 | | 086 | 0b 48 86 84 | occurrence | 189302404 |
| | | | (1975-12-31T23:59:60Z) | | | | | (1975-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 090 | 00 00 00 05 | correction | 5 | | 090 | 00 00 00 05 | correction | 5 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[5] | |
| | | leapsecond[5] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 094 | 0d 2b 0b 85 | occurrence | 220924805 | | 094 | 0d 2b 0b 85 | occurrence | 220924805 |
| | | | (1976-12-31T23:59:60Z) | | | | | (1976-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 098 | 00 00 00 06 | correction | 6 | | 098 | 00 00 00 06 | correction | 6 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[6] | |
| | | leapsecond[6] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 102 | 0f 0c 3f 06 | occurrence | 252460806 | | 102 | 0f 0c 3f 06 | occurrence | 252460806 |
| | | | (1977-12-31T23:59:60Z) | | | | | (1977-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 106 | 00 00 00 07 | correction | 7 | | 106 | 00 00 00 07 | correction | 7 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[7] | |
| | | leapsecond[7] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 110 | 10 ed 72 87 | occurrence | 283996807 | | 110 | 10 ed 72 87 | occurrence | 283996807 |
| | | | (1978-12-31T23:59:60Z) | | | | | (1978-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 114 | 00 00 00 08 | correction | 8 | | 114 | 00 00 00 08 | correction | 8 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[8] | |
| | | leapsecond[8] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 118 | 12 ce a6 08 | occurrence | 315532808 | | 118 | 12 ce a6 08 | occurrence | 315532808 |
| | | | (1979-12-31T23:59:60Z) | | | | | (1979-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 122 | 00 00 00 09 | correction | 9 | | 122 | 00 00 00 09 | correction | 9 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[9] | |
| | | leapsecond[9] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 126 | 15 9f ca 89 | occurrence | 362793609 | | 126 | 15 9f ca 89 | occurrence | 362793609 |
| | | | (1981-06-30T23:59:60Z) | | | | | (1981-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 130 | 00 00 00 0a | correction | 10 | | 130 | 00 00 00 0a | correction | 10 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[10] | |
| | | leapsecond[10] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 134 | 17 80 fe 0a | occurrence | 394329610 | | 134 | 17 80 fe 0a | occurrence | 394329610 |
| | | | (1982-06-30T23:59:60Z) | | | | | (1982-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 138 | 00 00 00 0b | correction | 11 | | 138 | 00 00 00 0b | correction | 11 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[11] | |
| | | leapsecond[11] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 142 | 19 62 31 8b | occurrence | 425865611 | | 142 | 19 62 31 8b | occurrence | 425865611 |
| | | | (1983-06-30T23:59:60Z) | | | | | (1983-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 146 | 00 00 00 0c | correction | 12 | | 146 | 00 00 00 0c | correction | 12 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[12] | |
| | | leapsecond[12] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 150 | 1d 25 ea 0c | occurrence | 489024012 | | 150 | 1d 25 ea 0c | occurrence | 489024012 |
| | | | (1985-06-30T23:59:60Z) | | | | | (1985-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 154 | 00 00 00 0d | correction | 13 | | 154 | 00 00 00 0d | correction | 13 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[13] | |
| | | leapsecond[13] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 158 | 21 da e5 0d | occurrence | 567993613 | | 158 | 21 da e5 0d | occurrence | 567993613 |
| | | | (1987-12-31T23:59:60Z) | | | | | (1987-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 162 | 00 00 00 0e | correction | 14 | | 162 | 00 00 00 0e | correction | 14 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[14] | |
| | | leapsecond[14] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 166 | 25 9e 9d 8e | occurrence | 631152014 | | 166 | 25 9e 9d 8e | occurrence | 631152014 |
| | | | (1989-12-31T23:59:60Z) | | | | | (1989-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 170 | 00 00 00 0f | correction | 15 | | 170 | 00 00 00 0f | correction | 15 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[15] | |
| | | leapsecond[15] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 174 | 27 7f d1 0f | occurrence | 662688015 | | 174 | 27 7f d1 0f | occurrence | 662688015 |
| | | | (1990-12-31T23:59:60Z) | | | | | (1990-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 178 | 00 00 00 10 | correction | 16 | | 178 | 00 00 00 10 | correction | 16 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[16] | |
| | | leapsecond[16] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 182 | 2a 50 f5 90 | occurrence | 709948816 | | 182 | 2a 50 f5 90 | occurrence | 709948816 |
| | | | (1992-06-30T23:59:60Z) | | | | | (1992-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 186 | 00 00 00 11 | correction | 17 | | 186 | 00 00 00 11 | correction | 17 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[17] | |
| | | leapsecond[17] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 190 | 2c 32 29 11 | occurrence | 741484817 | | 190 | 2c 32 29 11 | occurrence | 741484817 |
| | | | (1993-06-30T23:59:60Z) | | | | | (1993-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 194 | 00 00 00 12 | correction | 18 | | 194 | 00 00 00 12 | correction | 18 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[18] | |
| | | leapsecond[18] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 198 | 2e 13 5c 92 | occurrence | 773020818 | | 198 | 2e 13 5c 92 | occurrence | 773020818 |
| | | | (1994-06-30T23:59:60Z) | | | | | (1994-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 202 | 00 00 00 13 | correction | 19 | | 202 | 00 00 00 13 | correction | 19 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[19] | |
| | | leapsecond[19] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 206 | 30 e7 24 13 | occurrence | 820454419 | | 206 | 30 e7 24 13 | occurrence | 820454419 |
| | | | (1995-12-31T23:59:60Z) | | | | | (1995-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 210 | 00 00 00 14 | correction | 20 | | 210 | 00 00 00 14 | correction | 20 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[20] | |
| | | leapsecond[20] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 214 | 33 b8 48 94 | occurrence | 867715220 | | 214 | 33 b8 48 94 | occurrence | 867715220 |
| | | | (1997-06-30T23:59:60Z) | | | | | (1997-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 218 | 00 00 00 15 | correction | 21 | | 218 | 00 00 00 15 | correction | 21 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[21] | |
| | | leapsecond[21] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 222 | 36 8c 10 15 | occurrence | 915148821 | | 222 | 36 8c 10 15 | occurrence | 915148821 |
| | | | (1998-12-31T23:59:60Z) | | | | | (1998-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 226 | 00 00 00 16 | correction | 22 | | 226 | 00 00 00 16 | correction | 22 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[22] | |
| | | leapsecond[22] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 230 | 43 b7 1b 96 | occurrence | 1136073622 | | 230 | 43 b7 1b 96 | occurrence | 1136073622 |
| | | | (2005-12-31T23:59:60Z) | | | | | (2005-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 234 | 00 00 00 17 | correction | 23 | | 234 | 00 00 00 17 | correction | 23 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[23] | |
| | | leapsecond[23] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 238 | 49 5c 07 97 | occurrence | 1230768023 | | 238 | 49 5c 07 97 | occurrence | 1230768023 |
| | | | (2008-12-31T23:59:60Z) | | | | | (2008-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 242 | 00 00 00 18 | correction | 24 | | 242 | 00 00 00 18 | correction | 24 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[24] | |
| | | leapsecond[24] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 246 | 4f ef 93 18 | occurrence | 1341100824 | | 246 | 4f ef 93 18 | occurrence | 1341100824 |
| | | | (2012-06-30T23:59:60Z) | | | | | (2012-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 250 | 00 00 00 19 | correction | 25 | | 250 | 00 00 00 19 | correction | 25 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[25] | |
| | | leapsecond[25] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 254 | 55 93 2d 99 | occurrence | 1435708825 | | 254 | 55 93 2d 99 | occurrence | 1435708825 |
| | | | (2015-06-30T23:59:60Z) | | | | | (2015-06-30T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 258 | 00 00 00 1a | correction | 26 | | 258 | 00 00 00 1a | correction | 26 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | leapsecond[26] | |
| | | leapsecond[26] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 262 | 58 68 46 9a | occurrence | 1483228826 | | 262 | 58 68 46 9a | occurrence | 1483228826 |
| | | | (2016-12-31T23:59:60Z) | | | | | (2016-12-31T23:59:60Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 266 | 00 00 00 1b | correction | 27 | | 266 | 00 00 00 1b | correction | 27 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 270 | 00 | standard/wall[0] | 0 (wall) | | 270 | 00 | standard/wall[0] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 271 | 00 | UT/local[0] | 0 (local) | | 271 | 00 | UT/local[0] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
Table 1 Table 1
To determine TAI corresponding to 2000-01-01T00:00:00Z To determine TAI corresponding to 2000-01-01T00:00:00Z
(UNIX time = 946684800), the following procedure would be followed: (UNIX time = 946684800), the following procedure would be followed:
1. Find the latest leap-second occurrence prior to the time of 1. Find the latest leap-second occurrence prior to the time of
interest (leapsecond[21]) and note the correction value interest (leapsecond[21]) and note the correction value
skipping to change at page 33, line 32 skipping to change at line 1455
B.2. Version 2 File Representing Pacific/Honolulu B.2. Version 2 File Representing Pacific/Honolulu
+========+=============+==================+========================+ +========+=============+==================+========================+
| File | Hexadecimal | Record Name / | Field Value | | File | Hexadecimal | Record Name / | Field Value |
| Offset | Octets | Field Name | | | Offset | Octets | Field Name | |
+========+=============+==================+========================+ +========+=============+==================+========================+
| 000 | 54 5a 69 66 | magic | "TZif" | | 000 | 54 5a 69 66 | magic | "TZif" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 004 | 32 | version | '2' (2) | | 004 | 32 | version | '2' (2) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 005 | 00 00 00 00 | | | | 005 | 00 00 00 00 | |
| | 00 00 00 00 | | | | | 00 00 00 00 | |
| | 00 00 00 00 | | | | | 00 00 00 00 | |
| | 00 00 00 | | | | | 00 00 00 | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 020 | 00 00 00 06 | isutcnt | 6 | | 020 | 00 00 00 06 | isutcnt | 6 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 024 | 00 00 00 06 | isstdcnt | 6 | | 024 | 00 00 00 06 | isstdcnt | 6 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 028 | 00 00 00 00 | leapcnt | 0 | | 028 | 00 00 00 00 | leapcnt | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 032 | 00 00 00 07 | timecnt | 7 | | 032 | 00 00 00 07 | timecnt | 7 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 036 | 00 00 00 06 | typecnt | 6 | | 036 | 00 00 00 06 | typecnt | 6 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 040 | 00 00 00 14 | charcnt | 20 | | 040 | 00 00 00 14 | charcnt | 20 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 044 | 80 00 00 00 | trans time[0] | -2147483648 | | 044 | 80 00 00 00 | trans time[0] | -2147483648 |
| | | | (1901-12-13T20:45:52Z) | | | | | (1901-12-13T20:45:52Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 048 | bb 05 43 48 | trans time[1] | -1157283000 | | 048 | bb 05 43 48 | trans time[1] | -1157283000 |
| | | | (1933-04-30T12:30:00Z) | | | | | (1933-04-30T12:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 052 | bb 21 71 58 | trans time[2] | -1155436200 | | 052 | bb 21 71 58 | trans time[2] | -1155436200 |
| | | | (1933-05-21T21:30:00Z) | | | | | (1933-05-21T21:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 056 | cb 89 3d c8 | trans time[3] | -880198200 | | 056 | cb 89 3d c8 | trans time[3] | -880198200 |
skipping to change at page 34, line 23 skipping to change at line 1493
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 060 | d2 23 f4 70 | trans time[4] | -769395600 | | 060 | d2 23 f4 70 | trans time[4] | -769395600 |
| | | | (1945-08-14T23:00:00Z) | | | | | (1945-08-14T23:00:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 064 | d2 61 49 38 | trans time[5] | -765376200 | | 064 | d2 61 49 38 | trans time[5] | -765376200 |
| | | | (1945-09-30T11:30:00Z) | | | | | (1945-09-30T11:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 068 | d5 8d 73 48 | trans time[6] | -712150200 | | 068 | d5 8d 73 48 | trans time[6] | -712150200 |
| | | | (1947-06-08T12:30:00Z) | | | | | (1947-06-08T12:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 072 | 01 | trans type[0] | 1 | | 072 | 01 | trans type[0] | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 073 | 02 | trans type[1] | 2 | | 073 | 02 | trans type[1] | 2 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 074 | 01 | trans type[2] | 1 | | 074 | 01 | trans type[2] | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 075 | 03 | trans type[3] | 3 | | 075 | 03 | trans type[3] | 3 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 076 | 04 | trans type[4] | 4 | | 076 | 04 | trans type[4] | 4 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 077 | 01 | trans type[5] | 1 | | 077 | 01 | trans type[5] | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 078 | 05 | trans type[6] | 5 | | 078 | 05 | trans type[6] | 5 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[0] | |
| | | localtimetype[0] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 079 | ff ff 6c 02 | utoff | -37886 (-10:31:26) | | 079 | ff ff 6c 02 | utoff | -37886 (-10:31:26) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 083 | 00 | isdst | 0 (no) | | 083 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 084 | 00 | desigidx | 0 | | 084 | 00 | desigidx | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[1] | |
| | | localtimetype[1] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 085 | ff ff 6c 58 | utoff | -37800 (-10:30) | | 085 | ff ff 6c 58 | utoff | -37800 (-10:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 089 | 00 | isdst | 0 (no) | | 089 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 090 | 04 | desigidx | 4 | | 090 | 04 | desigidx | 4 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[2] | |
| | | localtimetype[2] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 091 | ff ff 7a 68 | utoff | -34200 (-09:30) | | 091 | ff ff 7a 68 | utoff | -34200 (-09:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 095 | 01 | isdst | 1 (yes) | | 095 | 01 | isdst | 1 (yes) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 096 | 08 | desigidx | 8 | | 096 | 08 | desigidx | 8 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[3] | |
| | | localtimetype[3] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 097 | ff ff 7a 68 | utoff | -34200 (-09:30) | | 097 | ff ff 7a 68 | utoff | -34200 (-09:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 101 | 01 | isdst | 1 (yes) | | 101 | 01 | isdst | 1 (yes) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 102 | 0c | desigidx | 12 | | 102 | 0c | desigidx | 12 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[4] | |
| | | localtimetype[4] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 103 | ff ff 7a 68 | utoff | -34200 (-09:30) | | 103 | ff ff 7a 68 | utoff | -34200 (-09:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 107 | 01 | isdst | 1 (yes) | | 107 | 01 | isdst | 1 (yes) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 108 | 10 | desigidx | 16 | | 108 | 10 | desigidx | 16 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[5] | |
| | | localtimetype[5] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 109 | ff ff 73 60 | utoff | -36000 (-10:00) | | 109 | ff ff 73 60 | utoff | -36000 (-10:00) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 113 | 00 | isdst | 0 (no) | | 113 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 114 | 04 | desigidx | 4 | | 114 | 04 | desigidx | 4 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 115 | 4c 4d 54 00 | designations[0] | "LMT\0" | | 115 | 4c 4d 54 00 | designations[0] | "LMT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 119 | 48 53 54 00 | designations[4] | "HST\0" | | 119 | 48 53 54 00 | designations[4] | "HST\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 123 | 48 44 54 00 | designations[8] | "HDT\0" | | 123 | 48 44 54 00 | designations[8] | "HDT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 127 | 48 57 54 00 | designations[12] | "HWT\0" | | 127 | 48 57 54 00 | designations[12] | "HWT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 131 | 48 50 54 00 | designations[16] | "HPT\0" | | 131 | 48 50 54 00 | designations[16] | "HPT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 135 | 00 | standard/wall[0] | 0 (wall) | | 135 | 00 | standard/wall[0] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 136 | 00 | standard/wall[1] | 0 (wall) | | 136 | 00 | standard/wall[1] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 137 | 00 | standard/wall[2] | 0 (wall) | | 137 | 00 | standard/wall[2] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 138 | 00 | standard/wall[3] | 0 (wall) | | 138 | 00 | standard/wall[3] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 139 | 01 | standard/wall[4] | 1 (standard) | | 139 | 01 | standard/wall[4] | 1 (standard) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 140 | 00 | standard/wall[5] | 0 (wall) | | 140 | 00 | standard/wall[5] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 141 | 00 | UT/local[0] | 0 (local) | | 141 | 00 | UT/local[0] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 142 | 00 | UT/local[1] | 0 (local) | | 142 | 00 | UT/local[1] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 143 | 00 | UT/local[2] | 0 (local) | | 143 | 00 | UT/local[2] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 144 | 00 | UT/local[3] | 0 (local) | | 144 | 00 | UT/local[3] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 145 | 01 | UT/local[4] | 1 (UT) | | 145 | 01 | UT/local[4] | 1 (UT) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 146 | 00 | UT/local[5] | 0 (local) | | 146 | 00 | UT/local[5] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 147 | 54 5a 69 66 | magic | "TZif" | | 147 | 54 5a 69 66 | magic | "TZif" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 151 | 32 | version | '2' (2) | | 151 | 32 | version | '2' (2) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 152 | 00 00 00 00 | | | | 152 | 00 00 00 00 | |
| | 00 00 00 00 | | | | | 00 00 00 00 | |
| | 00 00 00 00 | | | | | 00 00 00 00 | |
| | 00 00 00 | | | | | 00 00 00 | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 167 | 00 00 00 06 | isutcnt | 6 | | 167 | 00 00 00 06 | isutcnt | 6 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 171 | 00 00 00 06 | isstdcnt | 6 | | 171 | 00 00 00 06 | isstdcnt | 6 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 175 | 00 00 00 00 | leapcnt | 0 | | 175 | 00 00 00 00 | leapcnt | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 179 | 00 00 00 07 | timecnt | 7 | | 179 | 00 00 00 07 | timecnt | 7 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 183 | 00 00 00 06 | typecnt | 6 | | 183 | 00 00 00 06 | typecnt | 6 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 187 | 00 00 00 14 | charcnt | 20 | | 187 | 00 00 00 14 | charcnt | 20 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 191 | ff ff ff ff | trans time[0] | -2334101314 | | 191 | ff ff ff ff | trans time[0] | -2334101314 |
| | 74 e0 70 be | | (1896-01-13T22:31:26Z) | | | 74 e0 70 be | | (1896-01-13T22:31:26Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 199 | ff ff ff ff | trans time[1] | -1157283000 | | 199 | ff ff ff ff | trans time[1] | -1157283000 |
| | bb 05 43 48 | | (1933-04-30T12:30:00Z) | | | bb 05 43 48 | | (1933-04-30T12:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 207 | ff ff ff ff | trans time[2] | -1155436200 | | 207 | ff ff ff ff | trans time[2] | -1155436200 |
| | bb 21 71 58 | | (1933-05-21T21:30:00Z) | | | bb 21 71 58 | | (1933-05-21T21:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 215 | ff ff ff ff | trans time[3] | -880198200 | | 215 | ff ff ff ff | trans time[3] | -880198200 |
skipping to change at page 37, line 29 skipping to change at line 1631
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 223 | ff ff ff ff | trans time[4] | -769395600 | | 223 | ff ff ff ff | trans time[4] | -769395600 |
| | d2 23 f4 70 | | (1945-08-14T23:00:00Z) | | | d2 23 f4 70 | | (1945-08-14T23:00:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 231 | ff ff ff ff | trans time[5] | -765376200 | | 231 | ff ff ff ff | trans time[5] | -765376200 |
| | d2 61 49 38 | | (1945-09-30T11:30:00Z) | | | d2 61 49 38 | | (1945-09-30T11:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 239 | ff ff ff ff | trans time[6] | -712150200 | | 239 | ff ff ff ff | trans time[6] | -712150200 |
| | d5 8d 73 48 | | (1947-06-08T12:30:00Z) | | | d5 8d 73 48 | | (1947-06-08T12:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 247 | 01 | trans type[0] | 1 | | 247 | 01 | trans type[0] | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 248 | 02 | trans type[1] | 2 | | 248 | 02 | trans type[1] | 2 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 249 | 01 | trans type[2] | 1 | | 249 | 01 | trans type[2] | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 250 | 03 | trans type[3] | 3 | | 250 | 03 | trans type[3] | 3 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 251 | 04 | trans type[4] | 4 | | 251 | 04 | trans type[4] | 4 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 252 | 01 | trans type[5] | 1 | | 252 | 01 | trans type[5] | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 253 | 05 | trans type[6] | 5 | | 253 | 05 | trans type[6] | 5 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[0] | |
| | | localtimetype[0] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 254 | ff ff 6c 02 | utoff | -37886 (-10:31:26) | | 254 | ff ff 6c 02 | utoff | -37886 (-10:31:26) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 258 | 00 | isdst | 0 (no) | | 258 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 259 | 00 | desigidx | 0 | | 259 | 00 | desigidx | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[1] | |
| | | localtimetype[1] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 260 | ff ff 6c 58 | utoff | -37800 (-10:30) | | 260 | ff ff 6c 58 | utoff | -37800 (-10:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 264 | 00 | isdst | 0 (no) | | 264 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 265 | 04 | desigidx | 4 | | 265 | 04 | desigidx | 4 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[2] | |
| | | localtimetype[2] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 266 | ff ff 7a 68 | utoff | -34200 (-09:30) | | 266 | ff ff 7a 68 | utoff | -34200 (-09:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 270 | 01 | isdst | 1 (yes) | | 270 | 01 | isdst | 1 (yes) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 271 | 08 | desigidx | 8 | | 271 | 08 | desigidx | 8 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[3] | |
| | | localtimetype[3] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 272 | ff ff 7a 68 | utoff | -34200 (-09:30) | | 272 | ff ff 7a 68 | utoff | -34200 (-09:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 276 | 01 | isdst | 1 (yes) | | 276 | 01 | isdst | 1 (yes) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 277 | 0c | desigidx | 12 | | 277 | 0c | desigidx | 12 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[4] | |
| | | localtimetype[4] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 278 | ff ff 7a 68 | utoff | -34200 (-09:30) | | 278 | ff ff 7a 68 | utoff | -34200 (-09:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 282 | 01 | isdst | 1 (yes) | | 282 | 01 | isdst | 1 (yes) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 283 | 10 | desigidx | 16 | | 283 | 10 | desigidx | 16 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[5] | |
| | | localtimetype[5] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 284 | ff ff 73 60 | utoff | -36000 (-10:00) | | 284 | ff ff 73 60 | utoff | -36000 (-10:00) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 288 | 00 | isdst | 0 (no) | | 288 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 289 | 04 | desigidx | 4 | | 289 | 04 | desigidx | 4 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 290 | 4c 4d 54 00 | designations[0] | "LMT\0" | | 290 | 4c 4d 54 00 | designations[0] | "LMT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 294 | 48 53 54 00 | designations[4] | "HST\0" | | 294 | 48 53 54 00 | designations[4] | "HST\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 298 | 48 44 54 00 | designations[8] | "HDT\0" | | 298 | 48 44 54 00 | designations[8] | "HDT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 302 | 48 57 54 00 | designations[12] | "HWT\0" | | 302 | 48 57 54 00 | designations[12] | "HWT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 306 | 48 50 54 00 | designations[16] | "HPT\0" | | 306 | 48 50 54 00 | designations[16] | "HPT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 310 | 00 | standard/wall[0] | 0 (wall) | | 310 | 00 | standard/wall[0] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 311 | 00 | standard/wall[1] | 0 (wall) | | 311 | 00 | standard/wall[1] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 312 | 00 | standard/wall[2] | 0 (wall) | | 312 | 00 | standard/wall[2] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 313 | 00 | standard/wall[3] | 0 (wall) | | 313 | 00 | standard/wall[3] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 314 | 01 | standard/wall[4] | 1 (standard) | | 314 | 01 | standard/wall[4] | 1 (standard) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 315 | 00 | standard/wall[5] | 0 (wall) | | 315 | 00 | standard/wall[5] | 0 (wall) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 316 | 00 | UT/local[0] | 0 (local) | | 316 | 00 | UT/local[0] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 317 | 00 | UT/local[1] | 0 (local) | | 317 | 00 | UT/local[1] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 318 | 00 | UT/local[2] | 0 (local) | | 318 | 00 | UT/local[2] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 319 | 00 | UT/local[3] | 0 (local) | | 319 | 00 | UT/local[3] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 320 | 01 | UT/local[4] | 1 (UT) | | 320 | 01 | UT/local[4] | 1 (UT) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 321 | 00 | UT/local[5] | 0 (local) | | 321 | 00 | UT/local[5] | 0 (local) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 322 | 0a | NL | '\n' | | 322 | 0a | NL | '\n' |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 323 | 48 53 54 31 | TZ string | "HST10" | | 323 | 48 53 54 31 | TZ string | "HST10" |
| | 30 | | | | | 30 | | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 328 | 0a | NL | '\n' | | 328 | 0a | NL | '\n' |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
Table 2 Table 2
skipping to change at page 40, line 34 skipping to change at line 1766
daylight saving time of 1933-05-04T02:30:00-09:30 (HDT). daylight saving time of 1933-05-04T02:30:00-09:30 (HDT).
To determine the local time in this time zone corresponding to To determine the local time in this time zone corresponding to
2019-01-01T00:00:00Z (UNIX time = 1546300800), the following 2019-01-01T00:00:00Z (UNIX time = 1546300800), the following
procedure would be followed: procedure would be followed:
1. Find the latest time transition prior to the time of interest 1. Find the latest time transition prior to the time of interest
(there is no such transition). (there is no such transition).
2. Look up the TZ string in the footer ("HST10"), which indicates 2. Look up the TZ string in the footer ("HST10"), which indicates
that the time zone designation is "HST" year-round, and the that the time zone designation is "HST" year-round and the offset
offset to UTC is 10:00. to UTC is 10:00.
3. Subtract the UTC offset from the time of interest to yield a 3. Subtract the UTC offset from the time of interest to yield a
standard local time of 2018-12-31T14:00:00-10:00 (HST). standard local time of 2018-12-31T14:00:00-10:00 (HST).
B.3. Truncated Version 2 File Representing Pacific/Johnston B.3. Truncated Version 2 File Representing Pacific/Johnston
The following TZif file has been truncated to end on The following TZif file has been truncated to end on
2004-06-161T00:00:00Z (the atoll was abandoned sometime on 2004-06-161T00:00:00Z (the atoll was abandoned sometime on
2004-06-15). 2004-06-15).
In this example: In this example:
* The version 1 header contains only the required minimum data, * The version 1 header contains only the required minimum data,
which will be ignored by readers. which will be ignored by readers.
* The version 2 header leverages the fact that by specifying * The version 2 header leverages the fact that, by specifying
'isutcnt' and 'isstdcnt' as zero, all transition times associated 'isutcnt' and 'isstdcnt' as zero, all transition times associated
with local time types are assumed to be specified as local wall- with local time types are assumed to be specified as local wall-
clock time (see the definitions of UT/local indicators and clock time (see the definitions of UT/local indicators and
standard/wall indicators in Section 3.2). standard/wall indicators in Section 3.2).
* The time type of the last transition has designation "-00", * The time type of the last transition has designation "-00",
indicating that local time is unspecified. indicating that local time is unspecified.
* The TZ string is empty, indicating that there are no known future * The TZ string is empty, indicating that there are no known future
transitions. transitions.
skipping to change at page 41, line 42 skipping to change at line 1820
| 024 | 00 00 00 00 | isstdcnt | 0 | | 024 | 00 00 00 00 | isstdcnt | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 028 | 00 00 00 00 | leapcnt | 0 | | 028 | 00 00 00 00 | leapcnt | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 032 | 00 00 00 00 | timecnt | 0 | | 032 | 00 00 00 00 | timecnt | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 036 | 00 00 00 01 | typecnt | 1 | | 036 | 00 00 00 01 | typecnt | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 040 | 00 00 00 01 | charcnt | 1 | | 040 | 00 00 00 01 | charcnt | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[0] | |
| | | localtimetype[0] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 044 | 00 00 00 00 | utoff | 0 (+00:00) | | 044 | 00 00 00 00 | utoff | 0 (+00:00) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 048 | 00 | isdst | 0 (no) | | 048 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 049 | 00 | desigidx | 0 | | 049 | 00 | desigidx | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 050 | 00 | designations[0] | "\0" | | 050 | 00 | designations[0] | "\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 051 | 54 5a 69 66 | magic | "TZif" | | 051 | 54 5a 69 66 | magic | "TZif" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 055 | 32 | version | '2' (2) | | 055 | 32 | version | '2' (2) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 056 | 00 00 00 00 | | | | 056 | 00 00 00 00 | |
| | 00 00 00 00 | | | | | 00 00 00 00 | |
| | 00 00 00 00 | | | | | 00 00 00 00 | |
| | 00 00 00 | | | | | 00 00 00 | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 071 | 00 00 00 00 | isutcnt | 0 | | 071 | 00 00 00 00 | isutcnt | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 075 | 00 00 00 00 | isstdcnt | 0 | | 075 | 00 00 00 00 | isstdcnt | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 079 | 00 00 00 00 | leapcnt | 0 | | 079 | 00 00 00 00 | leapcnt | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 083 | 00 00 00 08 | timecnt | 8 | | 083 | 00 00 00 08 | timecnt | 8 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 087 | 00 00 00 07 | typecnt | 7 | | 087 | 00 00 00 07 | typecnt | 7 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 091 | 00 00 00 18 | charcnt | 24 | | 091 | 00 00 00 18 | charcnt | 24 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 095 | ff ff ff ff | trans time[0] | -2334101314 | | 095 | ff ff ff ff | trans time[0] | -2334101314 |
| | 74 e0 70 be | | (1896-01-13T22:31:26Z) | | | 74 e0 70 be | | (1896-01-13T22:31:26Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 103 | ff ff ff ff | trans time[1] | -1157283000 | | 103 | ff ff ff ff | trans time[1] | -1157283000 |
| | bb 05 43 48 | | (1933-04-30T12:30:00Z) | | | bb 05 43 48 | | (1933-04-30T12:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 111 | ff ff ff ff | trans time[2] | -1155436200 | | 111 | ff ff ff ff | trans time[2] | -1155436200 |
| | bb 21 71 58 | | (1933-05-21T21:30:00Z) | | | bb 21 71 58 | | (1933-05-21T21:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 119 | ff ff ff ff | trans time[3] | -880198200 | | 119 | ff ff ff ff | trans time[3] | -880198200 |
skipping to change at page 43, line 4 skipping to change at line 1875
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 135 | ff ff ff ff | trans time[5] | -765376200 | | 135 | ff ff ff ff | trans time[5] | -765376200 |
| | d2 61 49 38 | | (1945-09-30T11:30:00Z) | | | d2 61 49 38 | | (1945-09-30T11:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 143 | ff ff ff ff | trans time[6] | -712150200 | | 143 | ff ff ff ff | trans time[6] | -712150200 |
| | d5 8d 73 48 | | (1947-06-08T12:30:00Z) | | | d5 8d 73 48 | | (1947-06-08T12:30:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 151 | 00 00 00 00 | trans time[7] | 1087344000 | | 151 | 00 00 00 00 | trans time[7] | 1087344000 |
| | 40 cf 8d 80 | | (2004-06-16T00:00:00Z) | | | 40 cf 8d 80 | | (2004-06-16T00:00:00Z) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 159 | 02 | trans type[0] | 2 | | 159 | 02 | trans type[0] | 2 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 160 | 03 | trans type[1] | 3 | | 160 | 03 | trans type[1] | 3 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 161 | 02 | trans type[2] | 2 | | 161 | 02 | trans type[2] | 2 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 162 | 04 | trans type[3] | 4 | | 162 | 04 | trans type[3] | 4 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 163 | 05 | trans type[4] | 5 | | 163 | 05 | trans type[4] | 5 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 164 | 02 | trans type[5] | 2 | | 164 | 02 | trans type[5] | 2 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 165 | 06 | trans type[6] | 6 | | 165 | 06 | trans type[6] | 6 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 166 | 01 | trans type[7] | 1 | | 166 | 01 | trans type[7] | 1 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[0] | |
| | | localtimetype[0] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 167 | ff ff 6c 02 | utoff | -37886 (-10:31:26) | | 167 | ff ff 6c 02 | utoff | -37886 (-10:31:26) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 171 | 00 | isdst | 0 (no) | | 171 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 172 | 04 | desigidx | 4 | | 172 | 04 | desigidx | 4 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[1] | |
| | | localtimetype[1] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 173 | 00 00 00 00 | utoff | 0 (+00:00) | | 173 | 00 00 00 00 | utoff | 0 (+00:00) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 177 | 00 | isdst | 0 (no) | | 177 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 178 | 00 | desigidx | 0 | | 178 | 00 | desigidx | 0 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[2] | |
| | | localtimetype[2] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 179 | ff ff 6c 58 | utoff | -37800 (-10:30) | | 179 | ff ff 6c 58 | utoff | -37800 (-10:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 183 | 00 | isdst | 0 (no) | | 183 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 184 | 08 | desigidx | 8 | | 184 | 08 | desigidx | 8 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[3] | |
| | | localtimetype[3] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 185 | ff ff 7a 68 | utoff | -34200 (-09:30) | | 185 | ff ff 7a 68 | utoff | -34200 (-09:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 189 | 01 | isdst | 1 (yes) | | 189 | 01 | isdst | 1 (yes) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 190 | 0c | desigidx | 12 | | 190 | 0c | desigidx | 12 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[4] | |
| | | localtimetype[4] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 191 | ff ff 7a 68 | utoff | -34200 (-09:30) | | 191 | ff ff 7a 68 | utoff | -34200 (-09:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 195 | 01 | isdst | 1 (yes) | | 195 | 01 | isdst | 1 (yes) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 196 | 10 | desigidx | 16 | | 196 | 10 | desigidx | 16 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[5] | |
| | | localtimetype[5] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 197 | ff ff 7a 68 | utoff | -34200 (-09:30) | | 197 | ff ff 7a 68 | utoff | -34200 (-09:30) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 201 | 01 | isdst | 1 (yes) | | 201 | 01 | isdst | 1 (yes) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 202 | 14 | desigidx | 20 | | 202 | 14 | desigidx | 20 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+ | | localtimetype[6] | |
| | | localtimetype[6] | |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 203 | ff ff 73 60 | utoff | -36000 (-10:00) | | 203 | ff ff 73 60 | utoff | -36000 (-10:00) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 207 | 00 | isdst | 0 (no) | | 207 | 00 | isdst | 0 (no) |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 208 | 08 | desigidx | 8 | | 208 | 08 | desigidx | 8 |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 209 | 2d 30 30 00 | designations[0] | "-00\0" | | 209 | 2d 30 30 00 | designations[0] | "-00\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 213 | 4c 4d 54 00 | designations[4] | "LMT\0" | | 213 | 4c 4d 54 00 | designations[4] | "LMT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 217 | 48 53 54 00 | designations[8] | "HST\0" | | 217 | 48 53 54 00 | designations[8] | "HST\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 221 | 48 44 54 00 | designations[12] | "HDT\0" | | 221 | 48 44 54 00 | designations[12] | "HDT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 225 | 48 57 54 00 | designations[16] | "HWT\0" | | 225 | 48 57 54 00 | designations[16] | "HWT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 229 | 48 50 54 00 | designations[20] | "HPT\0" | | 229 | 48 50 54 00 | designations[20] | "HPT\0" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
+--------+-------------+------------------+------------------------+
| 233 | 0a | NL | '\n' | | 233 | 0a | NL | '\n' |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 234 | | TZ string | "" | | 234 | | TZ string | "" |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
| 234 | 0a | NL | '\n' | | 234 | 0a | NL | '\n' |
+--------+-------------+------------------+------------------------+ +--------+-------------+------------------+------------------------+
Table 3 Table 3
B.4. Truncated Version 3 File Representing Asia/Jerusalem B.4. Truncated Version 3 File Representing Asia/Jerusalem
The following TZif file has been truncated to start on The following TZif file has been truncated to start on
2038-01-01T00:00:00Z. 2038-01-01T00:00:00Z.
In this example: In this example:
* The start time value can not be represented using 32 bits, so the * The start time value cannot be represented using 32 bits, so the
version 1 header contains only the required minimum data, which version 1 header contains only the required minimum data, which
will be ignored by readers. will be ignored by readers.
* The version 3 header leverages the fact that by specifying * The version 3 header leverages the fact that, by specifying
'isutcnt' and 'isstdcnt' as zero, all transition times associated 'isutcnt' and 'isstdcnt' as zero, all transition times associated
with local time types are assumed to be specified as local wall- with local time types are assumed to be specified as local wall-
clock time (see the definitions of UT/local indicators and clock time (see the definitions of UT/local indicators and
standard/wall indicators in Section 3.2). standard/wall indicators in Section 3.2).
* Time type 0 has designation "-00", indicating that local time is * Time type 0 has designation "-00", indicating that local time is
unspecified prior to the truncation time. unspecified prior to the truncation time.
* The TZ string value has been line-wrapped for presentation * The TZ string value has been line-wrapped for presentation
purposes only. purposes only.
+======+===========+================+==============================+ +======+===========+================+==============================+
|File |Hexadecimal|Record Name / | Field Value | |File |Hexadecimal|Record Name / | Field Value |
|Offset|Octets |Field Name | | |Offset|Octets |Field Name | |
+======+===========+================+==============================+ +======+===========+================+==============================+
|000 |54 5a 69 66|magic | "TZif" | |000 |54 5a 69 66|magic | "TZif" |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|004 |33 |version | '3' (3) | |004 |33 |version | '3' (3) |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|005 |00 00 00 00| | | |005 |00 00 00 00| |
| |00 00 00 00| | | | |00 00 00 00| |
| |00 00 00 00| | | | |00 00 00 00| |
| |00 00 00 | | | | |00 00 00 | |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|020 |00 00 00 00|isutcnt | 0 | |020 |00 00 00 00|isutcnt | 0 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|024 |00 00 00 00|isstdcnt | 0 | |024 |00 00 00 00|isstdcnt | 0 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|028 |00 00 00 00|leapcnt | 0 | |028 |00 00 00 00|leapcnt | 0 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|032 |00 00 00 00|timecnt | 0 | |032 |00 00 00 00|timecnt | 0 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|036 |00 00 00 01|typecnt | 1 | |036 |00 00 00 01|typecnt | 1 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|040 |00 00 00 01|charcnt | 1 | |040 |00 00 00 01|charcnt | 1 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
+------+-----------+----------------+------------------------------+ | |localtimetype[0]| |
| | |localtimetype[0]| |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|044 |00 00 00 00|utoff | 0 (+00:00) | |044 |00 00 00 00|utoff | 0 (+00:00) |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|048 |00 |isdst | 0 (no) | |048 |00 |isdst | 0 (no) |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|049 |00 |desigidx | 0 | |049 |00 |desigidx | 0 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
+------+-----------+----------------+------------------------------+
|050 |00 |designations[0] | "\0" | |050 |00 |designations[0] | "\0" |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
+------+-----------+----------------+------------------------------+
|051 |54 5a 69 66|magic | "TZif" | |051 |54 5a 69 66|magic | "TZif" |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|055 |33 |version | '3' (3) | |055 |33 |version | '3' (3) |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|056 |00 00 00 00| | | |056 |00 00 00 00| |
| |00 00 00 00| | | | |00 00 00 00| |
| |00 00 00 00| | | | |00 00 00 00| |
| |00 00 00 | | | | |00 00 00 | |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|071 |00 00 00 00|isutcnt | 0 | |071 |00 00 00 00|isutcnt | 0 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|075 |00 00 00 00|isstdcnt | 0 | |075 |00 00 00 00|isstdcnt | 0 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|079 |00 00 00 00|leapcnt | 0 | |079 |00 00 00 00|leapcnt | 0 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|083 |00 00 00 01|timecnt | 1 | |083 |00 00 00 01|timecnt | 1 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|087 |00 00 00 02|typecnt | 2 | |087 |00 00 00 02|typecnt | 2 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|091 |00 00 00 08|charcnt | 8 | |091 |00 00 00 08|charcnt | 8 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
+------+-----------+----------------+------------------------------+
|095 |00 00 00 00|trans time[0] | 2145916800 | |095 |00 00 00 00|trans time[0] | 2145916800 |
| |7f e8 17 80| | (2038-01-01T00:00:00Z) | | |7f e8 17 80| | (2038-01-01T00:00:00Z) |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
+------+-----------+----------------+------------------------------+
|103 |01 |trans type[0] | 1 | |103 |01 |trans type[0] | 1 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
+------+-----------+----------------+------------------------------+ | |localtimetype[0]| |
| | |localtimetype[0]| |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|104 |00 00 00 00|utoff | 0 (+00:00) | |104 |00 00 00 00|utoff | 0 (+00:00) |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|108 |00 |isdst | 0 (no) | |108 |00 |isdst | 0 (no) |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|109 |00 |desigidx | 0 | |109 |00 |desigidx | 0 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
+------+-----------+----------------+------------------------------+ | |localtimetype[1]| |
| | |localtimetype[1]| |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|110 |00 00 1c 20|utoff | 7200 (+02:00) | |110 |00 00 1c 20|utoff | 7200 (+02:00) |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|114 |00 |isdst | 0 (no) | |114 |00 |isdst | 0 (no) |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|115 |04 |desigidx | 4 | |115 |04 |desigidx | 4 |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
+------+-----------+----------------+------------------------------+
|116 |2d 30 30 00|designations[0] | "-00\0" | |116 |2d 30 30 00|designations[0] | "-00\0" |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|120 |49 53 54 00|designations[4] | "IST\0" | |120 |49 53 54 00|designations[4] | "IST\0" |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
+------+-----------+----------------+------------------------------+
|124 |0a |NL | '\n' | |124 |0a |NL | '\n' |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
|125 |49 53 54 2d|TZ string | "IST-2IDT,M3.4.4/26,M10.5.0" | |125 |49 53 54 2d|TZ string | "IST-2IDT,M3.4.4/26,M10.5.0" |
| |32 49 44 54| | | | |32 49 44 54| | |
| |2c 4d 33 2e| | | | |2c 4d 33 2e| | |
| |34 2e 34 2f| | | | |34 2e 34 2f| | |
| |32 36 2c 4d| | | | |32 36 2c 4d| | |
| |31 30 2e 35| | | | |31 30 2e 35| | |
| |2e 30 | | | | |2e 30 | | |
+------+-----------+----------------+------------------------------+ +------+-----------+----------------+------------------------------+
skipping to change at page 48, line 5 skipping to change at line 2097
B.5. Truncated Version 4 File Representing Europe/London B.5. Truncated Version 4 File Representing Europe/London
The following TZif file has been truncated to start on The following TZif file has been truncated to start on
2022-01-01T00:00:00Z. 2022-01-01T00:00:00Z.
In this example: In this example:
* The version 1 header contains only the required minimum data, * The version 1 header contains only the required minimum data,
which will be ignored by readers. which will be ignored by readers.
* The version 4 header leverages the fact that by specifying * The version 4 header leverages the fact that, by specifying
'isutcnt' and 'isstdcnt' as zero, all transition times associated 'isutcnt' and 'isstdcnt' as zero, all transition times associated
with local time types are assumed to be specified as local wall- with local time types are assumed to be specified as local wall-
clock time (see the definitions of UT/local indicators and clock time (see the definitions of UT/local indicators and
standard/wall indicators in Section 3.2). standard/wall indicators in Section 3.2).
* Time type 0 has designation "-00", indicating that local time is * Time type 0 has designation "-00", indicating that local time is
unspecified prior to the truncation time. unspecified prior to the truncation time.
* The first leap-second occurrence is the most recent one prior to * The first leap-second occurrence is the most recent one prior to
the truncation time. the truncation time.
skipping to change at page 48, line 32 skipping to change at line 2124
purposes only. purposes only.
+======+===========+==================+============================+ +======+===========+==================+============================+
|File |Hexadecimal| Record Name / | Field Value | |File |Hexadecimal| Record Name / | Field Value |
|Offset|Octets | Field Name | | |Offset|Octets | Field Name | |
+======+===========+==================+============================+ +======+===========+==================+============================+
|000 |54 5a 69 66| magic | "TZif" | |000 |54 5a 69 66| magic | "TZif" |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|004 |34 | version | '4' (4) | |004 |34 | version | '4' (4) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|005 |00 00 00 00| | | |005 |00 00 00 00| |
| |00 00 00 00| | | | |00 00 00 00| |
| |00 00 00 00| | | | |00 00 00 00| |
| |00 00 00 | | | | |00 00 00 | |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|020 |00 00 00 00| isutcnt | 0 | |020 |00 00 00 00| isutcnt | 0 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|024 |00 00 00 00| isstdcnt | 0 | |024 |00 00 00 00| isstdcnt | 0 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|028 |00 00 00 00| leapcnt | 0 | |028 |00 00 00 00| leapcnt | 0 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|032 |00 00 00 00| timecnt | 0 | |032 |00 00 00 00| timecnt | 0 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|036 |00 00 00 01| typecnt | 1 | |036 |00 00 00 01| typecnt | 1 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|040 |00 00 00 01| charcnt | 1 | |040 |00 00 00 01| charcnt | 1 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+ | | localtimetype[0] | |
| | | localtimetype[0] | |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|044 |00 00 00 00| utoff | 0 (+00:00) | |044 |00 00 00 00| utoff | 0 (+00:00) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|048 |00 | isdst | 0 (no) | |048 |00 | isdst | 0 (no) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|049 |00 | desigidx | 0 | |049 |00 | desigidx | 0 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+
|050 |00 | designations[0] | "\0" | |050 |00 | designations[0] | "\0" |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+
|051 |54 5a 69 66| magic | "TZif" | |051 |54 5a 69 66| magic | "TZif" |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|055 |34 | version | '4' (4) | |055 |34 | version | '4' (4) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|056 |00 00 00 00| | | |056 |00 00 00 00| |
| |00 00 00 00| | | | |00 00 00 00| |
| |00 00 00 00| | | | |00 00 00 00| |
| |00 00 00 | | | | |00 00 00 | |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|071 |00 00 00 00| isutcnt | 0 | |071 |00 00 00 00| isutcnt | 0 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|075 |00 00 00 00| isstdcnt | 0 | |075 |00 00 00 00| isstdcnt | 0 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|079 |00 00 00 02| leapcnt | 2 | |079 |00 00 00 02| leapcnt | 2 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|083 |00 00 00 01| timecnt | 1 | |083 |00 00 00 01| timecnt | 1 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|087 |00 00 00 02| typecnt | 2 | |087 |00 00 00 02| typecnt | 2 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|091 |00 00 00 08| charcnt | 8 | |091 |00 00 00 08| charcnt | 8 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+
|095 |00 00 00 00| trans time[0] | 1640995227 | |095 |00 00 00 00| trans time[0] | 1640995227 |
| |61 cf 99 9b| | (2022-01-01T00:00:27Z) | | |61 cf 99 9b| | (2022-01-01T00:00:27Z) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+
|103 |01 | trans type[0] | 1 | |103 |01 | trans type[0] | 1 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+ | | localtimetype[0] | |
| | | localtimetype[0] | |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|104 |00 00 00 00| utoff | 0 (+00:00) | |104 |00 00 00 00| utoff | 0 (+00:00) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|108 |00 | isdst | 0 (no) | |108 |00 | isdst | 0 (no) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|109 |00 | desigidx | 0 | |109 |00 | desigidx | 0 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+ | | localtimetype[1] | |
| | | localtimetype[1] | |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|110 |00 00 00 00| utoff | 0 (+00:00) | |110 |00 00 00 00| utoff | 0 (+00:00) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|114 |00 | isdst | 0 (no) | |114 |00 | isdst | 0 (no) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|115 |04 | desigidx | 4 | |115 |04 | desigidx | 4 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+
|116 |2d 30 30 00| designations[0] | "-00\0" | |116 |2d 30 30 00| designations[0] | "-00\0" |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|120 |47 4d 54 00| designations[4] | "GMT\0" | |120 |47 4d 54 00| designations[4] | "GMT\0" |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+ | | leapsecond[0] | |
| | | leapsecond[0] | |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|124 |00 00 00 00| occurrence | 1483228826 | |124 |00 00 00 00| occurrence | 1483228826 |
| |58 68 46 9a| | (2016-12-31T23:59:60Z) | | |58 68 46 9a| | (2016-12-31T23:59:60Z) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|132 |00 00 00 1b| correction | 27 | |132 |00 00 00 1b| correction | 27 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+ | | leapsecond[1] | |
| | | leapsecond[1] | |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|136 |00 00 00 00| occurrence | 1719532827 | |136 |00 00 00 00| occurrence | 1719532827 |
| |66 7d fd 1b| | (2024-06-28T00:00:01Z) | | |66 7d fd 1b| | (2024-06-28T00:00:01Z) |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|144 |00 00 00 1b| correction | 27 | |144 |00 00 00 1b| correction | 27 |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
+------+-----------+------------------+----------------------------+
|148 |0a | NL | '\n' | |148 |0a | NL | '\n' |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|149 |47 4d 54 30| TZ string | "GMT0BST,M3.5.0/1,M10.5.0" | |149 |47 4d 54 30| TZ string | "GMT0BST,M3.5.0/1,M10.5.0" |
| |42 53 54 2c| | | | |42 53 54 2c| | |
| |4d 33 2e 35| | | | |4d 33 2e 35| | |
| |2e 30 2f 31| | | | |2e 30 2f 31| | |
| |2c 4d 31 30| | | | |2c 4d 31 30| | |
| |2e 35 2e 30| | | | |2e 35 2e 30| | |
+------+-----------+------------------+----------------------------+ +------+-----------+------------------+----------------------------+
|173 |0a | NL | '\n' | |173 |0a | NL | '\n' |
skipping to change at page 51, line 23 skipping to change at line 2247
* Required support in version 2 files for all-year daylight saving * Required support in version 2 files for all-year daylight saving
time, using POSIX TZ strings with negative DST, as this is not an time, using POSIX TZ strings with negative DST, as this is not an
extension to POSIX (Section 3.3.1). extension to POSIX (Section 3.3.1).
* Applied erratum [Err6435]. * Applied erratum [Err6435].
* Addressed errata [Err6426] and [Err6757] as well as several other * Addressed errata [Err6426] and [Err6757] as well as several other
errors in the examples. errors in the examples.
* Added additional interoperabilty considerations and common issues. * Added additional interoperability considerations and common
issues.
* Added an example of a TZif file truncated at the end.
(Appendix B.3)
* Added informational notes to Appendix B.4.
* Miscellaneous editorial changes.
Appendix D. Change Log
This section is to be removed by RFC Editor before publication.
D.1. Since rfc8536bis-14
* Correct direction reversal with UT offsets -10 and +0530.
D.2. Since rfc8536bis-13
* Referenced Section 8 of RFC 7808 in Security Considerations.
* Changed some terminology in Appendix A to be more inclusive.
* Added Internationalization Considerations section and clarified
the requirements for time zone designation strings.
* Stiffened the requirements for truncating TZif files.
D.3. Since rfc8536bis-12
* Clarified the difference between the two media types in their IANA
registrations.
* Removed dates from references to dynamic content.
D.4. Since rfc8536bis-11
* Clarified the consequences of not abiding by some SHOULDs.
* Miscellaneous editorial changes.
D.5. Since rfc8536bis-10
* Clarified in IANA Considerations that this document is updating
the existing media types.
D.6. Since rfc8536bis-09
* Clarified text of the example in the description of leap-second
table expiration.
D.7. Since rfc8536bis-08
* Added an example of a TZif file truncated at the end.
* Fixed utoff value of LMT in Honolulu example.
* Updated "tz-link" URL.
* Miscellaneous editorial changes.
D.8. Since rfc8536bis-07
* Miscellaneous editorial changes.
D.9. Since rfc8536bis-06
* Moved the specification of an all-year daylight saving time TZ
string (Section 3.3.1), to its own section as it is NOT an
extension.
* Noted that should leap seconds to become discontinued that leap-
second tables SHOULD NOT expire.
* Updated "tz-link" title and reference.
* Updated reference to RFC 7231 to RFC 9110.
* Miscellaneous editorial changes.
D.10. Since rfc8536bis-05
* Clarified the specification of an all-year daylight saving time TZ
string (Section 3.3.1), and changed the example to use negative
DST.
D.11. Since rfc8536bis-04
* None.
D.12. Since rfc8536bis-03
* Noted that erratum [Err6757] has been addressed.
* Added a definition of Leap Second, including UTC month.
D.13. Since rfc8536bis-02
* Documented "-00" as meaning unspecified local time.
* Recommended that "-00" be used for timestamps that are unspecified
due to TZif file truncation.
D.14. Since rfc8536bis-01
* Converted source from xml2rfc v2 to v3.
* Properly line-wrapped long TZ string values in examples (with no
added space).
* No other substantive changes.
D.15. Since rfc8536bis-00
* Added specification of the version 4 format and the optional leap-
second table truncation and expiration, along with an example and
relevant interoperability considerations.
* Specified column widths in example tables.
* Noted that long TZ string values in examples are line-wrapped for
presentation purposes only.
D.16. Since RFC 8536
* Applied erratum [Err6435].
* Addressed erratum [Err6426] and several other errors in the
examples.
* Clarified the specification of an all-year daylight saving time TZ * Added an example of a TZif file truncated at the end
string (Section 3.3.1), and changed the example to use negative (Appendix B.3).
DST.
* Added informational notes to Appendix B.4. * Added informational notes to Appendix B.4.
* Miscellaneous editorial changes. * Miscellaneous editorial changes.
* Added text obsoleting [RFC8536].
* Added Changes from RFC 8536 (Appendix C).
* Added Tim Parenti as a contributor.
Acknowledgments Acknowledgments
The authors would like to thank the following individuals for The authors would like to thank the following individuals for
contributing their ideas and support for writing this specification: contributing their ideas and support for writing this specification:
Michael Douglass, Ned Freed, Guy Harris, Eliot Lear, Alexey Melnikov, Michael Douglass, Ned Freed, Guy Harris, Eliot Lear, Alexey Melnikov,
and Tim Parenti. and Tim Parenti.
Authors' Addresses Authors' Addresses
Arthur David Olson Arthur David Olson
 End of changes. 211 change blocks. 
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