rfc9636.original.xml   rfc9636.xml 
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<rfc xmlns:xi="http://www.w3.org/2001/XInclude" category="std"
docName="draft-murchison-rfc8536bis-15" updates=""
ipr="trust200902" obsoletes="8536" consensus="true"
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<front> <rfc xmlns:xi="http://www.w3.org/2001/XInclude" category="std" docName="draft-mu
<title abbrev="TZif"> rchison-rfc8536bis-15" number="9636" updates="" ipr="trust200902" obsoletes="853
The Time Zone Information Format (TZif) 6" consensus="true" submissionType="IETF" xml:lang="en" tocInclude="true" symRef
</title> s="true" sortRefs="true" tocDepth="3" version="3">
<seriesInfo name="Internet-Draft" value="draft-murchison-rfc8536bis-15"/>
<author initials="A.D." surname="Olson" fullname="Arthur David Olson"> <front>
<organization/> <title abbrev="TZif">The Time Zone Information Format (TZif)</title>
<seriesInfo name="RFC" value="9636"/>
<author initials="A." surname="Olson" fullname="Arthur David Olson">
<address> <address>
<email>arthurdavidolson@gmail.com</email> <email>arthurdavidolson@gmail.com</email>
</address> </address>
</author> </author>
<author initials="P." surname="Eggert" fullname="Paul Eggert"> <author initials="P." surname="Eggert" fullname="Paul Eggert">
<organization abbrev="UCLA"> <organization abbrev="UCLA">University of California, Los Angeles</organiz
University of California, Los Angeles ation>
</organization>
<address> <address>
<email>eggert@cs.ucla.edu</email> <email>eggert@cs.ucla.edu</email>
</address> </address>
</author> </author>
<author initials="K." surname="Murchison" fullname="Kenneth Murchison"> <author initials="K." surname="Murchison" fullname="Kenneth Murchison">
<organization abbrev="Fastmail">Fastmail US LLC</organization> <organization abbrev="Fastmail">Fastmail US LLC</organization>
<address> <address>
<email>murch@fastmailteam.com</email> <email>murch@fastmailteam.com</email>
</address> </address>
</author> </author>
<date/> <date month="November" year="2024"/>
<area>General</area>
<workgroup>Internet Engineering Task Force (IETF)</workgroup>
<keyword>time zone</keyword> <keyword>time zone</keyword>
<keyword>tzdata</keyword> <keyword>tzdata</keyword>
<keyword>tzif</keyword> <keyword>tzif</keyword>
<abstract> <abstract>
<t>This document specifies the Time Zone Information Format (TZif) <t>This document specifies the Time Zone Information Format (TZif)
for representing and exchanging time zone information, for representing and exchanging time zone information,
independent of any particular service or protocol. independent of any particular service or protocol.
Two media types for this format are also defined. Two media types for this format are also defined.
</t> </t>
skipping to change at line 96 skipping to change at line 77
This format was introduced in the 1980s and has evolved since This format was introduced in the 1980s and has evolved since
then into multiple upward-compatible versions. 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 generating and reading files in this format
<xref target="tz-link" format="default"/>. <xref target="tz-link" format="default"/>.
</t> </t>
<t>This specification does not define the source of the data <t>This specification does not define the source of the data
assembled into a TZif file. assembled into a TZif file.
One such source is the IANA-hosted time zone database One such source is the IANA-hosted time zone database
<xref target="RFC6557" format="default"/>.</t> <xref target="RFC6557" format="default"/>.</t>
<t>This document obsoletes RFC 8536, providing editorial improvements, <t>This document obsoletes <xref target="RFC8536" format="default"/>, prov iding 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. the interchange format of <xref target="RFC8536" format="default"/>.
Additionally, a new version of the format is defined. Additionally, a new version of the format is defined.
The changes from RFC 8536 are summarized in The changes from <xref target="RFC8536" format="default"/> are summarized in
<xref target="changes" format="default"/>.</t> <xref target="changes" format="default"/>.</t>
</section> </section>
<section numbered="true" toc="default"> <section numbered="true" toc="default">
<name>Conventions Used in This Document</name> <name>Conventions Used in This Document</name>
<t>The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>",
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>",
"MAY", and "OPTIONAL" in this document are to be interpreted as "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
described in BCP&nbsp;14 <xref target="RFC2119" format="default"/> "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are
<xref target="RFC8174" format="default"/> to be interpreted as described in BCP&nbsp;14 <xref target="RFC2119"/>
when, and only when, they appear in all capitals, as shown here. <xref target="RFC8174"/> when, and only when, they appear in all
</t> capitals, as shown here.
</t>
<t>The following terms are used in this document <t>The following terms are used in this document
(see <xref target="tz-link" format="default"> (see <xref target="tz-link" format="default">
"Time zone and daylight saving time data"</xref> "Time zone and daylight saving time data"</xref>
for more detailed information about civil timekeeping data and for more detailed information about civil timekeeping data and
practice): practice):
</t> </t>
<dl newline="false" spacing="normal"> <dl newline="false" spacing="normal">
<dt>Coordinated Universal Time (UTC):</dt> <dt>Coordinated Universal Time (UTC):</dt>
skipping to change at line 155 skipping to change at line 137
<dd> <dd>
A one-second adjustment to keep UTC close to mean solar time A one-second adjustment to keep UTC close to mean solar time
at the prime meridian at the prime meridian
(see <xref target="ITU-R-TF.460" format="default"/>). (see <xref target="ITU-R-TF.460" format="default"/>).
Each inserted or deleted leap second occurs at the end of a Each inserted or deleted leap second occurs at the end of a
UTC month, that is, a month using the Gregorian calendar and UTC month, that is, a month using the Gregorian calendar and
the UTC timescale. the UTC timescale.
</dd> </dd>
<dt>Leap-Second Correction (LEAPCORR):</dt> <dt>Leap-Second Correction (LEAPCORR):</dt>
<dd> <dd>
The value of TAI - UTC - 10 for timestamps after the The value of "TAI - UTC - 10" for timestamps after the
first leap second, and zero for timestamps before that. first leap second, and zero for timestamps before that.
The expression "TAI - UTC - 10" comes from the fact The expression "TAI - UTC - 10" comes from the fact
that TAI - UTC was defined to be 10 just prior to that TAI - UTC was defined to be 10 just prior to
the first leap second in 1972, so clocks with leap the first leap second in 1972, so clocks with leap
seconds have a zero LEAPCORR before the first leap seconds have a zero LEAPCORR before the first leap
second. second.
</dd> </dd>
<dt>Local Time:</dt> <dt>Local Time:</dt>
<dd> <dd>
Civil time for a particular location. Its offset Civil time for a particular location. Its offset
from universal time can depend on the date and time of day. from universal time can depend on the date and time of day.
</dd> </dd>
<dt>POSIX Epoch:</dt> <dt>POSIX Epoch:</dt>
<dd> <dd>
1970-01-01 00:00:00 UTC, the basis for absolute timestamps 1970-01-01 00:00:00 UTC, the basis for absolute timestamps
in this document. in this document.
</dd> </dd>
<dt>Standard Time:</dt> <dt>Standard Time:</dt>
<dd> <dd>
The time according to a location's law or practice, The time according to a location's law or practice,
unadjusted for Daylight Saving Time. unadjusted for daylight saving time.
</dd> </dd>
<dt>Time Change:</dt> <dt>Time Change:</dt>
<dd> <dd>
<t> <t>
A change to civil timekeeping practice. It occurs when one A change to civil timekeeping practice. It occurs when one
or more of the following happen simultaneously: or more of the following happen simultaneously:
</t> </t>
<ol spacing="normal" type="1"><li>a change in UT offset</li> <ol spacing="normal" type="1">
<li>a change in UT offset</li>
<li>a change in whether daylight saving time is in effect</li> <li>a change in whether daylight saving time is in effect</li>
<li>a change in time zone abbreviation</li> <li>a change in time zone abbreviation</li>
<li>a leap second (i.e., a change in LEAPCORR)</li> <li>a leap second (i.e., a change in LEAPCORR)</li>
</ol> </ol>
</dd> </dd>
<dt>Time Zone Data:</dt> <dt>Time Zone Data:</dt>
<dd> <dd>
The <xref target="RFC7808" format="default"> The <xref target="RFC7808" format="default">
Time Zone Data Distribution Service (TZDIST)</xref> Time Zone Data Distribution Service (TZDIST)</xref>
defines "Time zone data" as "data defines "Time zone data" as "data
that defines a single time zone, including an identifier, that defines a single time zone, including an identifier,
UTC offset values, DST rules, and other information such as UTC offset values, DST rules, and other information such as
time zone abbreviations." The interchange format defined in time zone abbreviations". The interchange format defined in
this document is one such form of time zone data. this document is one such form of time zone data.
</dd> </dd>
<dt>Transition Time:</dt> <dt>Transition Time:</dt>
<dd> <dd>
The moment of occurrence of a time change that is not a leap The moment of occurrence of a time change that is not a leap
second. It is identified with a signed integer count of second. It is identified with a signed integer count of
UNIX leap time seconds since the POSIX epoch. UNIX leap time seconds since the POSIX epoch.
</dd> </dd>
<dt>Universal Time (UT):</dt> <dt>Universal Time (UT):</dt>
<dd> <dd>
skipping to change at line 260 skipping to change at line 241
<section anchor="format" numbered="true" toc="default"> <section anchor="format" numbered="true" toc="default">
<name>The Time Zone Information Format (TZif)</name> <name>The Time Zone Information Format (TZif)</name>
<t>The Time Zone Information Format begins with a fixed 44-octet <t>The Time Zone Information Format begins with a fixed 44-octet
<xref target="header" format="default">version 1 header</xref> <xref target="header" format="default">version 1 header</xref>
containing a field that specifies the version 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 N+1 files without too much trouble; data specific to
version N+1 either appears after version N data so version N+1 either appears after version N data so
that earlier-version readers can easily ignore later-version that earlier version readers can easily ignore later version
data they are not designed for, or it appears as a minor data they are not designed for, or it appears as a minor
extension to version N that version N readers are likely to extension to version N that version N readers are likely to
tolerate well.</t> tolerate well.</t>
<t>The version 1 header is followed by a variable-length <t>The version 1 header is followed by a variable-length
<xref target="data" format="default">version 1 data block</xref> <xref target="data" format="default">version 1 data block</xref>
containing four-octet (32-bit) transition times and leap-second containing four-octet (32-bit) transition times and leap-second
occurrences. These 32-bit values are limited to representing occurrences. These 32-bit values are limited to representing
time changes from 1901-12-13 20:45:52 through 2038-01-19 03:14:07 UT, 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 for backward and the version 1 header and data block are present only for backward
compatibility with obsolescent readers, as discussed in compatibility with obsolescent readers, as discussed in
<xref target="issues" format="default"> <xref target="issues" format="default">
Common Interoperability Issues</xref>.</t> "Common Interoperability Issues"</xref>.</t>
<t>Version 1 files terminate after the version 1 data block. <t>Version 1 files terminate after the version 1 data block.
Files from versions 2 and higher extend the format by appending a second Files from 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 occurrences, and a variable-length
<xref target="footer" format="default">footer</xref>. <xref target="footer" format="default">footer</xref>.
These 64-bit values can represent times approximately 292 These 64-bit values can represent times approximately 292
billion years into the past or future.</t> billion years into the past or future.</t>
<t> <t>
NOTE: All multi-octet integer values MUST be stored in NOTE: All multi-octet integer values <bcp14>MUST</bcp14> be stored in
network octet order format (high-order octet first, otherwise network octet order format (high-order octet first, otherwise
known as big-endian), with all bits significant. Signed known as big-endian), with all bits significant. Signed
integer values MUST be represented using two's complement. integer values <bcp14>MUST</bcp14> be represented using two's complement .
</t> </t>
<t>A TZif file is structured as follows:</t> <t>A TZif file is structured as follows:</t>
<figure> <figure>
<name>General Format of TZif Files</name> <name>General Format of TZif Files</name>
<artwork type="ascii-art" align="center" name="" alt=""><![CDATA[ <artwork align="center" name="" alt=""><![CDATA[
Version 1 Versions 2+ Version 1 Versions 2+
+-------------+ +-------------+ +-------------+ +-------------+
| Version 1 | | Version 1 | | Version 1 | | Version 1 |
| Header | | Header | | Header | | Header |
+-------------+ +-------------+ +-------------+ +-------------+
| Version 1 | | Version 1 | | Version 1 | | Version 1 |
| Data Block | | Data Block | | Data Block | | Data Block |
+-------------+ +-------------+ +-------------+ +-------------+
| Version 2+ | | Version 2+ |
| Header | | Header |
skipping to change at line 321 skipping to change at line 302
</figure> </figure>
<section anchor="header" numbered="true" toc="default"> <section anchor="header" numbered="true" toc="default">
<name>TZif Header</name> <name>TZif Header</name>
<t>A TZif header is structured as follows <t>A TZif header is structured as follows
(the lengths of multi-octet fields are shown in parentheses):</t> (the lengths of multi-octet fields are shown in parentheses):</t>
<figure> <figure>
<name>TZif Header</name> <name>TZif Header</name>
<artwork type="ascii-art" align="center" name="" alt=""><![CDATA[ <artwork align="center" name="" alt=""><![CDATA[
+---------------+---+ +---------------+---+
| magic (4) |ver| | magic (4) |ver|
+---------------+---+---------------------------------------+ +---------------+---+---------------------------------------+
| [unused - reserved for future use] (15) | | [unused - reserved for future use] (15) |
+---------------+---------------+---------------+-----------+ +---------------+---------------+---------------+-----------+
| isutcnt (4) | isstdcnt (4) | leapcnt (4) | | isutcnt (4) | isstdcnt (4) | leapcnt (4) |
+---------------+---------------+---------------+ +---------------+---------------+---------------+
| timecnt (4) | typecnt (4) | charcnt (4) | | timecnt (4) | typecnt (4) | charcnt (4) |
+---------------+---------------+---------------+ +---------------+---------------+---------------+
]]></artwork> ]]></artwork>
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<dd> <dd>
The four-octet <xref target="RFC20" format="default">ASCII</xref> The four-octet <xref target="RFC20" format="default">ASCII</xref>
sequence "TZif" (0x54 0x5A 0x69 0x66), sequence "TZif" (0x54 0x5A 0x69 0x66),
which identifies the file as utilizing the Time Zone which identifies the file as utilizing the Time Zone
Information Format. Information Format.
</dd> </dd>
<dt>ver(sion):</dt> <dt>ver(sion):</dt>
<dd> <dd>
<t> <t>
An octet identifying the version of the An octet identifying the version of the
file's format. The value MUST be one of the following: file's format. The value <bcp14>MUST</bcp14> be one of the follow ing:
</t> </t>
<dl newline="false" spacing="normal"> <ul spacing="normal">
<dt>NUL (0x00)</dt> <li><t>NUL (0x00) Version 1 - The file contains only the version 1
<dd> header and
Version 1 - The file contains only the version 1 data block. Version 1 files <bcp14>MUST NOT</bcp14> contain a
header and data block. version 2+ header, data block, or footer.</t></li>
Version 1 files MUST NOT contain a version 2+ header, <li><t>'2' (0x32) Version 2 - The file <bcp14>MUST</bcp14>
data block, or footer. contain the version 1 header and data block, a version 2+ header
</dd> and data block, and a footer. The TZ string in the <xref
<dt>'2' (0x32)</dt> target="footer" format="default">footer</xref>, if non-empty,
<dd> <bcp14>MUST</bcp14> strictly adhere to the requirements for the
Version 2 - The file MUST contain the version 1 TZ environment variable as defined in Section 8.3 of the "Base
header and data block, a version 2+ header and data Definitions" volume of <xref target="POSIX" format="default"/>
block, and a footer. and <bcp14>MUST</bcp14> encode the POSIX portable character set
The TZ string in the as ASCII. The leap-second records <bcp14>MUST NOT</bcp14> be
<xref target="footer" format="default">footer</xref>, if <xref target="truncation" format="default"> truncated at the
nonempty, MUST strictly adhere to the start</xref> and <bcp14>MUST NOT</bcp14> contain an expiration
requirements for the TZ environment variable time.</t></li>
as defined in <li><t>'3' (0x33) Version 3 - The file <bcp14>MUST</bcp14>
Section 8.3 of the "Base Definitions" volume of conform to all version 2 requirements, except that any TZ string
<xref target="POSIX" format="default"/> in the <xref target="footer" format="default">footer</xref>
and MUST encode the POSIX portable character set as <bcp14>MAY</bcp14> use the TZ string extension <xref
ASCII. target="tzstrext" format="default"> described
The leap-second records MUST NOT be below</xref>.</t></li>
<xref target="truncation" format="default"> <li><t>'4' (0x34) Version 4 - The file <bcp14>MUST</bcp14>
truncated at the start</xref>, conform to all version 3 requirements, except that the
and MUST NOT contain an expiration time. leap-second records <bcp14>MAY</bcp14> be truncated at the
</dd> start and <bcp14>MAY</bcp14> contain an expiration
<dt>'3' (0x33)</dt> time.</t></li>
<dd> </ul></dd>
Version 3 - The file MUST conform to all version 2
requirements, except that any TZ string in the
<xref target="footer" format="default">footer</xref>
MAY use the TZ string extension
<xref target="tzstrext" format="default">
described below</xref>.
</dd>
<dt>'4' (0x34)</dt>
<dd>
Version 4 - The file MUST conform to all version 3
requirements, except that the leap-second records
MAY be truncated at the start, and
MAY contain an expiration time.
</dd>
</dl>
</dd>
<dt>isutcnt:</dt> <dt>isutcnt:</dt>
<dd> <dd>
A four-octet unsigned integer specifying the number of A four-octet unsigned integer specifying the number of
UT/local indicators contained in the data block -- UT/local indicators contained in the data block --
MUST either be zero or equal to "typecnt". <bcp14>MUST</bcp14> either be zero or equal to "typecnt".
</dd> </dd>
<dt>isstdcnt:</dt> <dt>isstdcnt:</dt>
<dd> <dd>
A four-octet unsigned integer specifying the number of A four-octet unsigned integer specifying the number of
standard/wall indicators contained in the data block -- standard/wall indicators contained in the data block --
MUST either be zero or equal to "typecnt". <bcp14>MUST</bcp14> either be zero or equal to "typecnt".
</dd> </dd>
<dt>leapcnt:</dt> <dt>leapcnt:</dt>
<dd> <dd>
A four-octet unsigned integer specifying the number of 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.
</dd> </dd>
<dt>timecnt:</dt> <dt>timecnt:</dt>
<dd> <dd>
A four-octet unsigned integer specifying the number of A four-octet unsigned integer specifying the number of
transition times contained in the data block. transition times contained in the data block.
</dd> </dd>
<dt>typecnt:</dt> <dt>typecnt:</dt>
<dd> <dd>
A four-octet unsigned integer specifying the number of A four-octet unsigned integer specifying the number of
local time type records contained in the data block -- local time type records contained in the data block --
MUST NOT be zero. <bcp14>MUST NOT</bcp14> be zero.
(Although local time type records convey no useful (Although local time type records convey no useful
information in files that have nonempty TZ strings but information in files that have non-empty TZ strings but
no transitions, at least one such record is nevertheless no transitions, at least one such record is nevertheless
required because many TZif readers reject files that required because many TZif readers reject files that
have zero time types.) have zero time types.)
</dd> </dd>
<dt>charcnt:</dt> <dt>charcnt:</dt>
<dd> <dd>
A four-octet unsigned integer specifying the total number A four-octet unsigned integer specifying the total number
of octets used by the set of time zone designations of octets used by the set of time zone designations
contained in the data block - MUST NOT be zero. contained in the data block -- <bcp14>MUST NOT</bcp14> be zero.
The count includes the trailing NUL (0x00) octet at the The count includes the trailing NUL (0x00) octet at the
end of the last time zone designation. end of the last time zone designation.
</dd> </dd>
</dl> </dl>
<t>Although the version 1 and 2+ headers have the same format, <t>Although the version 1 and 2+ headers have the same format,
magic number, and version fields, their count magic number, and version fields, their count
fields may differ, because the version 1 data can be a subset of fields may differ, because the version 1 data can be a subset of
the version 2+ data.</t> the version 2+ data.</t>
</section> </section>
skipping to change at line 465 skipping to change at line 429
<t>In the version 1 data block, time values are 32 bits <t>In the version 1 data block, time values are 32 bits
(TIME_SIZE = 4 octets). In the version 2+ data block, present (TIME_SIZE = 4 octets). In the version 2+ data block, present
only in version 2 and higher files, time values are 64 bits only in version 2 and higher files, time values are 64 bits
(TIME_SIZE = 8 octets).</t> (TIME_SIZE = 8 octets).</t>
<t>The data block is structured as follows <t>The data block is structured as follows
(the lengths of multi-octet fields are shown in parentheses):</t> (the lengths of multi-octet fields are shown in parentheses):</t>
<figure> <figure>
<name>TZif Data Block</name> <name>TZif Data Block</name>
<artwork type="ascii-art" align="center" name="" alt=""><![CDATA[ <artwork align="center" name="" alt=""><![CDATA[
+---------------------------------------------------------+ +---------------------------------------------------------+
| transition times (timecnt x TIME_SIZE) | | transition times (timecnt x TIME_SIZE) |
+---------------------------------------------------------+ +---------------------------------------------------------+
| transition types (timecnt) | | transition types (timecnt) |
+---------------------------------------------------------+ +---------------------------------------------------------+
| local time type records (typecnt x 6) | | local time type records (typecnt x 6) |
+---------------------------------------------------------+ +---------------------------------------------------------+
| time zone designations (charcnt) | | time zone designations (charcnt) |
+---------------------------------------------------------+ +---------------------------------------------------------+
| leap-second records (leapcnt x (TIME_SIZE + 4)) | | leap-second records (leapcnt x (TIME_SIZE + 4)) |
skipping to change at line 494 skipping to change at line 458
<t>The elements of the data block are defined as follows:</t> <t>The elements of the data block are defined as follows:</t>
<dl newline="false" spacing="normal"> <dl newline="false" spacing="normal">
<dt>transition times:</dt> <dt>transition times:</dt>
<dd> <dd>
A series of four- or eight-octet UNIX leap time values sorted A series of four- or eight-octet UNIX leap time values sorted
in strictly ascending order. in strictly ascending order.
Each value is used as a transition time at which the rules Each value is used as a transition time at which the rules
for computing local time may change. for computing local time may change.
The number of time values is specified by the "timecnt" The number of time values is specified by the "timecnt"
field in the header. field in the header.
Each time value SHOULD be at least -2**59. Each time value <bcp14>SHOULD</bcp14> be at least -2<sup>59</sup>.
(-2**59 is the greatest negated power of 2 that predates (-2<sup>59</sup> is the greatest negated power of 2 that predates
the Big Bang, and avoiding earlier timestamps works the Big Bang, and avoiding earlier timestamps works
around known TZif reader bugs relating to outlandishly around known TZif reader bugs relating to outlandishly
negative timestamps.) negative timestamps.)
</dd> </dd>
<dt>transition types:</dt> <dt>transition types:</dt>
<dd> <dd>
A series of one-octet unsigned integers specifying the A series of one-octet unsigned integers specifying the
type of local time of the corresponding transition time. type of local time of the corresponding transition time.
These values serve as zero-based indices into the array These values serve as zero-based indices into the array
of local time type records. of local time type records.
The number of type indices is specified by the "timecnt" The number of type indices is specified by the "timecnt"
field in the header. field in the header.
Each type index MUST be in the range [0, "typecnt" - 1]. Each type index <bcp14>MUST</bcp14> be in the range [0, "typecnt" - 1].
</dd> </dd>
<dt>local time type records:</dt> <dt>local time type records:</dt>
<dd> <dd>
<t> <t>
A series of six-octet records specifying a local time A series of six-octet records specifying a local time
type. type.
The number of records is specified by the "typecnt" The number of records is specified by the "typecnt"
field in the header. field in the header.
Each record has the following format Each record has the following format
(the lengths of multi-octet fields are shown in parentheses): (the lengths of multi-octet fields are shown in parentheses):
</t> </t>
<artwork type="ascii-art" name="" align="left" alt=""><![CDATA[ <artwork name="" align="left" alt=""><![CDATA[
+---------------+---+---+ +---------------+---+---+
| utoff (4) |dst|idx| | utoff (4) |dst|idx|
+---------------+---+---+ +---------------+---+---+
]]></artwork> ]]></artwork>
<dl newline="false" spacing="normal"> <dl newline="false" spacing="normal">
<dt>utoff:</dt> <dt>utoff:</dt>
<dd> <dd>
A four-octet signed integer specifying the number of A four-octet signed integer specifying the number of
seconds to be added to UT in order to determine local seconds to be added to UT in order to determine local
time. The value MUST NOT be -2**31 and SHOULD be in time. The value <bcp14>MUST NOT</bcp14> be -2<sup>31</sup> and
the range [-89999, 93599] (i.e., its value SHOULD be <bcp14>SHOULD</bcp14> be in
the range [-89999, 93599] (i.e., its value <bcp14>SHOULD</bcp1
4> be
more than -25 hours and less than 26 hours). more than -25 hours and less than 26 hours).
Avoiding -2**31 allows 32-bit clients to negate Avoiding -2<sup>31</sup> allows 32-bit clients to negate
the value without overflow. the value without overflow.
Restricting it to [-89999, 93599] allows easy support by Restricting it to [-89999, 93599] allows easy support by
implementations that already support the implementations that already support the
POSIX-required range [-24:59:59, 25:59:59]. POSIX-required range [-24:59:59, 25:59:59].
</dd> </dd>
<dt>(is)dst:</dt> <dt>(is)dst:</dt>
<dd> <dd>
A one-octet value indicating whether local A one-octet value indicating whether local
time should be considered Daylight Saving Time (DST). time should be considered Daylight Saving Time (DST).
The value MUST be 0 or 1. The value <bcp14>MUST</bcp14> be 0 or 1.
A value of one (1) indicates that this type of time is DST. A value of one (1) indicates that this type of time is DST.
A value of zero (0) indicates that this time type A value of zero (0) indicates that this time type
is standard time. is standard time.
</dd> </dd>
<dt>(desig)idx:</dt> <dt>(desig)idx:</dt>
<dd> <dd>
A one-octet unsigned integer specifying a zero-based A one-octet unsigned integer specifying a zero-based
index into the series of time zone designation octets, index into the series of time zone designation octets,
thereby selecting a particular designation string. thereby selecting a particular designation string.
Each index MUST be in the range [0, "charcnt" - 1]; it Each index <bcp14>MUST</bcp14> be in the range [0, "charcnt" - 1]; it
designates the NUL&nbhy;terminated string of octets designates the NUL&nbhy;terminated string of octets
starting at position "idx" in the time zone starting at position "idx" in the time zone
designations. (This string MAY be empty.) A NUL designations. (This string <bcp14>MAY</bcp14> be empty.) A N
octet MUST exist in the time zone designations at or UL
octet <bcp14>MUST</bcp14> exist in the time zone designations
at or
after position "idx". after position "idx".
If the designation string is "-00", the time type is a If the designation string is "-00", the time type is a
placeholder indicating that local time is unspecified. placeholder indicating that local time is unspecified.
</dd> </dd>
</dl> </dl>
</dd> </dd>
<dt>time zone designations:</dt> <dt>time zone designations:</dt>
<dd> <dd>
A series of octets constituting an array of A series of octets constituting an array of
NUL&nbhy;terminated (0x00) time zone designation strings. NUL&nbhy;terminated (0x00) time zone designation strings.
The total number of octets is specified by the The total number of octets is specified by the
"charcnt" field in the header. "charcnt" field in the header.
Two designations MAY overlap if one is a Two designations <bcp14>MAY</bcp14> overlap if one is a
suffix of the other. suffix of the other.
The character encoding of time zone designation strings The character encoding of time zone designation strings
is not specified; however, is not specified; however,
see <xref target="interop" format="default"/> see <xref target="interop" format="default"/>
of this document. of this document.
</dd> </dd>
<dt>leap-second records:</dt> <dt>leap-second records:</dt>
<dd> <dd>
<t> <t>
A series of eight- or twelve-octet records specifying A series of eight- or twelve-octet records specifying
skipping to change at line 593 skipping to change at line 557
The records are sorted by the occurrence time in The records are sorted by the occurrence time in
strictly ascending order. strictly ascending order.
The number of records is specified by the The number of records is specified by the
"leapcnt" field in the header. "leapcnt" field in the header.
Each record has one of the following structures Each record has one of the following structures
(the lengths of multi-octet fields are shown in parentheses): (the lengths of multi-octet fields are shown in parentheses):
</t> </t>
<dl newline="false" spacing="normal"> <dl newline="false" spacing="normal">
<dt>Version 1 Data Block:</dt> <dt>Version 1 Data Block:</dt>
<dd> <dd>
<artwork type="ascii-art" name="" align="left" alt=""><![CDATA[ <artwork name="" align="left" alt=""><![CDATA[
+---------------+---------------+ +---------------+---------------+
| occur (4) | corr (4) | | occur (4) | corr (4) |
+---------------+---------------+ +---------------+---------------+
]]></artwork> ]]></artwork>
</dd> </dd>
<dt>version 2+ Data Block:</dt> <dt>version 2+ Data Block:</dt>
<dd> <dd>
<artwork type="ascii-art" name="" align="left" alt=""><![CDATA[ <artwork name="" align="left" alt=""><![CDATA[
+---------------+---------------+---------------+ +---------------+---------------+---------------+
| occur (8) | corr (4) | | occur (8) | corr (4) |
+---------------+---------------+---------------+ +---------------+---------------+---------------+
]]></artwork> ]]></artwork>
</dd> </dd>
</dl>
<dl newline="false" spacing="normal">
<dt>occur(rence):</dt> <dt>occur(rence):</dt>
<dd> <dd>
A four- or eight-octet UNIX leap time value specifying the A four- or eight-octet UNIX leap time value specifying the
time at which a leap-second correction occurs time at which a leap-second correction occurs
or at which the leap-second table expires. or at which the leap-second table expires.
The first value, if present, MUST be nonnegative, The first value, if present, <bcp14>MUST</bcp14> be non-negative
and each leap second MUST occur at the end of a UTC ,
and each leap second <bcp14>MUST</bcp14> occur at the end of a U
TC
month. month.
</dd> </dd>
<dt>corr(ection):</dt> <dt>corr(ection):</dt>
<dd> <dd>
<t> <t>
A four-octet signed integer specifying the value A four-octet signed integer specifying the value
of LEAPCORR on or after the occurrence. of LEAPCORR on or after the occurrence.
If "leapcnt" is zero, LEAPCORR is zero for all timestamps; If "leapcnt" is zero, LEAPCORR is zero for all timestamps.
otherwise, for timestamps before the first occurrence time, If "leapcnt" is nonzero,
LEAPCORR is zero if the first correction is one (1) for timestamps before the first occurrence time,
or minus one (-1), LEAPCORR is zero if the first correction is one (1) or minus
and is unspecified otherwise (which can happen only in files one (-1) and is unspecified otherwise (which can happen only
<xref target="truncation" format="default"> in files <xref target="truncation" format="default">
truncated at the start</xref>). truncated at the start</xref>).
</t> </t>
<t> <t>
The first leap second is a positive leap second if and The first leap second is a positive leap second if and only if
only if its correction is positive. its
Each correction after the first MUST differ from the correction is positive. Each correction after the first
previous correction by either <bcp14>MUST</bcp14> differ from the previous correction by
one (1) for a positive leap second or either one (1) for a positive leap second or minus one (-1)
minus one (-1) for a negative leap second, for a negative leap second, except that in version 4 files
except that in version 4 files with two or more leap-second with two or more leap-second records, the correction value
records, the correction value of the last two records of the last two records <bcp14>MAY</bcp14> be the same, with
MAY be the same, with the occurrence of last record the occurrence of last record indicating the expiration time
indicating the expiration time of the leap-second table. of the leap-second table.
</t> </t>
<t> <t>
The leap-second table expiration time is the time at The leap-second table expiration time is the time at
which the table no longer records the presence or which the table no longer records the presence or
absence of future leap-second corrections, and absence of future leap-second corrections, and
post-expiration timestamps can not be accurately calculated. post-expiration timestamps cannot be accurately calculated.
For example, a leap-second table published in For example, a leap-second table published in
January, which predicts the presence or absence of a January, which predicts the presence or absence of a
leap second at June's end, might expire in leap second at June's end, might expire in
mid-December because it is not known when the next leap mid-December because it is not known when the next leap
second will occur. second will occur.
</t> </t>
<t> <t>
If leap seconds become permanently If leap seconds become permanently
discontinued, as requested by the discontinued, as requested by the
<xref target="CGPM-2022-R4">General Conference <xref target="CGPM-2022-R4">General Conference
on Weights and Measures</xref>, leap-second tables on Weights and Measures</xref>, leap-second tables
published after the discontinuation time published after the discontinuation time
SHOULD NOT expire, since they will not be updated in <bcp14>SHOULD NOT</bcp14> expire, since they will not be updat ed in
the foreseeable future. the foreseeable future.
</t> </t>
</dd> </dd>
</dl> </dl>
</dd> </dd>
<dt>standard/wall indicators:</dt> <dt>standard/wall indicators:</dt>
<dd anchor="stdwall"> <dd anchor="stdwall">
A series of one-octet values indicating whether A series of one-octet values indicating whether
the transition times associated with local time types were the transition times associated with local time types were
specified as standard time or wall-clock time. specified as standard time or wall-clock time.
Each value MUST be 0 or 1. Each value <bcp14>MUST</bcp14> be 0 or 1.
A value of one (1) indicates standard time. The value A value of one (1) indicates standard time. The value
MUST be set to one (1) if the corresponding <bcp14>MUST</bcp14> be set to one (1) if the corresponding
UT/local indicator is set to one (1). UT/local indicator is set to one (1).
A value of zero (0) indicates wall time. A value of zero (0) indicates wall time.
The number of values is specified by the "isstdcnt" The number of values is specified by the "isstdcnt"
field in the header. field in the header.
If "isstdcnt" is zero (0), all transition times If "isstdcnt" is zero (0), all transition times
associated with local time types are assumed to be associated with local time types are assumed to be
specified as wall time. specified as wall time.
</dd> </dd>
<dt>UT/local indicators:</dt> <dt>UT/local indicators:</dt>
<dd anchor="utlocal"> <dd anchor="utlocal">
A series of one-octet values indicating whether A series of one-octet values indicating whether
the transition times associated with local time types were the transition times associated with local time types were
specified as UT or local time. specified as UT or local time.
Each value MUST be 0 or 1. Each value <bcp14>MUST</bcp14> be 0 or 1.
A value of one (1) indicates UT, A value of one (1) indicates UT,
and the corresponding standard/wall indicator MUST also and the corresponding standard/wall indicator <bcp14>MUST</bcp14> also
be set to one (1). be set to one (1).
A value of zero (0) indicates local time. A value of zero (0) indicates local time.
The number of values is specified by the "isutcnt" The number of values is specified by the "isutcnt"
field in the header. field in the header.
If "isutcnt" is zero (0), all transition times If "isutcnt" is zero (0), all transition times
associated with local time types are assumed to be associated with local time types are assumed to be
specified as local time. specified as local time.
</dd> </dd>
</dl> </dl>
<t>The type corresponding to a transition time specifies local <t>The type corresponding to a transition time specifies local
time for timestamps starting at the given transition time and time for timestamps starting at the given transition time and
continuing up to, but not including, the next transition time. continuing up to, but not including, the next transition time.
Local time for timestamps before the first transition is Local time for timestamps before the first transition is
specified by the first time type (time type 0). specified by the first time type (time type 0).
Local time for timestamps on or after the last transition is Local time for timestamps on or after the last transition is
specified by the TZ string in the specified by the TZ string in the
<xref target="footer" format="default">footer</xref> <xref target="footer" format="default">footer</xref>
if present and nonempty; otherwise, it is unspecified. if present and non-empty; otherwise, it is unspecified.
If there are no transitions, local time for all timestamps is If there are no transitions, local time for all timestamps is
specified by the TZ string in the footer if present and specified by the TZ string in the footer if present and
nonempty; otherwise, it is specified by time type 0. non-empty; otherwise, it is specified by time type 0.
A time type with a designation string of "-00" represents an A time type with a designation string of "-00" represents an
unspecified local time. unspecified local time.
</t> </t>
<t>A given pair of standard/wall and UT/local indicators is <t>A given pair of standard/wall and UT/local indicators is
used to designate whether the corresponding transition time used to designate whether the corresponding transition time
was specified as UT, standard time, or wall-clock time. was specified as UT, standard time, or wall-clock time.
There are only three combinations of the two There are only three combinations of the two
indicators, given that the standard/wall value MUST be one indicators, given that the standard/wall value <bcp14>MUST</bcp14> be on e
(1) if the UT/local value is one (1). (1) if the UT/local value is one (1).
This information can be useful if the transition times in a This information can be useful if the transition times in a
TZif file need to be transformed into transitions TZif file need to be transformed into transitions
appropriate for another time zone (e.g. when calculating appropriate for another time zone (e.g., when calculating
transition times for a simple POSIX-like TZ string such as transition times for a simple POSIX-like TZ string such as
"AKST9AKDT").</t> "AKST9AKDT").</t>
<t>In order to eliminate unused space in a TZif file, every <t>In order to eliminate unused space in a TZif file, every
nonzero local time type index SHOULD appear at least once in the nonzero local time type index <bcp14>SHOULD</bcp14> appear at least once in the
transition type array. transition type array.
Likewise, every octet in the time zone designations array Likewise, every octet in the time zone designations array
SHOULD be used by at least one time type record.</t> <bcp14>SHOULD</bcp14> be used by at least one time type record.</t>
</section> </section>
<section anchor="footer" numbered="true" toc="default"> <section anchor="footer" numbered="true" toc="default">
<name>TZif Footer</name> <name>TZif Footer</name>
<t>The TZif footer is structured as follows <t>The TZif footer is structured as follows
(the lengths of multi-octet fields are shown in parentheses):</t> (the lengths of multi-octet fields are shown in parentheses):</t>
<figure> <figure>
<name>TZif Footer</name> <name>TZif Footer</name>
<artwork type="ascii-art" align="center" name="" alt=""><![CDATA[ <artwork align="center" name="" alt=""><![CDATA[
+---+--------------------+---+ +---+--------------------+---+
| NL| TZ string (0...) |NL | | NL| TZ string (0...) |NL |
+---+--------------------+---+ +---+--------------------+---+
]]></artwork> ]]></artwork>
</figure> </figure>
<t>The elements of the footer are defined as follows:</t> <t>The elements of the footer are defined as follows:</t>
<dl newline="false" spacing="normal"> <dl newline="false" spacing="normal">
<dt>NL:</dt> <dt>NL:</dt>
<dd> <dd>
skipping to change at line 774 skipping to change at line 736
The string is either empty or uses the expanded format The string is either empty or uses the expanded format
of the "TZ" environment variable as defined in of the "TZ" environment variable as defined in
Section 8.3 of the "Base Definitions" volume of Section 8.3 of the "Base Definitions" volume of
<xref target="POSIX" format="default"/> with ASCII <xref target="POSIX" format="default"/> with ASCII
encoding, possibly utilizing the encoding, possibly utilizing the
<xref target="tzstrext" format="default"> <xref target="tzstrext" format="default">
extension described below</xref> extension described below</xref>
in version 3 and higher files. in version 3 and higher files.
If the string is empty, the corresponding information is If the string is empty, the corresponding information is
not available. not available.
If the string is nonempty and one or more transitions If the string is non-empty and one or more transitions
appear in the version 2+ data, the string MUST be appear in the version 2+ data, the string <bcp14>MUST</bcp14> be
consistent with the last version 2+ transition. In other words, consistent with the last version 2+ transition. In other words,
evaluating the TZ string at the time of the last evaluating the TZ string at the time of the last
transition should yield the same time type as was specified in transition should yield the same time type as was specified in
the last transition. the last transition.
The string MUST NOT contain NUL octets or be The string <bcp14>MUST NOT</bcp14> contain NUL octets or be
NUL&nbhy;terminated, and it NUL&nbhy;terminated, and it
SHOULD NOT begin with the ':' (colon) character. <bcp14>SHOULD NOT</bcp14> begin with the ":" (colon) character.
</dd> </dd>
</dl> </dl>
<t>The TZif footer is present only in version 2 and higher files, <t>The TZif footer is present only in version 2 and higher files,
as the obsolescent version 1 format was designed before the as the obsolescent version 1 format was designed before the
need for a footer was apparent.</t> need for a footer was apparent.</t>
<section anchor="permdst" numbered="true" toc="default"> <section anchor="permdst" numbered="true" toc="default">
<name>All-Year Daylight Saving Time</name> <name>All-Year Daylight Saving Time</name>
<t>DST is considered to be in effect all year if its UT <t>DST is considered to be in effect all year if its UT
offset is less than (i.e., west of) that of standard time, offset is less than (i.e., west of) that of standard time,
and it starts January 1 at 00:00 and ends December 31 at and it starts January 1 at 00:00 and ends December 31 at
24:00 minus the difference between standard and daylight 24:00 minus the difference between standard and daylight
saving time, leaving no room for standard time saving time, leaving no room for standard time
in the calendar. in the calendar.
<xref target="POSIX" format="default"/> implies, but does not <xref target="POSIX" format="default"/> implies but does not
explicitly state this, so it is spelled out here for clarity. explicitly state this, so it is spelled out here for clarity.
</t> </t>
<dl newline="true" spacing="normal"> <dl newline="true" spacing="normal">
<dt>Example: XXX3EDT4,0/0,J365/23</dt> <dt>Example: XXX3EDT4,0/0,J365/23</dt>
<dd> <dd>
This represents a time zone that is perpetually 4 hours This represents a time zone that is perpetually 4 hours
west of UT and is abbreviated "EDT". west of UT and is abbreviated "EDT".
The "XXX" is ignored. The "XXX" is ignored.
</dd> </dd>
</dl> </dl>
</section> </section>
<section anchor="tzstrext" numbered="true" toc="default"> <section anchor="tzstrext" numbered="true" toc="default">
<name>TZ String Extension</name> <name>TZ String Extension</name>
<t>The TZ string in a version 3 or higher TZif file MAY use the <t>The TZ string in a version 3 or higher TZif file
following extension to POSIX TZ strings. <bcp14>MAY</bcp14> use the following extension to POSIX TZ strings.
This extension is described using the terminology of This extension is described using the terminology of Section 8.3 of
Section 8.3 of the "Base Definitions" volume of the "Base Definitions" volume of <xref target="POSIX"
<xref target="POSIX" format="default"/>. format="default"/>.</t>
</t> <t>The hours part of the transition times may be signed and range
from -167 through 167 (-167 &lt;= hh &lt;= 167) instead of the
<ul spacing="normal"> POSIX-required unsigned values from 0 through 24.</t>
<li> <dl newline="true" spacing="normal">
<t>The hours part of the transition times may be <dt>Example: &lt;-03&gt;3&lt;-02&gt;,M3.5.0/-2,M10.5.0/-1</dt>
signed and range from -167 through 167 <dd>This represents a time zone that observes daylight saving time
(-167 &lt;= hh &lt;= 167) instead of from 22:00 on the day before March's last Sunday until 23:00 on
the POSIX-required unsigned values from 0 through 24. the day before October's last Sunday. Standard time is 3 hours
</t> west of UT and is abbreviated "-03"; daylight saving time is 2
<dl newline="true" spacing="normal"> hours west of UT and is abbreviated "-02".</dd>
<dt>Example: &lt;-03&gt;3&lt;-02&gt;,M3.5.0/-2,M10.5.0/-1</dt> </dl>
<dd>
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 the day before October's last
Sunday. Standard time is 3 hours west of UT and is
abbreviated "-03"; daylight saving time is 2 hours
west of UT and is abbreviated "-02".
</dd>
</dl>
</li>
</ul>
<t>A TZif file that uses the above extension <t>A TZif file that uses the above extension
MUST be designated as version 3 (or higher), <bcp14>MUST</bcp14> be designated as version 3 (or higher),
even if a future version of POSIX adopts this extension.</t> even if a future version of POSIX adopts this extension.</t>
</section> </section>
</section> </section>
</section> </section>
<section anchor="interop" numbered="true" toc="default"> <section anchor="interop" numbered="true" toc="default">
<name>Interoperability Considerations</name> <name>Interoperability Considerations</name>
<t>The following practices help ensure the interoperability of TZif <t>The following practices help ensure the interoperability of TZif
applications.</t> applications.</t>
<ul spacing="normal"> <ul spacing="normal">
<li>Version 1 files are considered a legacy format and <li>Version 1 files are considered a legacy format and
SHOULD NOT be generated, as they do not support transition <bcp14>SHOULD NOT</bcp14> be generated, as they do not support transitio n
times after the year 2038.</li> times after the year 2038.</li>
<li>Readers that understand only version 1 MUST ignore <li>Readers that understand only version 1 <bcp14>MUST</bcp14> ignore
any data that extends beyond the calculated end of the version any data that extends beyond the calculated end of the version
1 data block.</li> 1 data block.</li>
<li>Other than version 1, writers SHOULD generate the lowest <li>Other than version 1, writers <bcp14>SHOULD</bcp14> generate the low est
version number needed by a file's data. version number needed by a file's data.
This helps interoperability with older readers. This helps interoperability with older readers.
For example, a writer For example, a writer
SHOULD generate a version 4 file only if its leap-second table <bcp14>SHOULD</bcp14> generate a version 4 file only if its leap-second table
either expires or is truncated at the start. Likewise, a either expires or is truncated at the start. Likewise, a
writer not generating a version 4 file SHOULD generate a writer not generating a version 4 file <bcp14>SHOULD</bcp14> generate a
version 3 file only if the TZ string extension is necessary to version 3 file only if the TZ string extension is necessary to
accurately model transition times.</li> accurately model transition times.</li>
<li>To save space, writers of version 2+ files MAY output a <li>To save space, writers of version 2+ files <bcp14>MAY</bcp14> output a
placeholder version 1 data block with all counts zero except placeholder version 1 data block with all counts zero except
that "typecnt" and "charcnt" are both one (1). that "typecnt" and "charcnt" are both one (1).
If this is done, obsolescent version-1-only readers MUST If this is done, obsolescent version-1-only readers <bcp14>MUST</bcp14>
interpret these files as lacking time changes and time zone interpret these files as lacking time changes and time zone
abbreviations.</li> abbreviations.</li>
<li>Unless the version 1 data block is a placeholder, <li>Unless the version 1 data block is a placeholder,
the sequence of timestamps defined by the version 1 the sequence of timestamps defined by the version 1
header and data block SHOULD be a contiguous sub-sequence header and data block <bcp14>SHOULD</bcp14> be a contiguous sub-sequence
of the timestamps defined by the version 2+ header and data of the timestamps defined by the version 2+ header and data
block, and by the footer. block and by the footer.
This guideline helps obsolescent version 1 readers This guideline helps obsolescent version 1 readers
agree with current readers about timestamps within the agree with current readers about timestamps within the
contiguous sub-sequence.</li> contiguous sub-sequence.</li>
<li>When a TZif file contains a leap-second table expiration <li>When a TZif file contains a leap-second table expiration
time, TZif readers SHOULD either refuse to process time, TZif readers <bcp14>SHOULD</bcp14> either refuse to process
post-expiration timestamps, or process them as if the expiration post-expiration timestamps or process them as if the expiration
time did not exist (possibly with an error indication). time did not exist (possibly with an error indication).
This lessens disagreement among implementations when This lessens disagreement among implementations when
processing far-future timestamps that cannot yet be handled processing far-future timestamps that cannot yet be handled
exactly.</li> exactly.</li>
<li>Time zone designations MUST consist of at least three (3) <li>Time zone designations <bcp14>MUST</bcp14> consist of at least three (3)
and no more than six (6) ASCII characters from the set of and no more than six (6) ASCII characters from the set of
alphanumerics, '-', and '+'. alphanumerics, "-", and "+".
This is compatible with POSIX requirements for This is compatible with POSIX requirements for
time zone abbreviations.</li> time zone abbreviations.</li>
<li>A reader that encounters a time zone designation containing <li>A reader that encounters a time zone designation containing
bytes other than ASCII alphanumerics, '-', and '+' SHOULD bytes other than ASCII alphanumerics, "-", and "+" <bcp14>SHOULD</bcp14>
act if the designation instead contained a signed numeric string act if the designation instead contained a signed numeric string
derived from the UT offset, for example, "-10" and "+0530" to derived from the UT offset, for example, "-10" and "+0530" to
indicate 10 hours west and 5.5 hours east of Greenwich, indicate 10 hours west and 5.5 hours east of Greenwich,
respectively.</li> respectively.</li>
<li>When reading a version 2 or higher file, readers <li>When reading a version 2 or higher file, readers
SHOULD ignore the version 1 header and data block except for <bcp14>SHOULD</bcp14> ignore the version 1 header and data block except for
the purpose of skipping over them. the purpose of skipping over them.
This improves compatibility among readers of nonconforming This improves compatibility among readers of non-conforming
files where version 2+ data is not upward compatible with files where version 2+ data is not upward compatible with
version 1.</li> version 1.</li>
<li>Readers SHOULD calculate the total lengths of the <li>Readers <bcp14>SHOULD</bcp14> calculate the total lengths of the
headers and data blocks and check that they all fit within headers and data blocks and check that they all fit within
the actual file size, as part of a validity check for the file.</li> the actual file size, as part of a validity check for the file.</li>
<li> <li>
<t>When a TZif file is used in a MIME message entity, it SHOULD <t>When a TZif file is used in a MIME message entity, it <bcp14>SHOULD </bcp14>
be indicated by one of the following media types:</t> be indicated by one of the following media types:</t>
<ul spacing="normal"> <ul spacing="normal">
<li> <li>
<xref target="tzif-leap" format="default"> <xref target="tzif-leap" format="default">
"application/tzif-leap"</xref> "application/tzif-leap"</xref>
to indicate that leap-second records are included in the to indicate that leap-second records are included in the
TZif data as necessary (none are necessary if the file TZif data as necessary (none are necessary if the file
is truncated to a range that precedes the first leap is truncated to a range that precedes the first leap
second).</li> second).</li>
<li> <li>
<xref target="tzif" format="default">"application/tzif"</xref> <xref target="tzif" format="default">"application/tzif"</xref>
to indicate that leap-second records are not included in the to indicate that leap-second records are not included in the
TZif data; "leapcnt" in the header(s) MUST be zero (0).</li> TZif data; "leapcnt" in the header(s) <bcp14>MUST</bcp14> be zero (0). </li>
</ul> </ul>
</li> </li>
<li><t>Common interoperability issues and possible workarounds
<li>Common interoperability issues and possible workarounds are described in <xref target="issues" format="default"/>.</t></li>
are described in <xref target="issues" format="default"/>.</li>
</ul> </ul>
</section> <!-- interop -->
</section>
<section anchor="i18n" numbered="true" toc="default"> <section anchor="i18n" numbered="true" toc="default">
<name>Internationalization Considerations</name> <name>Internationalization Considerations</name>
<t>TZif time zone designations contain only ASCII alphanumerics, <t>TZif time zone designations contain only ASCII alphanumerics, "-",
"-", and "+". Commonly used designations include numeric strings and "+". Commonly used designations include numeric strings like "-10"
like "-10" and "+0530" for UT offsets, and English-language and "+0530" for UT offsets and English language abbreviations like
abbreviations like "CEST" for Central European Summer Time and "CEST" for Central European Summer Time and "GMT" for Greenwich Mean
"GMT" for Greenwich Mean Time. It is the TZif reader's Time. It is the TZif reader's responsibility to substitute different
responsibility to substitute different abbreviations when needed abbreviations when needed for internationalization, such as substituting
for internationalization, such as substituting "HNC" (l'heure "HNC" (l'heure normale du Centre) for "CST" (Central Standard Time) in
normale du Centre) for "CST" (Central Standard Time) in French-speaking regions. This substitution can be problematic, as
French-speaking regions. This substitution can be problematic, abbreviations can be ambiguous; for example, "CST" commonly stands for
as abbreviations can be ambiguous: for example, "CST" commonly China Standard Time and Cuba Standard Time as well as Central Standard
stands for China Standard Time and Cuba Standard Time as well as Time. One approach for addressing this issue can be found in the
Central Standard Time. One approach for addressing this issue time zone charts of the <xref target="CLDR">Unicode Common Locale Data
can be found in the timezone charts of the Repository (CLDR) Project</xref>.</t>
<xref target="CLDR">
Unicode Common Locale Data Repository (CLDR) Project.</xref></t>
<t>Although the original TZif design allowed for any nonzero <t>Although the original TZif design allowed for any nonzero
octets in time zone designations and it was common practice octets in time zone designations, and it was common practice
until the mid-1990s for designations to contain ASCII spaces, until the mid-1990s for designations to contain ASCII spaces,
designations are now limited to ASCII alphanumerics, "-", and designations are now limited to ASCII alphanumerics, "-", and
"+" to avoid confusion and to encourage portability to a wide "+" to avoid confusion and to encourage portability to a wide
variety of locales.</t> variety of locales.</t>
</section> <!-- i18n --> </section>
<section anchor="tzdist" numbered="true" toc="default"> <section anchor="tzdist" numbered="true" toc="default">
<name>Use with the Time Zone Data Distribution Service</name> <name>Use with the Time Zone Data Distribution Service</name>
<t>The <xref target="RFC7808" format="default">Time Zone Data Distribution <t>The <xref target="RFC7808" format="default">Time Zone Data Distribution
Service (TZDIST)</xref> is a service that allows reliable, Service (TZDIST)</xref> is a service that allows reliable,
secure, and fast delivery of time zone data and leap-second secure, and fast delivery of time zone data and leap-second
rules to client systems such as calendaring and scheduling rules to client systems such as calendaring and scheduling
applications or operating systems.</t> applications or operating systems.</t>
<t>A TZDIST service MAY supply time zone data to clients in <t>A TZDIST service <bcp14>MAY</bcp14> supply time zone data to clients in
the Time Zone Information Format. Such a service MUST indicate the Time Zone Information Format. Such a service <bcp14>MUST</bcp14> indi
cate
that it supports this format by including the media type that it supports this format by including the media type
<xref target="tzif" format="default">"application/tzif"</xref> in its <xref target="tzif" format="default">"application/tzif"</xref> in its
"capabilities" response "capabilities" response
(<xref target="RFC7808" section="5.1" format="default"/>). (<xref target="RFC7808" section="5.1" format="default"/>).
A TZDIST service MAY also include the media type A TZDIST service <bcp14>MAY</bcp14> also include the media type
<xref target="tzif-leap" format="default"> <xref target="tzif-leap" format="default">
"application/tzif-leap"</xref> in its "application/tzif-leap"</xref> in its
"capabilities" response if it is able to generate TZif files "capabilities" response if it is able to generate TZif files
containing leap-second records. containing leap-second records.
A TZDIST service MUST NOT advertise the "application/tzif-leap" A TZDIST service <bcp14>MUST NOT</bcp14> advertise the "application/tzif-l eap"
media type without also advertising "application/tzif".</t> media type without also advertising "application/tzif".</t>
<t>TZDIST clients MUST use the <t>TZDIST clients <bcp14>MUST</bcp14> use the HTTP "Accept"
<xref target="RFC9110" section="12.5.1" sectionFormat="comma" header field (<xref target="RFC9110"
format="default">HTTP "Accept" header field</xref> section="12.5.1" sectionFormat="comma"/>) to indicate their preference to
to indicate receive data in the
their preference to receive data in the "application/tzif" "application/tzif" and/or "application/tzif-leap" formats.</t>
and/or "application/tzif-leap" formats.</t>
<section anchor="truncation" numbered="true" toc="default"> <section anchor="truncation" numbered="true" toc="default">
<name>Truncating TZif Files</name> <name>Truncating TZif Files</name>
<t>As described in <t>As described in
<xref target="RFC7808" section="3.9" format="default"/>, <xref target="RFC7808" section="3.9" format="default"/>,
a TZDIST service MAY truncate time zone transition data. a TZDIST service <bcp14>MAY</bcp14> truncate time zone transition data.
A truncated TZif file is valid from its first and up to, but A truncated TZif file is valid from its first and up to, but
not including, its last version 2+ transition time, if present.</t> not including, its last version 2+ transition time, if present.</t>
<t>When truncating the start of a TZif file, the service MUST <t>When truncating the start of a TZif file, the service <bcp14>MUST</bc p14>
supply in the version 2+ data a first transition time that is supply in the version 2+ data a first transition time that is
the start point of the truncation range. the start point of the truncation range.
As with untruncated TZif files, time type 0 indicates local As with untruncated TZif files, time type 0 indicates local
time immediately before the start point, and the time type of time immediately before the start point, and the time type of
the first transition indicates local time thereafter. the first transition indicates local time thereafter.
Time type 0 MUST be a placeholder indicating that local time Time type 0 <bcp14>MUST</bcp14> be a placeholder indicating that local t ime
is unspecified, so that the reader is unambiguously informed is unspecified, so that the reader is unambiguously informed
of truncation at the start.</t> of truncation at the start.</t>
<t>When truncating the start of a TZif file containing <t>When truncating the start of a TZif file containing
leap-second records, the service MUST keep all leap-second leap-second records, the service <bcp14>MUST</bcp14> keep all leap-secon d
records governing timestamps within the truncation range, records governing timestamps within the truncation range,
even if the first such record precedes the start point of even if the first such record precedes the start point of
the truncation range. the truncation range.
If the truncated leap-second table is nonempty, If the truncated leap-second table is non-empty,
its first record MUST have a positive correction its first record <bcp14>MUST</bcp14> have a positive correction
if and only if it represents a positive leap second.</t> if and only if it represents a positive leap second.</t>
<t>When truncating the end of a TZif file, the service MUST <t>When truncating the end of a TZif file, the service <bcp14>MUST</bcp1 4>
supply in the version 2+ data a last transition time that is supply in the version 2+ data a last transition time that is
the end point of the truncation range and MUST supply an the end point of the truncation range and <bcp14>MUST</bcp14> supply an
empty TZ string. empty TZ string.
As with untruncated TZif files with empty TZ strings, a As with untruncated TZif files with empty TZ strings, a
truncated TZif file does not indicate local time after the truncated TZif file does not indicate local time after the
last transition. last transition.
To this end, the time type of the last transition MUST be a To this end, the time type of the last transition <bcp14>MUST</bcp14> be a
placeholder indicating that local time is unspecified.</t> placeholder indicating that local time is unspecified.</t>
<t>All represented information that falls inside the <t>All represented information that falls inside the
truncation range MUST be the same as that represented by a truncation range <bcp14>MUST</bcp14> be the same as that represented by a
corresponding untruncated TZif file.</t> corresponding untruncated TZif file.</t>
<t>TZDIST clients SHOULD NOT use a truncated TZif file (as <t>TZDIST clients <bcp14>SHOULD NOT</bcp14> use a truncated TZif file (a s
described above) to interpret timestamps outside the described above) to interpret timestamps outside the
truncation time range.</t> truncation time range.</t>
</section> </section>
<section numbered="true" toc="default"> <section numbered="true" toc="default">
<name>Example TZDIST Request for TZif Data</name> <name>Example TZDIST Request for TZif Data</name>
<t>In this example, the client checks the server for the <t>In this example, the client checks the server for the
available formats and then requests that the time zone with a available formats and then requests that the time zone with a
specific time zone identifier be returned in Time Zone specific time zone identifier be returned in Time Zone
Information Format. Information Format.
</t> </t>
<t keepWithNext="true">This example presumes that <t keepWithNext="true">This example presumes that
the time zone context path has been discovered the time zone context path has been discovered
(see <xref target="RFC7808" section="4.2.1" (see <xref target="RFC7808" section="4.2.1"
sectionFormat="comma" format="default"/>) sectionFormat="comma" format="default"/>)
to be "/tzdist". to be "/tzdist".
</t> </t>
<artwork type="ascii-art" name="" align="left" alt=""><![CDATA[
<artwork name="" align="left" alt=""><![CDATA[
>> Request << >> Request <<
GET /tzdist/capabilities HTTP/1.1 GET /tzdist/capabilities HTTP/1.1
Host: tz.example.com Host: tz.example.com
>> Response << >> Response <<
HTTP/1.1 200 OK HTTP/1.1 200 OK
Date: Fri, 01 Jun 2018 14:52:23 GMT Date: Fri, 01 Jun 2018 14:52:23 GMT
Content-Type: application/json Content-Type: application/json
skipping to change at line 1141 skipping to change at line 1090
Time zone information is normally public and does not call Time zone information is normally public and does not call
for confidentiality protection. Since time zone for confidentiality protection. Since time zone
information is used in many critical applications, information is used in many critical applications,
integrity protection may be required and must be provided integrity protection may be required and must be provided
externally.</t> externally.</t>
<t>As discussed in <xref target="RFC7808" section="8"/>, <t>As discussed in <xref target="RFC7808" section="8"/>,
transmission of time zone data over an insecure communication transmission of time zone data over an insecure communication
channel could result in tampered data, harming calendaring and channel could result in tampered data, harming calendaring and
scheduling operations. As such, TZif data transmitted over a scheduling operations. As such, TZif data transmitted over a
public communications channel MUST be protected with a security public communications channel <bcp14>MUST</bcp14> be protected with a secu rity
layer such as that provided by <xref target="RFC8446"> layer such as that provided by <xref target="RFC8446">
Transport Layer Security (TLS)</xref>.</t> Transport Layer Security (TLS)</xref>.</t>
</section> </section>
<section anchor="privacy" numbered="true" toc="default"> <section anchor="privacy" numbered="true" toc="default">
<name>Privacy Considerations</name> <name>Privacy Considerations</name>
<t>The Time Zone Information Format contains publicly available <t>The Time Zone Information Format contains publicly available
data, and it does not define any extensible areas that data, and it does not define any extensible areas that
could be used to store private data.</t> could be used to store private data.</t>
<t>As discussed in <xref target="RFC7808" section="9" format="default"/>, <t>As discussed in <xref target="RFC7808" section="9" format="default"/>,
transmission of time zone data over an insecure communications transmission of time zone data over an insecure communications
channel could leak the past, current, or future location of a channel could leak the past, current, or future location of a
device or user. device or user.
As such, TZif data transmitted over a public communications As such, TZif data transmitted over a public communications
channel MUST be protected with a confidentiality layer such as channel <bcp14>MUST</bcp14> be protected with a confidentiality layer such as
that provided by <xref target="RFC8446" format="default"> that provided by <xref target="RFC8446" format="default">
Transport Layer Security (TLS)</xref>.</t> Transport Layer Security (TLS)</xref>.</t>
</section> </section>
<section anchor="iana" numbered="true" toc="default"> <section anchor="iana" numbered="true" toc="default">
<name>IANA Considerations</name> <name>IANA Considerations</name>
<t>The IANA is requested to update the <t>IANA has updated the
<eref target="https://www.iana.org/assignments/media-types/media-types.xht <eref target="https://www.iana.org/assignments/media-types">"Media Types"
ml">Media Types Registry</eref> as follows:</t> registry</eref> as follows.</t>
<t>This document defines two <t>This document defines two
media types <xref target="RFC6838" format="default"/> media types <xref target="RFC6838" format="default"/>
for the exchange of data utilizing the Time Zone for the exchange of data utilizing the Time Zone
Information Format.</t> Information Format.</t>
<section anchor="tzif" numbered="true" toc="default"> <section anchor="tzif" numbered="true" toc="default">
<name>application/tzif</name> <name>application/tzif</name>
<dl newline="true" spacing="normal"> <dl newline="false" spacing="normal">
<dt>Type name:</dt> <dt>Type name:</dt>
<dd>application</dd> <dd>application</dd>
<dt>Subtype name:</dt> <dt>Subtype name:</dt>
<dd>tzif</dd> <dd>tzif</dd>
<dt>Required parameters:</dt> <dt>Required parameters:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Optional parameters:</dt> <dt>Optional parameters:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Encoding considerations:</dt> <dt>Encoding considerations:</dt>
<dd>binary</dd> <dd>binary</dd>
<dt>Security considerations:</dt> <dt>Security considerations:</dt>
<dd> <dd> See <xref target="security" format="default"/> of RFC 9636.</dd>
See <xref target="security" format="default"/> of This Document.
</dd>
<dt>Interoperability considerations:</dt> <dt>Interoperability considerations:</dt>
<dd> <dd>See <xref target="interop" format="default"/> of RFC 9636.</dd>
See <xref target="interop" format="default"/> of This Document.
</dd>
<dt>Published specification:</dt> <dt>Published specification:</dt>
<dd> <dd>RFC 9636.</dd>
This specification.
</dd>
<dt>Applications that use this media type:</dt> <dt>Applications that use this media type:</dt>
<dd> <dd>This media type is designed for widespread use by applications
This media type is designed for widespread use by that need to use or exchange time zone information relative to UNIX
applications that need to use or exchange time zone time, such as the <xref target="ZIC" format="default"> Time Zone
information relative to UNIX Time, Information Compiler (zic)</xref> and the <xref target="GNU-C"
such as the format="default"> GNU C Library</xref>. The <xref target="RFC7808"
<xref target="ZIC" format="default"> format="default">Time Zone Distribution Service</xref> can directly
Time Zone Information Compiler (zic)</xref> use this media type.</dd>
and the
<xref target="GNU-C" format="default">
GNU C Library</xref>.
The <xref target="RFC7808" format="default">Time Zone Distribution
Service</xref> can directly use this media type.
</dd>
<dt>Fragment identifier considerations:</dt> <dt>Fragment identifier considerations:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Additional information:</dt> <dt>Additional information:</dt><dd>
<dd> <t><br/></t>
<dl newline="false" spacing="normal"> <dl newline="false" spacing="compact">
<dt>Magic number(s):</dt> <dt>Magic number(s):</dt>
<dd> <dd>
The first 4 octets are 0x54, 0x5A, 0x69, 0x66</dd> The first 4 octets are 0x54, 0x5A, 0x69, 0x66</dd>
<dt>File extensions(s):</dt> <dt>File extensions(s):</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Macintosh file type code(s):</dt> <dt>Macintosh file type code(s):</dt>
<dd>N/A</dd> <dd>N/A</dd>
</dl> </dl>
</dd> </dd>
<dt>Person &amp; email address to contact for further information:</dt > <dt>Person &amp; email address to contact for further information:</dt >
<dd> <dd>
Time Zone Database mailing list &lt;tz@iana.org&gt; Time Zone Database mailing list &lt;tz@iana.org&gt;
</dd> </dd>
<dt>Intended usage:</dt> <dt>Intended usage:</dt>
<dd>COMMON</dd> <dd>COMMON</dd>
<dt>Restrictions on usage:</dt> <dt>Restrictions on usage:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Author:</dt> <dt>Author:</dt>
<dd> <dd>
See the "Authors' Addresses" section of This Document. See the "Authors' Addresses" section of RFC 9636.
</dd> </dd>
<dt>Change controller:</dt> <dt>Change controller:</dt>
<dd>IETF</dd> <dd>IETF</dd>
</dl> </dl>
</section> </section>
<section anchor="tzif-leap" numbered="true" toc="default"> <section anchor="tzif-leap" numbered="true" toc="default">
<name>application/tzif-leap</name> <name>application/tzif-leap</name>
<dl newline="true" spacing="normal"> <dl newline="false" spacing="normal">
<dt>Type name:</dt> <dt>Type name:</dt>
<dd>application</dd> <dd>application</dd>
<dt>Subtype name:</dt> <dt>Subtype name:</dt>
<dd>tzif-leap</dd> <dd>tzif-leap</dd>
<dt>Required parameters:</dt> <dt>Required parameters:</dt>
<dd>none</dd> <dd>none</dd>
<dt>Optional parameters:</dt> <dt>Optional parameters:</dt>
<dd>none</dd> <dd>none</dd>
<dt>Encoding considerations:</dt> <dt>Encoding considerations:</dt>
<dd>binary</dd> <dd>binary</dd>
<dt>Security considerations:</dt> <dt>Security considerations:</dt>
<dd> <dd>
See <xref target="security" format="default"/> of This Document. See <xref target="security" format="default"/> of RFC 9636.
</dd> </dd>
<dt>Interoperability considerations:</dt> <dt>Interoperability considerations:</dt>
<dd> <dd>
See <xref target="interop" format="default"/> of This Document. See <xref target="interop" format="default"/> of RFC 9636.
</dd> </dd>
<dt>Published specification:</dt> <dt>Published specification:</dt>
<dd> <dd>
This specification. RFC 9636.
</dd> </dd>
<dt>Applications that use this media type:</dt> <dt>Applications that use this media type:</dt>
<dd> <dd>
This media type is designed for widespread use by This media type is designed for widespread use by
applications that need to use or exchange time zone applications that need to use or exchange time zone
information relative to UNIX Leap Time, information relative to UNIX leap time,
such as the such as the
<xref target="ZIC" format="default"> <xref target="ZIC" format="default">
Time Zone Information Compiler (zic) Time Zone Information Compiler (zic)
</xref> </xref>
and the and the
<xref target="GNU-C" format="default"> <xref target="GNU-C" format="default">
GNU C Library</xref>. GNU C Library</xref>.
The <xref target="RFC7808" format="default">Time Zone Distribution The <xref target="RFC7808" format="default">Time Zone Distribution
Service</xref> can directly use this media type. Service</xref> can directly use this media type.
</dd> </dd>
<dt>Fragment identifier considerations:</dt> <dt>Fragment identifier considerations:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Additional information:</dt> <dt>Additional information:</dt><dd>
<dd> <t><br/></t>
<dl newline="false" spacing="normal"> <dl newline="false" spacing="compact">
<dt>Magic number(s):</dt> <dt>Magic number(s):</dt>
<dd> <dd>
The first 4 octets are 0x54, 0x5A, 0x69, 0x66</dd> The first 4 octets are 0x54, 0x5A, 0x69, 0x66</dd>
<dt>File extensions(s):</dt> <dt>File extensions(s):</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Macintosh file type code(s):</dt> <dt>Macintosh file type code(s):</dt>
<dd>N/A</dd> <dd>N/A</dd>
</dl> </dl>
</dd> </dd>
<dt>Person &amp; email address to contact for further information:</dt > <dt>Person &amp; email address to contact for further information:</dt >
<dd> <dd>
Time Zone Database mailing list &lt;tz@iana.org&gt; Time Zone Database mailing list &lt;tz@iana.org&gt;
</dd> </dd>
<dt>Intended usage:</dt> <dt>Intended usage:</dt>
<dd>COMMON</dd> <dd>COMMON</dd>
<dt>Restrictions on usage:</dt> <dt>Restrictions on usage:</dt>
<dd>N/A</dd> <dd>N/A</dd>
<dt>Author:</dt> <dt>Author:</dt>
<dd> <dd>
See the "Authors' Addresses" section of This Document. See the "Authors' Addresses" section of RFC 9636.
</dd> </dd>
<dt>Change controller:</dt> <dt>Change controller:</dt>
<dd>IETF</dd> <dd>IETF</dd>
</dl> </dl>
</section> </section>
</section> </section>
</middle> </middle>
<back> <back>
<references> <references>
<name>References</name> <name>References</name>
<references> <references>
<name>Normative References</name> <name>Normative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2
FC.2119.xml"/> 119.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6
FC.6838.xml"/> 838.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7
FC.7808.xml"/> 808.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8
FC.8174.xml"/> 174.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9
FC.9110.xml"/> 110.xml"/>
<!-- <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/referen <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2
ce.RFC.0020.xml"/>--> 0.xml"/>
<reference anchor="POSIX" target="https://pubs.opengroup.org/onlinepubs/
<reference anchor="RFC20" target="https://www.rfc-editor.org/info/rfc20" 9699919799/">
>
<front>
<title>ASCII format for network interchange</title>
<author initials="V.G." surname="Cerf" fullname="V.G. Cerf">
<organization/>
</author>
<date year="1969" month="October"/>
</front>
<seriesInfo name="STD" value="80"/>
<seriesInfo name="RFC" value="20"/>
<seriesInfo name="DOI" value="10.17487/RFC0020"/>
</reference>
<reference anchor="POSIX"
target="https://pubs.opengroup.org/onlinepubs/9699919799/">
<front> <front>
<title>Standard for Information Technology--Portable Operating <title>IEEE Standard for Information Technology--Portable Operating
System Interface (POSIX(R)) Base Specifications, Issue 7</title> System Interface (POSIX(TM)) Base Specifications, Issue 7</title>
<author> <author>
<organization>IEEE</organization> <organization>IEEE</organization>
</author> </author>
<date day="31" month="January" year="2018"/> <date month="January" year="2018"/>
</front> </front>
<seriesInfo name="IEEE" value="1003.1-2017"/> <refcontent>POSIX.1-2017</refcontent>
<seriesInfo name="IEEE Std" value="1003.1-2017"/>
<seriesInfo name="DOI" value="10.1109/IEEESTD.2018.8277153"/> <seriesInfo name="DOI" value="10.1109/IEEESTD.2018.8277153"/>
</reference> </reference>
<reference anchor="ZIC" <reference anchor="ZIC" target="http://man7.org/linux/man-pages/man8/zic
target="http://man7.org/linux/man-pages/man8/zic.8.html"> .8.html">
<front> <front>
<title>ZIC(8)</title> <title>zic(8) - Linux manual page</title>
<author initials="M" surname="Kerrisk" fullname="Michael Kerrisk"> <author initials="M" surname="Kerrisk" fullname="Michael Kerrisk">
<organization/>
</author> </author>
</front> </front>
</reference> </reference>
<reference anchor="GNU-C" target="https://www.gnu.org/software/libc/"> <reference anchor="GNU-C" target="https://www.gnu.org/software/libc/">
<front> <front>
<title>The GNU C Library (glibc)</title> <title>The GNU C Library</title>
<author initials="" surname="" fullname=""> <author>
<organization/> <organization>Free Software Foundation</organization>
</author> </author>
</front> </front>
</reference> </reference>
<reference anchor="ITU-R-TF.460" <reference anchor="ITU-R-TF.460" target="https://www.itu.int/rec/R-REC-T
target="https://www.itu.int/rec/R-REC-TF.460/en"> F.460/en">
<front> <front>
<title>Standard-frequency and time-signal emissions</title> <title>Standard-frequency and time-signal emissions</title>
<author> <author>
<organization>International Telecommunications Union</organization > <organization>International Telecommunication Union</organization>
</author> </author>
<date month="February" year="2002" /> <date month="February" year="2002" />
</front> </front>
<seriesInfo name="ITU-R" value="Recommendation TF.460" /> <seriesInfo name="ITU-R Recommendation" value="TF.460"/>
</reference> </reference>
</references> </references>
<references> <references>
<name>Informative References</name> <name>Informative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5
FC.5545.xml"/> 545.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6
FC.6557.xml"/> 557.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8
FC.8446.xml"/> 446.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8
FC.8536.xml"/> 536.xml"/>
<reference anchor="tz-link" <reference anchor="tz-link" target="https://www.iana.org/time-zones/repo
target="https://www.iana.org/time-zones/repository/tz-link.ht sitory/tz-link.html">
ml">
<front> <front>
<title> <title>Time zone and daylight saving time data</title>
Time zone and daylight saving time data
</title>
<author initials="P." surname="Eggert" fullname="Paul Eggert"/> <author initials="P." surname="Eggert" fullname="Paul Eggert"/>
<author initials="A.D." surname="Olson" fullname="Arthur David Olson "/> <author initials="A." surname="Olson" fullname="Arthur David Olson"/ >
</front> </front>
</reference> </reference>
<reference anchor="EGGERT-TZ" <reference anchor="EGGERT-TZ" target="https://github.com/eggert/tz/commi
target="https://github.com/eggert/tz/commits/main/tzfile.5"> ts/main/tzfile.5">
<front> <front>
<title>History for tz</title> <title>History for tz</title>
<author initials="" surname="" fullname=""> <author>
<organization/> <organization/>
</author> </author>
<date month="June" year="2024"/>
</front> </front>
<refcontent>commit b5318b5</refcontent>
</reference> </reference>
<reference anchor="CGPM-2022-R4" <reference anchor="CGPM-2022-R4" target="https://www.bipm.org/en/cgpm-20
target="https://www.bipm.org/en/cgpm-2022/resolution-4"> 22/resolution-4">
<front> <front>
<title>Resolution 4 of the 27th CGPM (2022)</title> <title>Resolution 4 of the 27th CGPM (2022)</title>
<author initials='' surname='' fullname=''> <author>
<organization>General Conference on Weights and Measures</organiza tion> <organization>General Conference on Weights and Measures</organiza tion>
</author> </author>
<date month='November' year='2022'/> <date month='November' year='2022'/>
</front> </front>
<seriesInfo name="DOI" value="10.59161/CGPM2022RES4E"/>
</reference> </reference>
<reference anchor="CLDR" <reference anchor="CLDR" target="https://cldr.unicode.org/">
target="https://cldr.unicode.org/">
<front> <front>
<title>Unicode CLDR Project</title> <title>Unicode CLDR Project</title>
<author initials='' surname='' fullname=''> <author>
<organization>Unicode, Inc.</organization> <organization>Unicode, Inc.</organization>
</author> </author>
<date month='' year='2024'/>
</front> </front>
</reference> </reference>
<reference anchor="Err6426" <reference anchor="Err6426" target="https://www.rfc-editor.org/errata/ei
target="https://www.rfc-editor.org/errata/eid6426"> d6426">
<front> <front>
<title>Erratum ID 6426</title> <title>Erratum ID 6426</title>
<author initials='' surname='' fullname=''> <author initials='' surname='' fullname=''>
<organization>RFC Errata</organization> <organization>RFC Errata</organization>
</author> </author>
<date month='' year=''/>
</front> </front>
<seriesInfo name="RFC" value="8536"/> <refcontent>RFC 8536</refcontent>
</reference> </reference>
<reference anchor="Err6435" <reference anchor="Err6435" target="https://www.rfc-editor.org/errata/ei
target="https://www.rfc-editor.org/errata/eid6435"> d6435">
<front> <front>
<title>Erratum ID 6435</title> <title>Erratum ID 6435</title>
<author initials='' surname='' fullname=''> <author initials='' surname='' fullname=''>
<organization>RFC Errata</organization> <organization>RFC Errata</organization>
</author> </author>
<date month='' year=''/>
</front> </front>
<seriesInfo name="RFC" value="8536"/> <refcontent>RFC 8536</refcontent>
</reference> </reference>
<reference anchor="Err6757" <reference anchor="Err6757" target="https://www.rfc-editor.org/errata/ei
target="https://www.rfc-editor.org/errata/eid6757"> d6757">
<front> <front>
<title>Erratum ID 6757</title> <title>Erratum ID 6757</title>
<author initials='' surname='' fullname=''> <author initials='' surname='' fullname=''>
<organization>RFC Errata</organization> <organization>RFC Errata</organization>
</author> </author>
<date month='' year=''/>
</front> </front>
<seriesInfo name="RFC" value="8536"/> <refcontent>RFC 8536</refcontent>
</reference> </reference>
<reference anchor="Err7681" target="https://www.rfc-editor.org/errata/ei
d7681">
<front>
<title>Erratum ID 7681</title>
<author initials='' surname='' fullname=''>
<organization>RFC Errata</organization>
</author>
</front>
<refcontent>RFC 8536</refcontent>
</reference>
</references> </references>
</references> </references>
<section anchor="issues" numbered="true" toc="default"> <section anchor="issues" numbered="true" toc="default">
<name>Common Interoperability Issues</name> <name>Common Interoperability Issues</name>
<t>This section documents common problems in implementing this <t>This section documents common problems in implementing this
specification. specification.
Most of these are problems in generating TZif files for use by Most of these are problems in generating TZif files for use by
readers conforming to readers conforming to
<xref target="EGGERT-TZ" format="default"> <xref target="EGGERT-TZ" format="default">
predecessors of this specification</xref>. predecessors of this specification</xref>.
The goals of this section are:</t> The goals of this section are to help:</t>
<ol spacing="normal" type="1"> <ol spacing="normal" type="1">
<li>to help TZif writers output <li>TZif writers output files that avoid common pitfalls in older or
files that avoid common buggy TZif readers,</li>
pitfalls in older or buggy TZif readers,</li>
<li>to help TZif readers avoid common pitfalls when reading <li>TZif readers avoid common pitfalls when reading files generated by
files generated by future TZif writers, and</li> future TZif writers, and</li>
<li>to help any future specification authors see what sort of <li>any future specification authors see what sort of problems arise
problems arise when the TZif format is changed.</li> when the TZif format is changed.</li>
</ol> </ol>
<t>When new versions of the TZif format have been defined, a <t>When new versions of the TZif format have been defined, a
design goal has been that a reader can successfully use a TZif design goal has been that a reader can successfully use a TZif
file even if the file is of a later TZif version than what the file even if the file is of a later TZif version than what the
reader was designed for. reader was designed for.
When complete compatibility was not achieved, an attempt was When complete compatibility was not achieved, an attempt was
made to limit glitches to rarely used timestamps and allow made to limit glitches to rarely used timestamps and allow
simple partial workarounds in writers designed to generate simple partial workarounds in writers designed to generate
new-version data useful even for older-version readers. newer-version data useful even for older-version readers.
This section attempts to document these compatibility issues and This section attempts to document these compatibility issues and
workarounds, as well as documenting other common bugs in workarounds as well as other common bugs in readers.</t>
readers.</t>
<t>Interoperability problems with TZif include the following:</t> <t>Interoperability problems with TZif include the following:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>Some readers examine only version 1 data. <li>Some readers examine only version 1 data.
As a partial workaround, a writer can output as much version 1 As a partial workaround, a writer can output as much version 1
data as possible. data as possible.
However, a reader should ignore version 1 data and use However, a reader should ignore version 1 data and use
version 2+ data, even if the reader's timestamps have only version 2+ data, even if the reader's timestamps have only
32 bits.</li> 32 bits.</li>
<li>Some readers designed for version 2 might mishandle <li>Some readers designed for version 2 might mishandle
timestamps after a version 3 or higher file's last transition, because timestamps after a version 3 or higher file's last transition, because
they cannot parse extensions to POSIX in the TZ-like string. they cannot parse extensions to POSIX in the TZ-like string.
As a partial workaround, a writer can output more transitions As a partial workaround, a writer can output more transitions
than necessary, so that only far-future timestamps are than necessary, so that only far-future timestamps are
mishandled by version 2 readers.</li> mishandled by version 2 readers.</li>
<li>Some readers designed for version 2 do not support <li>Some readers designed for version 2 do not support permanent
permanent daylight saving time with transitions after 24:00 daylight saving time with transitions after 24:00 -- e.g., a TZ string
-- e.g., a TZ string "EST5EDT,0/0,J365/25" denoting permanent Eastern Daylight Time (-04).
"EST5EDT,0/0,J365/25" denoting permanent Eastern Daylight Time As a workaround, a writer can substitute standard time for two time
(-04). zones east, e.g., "XXX3EDT4,0/0,J365/23" for a time zone with a
As a workaround, a writer can substitute standard time never-used standard time (XXX, -03) and negative daylight saving time
for two time zones east, e.g., (EDT, -04) all year. Alternatively, as a partial workaround, a writer
"XXX3EDT4,0/0,J365/23" can substitute standard time for the next time zone east -- e.g.,
for a time zone with a never-used standard time (XXX, -03) "AST4" for permanent Atlantic Standard Time (-04).</li>
and negative daylight saving time (EDT, -04) all year.
Alternatively,
as a partial workaround a writer can substitute standard time
for the next time zone east -- e.g., "AST4" for permanent
Atlantic Standard Time (-04).</li>
<li>Some readers designed for version 2 or 3, and that require strict <li>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 <xref target="RFC8536"/> reject version 4 files whose
tables are truncated at the start or that end in expiration times.</li> leap-second tables are truncated at the start or end in expiration
times.</li>
<li>Some readers ignore the footer and instead predict future <li>Some readers ignore the footer and instead predict future
timestamps from the time type of the last transition. timestamps from the time type of the last transition. As a partial
As a partial workaround, a writer can output more transitions workaround, a writer can output more transitions than necessary.</li>
than necessary.</li>
<li>Some readers do not use time type 0 for timestamps before <li>Some readers do not use time type 0 for timestamps before the
the first transition, in that they infer a time type using a first transition, in that they infer a time type using a heuristic
heuristic that does not always select time type 0. that does not always select time type 0. As a partial workaround, a
As a partial workaround, a writer can output a placeholder (no-op) writer can output a placeholder (no-op) first transition at an early
first transition at an early time.</li> time.</li>
<li>Some readers mishandle timestamps before the first <li>Some readers mishandle timestamps before the first transition that
transition that has a timestamp not less than -2**31. has a timestamp that is not less than -2<sup>31</sup>. Readers that sup
Readers that support only 32-bit timestamps are likely to be port
more prone to this problem, for example, when they process only 32-bit timestamps are likely to be more prone to this problem,
64-bit transitions, only some of which are representable in 32 for example, when they process 64-bit transitions, only some of which
bits. are representable in 32 bits. As a partial workaround, a writer can
As a partial workaround, a writer can output a placeholder output a placeholder transition at timestamp -2<sup>31</sup>.</li>
transition at timestamp -2**31.</li>
<li>Some readers mishandle a transition if its timestamp has <li>Some readers mishandle a transition if its timestamp has the
the minimum possible signed 64-bit value. minimum possible signed 64-bit value. Timestamps less than -2<sup>59</s
Timestamps less than -2**59 are not recommended.</li> up> are
not recommended.</li>
<li>Some readers mishandle POSIX-style TZ strings that <li>Some readers mishandle POSIX-style TZ strings that contain "&lt;"
contain "&lt;" or "&gt;". or "&gt;". As a partial workaround, a writer can avoid using "&lt;"
As a partial workaround, a writer can avoid using '&lt;' or '&gt;' or "&gt;" for time zone abbreviations containing only alphabetic
for time zone abbreviations containing only alphabetic
characters.</li> characters.</li>
<li>Many readers mishandle time zone abbreviations that contain <li>Many readers mishandle time zone abbreviations that contain
non-ASCII characters. non-ASCII characters. These characters are not recommended.</li>
These characters are not recommended.</li>
<li>Some readers may mishandle time zone abbreviations that <li>Some readers may mishandle time zone abbreviations that contain
contain fewer than 3 or more than 6 characters, or that fewer than 3 or more than 6 characters or that contain ASCII
contain ASCII characters other than alphanumerics, '-', and characters other than alphanumerics, "-", and "+". These
'+'. abbreviations are not recommended.</li>
These abbreviations are not recommended.</li>
<li>This specification does not dictate how readers should deal <li>This specification does not dictate how readers should deal with
with timestamps when local time is unspecified. timestamps when local time is unspecified. Common practice is for
Common practice is for readers to report UT with designation readers to report UT with designation string "-00". A reader could
string "-00". return an error indication instead.</li>
A reader could return an error indication instead.</li>
<li>Some readers mishandle TZif files that specify <li>Some readers mishandle TZif files that specify daylight saving
daylight saving time UT offsets that are less than the UT time UT offsets that are less than the UT offsets for the
offsets for the corresponding standard time. corresponding standard time. These readers do not support locations
These readers do not support locations like Ireland, which like Ireland, which uses the equivalent of the POSIX TZ string
uses the equivalent of the POSIX TZ string "IST-1GMT0,M10.5.0,M3.5.0/1", observing standard time (IST, +01) in
"IST-1GMT0,M10.5.0,M3.5.0/1", observing standard time summer and daylight saving time (GMT, +00) in winter. As a partial
(IST, +01) in summer and daylight saving time (GMT, +00) in workaround, a writer can output data for the equivalent of the POSIX
winter. TZ string "GMT0IST,M3.5.0/1,M10.5.0", thus swapping standard and
As a partial workaround, a writer can output data for the daylight saving time. Although this workaround misidentifies which
equivalent of the POSIX TZ string "GMT0IST,M3.5.0/1,M10.5.0", part of the year uses daylight saving time, it records UT offsets and
thus swapping standard and daylight saving time. time zone abbreviations correctly.</li>
Although this workaround misidentifies which part of the year
uses daylight saving time, it records UT offsets and time zone
abbreviations correctly.</li>
<li>Some readers generate ambiguous timestamps for positive <li>Some readers generate ambiguous timestamps for positive leap
leap seconds that occur when the UTC offset is not a multiple seconds that occur when the UTC offset is not a multiple of 60
of 60 seconds. seconds. For example, with UTC offset +01:23:45 and
For example, in a timezone with UTC offset +01:23:45 and with a positive leap second 78796801 (1972-06-30 23:59:60 UTC), some
a positive leap second 78796801 (1972-06-30 23:59:60 UTC), readers will map both 78796800 and 78796801 to 01:23:45 local time the
some readers will map both 78796800 and 78796801 to 01:23:45 next day instead of mapping the latter to 01:23:46, and they will map
local time the next day instead of mapping the latter to 78796815 to 01:23:59 instead of to 01:23:60. This has not yet been a
01:23:46, and they will map 78796815 to 01:23:59 instead of to practical problem, since no civil authority has observed such UTC
01:23:60. offsets since leap seconds were introduced in 1972.</li>
This has not yet been a practical problem, since no civil
authority has observed such UTC offsets since leap seconds
were introduced in 1972.</li>
</ul> </ul>
<t>Some interoperability problems are reader bugs that <t>Some interoperability problems are reader bugs that
are listed here mostly as warnings to developers of readers.</t> are listed here mostly as warnings to developers of readers.</t>
<ul spacing="normal"> <ul spacing="normal">
<li>Some readers do not support negative timestamps. <li>Some readers do not support negative timestamps. Developers of
Developers of distributed applications should keep this distributed applications should keep this in mind if they need to deal
in mind if they need to deal with pre-1970 data.</li> with pre-1970 data.</li>
<li>Some readers mishandle timestamps before the first <li>Some readers mishandle timestamps before the first transition that
transition that has a nonnegative timestamp. has a non-negative timestamp. Readers that do not support negative
Readers that do not support negative timestamps are likely to timestamps are likely to be more prone to this problem.</li>
be more prone to this problem.</li>
<li>Some readers mishandle time zone abbreviations like "-08" <li>Some readers mishandle time zone abbreviations like "-08" that
that contain '+', '-', or digits.</li> contain "+", "-", or digits.</li>
<li>Some readers mishandle UT offsets that are out of the <li>Some readers mishandle UT offsets that are out of the conventional
conventional range of -12 through +12 hours and so do not range of -12 through +12 hours and so do not support locations like
support locations like Kiritimati that are outside this Kiritimati that are outside this range.</li>
range.</li>
<li>Some readers mishandle UT offsets in the range [-3599, -1] <li>Some readers mishandle UT offsets in the range [-3599, -1] seconds
seconds from UT, because they integer-divide the offset by from UT because they integer-divide the offset by 3600 to get 0 and
3600 to get 0 and then display the hour part as "+00".</li> then display the hour part as "+00".</li>
<li>Some readers mishandle UT offsets that are not a multiple
of one hour, 15 minutes, or 1 minute.</li> <li>Some readers mishandle UT offsets that are not a multiple of one
hour, 15 minutes, or 1 minute.</li>
</ul> </ul>
</section> </section>
<section anchor="examples" numbered="true" toc="default"> <section anchor="examples" numbered="true" toc="default">
<name>Example TZif Files</name> <name>Example TZif Files</name>
<t>The following sections contain annotated hexadecimal dumps of <t>The following sections contain annotated hexadecimal dumps of example
example TZif files.</t> TZif files.</t>
<t>These examples should only be considered informative. <t>These examples should only be considered informative. Although the
Although the example data entries are current as of the example data entries are current as of the publication date of this
publication date of this document, the data will likely change document, the data will likely change in the future as leap seconds are
in the future as leap seconds are added and changes are made to added and changes are made to civil time.</t>
civil time.</t>
<section numbered="true" toc="default"> <section numbered="true" toc="default">
<name>Version 1 File Representing UTC (with Leap Seconds)</name> <name>Version 1 File Representing UTC (with Leap Seconds)</name>
<table align="center"> <table align="center">
<thead> <thead>
<tr> <tr>
<th align="left">File Offset</th> <th align="left">File Offset</th>
<th align="left">Hexadecimal Octets</th> <th align="left">Hexadecimal Octets</th>
<th align="left">Record Name / Field Name</th> <th align="left">Record Name / Field Name</th>
skipping to change at line 1693 skipping to change at line 1593
</tr> </tr>
<tr> <tr>
<td align="left">004</td> <td align="left">004</td>
<td align="left">00</td> <td align="left">00</td>
<td align="left">version</td> <td align="left">version</td>
<td align="left">0 (1)</td> <td align="left">0 (1)</td>
</tr> </tr>
<tr> <tr>
<td align="left">005</td> <td align="left">005</td>
<td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td> <td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">020</td> <td align="left">020</td>
<td align="left">00 00 00 01</td> <td align="left">00 00 00 01</td>
<td align="left">isutcnt</td> <td align="left">isutcnt</td>
<td align="left">1</td> <td align="left">1</td>
</tr> </tr>
<tr> <tr>
<td align="left">024</td> <td align="left">024</td>
<td align="left">00 00 00 01</td> <td align="left">00 00 00 01</td>
skipping to change at line 1736 skipping to change at line 1635
<tr> <tr>
<td align="left">040</td> <td align="left">040</td>
<td align="left">00 00 00 04</td> <td align="left">00 00 00 04</td>
<td align="left">charcnt</td> <td align="left">charcnt</td>
<td align="left">4</td> <td align="left">4</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[0]</td> <td align="left">localtimetype[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">044</td> <td align="left">044</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">0 (+00:00)</td> <td align="left">0 (+00:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 1772 skipping to change at line 1670
<tr> <tr>
<td align="left">050</td> <td align="left">050</td>
<td align="left">55 54 43 00</td> <td align="left">55 54 43 00</td>
<td align="left">designations[0]</td> <td align="left">designations[0]</td>
<td align="left">"UTC\0"</td> <td align="left">"UTC\0"</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[0]</td> <td align="left">leapsecond[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">054</td> <td align="left">054</td>
<td align="left">04 b2 58 00</td> <td align="left">04 b2 58 00</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">78796800 (1972-06-30T23:59:60Z)</td> <td align="left">78796800 (1972-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">058</td> <td align="left">058</td>
<td align="left">00 00 00 01</td> <td align="left">00 00 00 01</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">1</td> <td align="left">1</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[1]</td> <td align="left">leapsecond[1]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">062</td> <td align="left">062</td>
<td align="left">05 a4 ec 01</td> <td align="left">05 a4 ec 01</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">94694401 (1972-12-31T23:59:60Z)</td> <td align="left">94694401 (1972-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">066</td> <td align="left">066</td>
<td align="left">00 00 00 02</td> <td align="left">00 00 00 02</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">2</td> <td align="left">2</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[2]</td> <td align="left">leapsecond[2]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">070</td> <td align="left">070</td>
<td align="left">07 86 1f 82</td> <td align="left">07 86 1f 82</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">126230402 (1973-12-31T23:59:60Z)</td> <td align="left">126230402 (1973-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">074</td> <td align="left">074</td>
<td align="left">00 00 00 03</td> <td align="left">00 00 00 03</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">3</td> <td align="left">3</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[3]</td> <td align="left">leapsecond[3]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">078</td> <td align="left">078</td>
<td align="left">09 67 53 03</td> <td align="left">09 67 53 03</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">157766403 (1974-12-31T23:59:60Z)</td> <td align="left">157766403 (1974-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">082</td> <td align="left">082</td>
<td align="left">00 00 00 04</td> <td align="left">00 00 00 04</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">4</td> <td align="left">4</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[4]</td> <td align="left">leapsecond[4]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">086</td> <td align="left">086</td>
<td align="left">0b 48 86 84</td> <td align="left">0b 48 86 84</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">189302404 (1975-12-31T23:59:60Z)</td> <td align="left">189302404 (1975-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">090</td> <td align="left">090</td>
<td align="left">00 00 00 05</td> <td align="left">00 00 00 05</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">5</td> <td align="left">5</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[5]</td> <td align="left">leapsecond[5]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">094</td> <td align="left">094</td>
<td align="left">0d 2b 0b 85</td> <td align="left">0d 2b 0b 85</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">220924805 (1976-12-31T23:59:60Z)</td> <td align="left">220924805 (1976-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">098</td> <td align="left">098</td>
<td align="left">00 00 00 06</td> <td align="left">00 00 00 06</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">6</td> <td align="left">6</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[6]</td> <td align="left">leapsecond[6]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">102</td> <td align="left">102</td>
<td align="left">0f 0c 3f 06</td> <td align="left">0f 0c 3f 06</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">252460806 (1977-12-31T23:59:60Z)</td> <td align="left">252460806 (1977-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">106</td> <td align="left">106</td>
<td align="left">00 00 00 07</td> <td align="left">00 00 00 07</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">7</td> <td align="left">7</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[7]</td> <td align="left">leapsecond[7]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">110</td> <td align="left">110</td>
<td align="left">10 ed 72 87</td> <td align="left">10 ed 72 87</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">283996807 (1978-12-31T23:59:60Z)</td> <td align="left">283996807 (1978-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">114</td> <td align="left">114</td>
<td align="left">00 00 00 08</td> <td align="left">00 00 00 08</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">8</td> <td align="left">8</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[8]</td> <td align="left">leapsecond[8]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">118</td> <td align="left">118</td>
<td align="left">12 ce a6 08</td> <td align="left">12 ce a6 08</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">315532808 (1979-12-31T23:59:60Z)</td> <td align="left">315532808 (1979-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">122</td> <td align="left">122</td>
<td align="left">00 00 00 09</td> <td align="left">00 00 00 09</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">9</td> <td align="left">9</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[9]</td> <td align="left">leapsecond[9]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">126</td> <td align="left">126</td>
<td align="left">15 9f ca 89</td> <td align="left">15 9f ca 89</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">362793609 (1981-06-30T23:59:60Z)</td> <td align="left">362793609 (1981-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">130</td> <td align="left">130</td>
<td align="left">00 00 00 0a</td> <td align="left">00 00 00 0a</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">10</td> <td align="left">10</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[10]</td> <td align="left">leapsecond[10]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">134</td> <td align="left">134</td>
<td align="left">17 80 fe 0a</td> <td align="left">17 80 fe 0a</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">394329610 (1982-06-30T23:59:60Z)</td> <td align="left">394329610 (1982-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">138</td> <td align="left">138</td>
<td align="left">00 00 00 0b</td> <td align="left">00 00 00 0b</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">11</td> <td align="left">11</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[11]</td> <td align="left">leapsecond[11]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">142</td> <td align="left">142</td>
<td align="left">19 62 31 8b</td> <td align="left">19 62 31 8b</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">425865611 (1983-06-30T23:59:60Z)</td> <td align="left">425865611 (1983-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">146</td> <td align="left">146</td>
<td align="left">00 00 00 0c</td> <td align="left">00 00 00 0c</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">12</td> <td align="left">12</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[12]</td> <td align="left">leapsecond[12]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">150</td> <td align="left">150</td>
<td align="left">1d 25 ea 0c</td> <td align="left">1d 25 ea 0c</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">489024012 (1985-06-30T23:59:60Z)</td> <td align="left">489024012 (1985-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">154</td> <td align="left">154</td>
<td align="left">00 00 00 0d</td> <td align="left">00 00 00 0d</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">13</td> <td align="left">13</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[13]</td> <td align="left">leapsecond[13]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">158</td> <td align="left">158</td>
<td align="left">21 da e5 0d</td> <td align="left">21 da e5 0d</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">567993613 (1987-12-31T23:59:60Z)</td> <td align="left">567993613 (1987-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">162</td> <td align="left">162</td>
<td align="left">00 00 00 0e</td> <td align="left">00 00 00 0e</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">14</td> <td align="left">14</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[14]</td> <td align="left">leapsecond[14]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">166</td> <td align="left">166</td>
<td align="left">25 9e 9d 8e</td> <td align="left">25 9e 9d 8e</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">631152014 (1989-12-31T23:59:60Z)</td> <td align="left">631152014 (1989-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">170</td> <td align="left">170</td>
<td align="left">00 00 00 0f</td> <td align="left">00 00 00 0f</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">15</td> <td align="left">15</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[15]</td> <td align="left">leapsecond[15]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">174</td> <td align="left">174</td>
<td align="left">27 7f d1 0f</td> <td align="left">27 7f d1 0f</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">662688015 (1990-12-31T23:59:60Z)</td> <td align="left">662688015 (1990-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">178</td> <td align="left">178</td>
<td align="left">00 00 00 10</td> <td align="left">00 00 00 10</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">16</td> <td align="left">16</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[16]</td> <td align="left">leapsecond[16]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">182</td> <td align="left">182</td>
<td align="left">2a 50 f5 90</td> <td align="left">2a 50 f5 90</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">709948816 (1992-06-30T23:59:60Z)</td> <td align="left">709948816 (1992-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">186</td> <td align="left">186</td>
<td align="left">00 00 00 11</td> <td align="left">00 00 00 11</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">17</td> <td align="left">17</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[17]</td> <td align="left">leapsecond[17]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">190</td> <td align="left">190</td>
<td align="left">2c 32 29 11</td> <td align="left">2c 32 29 11</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">741484817 (1993-06-30T23:59:60Z)</td> <td align="left">741484817 (1993-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">194</td> <td align="left">194</td>
<td align="left">00 00 00 12</td> <td align="left">00 00 00 12</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">18</td> <td align="left">18</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[18]</td> <td align="left">leapsecond[18]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">198</td> <td align="left">198</td>
<td align="left">2e 13 5c 92</td> <td align="left">2e 13 5c 92</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">773020818 (1994-06-30T23:59:60Z)</td> <td align="left">773020818 (1994-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">202</td> <td align="left">202</td>
<td align="left">00 00 00 13</td> <td align="left">00 00 00 13</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">19</td> <td align="left">19</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[19]</td> <td align="left">leapsecond[19]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">206</td> <td align="left">206</td>
<td align="left">30 e7 24 13</td> <td align="left">30 e7 24 13</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">820454419 (1995-12-31T23:59:60Z)</td> <td align="left">820454419 (1995-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">210</td> <td align="left">210</td>
<td align="left">00 00 00 14</td> <td align="left">00 00 00 14</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">20</td> <td align="left">20</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[20]</td> <td align="left">leapsecond[20]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">214</td> <td align="left">214</td>
<td align="left">33 b8 48 94</td> <td align="left">33 b8 48 94</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">867715220 (1997-06-30T23:59:60Z)</td> <td align="left">867715220 (1997-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">218</td> <td align="left">218</td>
<td align="left">00 00 00 15</td> <td align="left">00 00 00 15</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">21</td> <td align="left">21</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[21]</td> <td align="left">leapsecond[21]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">222</td> <td align="left">222</td>
<td align="left">36 8c 10 15</td> <td align="left">36 8c 10 15</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">915148821 (1998-12-31T23:59:60Z)</td> <td align="left">915148821 (1998-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">226</td> <td align="left">226</td>
<td align="left">00 00 00 16</td> <td align="left">00 00 00 16</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">22</td> <td align="left">22</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[22]</td> <td align="left">leapsecond[22]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">230</td> <td align="left">230</td>
<td align="left">43 b7 1b 96</td> <td align="left">43 b7 1b 96</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">1136073622 (2005-12-31T23:59:60Z)</td> <td align="left">1136073622 (2005-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">234</td> <td align="left">234</td>
<td align="left">00 00 00 17</td> <td align="left">00 00 00 17</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">23</td> <td align="left">23</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[23]</td> <td align="left">leapsecond[23]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">238</td> <td align="left">238</td>
<td align="left">49 5c 07 97</td> <td align="left">49 5c 07 97</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">1230768023 (2008-12-31T23:59:60Z)</td> <td align="left">1230768023 (2008-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">242</td> <td align="left">242</td>
<td align="left">00 00 00 18</td> <td align="left">00 00 00 18</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">24</td> <td align="left">24</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[24]</td> <td align="left">leapsecond[24]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">246</td> <td align="left">246</td>
<td align="left">4f ef 93 18</td> <td align="left">4f ef 93 18</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">1341100824 (2012-06-30T23:59:60Z)</td> <td align="left">1341100824 (2012-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">250</td> <td align="left">250</td>
<td align="left">00 00 00 19</td> <td align="left">00 00 00 19</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">25</td> <td align="left">25</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[25]</td> <td align="left">leapsecond[25]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">254</td> <td align="left">254</td>
<td align="left">55 93 2d 99</td> <td align="left">55 93 2d 99</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">1435708825 (2015-06-30T23:59:60Z)</td> <td align="left">1435708825 (2015-06-30T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">258</td> <td align="left">258</td>
<td align="left">00 00 00 1a</td> <td align="left">00 00 00 1a</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">26</td> <td align="left">26</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[26]</td> <td align="left">leapsecond[26]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">262</td> <td align="left">262</td>
<td align="left">58 68 46 9a</td> <td align="left">58 68 46 9a</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">1483228826 (2016-12-31T23:59:60Z)</td> <td align="left">1483228826 (2016-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 2361 skipping to change at line 2232
<td align="left">0 (local)</td> <td align="left">0 (local)</td>
</tr> </tr>
</tbody> </tbody>
</table> </table>
<t>To determine TAI corresponding <t>To determine TAI corresponding
to 2000-01-01T00:00:00Z (UNIX&nbsp;time&nbsp;=&nbsp;946684800), to 2000-01-01T00:00:00Z (UNIX&nbsp;time&nbsp;=&nbsp;946684800),
the following procedure would be followed:</t> the following procedure would be followed:</t>
<ol spacing="normal" type="1"> <ol spacing="normal" type="1">
<li>Find the latest leap-second occurrence prior to the <li>Find the latest leap-second occurrence prior to the time of
time of interest (leapsecond[21]) and note the correction interest (leapsecond[21]) and note the correction value
value (LEAPCORR&nbsp;=&nbsp;22).</li> (LEAPCORR&nbsp;=&nbsp;22).</li>
<li>Add LEAPCORR + 10 to the time of interest to <li>Add LEAPCORR + 10 to the time of interest to yield TAI of
yield TAI of 2000-01-01T00:00:32.</li> 2000-01-01T00:00:32.</li>
</ol> </ol>
</section> </section>
<section numbered="true" toc="default"> <section numbered="true" toc="default">
<name>Version 2 File Representing Pacific/Honolulu</name> <name>Version 2 File Representing Pacific/Honolulu</name>
<table align="center"> <table align="center">
<thead> <thead>
<tr> <tr>
<th align="left">File Offset</th> <th align="left">File Offset</th>
skipping to change at line 2398 skipping to change at line 2269
</tr> </tr>
<tr> <tr>
<td align="left">004</td> <td align="left">004</td>
<td align="left">32</td> <td align="left">32</td>
<td align="left">version</td> <td align="left">version</td>
<td align="left">'2' (2)</td> <td align="left">'2' (2)</td>
</tr> </tr>
<tr> <tr>
<td align="left">005</td> <td align="left">005</td>
<td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td> <td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">020</td> <td align="left">020</td>
<td align="left">00 00 00 06</td> <td align="left">00 00 00 06</td>
<td align="left">isutcnt</td> <td align="left">isutcnt</td>
<td align="left">6</td> <td align="left">6</td>
</tr> </tr>
<tr> <tr>
<td align="left">024</td> <td align="left">024</td>
<td align="left">00 00 00 06</td> <td align="left">00 00 00 06</td>
skipping to change at line 2531 skipping to change at line 2401
<tr> <tr>
<td align="left">078</td> <td align="left">078</td>
<td align="left">05</td> <td align="left">05</td>
<td align="left">trans type[6]</td> <td align="left">trans type[6]</td>
<td align="left">5</td> <td align="left">5</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[0]</td> <td align="left">localtimetype[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">079</td> <td align="left">079</td>
<td align="left">ff ff 6c 02</td> <td align="left">ff ff 6c 02</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-37886 (-10:31:26)</td> <td align="left">-37886 (-10:31:26)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 2558 skipping to change at line 2427
<tr> <tr>
<td align="left">084</td> <td align="left">084</td>
<td align="left">00</td> <td align="left">00</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">0</td> <td align="left">0</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[1]</td> <td align="left">localtimetype[1]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">085</td> <td align="left">085</td>
<td align="left">ff ff 6c 58</td> <td align="left">ff ff 6c 58</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-37800 (-10:30)</td> <td align="left">-37800 (-10:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 2585 skipping to change at line 2453
<tr> <tr>
<td align="left">090</td> <td align="left">090</td>
<td align="left">04</td> <td align="left">04</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">4</td> <td align="left">4</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[2]</td> <td align="left">localtimetype[2]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">091</td> <td align="left">091</td>
<td align="left">ff ff 7a 68</td> <td align="left">ff ff 7a 68</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-34200 (-09:30)</td> <td align="left">-34200 (-09:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 2612 skipping to change at line 2479
<tr> <tr>
<td align="left">096</td> <td align="left">096</td>
<td align="left">08</td> <td align="left">08</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">8</td> <td align="left">8</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[3]</td> <td align="left">localtimetype[3]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">097</td> <td align="left">097</td>
<td align="left">ff ff 7a 68</td> <td align="left">ff ff 7a 68</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-34200 (-09:30)</td> <td align="left">-34200 (-09:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 2639 skipping to change at line 2505
<tr> <tr>
<td align="left">102</td> <td align="left">102</td>
<td align="left">0c</td> <td align="left">0c</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">12</td> <td align="left">12</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[4]</td> <td align="left">localtimetype[4]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">103</td> <td align="left">103</td>
<td align="left">ff ff 7a 68</td> <td align="left">ff ff 7a 68</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-34200 (-09:30)</td> <td align="left">-34200 (-09:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 2666 skipping to change at line 2531
<tr> <tr>
<td align="left">108</td> <td align="left">108</td>
<td align="left">10</td> <td align="left">10</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">16</td> <td align="left">16</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[5]</td> <td align="left">localtimetype[5]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">109</td> <td align="left">109</td>
<td align="left">ff ff 73 60</td> <td align="left">ff ff 73 60</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-36000 (-10:00)</td> <td align="left">-36000 (-10:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 2818 skipping to change at line 2682
</tr> </tr>
<tr> <tr>
<td align="left">151</td> <td align="left">151</td>
<td align="left">32</td> <td align="left">32</td>
<td align="left">version</td> <td align="left">version</td>
<td align="left">'2' (2)</td> <td align="left">'2' (2)</td>
</tr> </tr>
<tr> <tr>
<td align="left">152</td> <td align="left">152</td>
<td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td> <td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">167</td> <td align="left">167</td>
<td align="left">00 00 00 06</td> <td align="left">00 00 00 06</td>
<td align="left">isutcnt</td> <td align="left">isutcnt</td>
<td align="left">6</td> <td align="left">6</td>
</tr> </tr>
<tr> <tr>
<td align="left">171</td> <td align="left">171</td>
<td align="left">00 00 00 06</td> <td align="left">00 00 00 06</td>
skipping to change at line 2951 skipping to change at line 2814
<tr> <tr>
<td align="left">253</td> <td align="left">253</td>
<td align="left">05</td> <td align="left">05</td>
<td align="left">trans type[6]</td> <td align="left">trans type[6]</td>
<td align="left">5</td> <td align="left">5</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[0]</td> <td align="left">localtimetype[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">254</td> <td align="left">254</td>
<td align="left">ff ff 6c 02</td> <td align="left">ff ff 6c 02</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-37886 (-10:31:26)</td> <td align="left">-37886 (-10:31:26)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 2978 skipping to change at line 2840
<tr> <tr>
<td align="left">259</td> <td align="left">259</td>
<td align="left">00</td> <td align="left">00</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">0</td> <td align="left">0</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[1]</td> <td align="left">localtimetype[1]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">260</td> <td align="left">260</td>
<td align="left">ff ff 6c 58</td> <td align="left">ff ff 6c 58</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-37800 (-10:30)</td> <td align="left">-37800 (-10:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3005 skipping to change at line 2866
<tr> <tr>
<td align="left">265</td> <td align="left">265</td>
<td align="left">04</td> <td align="left">04</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">4</td> <td align="left">4</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[2]</td> <td align="left">localtimetype[2]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">266</td> <td align="left">266</td>
<td align="left">ff ff 7a 68</td> <td align="left">ff ff 7a 68</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-34200 (-09:30)</td> <td align="left">-34200 (-09:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3032 skipping to change at line 2892
<tr> <tr>
<td align="left">271</td> <td align="left">271</td>
<td align="left">08</td> <td align="left">08</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">8</td> <td align="left">8</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[3]</td> <td align="left">localtimetype[3]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">272</td> <td align="left">272</td>
<td align="left">ff ff 7a 68</td> <td align="left">ff ff 7a 68</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-34200 (-09:30)</td> <td align="left">-34200 (-09:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3059 skipping to change at line 2918
<tr> <tr>
<td align="left">277</td> <td align="left">277</td>
<td align="left">0c</td> <td align="left">0c</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">12</td> <td align="left">12</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[4]</td> <td align="left">localtimetype[4]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">278</td> <td align="left">278</td>
<td align="left">ff ff 7a 68</td> <td align="left">ff ff 7a 68</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-34200 (-09:30)</td> <td align="left">-34200 (-09:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3086 skipping to change at line 2944
<tr> <tr>
<td align="left">283</td> <td align="left">283</td>
<td align="left">10</td> <td align="left">10</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">16</td> <td align="left">16</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[5]</td> <td align="left">localtimetype[5]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">284</td> <td align="left">284</td>
<td align="left">ff ff 73 60</td> <td align="left">ff ff 73 60</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-36000 (-10:00)</td> <td align="left">-36000 (-10:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3276 skipping to change at line 3133
<t>To determine the local time in this time zone corresponding <t>To determine the local time in this time zone corresponding
to 2019-01-01T00:00:00Z (UNIX time = 1546300800), the following to 2019-01-01T00:00:00Z (UNIX time = 1546300800), the following
procedure would be followed:</t> procedure would be followed:</t>
<ol spacing="normal" type="1"> <ol spacing="normal" type="1">
<li>Find the latest time transition prior to the time of <li>Find the latest time transition prior to the time of
interest (there is no such transition).</li> interest (there is no such transition).</li>
<li>Look up the TZ string in the footer ("HST10"), which <li>Look up the TZ string in the footer ("HST10"), which
indicates that the time zone designation is "HST" year-round, and indicates that the time zone designation is "HST" year-round and
the offset to UTC is 10:00.</li> the offset to UTC is 10:00.</li>
<li>Subtract the UTC offset from the time of interest to <li>Subtract the UTC offset from the time of interest to
yield a standard local time of 2018-12-31T14:00:00-10:00 (HST).</li> yield a standard local time of 2018-12-31T14:00:00-10:00 (HST).</li>
</ol> </ol>
</section> </section>
<section anchor="v2truncated" numbered="true" toc="default"> <section anchor="v2truncated" numbered="true" toc="default">
<name>Truncated Version 2 File Representing Pacific/Johnston</name> <name>Truncated Version 2 File Representing Pacific/Johnston</name>
<t>The following TZif file has been truncated to end on <t>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).</t> 2004-06-15).</t>
<t>In this example:</t> <t>In this example:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>The version 1 header contains only the required <li>The version 1 header contains only the required
minimum data, which will be ignored by readers.</li> minimum data, which will be ignored by readers.</li>
<li>The version 2 header leverages the fact that by specifying <li>The version 2 header leverages the fact that, by specifying
'isutcnt' and 'isstdcnt' as zero, all transition times 'isutcnt' and 'isstdcnt' as zero, all transition times
associated with local time types are assumed to be specified associated with local time types are assumed to be specified
as local wall-clock time as local wall-clock time
(see the definitions of UT/local indicators (see the definitions of UT/local indicators
and standard/wall indicators in and standard/wall indicators in
<xref target="data" format="default"/>).</li> <xref target="data" format="default"/>).</li>
<li>The time type of the last transition has designation "-00", <li>The time type of the last transition has designation "-00",
indicating that local time is unspecified.</li> indicating that local time is unspecified.</li>
skipping to change at line 3380 skipping to change at line 3237
<tr> <tr>
<td align="left">040</td> <td align="left">040</td>
<td align="left">00 00 00 01</td> <td align="left">00 00 00 01</td>
<td align="left">charcnt</td> <td align="left">charcnt</td>
<td align="left">1</td> <td align="left">1</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[0]</td> <td align="left">localtimetype[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">044</td> <td align="left">044</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">0 (+00:00)</td> <td align="left">0 (+00:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3430 skipping to change at line 3286
</tr> </tr>
<tr> <tr>
<td align="left">055</td> <td align="left">055</td>
<td align="left">32</td> <td align="left">32</td>
<td align="left">version</td> <td align="left">version</td>
<td align="left">'2' (2)</td> <td align="left">'2' (2)</td>
</tr> </tr>
<tr> <tr>
<td align="left">056</td> <td align="left">056</td>
<td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td> <td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">071</td> <td align="left">071</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">isutcnt</td> <td align="left">isutcnt</td>
<td align="left">0</td> <td align="left">0</td>
</tr> </tr>
<tr> <tr>
<td align="left">075</td> <td align="left">075</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
skipping to change at line 3575 skipping to change at line 3430
<tr> <tr>
<td align="left">166</td> <td align="left">166</td>
<td align="left">01</td> <td align="left">01</td>
<td align="left">trans type[7]</td> <td align="left">trans type[7]</td>
<td align="left">1</td> <td align="left">1</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[0]</td> <td align="left">localtimetype[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">167</td> <td align="left">167</td>
<td align="left">ff ff 6c 02</td> <td align="left">ff ff 6c 02</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-37886 (-10:31:26)</td> <td align="left">-37886 (-10:31:26)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3602 skipping to change at line 3456
<tr> <tr>
<td align="left">172</td> <td align="left">172</td>
<td align="left">04</td> <td align="left">04</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">4</td> <td align="left">4</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[1]</td> <td align="left">localtimetype[1]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">173</td> <td align="left">173</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">0 (+00:00)</td> <td align="left">0 (+00:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3629 skipping to change at line 3482
<tr> <tr>
<td align="left">178</td> <td align="left">178</td>
<td align="left">00</td> <td align="left">00</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">0</td> <td align="left">0</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[2]</td> <td align="left">localtimetype[2]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">179</td> <td align="left">179</td>
<td align="left">ff ff 6c 58</td> <td align="left">ff ff 6c 58</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-37800 (-10:30)</td> <td align="left">-37800 (-10:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3656 skipping to change at line 3508
<tr> <tr>
<td align="left">184</td> <td align="left">184</td>
<td align="left">08</td> <td align="left">08</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">8</td> <td align="left">8</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[3]</td> <td align="left">localtimetype[3]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">185</td> <td align="left">185</td>
<td align="left">ff ff 7a 68</td> <td align="left">ff ff 7a 68</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-34200 (-09:30)</td> <td align="left">-34200 (-09:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3683 skipping to change at line 3534
<tr> <tr>
<td align="left">190</td> <td align="left">190</td>
<td align="left">0c</td> <td align="left">0c</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">12</td> <td align="left">12</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[4]</td> <td align="left">localtimetype[4]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">191</td> <td align="left">191</td>
<td align="left">ff ff 7a 68</td> <td align="left">ff ff 7a 68</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-34200 (-09:30)</td> <td align="left">-34200 (-09:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3710 skipping to change at line 3560
<tr> <tr>
<td align="left">196</td> <td align="left">196</td>
<td align="left">10</td> <td align="left">10</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">16</td> <td align="left">16</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[5]</td> <td align="left">localtimetype[5]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">197</td> <td align="left">197</td>
<td align="left">ff ff 7a 68</td> <td align="left">ff ff 7a 68</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-34200 (-09:30)</td> <td align="left">-34200 (-09:30)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3737 skipping to change at line 3586
<tr> <tr>
<td align="left">202</td> <td align="left">202</td>
<td align="left">14</td> <td align="left">14</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">20</td> <td align="left">20</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[6]</td> <td align="left">localtimetype[6]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">203</td> <td align="left">203</td>
<td align="left">ff ff 73 60</td> <td align="left">ff ff 73 60</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">-36000 (-10:00)</td> <td align="left">-36000 (-10:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3833 skipping to change at line 3681
<section anchor="v3example" numbered="true" toc="default"> <section anchor="v3example" numbered="true" toc="default">
<name>Truncated Version 3 File Representing Asia/Jerusalem</name> <name>Truncated Version 3 File Representing Asia/Jerusalem</name>
<t>The following TZif file has been truncated to start on <t>The following TZif file has been truncated to start on
2038-01-01T00:00:00Z.</t> 2038-01-01T00:00:00Z.</t>
<t>In this example:</t> <t>In this example:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>The start time value can not be represented using 32 <li>The start time value cannot be represented using 32
bits, so the version 1 header contains only the required bits, so the version 1 header contains only the required
minimum data, which will be ignored by readers.</li> minimum data, which will be ignored by readers.</li>
<li>The version 3 header leverages the fact that by specifying <li>The version 3 header leverages the fact that, by specifying
'isutcnt' and 'isstdcnt' as zero, all transition times 'isutcnt' and 'isstdcnt' as zero, all transition times
associated with local time types are assumed to be specified associated with local time types are assumed to be specified
as local wall-clock time as local wall-clock time
(see the definitions of UT/local indicators (see the definitions of UT/local indicators
and standard/wall indicators in and standard/wall indicators in
<xref target="data" format="default"/>).</li> <xref target="data" format="default"/>).</li>
<li>Time type 0 has designation "-00", indicating that local <li>Time type 0 has designation "-00", indicating that local
time is unspecified prior to the truncation time.</li> time is unspecified prior to the truncation time.</li>
skipping to change at line 3877 skipping to change at line 3725
</tr> </tr>
<tr> <tr>
<td align="left">004</td> <td align="left">004</td>
<td align="left">33</td> <td align="left">33</td>
<td align="left">version</td> <td align="left">version</td>
<td align="left">'3' (3)</td> <td align="left">'3' (3)</td>
</tr> </tr>
<tr> <tr>
<td align="left">005</td> <td align="left">005</td>
<td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td> <td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">020</td> <td align="left">020</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">isutcnt</td> <td align="left">isutcnt</td>
<td align="left">0</td> <td align="left">0</td>
</tr> </tr>
<tr> <tr>
<td align="left">024</td> <td align="left">024</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
skipping to change at line 3920 skipping to change at line 3767
<tr> <tr>
<td align="left">040</td> <td align="left">040</td>
<td align="left">00 00 00 01</td> <td align="left">00 00 00 01</td>
<td align="left">charcnt</td> <td align="left">charcnt</td>
<td align="left">1</td> <td align="left">1</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[0]</td> <td align="left">localtimetype[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">044</td> <td align="left">044</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">0 (+00:00)</td> <td align="left">0 (+00:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 3970 skipping to change at line 3816
</tr> </tr>
<tr> <tr>
<td align="left">055</td> <td align="left">055</td>
<td align="left">33</td> <td align="left">33</td>
<td align="left">version</td> <td align="left">version</td>
<td align="left">'3' (3)</td> <td align="left">'3' (3)</td>
</tr> </tr>
<tr> <tr>
<td align="left">056</td> <td align="left">056</td>
<td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td> <td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">071</td> <td align="left">071</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">isutcnt</td> <td align="left">isutcnt</td>
<td align="left">0</td> <td align="left">0</td>
</tr> </tr>
<tr> <tr>
<td align="left">075</td> <td align="left">075</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
skipping to change at line 4031 skipping to change at line 3876
<tr> <tr>
<td align="left">103</td> <td align="left">103</td>
<td align="left">01</td> <td align="left">01</td>
<td align="left">trans type[0]</td> <td align="left">trans type[0]</td>
<td align="left">1</td> <td align="left">1</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[0]</td> <td align="left">localtimetype[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">104</td> <td align="left">104</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">0 (+00:00)</td> <td align="left">0 (+00:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 4058 skipping to change at line 3902
<tr> <tr>
<td align="left">109</td> <td align="left">109</td>
<td align="left">00</td> <td align="left">00</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">0</td> <td align="left">0</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[1]</td> <td align="left">localtimetype[1]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">110</td> <td align="left">110</td>
<td align="left">00 00 1c 20</td> <td align="left">00 00 1c 20</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">7200 (+02:00)</td> <td align="left">7200 (+02:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 4134 skipping to change at line 3977
<t>The following TZif file has been truncated to start on <t>The following TZif file has been truncated to start on
2022-01-01T00:00:00Z.</t> 2022-01-01T00:00:00Z.</t>
<t>In this example:</t> <t>In this example:</t>
<ul spacing="normal"> <ul spacing="normal">
<li>The version 1 header contains only the required <li>The version 1 header contains only the required
minimum data, which will be ignored by readers.</li> minimum data, which will be ignored by readers.</li>
<li>The version 4 header leverages the fact that by specifying <li>The version 4 header leverages the fact that, by specifying
'isutcnt' and 'isstdcnt' as zero, all transition times 'isutcnt' and 'isstdcnt' as zero, all transition times
associated with local time types are assumed to be specified associated with local time types are assumed to be specified
as local wall-clock time as local wall-clock time
(see the definitions of UT/local indicators (see the definitions of UT/local indicators
and standard/wall indicators in and standard/wall indicators in
<xref target="data" format="default"/>).</li> <xref target="data" format="default"/>).</li>
<li>Time type 0 has designation "-00", indicating that local <li>Time type 0 has designation "-00", indicating that local
time is unspecified prior to the truncation time.</li> time is unspecified prior to the truncation time.</li>
skipping to change at line 4181 skipping to change at line 4024
</tr> </tr>
<tr> <tr>
<td align="left">004</td> <td align="left">004</td>
<td align="left">34</td> <td align="left">34</td>
<td align="left">version</td> <td align="left">version</td>
<td align="left">'4' (4)</td> <td align="left">'4' (4)</td>
</tr> </tr>
<tr> <tr>
<td align="left">005</td> <td align="left">005</td>
<td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td> <td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">020</td> <td align="left">020</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">isutcnt</td> <td align="left">isutcnt</td>
<td align="left">0</td> <td align="left">0</td>
</tr> </tr>
<tr> <tr>
<td align="left">024</td> <td align="left">024</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
skipping to change at line 4224 skipping to change at line 4066
<tr> <tr>
<td align="left">040</td> <td align="left">040</td>
<td align="left">00 00 00 01</td> <td align="left">00 00 00 01</td>
<td align="left">charcnt</td> <td align="left">charcnt</td>
<td align="left">1</td> <td align="left">1</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[0]</td> <td align="left">localtimetype[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">044</td> <td align="left">044</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">0 (+00:00)</td> <td align="left">0 (+00:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 4274 skipping to change at line 4115
</tr> </tr>
<tr> <tr>
<td align="left">055</td> <td align="left">055</td>
<td align="left">34</td> <td align="left">34</td>
<td align="left">version</td> <td align="left">version</td>
<td align="left">'4' (4)</td> <td align="left">'4' (4)</td>
</tr> </tr>
<tr> <tr>
<td align="left">056</td> <td align="left">056</td>
<td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td> <td align="left">00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</td>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">071</td> <td align="left">071</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">isutcnt</td> <td align="left">isutcnt</td>
<td align="left">0</td> <td align="left">0</td>
</tr> </tr>
<tr> <tr>
<td align="left">075</td> <td align="left">075</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
skipping to change at line 4335 skipping to change at line 4175
<tr> <tr>
<td align="left">103</td> <td align="left">103</td>
<td align="left">01</td> <td align="left">01</td>
<td align="left">trans type[0]</td> <td align="left">trans type[0]</td>
<td align="left">1</td> <td align="left">1</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[0]</td> <td align="left">localtimetype[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">104</td> <td align="left">104</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">0 (+00:00)</td> <td align="left">0 (+00:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 4362 skipping to change at line 4201
<tr> <tr>
<td align="left">109</td> <td align="left">109</td>
<td align="left">00</td> <td align="left">00</td>
<td align="left">desigidx</td> <td align="left">desigidx</td>
<td align="left">0</td> <td align="left">0</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">localtimetype[1]</td> <td align="left">localtimetype[1]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">110</td> <td align="left">110</td>
<td align="left">00 00 00 00</td> <td align="left">00 00 00 00</td>
<td align="left">utoff</td> <td align="left">utoff</td>
<td align="left">0 (+00:00)</td> <td align="left">0 (+00:00)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 4404 skipping to change at line 4242
<tr> <tr>
<td align="left">120</td> <td align="left">120</td>
<td align="left">47 4d 54 00</td> <td align="left">47 4d 54 00</td>
<td align="left">designations[4]</td> <td align="left">designations[4]</td>
<td align="left">"GMT\0"</td> <td align="left">"GMT\0"</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[0]</td> <td align="left">leapsecond[0]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">124</td> <td align="left">124</td>
<td align="left">00 00 00 00 58 68 46 9a</td> <td align="left">00 00 00 00 58 68 46 9a</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">1483228826 (2016-12-31T23:59:60Z)</td> <td align="left">1483228826 (2016-12-31T23:59:60Z)</td>
</tr> </tr>
<tr> <tr>
<td align="left">132</td> <td align="left">132</td>
<td align="left">00 00 00 1b</td> <td align="left">00 00 00 1b</td>
<td align="left">correction</td> <td align="left">correction</td>
<td align="left">27</td> <td align="left">27</td>
</tr> </tr>
<tr> <tr>
<td colspan="4"/> <td colspan="4"/>
</tr> </tr>
<tr> <tr>
<td align="left"></td> <td colspan="2" align="left"></td>
<td align="left"></td>
<td align="left">leapsecond[1]</td> <td align="left">leapsecond[1]</td>
<td align="left"></td> <td align="left"></td>
</tr> </tr>
<tr> <tr>
<td align="left">136</td> <td align="left">136</td>
<td align="left">00 00 00 00 66 7d fd 1b</td> <td align="left">00 00 00 00 66 7d fd 1b</td>
<td align="left">occurrence</td> <td align="left">occurrence</td>
<td align="left">1719532827 (2024-06-28T00:00:01Z)</td> <td align="left">1719532827 (2024-06-28T00:00:01Z)</td>
</tr> </tr>
<tr> <tr>
skipping to change at line 4491 skipping to change at line 4327
designation string "-00" denotes unspecified local time. designation string "-00" denotes unspecified local time.
Added recommendation that this designation string should be Added recommendation that this designation string should be
used for timestamps excluded by TZif file truncation.</li> used for timestamps excluded by TZif file truncation.</li>
<li>Required support in version 2 files for all-year daylight <li>Required support in version 2 files for all-year daylight
saving time, using POSIX TZ strings with negative DST, as this saving time, using POSIX TZ strings with negative DST, as this
is not an extension to POSIX (<xref target="permdst"/>).</li> is not an extension to POSIX (<xref target="permdst"/>).</li>
<li>Applied erratum <xref target="Err6435" format="default"/>.</li> <li>Applied erratum <xref target="Err6435" format="default"/>.</li>
<li>Addressed errata <xref target="Err6426" format="default"/> <li>Addressed errata <xref target="Err6426" format="default"/>,
and <xref target="Err6757" format="default"/> <xref target="Err6757" format="default"/>, and
<xref target="Err7681" format="default"/>
as well as several other errors in the examples.</li> as well as several other errors in the examples.</li>
<li>Added additional interoperabilty considerations and common <li>Added additional interoperability considerations and common
issues.</li> issues.</li>
<li>Added an <xref target="v2truncated" format="default"> <li>Added an <xref target="v2truncated" format="default">
example of a TZif file truncated at the end.</xref></li> example of a TZif file truncated at the end</xref>.</li>
<li>Added informational notes to <li>Added informational notes to
<xref target="v3example" format="default"/>.</li> <xref target="v3example" format="default"/>.</li>
<li>Miscellaneous editorial changes.</li> <li>Miscellaneous editorial changes.</li>
</ul> </ul>
</section> </section>
<section numbered="true" toc="default">
<name>Change Log</name>
<t>This section is to be removed by RFC Editor before publication.</t>
<section numbered="true" toc="default">
<name>Since rfc8536bis-14</name>
<ul spacing="normal">
<li>Correct direction reversal with UT offsets -10 and +0530.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-13</name>
<ul spacing="normal">
<li>Referenced Section 8 of RFC 7808 in Security Considerations.</li>
<li>Changed some terminology in Appendix A to be more
inclusive.</li>
<li>Added Internationalization Considerations section and
clarified the requirements for time zone designation
strings.</li>
<li>Stiffened the requirements for truncating TZif files.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-12</name>
<ul spacing="normal">
<li>Clarified the difference between the two media types in their
IANA registrations.</li>
<li>Removed dates from references to dynamic content.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-11</name>
<ul spacing="normal">
<li>Clarified the consequences of not abiding by some SHOULDs.</li>
<li>Miscellaneous editorial changes.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-10</name>
<ul spacing="normal">
<li>Clarified in IANA Considerations that this document is updating
the existing media types.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-09</name>
<ul spacing="normal">
<li>Clarified text of the example in the description of
leap-second table expiration.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-08</name>
<ul spacing="normal">
<li>Added an example of a TZif file truncated at the
end.</li>
<li>Fixed utoff value of LMT in Honolulu example.</li>
<li>Updated "tz-link" URL.</li>
<li>Miscellaneous editorial changes.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-07</name>
<ul spacing="normal">
<li>Miscellaneous editorial changes.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-06</name>
<ul spacing="normal">
<li>Moved the specification of an all-year daylight saving time
<xref target="permdst" format="default">TZ string</xref>,
to its own section as it is NOT an extension.</li>
<li>Noted that should leap seconds to become discontinued
that leap-second tables SHOULD NOT expire.</li>
<li>Updated "tz-link" title and reference.</li>
<li>Updated reference to RFC 7231 to RFC 9110.</li>
<li>Miscellaneous editorial changes.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-05</name>
<ul spacing="normal">
<li>Clarified the specification of an all-year daylight saving time
<xref target="permdst" format="default">TZ string</xref>,
and changed the example to use negative DST.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-04</name>
<ul spacing="normal">
<li>None.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-03</name>
<ul spacing="normal">
<li>Noted that erratum <xref target="Err6757" format="default"/>
has been addressed.</li>
<li>Added a definition of Leap Second, including UTC month.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-02</name>
<ul spacing="normal">
<li>Documented "-00" as meaning unspecified local time.</li>
<li>Recommended that "-00" be used for timestamps that
are unspecified due to TZif file truncation.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-01</name>
<ul spacing="normal">
<li>Converted source from xml2rfc v2 to v3.</li>
<li>Properly line-wrapped long TZ string values in examples
(with no added space).</li>
<li>No other substantive changes.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since rfc8536bis-00</name>
<ul spacing="normal">
<li>Added specification of the version 4 format and the
optional leap-second table truncation and expiration,
along with an example and relevant
interoperability considerations.</li>
<li>Specified column widths in example tables.</li>
<li>Noted that long TZ string values in examples are
line-wrapped for presentation purposes only.</li>
</ul>
</section>
<section numbered="true" toc="default">
<name>Since RFC 8536</name>
<ul spacing="normal">
<li>Applied erratum <xref target="Err6435" format="default"/>.</li>
<li>Addressed erratum <xref target="Err6426" format="default"/>
and several other errors in the examples.</li>
<li>Clarified the specification of an all-year daylight saving time
<xref target="permdst" format="default">TZ string</xref>,
and changed the example to use negative DST.</li>
<li>Added informational notes to
<xref target="v3example" format="default"/>.</li>
<li>Miscellaneous editorial changes.</li>
<li>Added text obsoleting
<xref target="RFC8536" format="default"/>.</li>
<li>Added <xref target="changes" format="default">
Changes from RFC 8536</xref>.</li>
<li>Added Tim Parenti as a contributor.</li>
</ul>
</section>
</section>
<section numbered="false" toc="default"> <section numbered="false" toc="default">
<name>Acknowledgments</name> <name>Acknowledgments</name>
<t>The authors would like to thank the following individuals for <t>The authors thank the following individuals for
contributing their ideas and support for writing this contributing their ideas and support for writing this specification:
specification: Michael Douglass, Ned Freed, Guy Harris, <contact fullname="Michael Douglass"/>, <contact fullname="Ned Freed"/>,
Eliot Lear, Alexey Melnikov, and Tim Parenti.</t> <contact fullname="Guy Harris"/>, <contact fullname="Eliot Lear"/>,
<contact fullname="Alexey Melnikov"/>, and <contact fullname="Tim
Parenti"/>.</t>
</section> </section>
</back> </back>
</rfc> </rfc>
 End of changes. 255 change blocks. 
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