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<rfc xmlns:xi="http://www.w3.org/2001/XInclude" category="std" docName="draft-murchison-rfc8536bis-15" number="9636" updates="" ipr="trust200902" obsoletes="8536" consensus="true" submissionType="IETF" xml:lang="en" tocInclude="true" symRefs="true" sortRefs="true" tocDepth="3" version="3">
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  <front>
    <title abbrev="TZif">
      The abbrev="TZif">The Time Zone Information Format (TZif)
    </title> (TZif)</title>
    <seriesInfo name="Internet-Draft" value="draft-murchison-rfc8536bis-15"/> name="RFC" value="9636"/>
    <author initials="A.D." initials="A." surname="Olson" fullname="Arthur David Olson">
      <organization/>
      <address>
        <email>arthurdavidolson@gmail.com</email>
      </address>
    </author>

    <author initials="P." surname="Eggert" fullname="Paul Eggert">
      <organization abbrev="UCLA">
        University abbrev="UCLA">University of California, Los Angeles
      </organization> Angeles</organization>
      <address>
        <email>eggert@cs.ucla.edu</email>
      </address>
    </author>

    <author initials="K." surname="Murchison" fullname="Kenneth Murchison">
      <organization abbrev="Fastmail">Fastmail US LLC</organization>
      <address>
        <email>murch@fastmailteam.com</email>
      </address>
    </author>

    <date/>
    <area>General</area>
    <workgroup>Internet Engineering Task Force (IETF)</workgroup>

    <date month="November" year="2024"/>

    <keyword>time zone</keyword>
    <keyword>tzdata</keyword>
    <keyword>tzif</keyword>

    <abstract>
      <t>This document specifies the Time Zone Information Format (TZif)
      for representing and exchanging time zone information,
      independent of any particular service or protocol.
      Two media types for this format are also defined.
      </t>
      <t>This document replaces and obsoletes RFC 8536.</t>
    </abstract>
  </front>

  <middle>
    <section numbered="true" toc="default">
      <name>Introduction</name>

      <t>Time zone data typically consists of offsets from universal
      time (UT), daylight saving transition rules, one or
      more local time designations (acronyms or abbreviations), and
      optional leap-second adjustments.
      One such format for conveying this information is
      <xref target="RFC5545" format="default">iCalendar</xref>.
      It is a text-based format used by calendaring and scheduling systems.
      </t>
      <t>This document specifies the widely deployed Time Zone
      Information Format (TZif).
      It is a binary format used by most UNIX systems to calculate
      local time.
      This format was introduced in the 1980s and has evolved since
      then into multiple upward-compatible versions.
      There is a wide variety of interoperable software capable of
      generating and reading files in this format
      <xref target="tz-link" format="default"/>.
      </t>
      <t>This specification does not define the source of the data
      assembled into a TZif file.
      One such source is the IANA-hosted time zone database
      <xref target="RFC6557" format="default"/>.</t>
      <t>This document obsoletes RFC 8536, <xref target="RFC8536" format="default"/>, providing editorial improvements,
      new details, and errata fixes while keeping full compatibility with
      the interchange format of RFC 8536. <xref target="RFC8536" format="default"/>.

      Additionally, a new version of the format is defined.
      The changes from RFC 8536 <xref target="RFC8536" format="default"/> are summarized in
      <xref target="changes" format="default"/>.</t>
    </section>

    <section numbered="true" toc="default">
      <name>Conventions Used in This Document</name>
      <t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
      NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
      "MAY", "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>",
      "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
      NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>",
      "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
      "<bcp14>MAY</bcp14>", and "OPTIONAL" "<bcp14>OPTIONAL</bcp14>" in this document are
      to be interpreted as described in BCP&nbsp;14 <xref target="RFC2119" format="default"/> target="RFC2119"/>
      <xref target="RFC8174" format="default"/> target="RFC8174"/> when, and only when, they appear in all
      capitals, as shown here.
        </t>

      <t>The following terms are used in this document
      (see <xref target="tz-link" format="default">
      "Time zone and daylight saving time data"</xref>
      for more detailed information about civil timekeeping data and
      practice):

      </t>
      <dl newline="false" spacing="normal">
        <dt>Coordinated Universal Time (UTC):</dt>
        <dd>
          The basis for civil time since 1960.
          It is approximately equal to mean solar time at the prime
          meridian (0 degrees longitude).
        </dd>
        <dt>Daylight Saving Time (DST):</dt>
        <dd>
          The time according to a location's law or practice,
          when adjusted as necessary from standard time.  The
          adjustment may be positive or negative, and the amount of
          adjustment may vary depending on the date and time; the TZif
          format even allows the adjustment to be zero, although this
          is not common practice.
        </dd>
        <dt>International Atomic Time (TAI):</dt>
        <dd>
          The time standard based on atomic clocks since 1972.
          It is equal to UTC but without leap-second adjustments.
        </dd>
        <dt>Leap Second:</dt>
        <dd>
          A one-second adjustment to keep UTC close to mean solar time
          at the prime meridian
          (see <xref target="ITU-R-TF.460" format="default"/>).
          Each inserted or deleted leap second occurs at the end of a
          UTC month, that is, a month using the Gregorian calendar and
          the UTC timescale.
        </dd>
        <dt>Leap-Second Correction (LEAPCORR):</dt>
        <dd>
          The value of TAI "TAI - UTC - 10 10" for timestamps after the
          first leap second, and zero for timestamps before that.
          The expression "TAI - UTC - 10" comes from the fact
          that TAI - UTC was defined to be 10 just prior to
          the first leap second in 1972, so clocks with leap
          seconds have a zero LEAPCORR before the first leap
          second.
        </dd>
        <dt>Local Time:</dt>
        <dd>
          Civil time for a particular location.  Its offset
          from universal time can depend on the date and time of day.
        </dd>
        <dt>POSIX Epoch:</dt>
        <dd>
          1970-01-01 00:00:00 UTC, the basis for absolute timestamps
          in this document.
        </dd>
        <dt>Standard Time:</dt>
        <dd>
          The time according to a location's law or practice,
          unadjusted for Daylight Saving Time. daylight saving time.
        </dd>
        <dt>Time Change:</dt>
        <dd>
          <t>
          A change to civil timekeeping practice. It occurs when one
          or more of the following happen simultaneously:
          </t>
          <ol spacing="normal" type="1"><li>a 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 time zone abbreviation</li>
            <li>a leap second (i.e., a change in LEAPCORR)</li>
          </ol>
        </dd>
        <dt>Time Zone Data:</dt>
        <dd>
          The <xref target="RFC7808" format="default">
          Time Zone Data Distribution Service (TZDIST)</xref>
          defines "Time zone data" as "data
          that defines a single time zone, including an identifier,
          UTC offset values, DST rules, and other information such as
          time zone abbreviations." abbreviations".  The interchange format defined in
          this document is one such form of time zone data.
        </dd>
        <dt>Transition Time:</dt>
        <dd>
          The moment of occurrence of a time change that is not a leap
          second.  It is identified with a signed integer count of
          UNIX leap time seconds since the POSIX epoch.
        </dd>
        <dt>Universal Time (UT):</dt>
        <dd>
          The basis of civil time.
          This is the principal form of the mean solar time at the
          prime meridian (0 degrees longitude) for timestamps before
          UTC was introduced in 1960 and is UTC for timestamps
          thereafter.
          Although UT is sometimes called "UTC" or "GMT" in other
          sources, this specification uses the term "UT" to avoid
          confusion with UTC or with GMT.
        </dd>
        <dt>UNIX Time:</dt>
        <dd>
          The time as returned by the time() function provided by the C
          programming language
          (see Section 3 of the "System Interfaces" volume of
          <xref target="POSIX" format="default"/>).
          This is an integer number of seconds
          since the POSIX epoch, not counting
          leap seconds.  As an extension to POSIX, negative values
          represent times before the POSIX epoch, using UT.
        </dd>
        <dt>UNIX Leap Time:</dt>
        <dd>
          UNIX time plus all preceding leap-second corrections.
          For example, if the first leap-second record in a TZif file
          occurs at 1972-06-30 23:59:60 UTC, the UNIX leap time for
          the timestamp 1972-07-01 00:00:00 UTC would be 78796801, one
          greater than the UNIX time for the same timestamp.
          Similarly, if the second leap-second record occurs at
          1972-12-31 23:59:60 UTC, it accounts for the first leap second,
          so the UNIX leap time of 1972-12-31 23:59:60 UTC would be 94694401,
          and the UNIX leap time of 1973-01-01 00:00:00 UTC would be 94694402.
          If a TZif file specifies no leap-second records,
          UNIX leap time is equal to UNIX time.
        </dd>
        <dt>Wall Time:</dt>
        <dd>
          Another name for local time; short for "wall-clock time".
        </dd>
      </dl>
    </section>

    <section anchor="format" numbered="true" toc="default">
      <name>The Time Zone Information Format (TZif)</name>

      <t>The Time Zone Information Format begins with a fixed 44-octet
      <xref target="header" format="default">version 1 header</xref>
      containing a field that specifies the version
      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 either appears after version N data so
      that earlier-version earlier version readers can easily ignore later-version later version
      data they are not designed for, or it appears as a minor
      extension to version N that version N readers are likely to
      tolerate well.</t>

      <t>The version 1 header is followed by a variable-length
      <xref target="data" format="default">version 1 data block</xref>
      containing four-octet (32-bit) transition times and leap-second
      occurrences. These 32-bit values are limited to representing
      time changes from 1901-12-13 20:45:52 through 2038-01-19 03:14:07 UT,
      and the version 1 header and data block are present only for backward
      compatibility with obsolescent readers, as discussed in
      <xref target="issues" format="default">
      Common
      "Common Interoperability Issues</xref>.</t> Issues"</xref>.</t>
      <t>Version 1 files terminate after the version 1 data block.
      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
      containing eight-octet (64-bit) transition times and leap-second
      occurrences, and a variable-length
      <xref target="footer" format="default">footer</xref>.
      These 64-bit values can represent times approximately 292
      billion years into the past or future.</t>

      <t>
        NOTE: All multi-octet integer values MUST <bcp14>MUST</bcp14> be stored in
        network octet order format (high-order octet first, otherwise
        known as big-endian), with all bits significant. Signed
        integer values MUST <bcp14>MUST</bcp14> be represented using two's complement.
      </t>
      <t>A TZif file is structured as follows:</t>

      <figure>
        <name>General Format of TZif Files</name>
        <artwork type="ascii-art" align="center" name="" alt=""><![CDATA[
   Version 1        Versions 2+
+-------------+   +-------------+
|  Version 1  |   |  Version 1  |
|   Header    |   |   Header    |
+-------------+   +-------------+
|  Version 1  |   |  Version 1  |
|  Data Block |   |  Data Block |
+-------------+   +-------------+
                  |  Version 2+ |
                  |   Header    |
                  +-------------+
                  |  Version 2+ |
                  |  Data Block |
                  +-------------+
                  |   Footer    |
                  +-------------+
]]></artwork>
      </figure>

      <section anchor="header" numbered="true" toc="default">
        <name>TZif Header</name>

        <t>A TZif header is structured as follows
        (the lengths of multi-octet fields are shown in parentheses):</t>

        <figure>
          <name>TZif Header</name>
          <artwork type="ascii-art" align="center" name="" alt=""><![CDATA[
+---------------+---+
|  magic    (4) |ver|
+---------------+---+---------------------------------------+
|           [unused - reserved for future use] (15)         |
+---------------+---------------+---------------+-----------+
|  isutcnt  (4) |  isstdcnt (4) |  leapcnt  (4) |
+---------------+---------------+---------------+
|  timecnt  (4) |  typecnt  (4) |  charcnt  (4) |
+---------------+---------------+---------------+
]]></artwork>
        </figure>

        <t>The fields of the header are defined as follows:</t>
        <dl newline="false" spacing="normal">
          <dt>magic:</dt>
          <dd>
            The four-octet <xref target="RFC20" format="default">ASCII</xref>
              sequence "TZif" (0x54 0x5A 0x69 0x66),
              which identifies the file as utilizing the Time Zone
              Information Format.
          </dd>
          <dt>ver(sion):</dt>
          <dd>
            <t>
              An octet identifying the version of the
              file's format.  The value MUST <bcp14>MUST</bcp14> be one of the following:

            </t>
            <dl newline="false"
            <ul spacing="normal">
              <dt>NUL (0x00)</dt>
              <dd>
              <li><t>NUL (0x00) Version 1 - The file contains only the version 1 header and
              data block.  Version 1 files MUST NOT <bcp14>MUST NOT</bcp14> contain a
              version 2+ header, data block, or footer.
              </dd>
              <dt>'2' (0x32)</dt>
              <dd> footer.</t></li>
              <li><t>'2' (0x32) Version 2 - The file MUST <bcp14>MUST</bcp14>
              contain the version 1 header and data block, a version 2+ header
              and data block, and a footer.  The TZ string in the <xref
              target="footer" format="default">footer</xref>, if
                  nonempty, MUST non-empty,
              <bcp14>MUST</bcp14> strictly adhere to the requirements for the
              TZ environment variable as defined in Section 8.3 of the "Base
              Definitions" volume of <xref target="POSIX" format="default"/>
              and MUST <bcp14>MUST</bcp14> encode the POSIX portable character set
              as ASCII.  The leap-second records MUST NOT <bcp14>MUST NOT</bcp14> be
              <xref target="truncation" format="default"> truncated at the start</xref>,
              start</xref> and MUST NOT <bcp14>MUST NOT</bcp14> contain an expiration time.
              </dd>
              <dt>'3' (0x33)</dt>
              <dd>
              time.</t></li>
              <li><t>'3' (0x33) Version 3 - The file MUST <bcp14>MUST</bcp14>
              conform to all version 2 requirements, except that any TZ string
              in the <xref target="footer" format="default">footer</xref>
                MAY
              <bcp14>MAY</bcp14> use the TZ string extension <xref
              target="tzstrext" format="default"> described below</xref>.
              </dd>
              <dt>'4' (0x34)</dt>
              <dd>
              below</xref>.</t></li>
              <li><t>'4' (0x34) Version 4 - The file MUST <bcp14>MUST</bcp14>
              conform to all version 3 requirements, except that the
              leap-second records
                MAY <bcp14>MAY</bcp14> be truncated at the start,
              start and
                MAY <bcp14>MAY</bcp14> contain an expiration time.
              </dd>
            </dl>
          </dd>
              time.</t></li>
          </ul></dd>
          <dt>isutcnt:</dt>
          <dd>
              A four-octet unsigned integer specifying the number of
              UT/local indicators contained in the data block --
              MUST
              <bcp14>MUST</bcp14> either be zero or equal to "typecnt".
          </dd>
          <dt>isstdcnt:</dt>
          <dd>
              A four-octet unsigned integer specifying the number of
              standard/wall indicators contained in the data block --
              MUST
              <bcp14>MUST</bcp14> either be zero or equal to "typecnt".
          </dd>
          <dt>leapcnt:</dt>
          <dd>
              A four-octet unsigned integer specifying the number of
              leap-second records contained in the data block.
          </dd>
          <dt>timecnt:</dt>
          <dd>
              A four-octet unsigned integer specifying the number of
              transition times contained in the data block.
          </dd>
          <dt>typecnt:</dt>
          <dd>
              A four-octet unsigned integer specifying the number of
              local time type records contained in the data block --
              MUST NOT
              <bcp14>MUST NOT</bcp14> be zero.
              (Although local time type records convey no useful
              information in files that have nonempty non-empty TZ strings but
              no transitions, at least one such record is nevertheless
              required because many TZif readers reject files that
              have zero time types.)
          </dd>
          <dt>charcnt:</dt>
          <dd>
              A four-octet unsigned integer specifying the total number
              of octets used by the set of time zone designations
              contained in the data block - MUST NOT -- <bcp14>MUST NOT</bcp14> be zero.
              The count includes the trailing NUL (0x00) octet at the
              end of the last time zone designation.
          </dd>
        </dl>
        <t>Although the version 1 and 2+ headers have the same format,
        magic number, and version fields, their count
        fields may differ, because the version 1 data can be a subset of
        the version 2+ data.</t>
      </section>

      <section anchor="data" numbered="true" toc="default">
        <name>TZif Data Block</name>

        <t>A TZif data block consists of seven variable-length
        elements, each of which is a series of items.  The
        number of items in each series is determined by the
        corresponding count field in the header. The total length of
        each element is calculated by multiplying the number of items
        by the size of each item.  Therefore, implementations that
        do not wish to parse or use the version 1 data block can
        calculate its total length and skip directly to the header of
        the version 2+ data block.</t>
        <t>In the version 1 data block, time values are 32 bits
        (TIME_SIZE = 4 octets).  In the version 2+ data block, present
        only in version 2 and higher files, time values are 64 bits
        (TIME_SIZE = 8 octets).</t>

        <t>The data block is structured as follows
        (the lengths of multi-octet fields are shown in parentheses):</t>

        <figure>
          <name>TZif Data Block</name>
          <artwork type="ascii-art" align="center" name="" alt=""><![CDATA[
+---------------------------------------------------------+
|  transition times          (timecnt x TIME_SIZE)        |
+---------------------------------------------------------+
|  transition types          (timecnt)                    |
+---------------------------------------------------------+
|  local time type records   (typecnt x 6)                |
+---------------------------------------------------------+
|  time zone designations    (charcnt)                    |
+---------------------------------------------------------+
|  leap-second records       (leapcnt x (TIME_SIZE + 4))  |
+---------------------------------------------------------+
|  standard/wall indicators  (isstdcnt)                   |
+---------------------------------------------------------+
|  UT/local indicators       (isutcnt)                    |
+---------------------------------------------------------+
]]></artwork>
        </figure>

        <t>The elements of the data block are defined as follows:</t>
        <dl newline="false" spacing="normal">
          <dt>transition times:</dt>
          <dd>
            A series of four- or eight-octet UNIX leap time values sorted
              in strictly ascending order.
              Each value is used as a transition time at which the rules
              for computing local time may change.
              The number of time values is specified by the "timecnt"
              field in the header.
              Each time value SHOULD <bcp14>SHOULD</bcp14> be at least -2**59.
              (-2**59 -2<sup>59</sup>.
              (-2<sup>59</sup> is the greatest negated power of 2 that predates
              the Big Bang, and avoiding earlier timestamps works
              around known TZif reader bugs relating to outlandishly
              negative timestamps.)
          </dd>
          <dt>transition types:</dt>
          <dd>
            A series of one-octet unsigned integers specifying the
              type of local time of the corresponding transition time.
              These values serve as zero-based indices into the array
              of local time type records.
              The number of type indices is specified by the "timecnt"
              field in the header.
              Each type index MUST <bcp14>MUST</bcp14> be in the range [0, "typecnt" - 1].
          </dd>
          <dt>local time type records:</dt>
          <dd>
            <t>
              A series of six-octet records specifying a local time
              type.
              The number of records is specified by the "typecnt"
              field in the header.
              Each record has the following format
              (the lengths of multi-octet fields are shown in parentheses):
            </t>
            <artwork type="ascii-art" name="" align="left" alt=""><![CDATA[
+---------------+---+---+
|  utoff (4)    |dst|idx|
+---------------+---+---+
]]></artwork>
            <dl newline="false" spacing="normal">
              <dt>utoff:</dt>
              <dd>
                  A four-octet signed integer specifying the number of
                  seconds to be added to UT in order to determine local
                  time. The value MUST NOT <bcp14>MUST NOT</bcp14> be -2**31 -2<sup>31</sup> and SHOULD <bcp14>SHOULD</bcp14> be in
                  the range [-89999, 93599] (i.e., its value SHOULD <bcp14>SHOULD</bcp14> be
                  more than -25 hours and less than 26 hours).
                  Avoiding -2**31 -2<sup>31</sup> allows 32-bit clients to negate
                  the value without overflow.
                  Restricting it to [-89999, 93599] allows easy support by
                  implementations that already support the
                  POSIX-required range [-24:59:59, 25:59:59].
                </dd>
              <dt>(is)dst:</dt>
              <dd>
                  A one-octet value indicating whether local
                  time should be considered Daylight Saving Time (DST).
                  The value MUST <bcp14>MUST</bcp14> be 0 or 1.
                  A value of one (1) indicates that this type of time is DST.
                  A value of zero (0) indicates that this time type
                  is standard time.
                </dd>
              <dt>(desig)idx:</dt>
              <dd>
                  A one-octet unsigned integer specifying a zero-based
                  index into the series of time zone designation octets,
                  thereby selecting a particular designation string.
                  Each index MUST <bcp14>MUST</bcp14> be in the range [0, "charcnt" - 1]; it
                  designates the NUL&nbhy;terminated string of octets
                  starting at position "idx" in the time zone
                  designations.  (This string MAY <bcp14>MAY</bcp14> be empty.)  A NUL
                  octet MUST <bcp14>MUST</bcp14> exist in the time zone designations at or
                  after position "idx".
                  If the designation string is "-00", the time type is a
                  placeholder indicating that local time is unspecified.
                </dd>
            </dl>
          </dd>
          <dt>time zone designations:</dt>
          <dd>
              A series of octets constituting an array of
              NUL&nbhy;terminated (0x00) time zone designation strings.
              The total number of octets is specified by the
              "charcnt" field in the header.
              Two designations MAY <bcp14>MAY</bcp14> overlap if one is a
              suffix of the other.
              The character encoding of time zone designation strings
              is not specified; however,
              see <xref target="interop" format="default"/>
              of this document.
          </dd>
          <dt>leap-second records:</dt>
          <dd>
            <t>
              A series of eight- or twelve-octet records specifying
              the corrections that need to be applied to UTC in order to
              determine TAI, also known as the leap-second table.
              The records are sorted by the occurrence time in
              strictly ascending order.
              The number of records is specified by the
              "leapcnt" field in the header.
              Each record has one of the following structures
              (the lengths of multi-octet fields are shown in parentheses):
            </t>
            <dl newline="false" spacing="normal">
              <dt>Version 1 Data Block:</dt>
              <dd>
                <artwork type="ascii-art" name="" align="left" alt=""><![CDATA[
+---------------+---------------+
|  occur (4)    |  corr (4)     |
+---------------+---------------+
]]></artwork>
              </dd>
              <dt>version 2+ Data Block:</dt>
              <dd>
                <artwork type="ascii-art" name="" align="left" alt=""><![CDATA[
+---------------+---------------+---------------+
|  occur (8)                    |  corr (4)     |
+---------------+---------------+---------------+
]]></artwork>
              </dd>
            </dl>
            <dl newline="false" spacing="normal">

              <dt>occur(rence):</dt>
              <dd>
                A four- or eight-octet UNIX leap time value specifying the
                time at which a leap-second correction occurs
                or at which the leap-second table expires.
                The first value, if present, MUST <bcp14>MUST</bcp14> be nonnegative, non-negative,
                and each leap second MUST <bcp14>MUST</bcp14> occur at the end of a UTC
                month.
                </dd>
              <dt>corr(ection):</dt>
              <dd>
                <t>
                  A four-octet signed integer specifying the value
                  of LEAPCORR on or after the occurrence.

                  If "leapcnt" is zero, LEAPCORR is zero for all timestamps;
                  otherwise, timestamps.
                  If "leapcnt" is nonzero,
                  for timestamps before the first occurrence time,
                  LEAPCORR is zero if the first correction is one (1) or minus
                  one (-1), (-1) and is unspecified otherwise (which can happen only
                  in files <xref target="truncation" format="default">
                  truncated at the start</xref>).

                </t>
                <t>
                  The first leap second is a positive leap second if and only if its
                  correction is positive.  Each correction after the first MUST
                  <bcp14>MUST</bcp14> differ from the previous correction by
                  either one (1) for a positive leap second or minus one (-1)
                  for a negative leap second, except that in version 4 files
                  with two or more leap-second records, the correction value
                  of the last two records
                  MAY <bcp14>MAY</bcp14> be the same, with
                  the occurrence of last record indicating the expiration time
                  of the leap-second table.
                </t>

                <t>
                  The leap-second table expiration time is the time at
                  which the table no longer records the presence or
                  absence of future leap-second corrections, and
                  post-expiration timestamps can not cannot be accurately calculated.
                  For example, a leap-second table published in
                  January, which predicts the presence or absence of a
                  leap second at June's end, might expire in
                  mid-December because it is not known when the next leap
                  second will occur.
                </t>

                <t>
                  If leap seconds become permanently
                  discontinued, as requested by the
                  <xref target="CGPM-2022-R4">General Conference
                  on Weights and Measures</xref>, leap-second tables
                  published after the discontinuation time
                  SHOULD NOT
                  <bcp14>SHOULD NOT</bcp14> expire, since they will not be updated in
                  the foreseeable future.
                </t>
              </dd>
            </dl>
          </dd>
          <dt>standard/wall indicators:</dt>
          <dd anchor="stdwall">
              A series of one-octet values indicating whether
              the transition times associated with local time types were
              specified as standard time or wall-clock time.
              Each value MUST <bcp14>MUST</bcp14> be 0 or 1.
              A value of one (1) indicates standard time. The value
              MUST
              <bcp14>MUST</bcp14> be set to one (1) if the corresponding
              UT/local indicator is set to one (1).
              A value of zero (0) indicates wall time.
              The number of values is specified by the "isstdcnt"
              field in the header.
              If "isstdcnt" is zero (0), all transition times
              associated with local time types are assumed to be
              specified as wall time.
          </dd>
          <dt>UT/local indicators:</dt>
          <dd anchor="utlocal">
              A series of one-octet values indicating whether
              the transition times associated with local time types were
              specified as UT or local time.
              Each value MUST <bcp14>MUST</bcp14> be 0 or 1.
              A value of one (1) indicates UT,
              and the corresponding standard/wall indicator MUST <bcp14>MUST</bcp14> also
              be set to one (1).
              A value of zero (0) indicates local time.
              The number of values is specified by the "isutcnt"
              field in the header.
              If "isutcnt" is zero (0), all transition times
              associated with local time types are assumed to be
              specified as local time.
          </dd>
        </dl>

        <t>The type corresponding to a transition time specifies local
        time for timestamps starting at the given transition time and
        continuing up to, but not including, the next transition time.
        Local time for timestamps before the first transition is
        specified by the first time type (time type 0).
        Local time for timestamps on or after the last transition is
        specified by the TZ string in the
        <xref target="footer" format="default">footer</xref>
        if present and nonempty; non-empty; otherwise, it is unspecified.
        If there are no transitions, local time for all timestamps is
        specified by the TZ string in the footer if present and
        nonempty;
        non-empty; otherwise, it is specified by time type 0.
        A time type with a designation string of "-00" represents an
        unspecified local time.
        </t>

        <t>A given pair of standard/wall and UT/local indicators is
        used to designate whether the corresponding transition time
        was specified as UT, standard time, or wall-clock time.
        There are only three combinations of the two
        indicators, given that the standard/wall value MUST <bcp14>MUST</bcp14> be one
        (1) if the UT/local value is one (1).
        This information can be useful if the transition times in a
        TZif file need to be transformed into transitions
        appropriate for another time zone (e.g. (e.g., when calculating
        transition times for a simple POSIX-like TZ string such as
        "AKST9AKDT").</t>

        <t>In order to eliminate unused space in a TZif file, every
        nonzero local time type index SHOULD <bcp14>SHOULD</bcp14> appear at least once in the
        transition type array.
        Likewise, every octet in the time zone designations array
        SHOULD
        <bcp14>SHOULD</bcp14> be used by at least one time type record.</t>
      </section>

      <section anchor="footer" numbered="true" toc="default">
        <name>TZif Footer</name>

        <t>The TZif footer is structured as follows
        (the lengths of multi-octet fields are shown in parentheses):</t>

        <figure>
          <name>TZif Footer</name>
          <artwork type="ascii-art" align="center" name="" alt=""><![CDATA[
+---+--------------------+---+
| NL|  TZ string (0...)  |NL |
+---+--------------------+---+
]]></artwork>
        </figure>

        <t>The elements of the footer are defined as follows:</t>
        <dl newline="false" spacing="normal">
          <dt>NL:</dt>
          <dd>
              An ASCII new line character (0x0A).
            </dd>
          <dt>TZ string:</dt>
          <dd>
              A rule for computing local time changes after the last
              transition time stored in the version 2+ data block.
              The string is either empty or uses the expanded format
              of the "TZ" environment variable as defined in
              Section 8.3 of the "Base Definitions" volume of
              <xref target="POSIX" format="default"/> with ASCII
              encoding, possibly utilizing the
              <xref target="tzstrext" format="default">
              extension described below</xref>
              in version 3 and higher files.
              If the string is empty, the corresponding information is
              not available.
              If the string is nonempty non-empty and one or more transitions
              appear in the version 2+ data, the string MUST <bcp14>MUST</bcp14> be
              consistent with the last version 2+ transition. In other words,
              evaluating the TZ string at the time of the last
              transition should yield the same time type as was specified in
              the last transition.
              The string MUST NOT <bcp14>MUST NOT</bcp14> contain NUL octets or be
              NUL&nbhy;terminated, and it
              SHOULD NOT
              <bcp14>SHOULD NOT</bcp14> begin with the ':' ":" (colon) character.
            </dd>
        </dl>

        <t>The TZif footer is present only in version 2 and higher files,
        as the obsolescent version 1 format was designed before the
        need for a footer was apparent.</t>

        <section anchor="permdst" numbered="true" toc="default">
          <name>All-Year Daylight Saving Time</name>

          <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,
          and it starts January 1 at 00:00 and ends December 31 at
          24:00 minus the difference between standard and daylight
          saving time, leaving no room for standard time
          in the calendar.
          <xref target="POSIX" format="default"/> implies, implies but does not
          explicitly state this, so it is spelled out here for clarity.
          </t>

          <dl newline="true" spacing="normal">
            <dt>Example: XXX3EDT4,0/0,J365/23</dt>
            <dd>
              This represents a time zone that is perpetually 4 hours
              west of UT and is abbreviated "EDT".
              The "XXX" is ignored.
            </dd>
          </dl>

        </section>

        <section anchor="tzstrext" numbered="true" toc="default">
          <name>TZ String Extension</name>

          <t>The TZ string in a version 3 or higher TZif file MAY
          <bcp14>MAY</bcp14> use the following extension to POSIX TZ strings.
          This extension is described using the terminology of Section 8.3 of
          the "Base Definitions" volume of <xref target="POSIX" format="default"/>.
          </t>

          <ul spacing="normal">
            <li>
          format="default"/>.</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
          POSIX-required unsigned values from 0 through 24.
              </t> 24.</t>
          <dl newline="true" spacing="normal">
            <dt>Example: &lt;-03&gt;3&lt;-02&gt;,M3.5.0/-2,M10.5.0/-1</dt>
                <dd>
                  This
            <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> "-02".</dd>
          </dl>
            </li>
          </ul>

          <t>A TZif file that uses the above extension
          MUST
          <bcp14>MUST</bcp14> be designated as version 3 (or higher),
          even if a future version of POSIX adopts this extension.</t>
        </section>
      </section>
    </section>

    <section anchor="interop" numbered="true" toc="default">
      <name>Interoperability Considerations</name>

      <t>The following practices help ensure the interoperability of TZif
      applications.</t>

      <ul spacing="normal">
        <li>Version 1 files are considered a legacy format and
        SHOULD NOT
        <bcp14>SHOULD NOT</bcp14> be generated, as they do not support transition
        times after the year 2038.</li>

        <li>Readers that understand only version 1 MUST <bcp14>MUST</bcp14> ignore
        any data that extends beyond the calculated end of the version
        1 data block.</li>

        <li>Other than version 1, writers SHOULD <bcp14>SHOULD</bcp14> generate the lowest
        version number needed by a file's data.
        This helps interoperability with older readers.
        For example, a writer
        SHOULD
        <bcp14>SHOULD</bcp14> generate a version 4 file only if its leap-second table
        either expires or is truncated at the start.  Likewise, a
        writer not generating a version 4 file SHOULD <bcp14>SHOULD</bcp14> generate a
        version 3 file only if the TZ string extension is necessary to
        accurately model transition times.</li>

        <li>To save space, writers of version 2+ files MAY <bcp14>MAY</bcp14> output a
        placeholder version 1 data block with all counts zero except
        that "typecnt" and "charcnt" are both one (1).
        If this is done, obsolescent version-1-only readers MUST <bcp14>MUST</bcp14>
        interpret these files as lacking time changes and time zone
        abbreviations.</li>

        <li>Unless the version 1 data block is a placeholder,
        the sequence of timestamps defined by the version 1
        header and data block SHOULD <bcp14>SHOULD</bcp14> be a contiguous sub-sequence
        of the timestamps defined by the version 2+ header and data
        block,
        block and by the footer.
        This guideline helps obsolescent version 1 readers
        agree with current readers about timestamps within the
        contiguous sub-sequence.</li>

        <li>When a TZif file contains a leap-second table expiration
        time, TZif readers SHOULD <bcp14>SHOULD</bcp14> either refuse to process
        post-expiration timestamps, timestamps or process them as if the expiration
        time did not exist (possibly with an error indication).
        This lessens disagreement among implementations when
        processing far-future timestamps that cannot yet be handled
        exactly.</li>

        <li>Time zone designations MUST <bcp14>MUST</bcp14> consist of at least three (3)
        and no more than six (6) ASCII characters from the set of
        alphanumerics, '-', "-", and '+'. "+".
        This is compatible with POSIX requirements for
        time zone abbreviations.</li>

        <li>A reader that encounters a time zone designation containing
        bytes other than ASCII alphanumerics, '-', "-", and '+' SHOULD "+" <bcp14>SHOULD</bcp14>
        act if the designation instead contained a signed numeric string
        derived from the UT offset, for example, "-10" and "+0530" to
        indicate 10 hours west and 5.5 hours east of Greenwich,
        respectively.</li>

        <li>When reading a version 2 or higher file, readers
        SHOULD
        <bcp14>SHOULD</bcp14> ignore the version 1 header and data block except for
        the purpose of skipping over them.
        This improves compatibility among readers of nonconforming non-conforming
        files where version 2+ data is not upward compatible with
        version 1.</li>

        <li>Readers SHOULD <bcp14>SHOULD</bcp14> calculate the total lengths of the
        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>

        <li>
          <t>When a TZif file is used in a MIME message entity, it SHOULD <bcp14>SHOULD</bcp14>
          be indicated by one of the following media types:</t>

          <ul spacing="normal">
            <li>
              <xref target="tzif-leap" format="default">
              "application/tzif-leap"</xref>
              to indicate that leap-second records are included in the
              TZif data as necessary (none are necessary if the file
              is truncated to a range that precedes the first leap
            second).</li>

          <li>
              <xref target="tzif" format="default">"application/tzif"</xref>
          to indicate that leap-second records are not included in the
          TZif data; "leapcnt" in the header(s) MUST <bcp14>MUST</bcp14> be zero (0).</li>
          </ul>
        </li>

        <li>Common
	<li><t>Common interoperability issues and possible workarounds
        are described in <xref target="issues" format="default"/>.</li> format="default"/>.</t></li>
      </ul>

    </section> <!-- interop -->

    <section anchor="i18n" numbered="true" toc="default">
      <name>Internationalization Considerations</name>

      <t>TZif time zone designations contain only ASCII alphanumerics, "-",
      and "+". Commonly used designations include numeric strings like "-10"
      and "+0530" for UT offsets, offsets and English-language English language abbreviations like
      "CEST" for Central European Summer Time and "GMT" for Greenwich Mean
      Time. It is the TZif reader's responsibility to substitute different
      abbreviations when needed for internationalization, such as substituting
      "HNC" (l'heure normale du Centre) for "CST" (Central Standard Time) in
      French-speaking regions. This substitution can be problematic, as
      abbreviations can be ambiguous: ambiguous; for example, "CST" commonly stands for
      China Standard Time and Cuba Standard Time as well as Central Standard
      Time. One approach for addressing this issue can be found in the timezone
      time zone charts of the <xref target="CLDR">
      Unicode target="CLDR">Unicode Common Locale Data
      Repository (CLDR) Project.</xref></t> Project</xref>.</t>

      <t>Although the original TZif design allowed for any nonzero
      octets in time zone designations designations, and it was common practice
      until the mid-1990s for designations to contain ASCII spaces,
      designations are now limited to ASCII alphanumerics, "-", and
      "+" to avoid confusion and to encourage portability to a wide
      variety of locales.</t>

    </section> <!-- i18n -->

    <section anchor="tzdist" numbered="true" toc="default">
      <name>Use with the Time Zone Data Distribution Service</name>

      <t>The <xref target="RFC7808" format="default">Time Zone Data Distribution
      Service (TZDIST)</xref> is a service that allows reliable,
      secure, and fast delivery of time zone data and leap-second
      rules to client systems such as calendaring and scheduling
      applications or operating systems.</t>

      <t>A TZDIST service MAY <bcp14>MAY</bcp14> supply time zone data to clients in
      the Time Zone Information Format.  Such a service MUST <bcp14>MUST</bcp14> indicate
      that it supports this format by including the media type
      <xref target="tzif" format="default">"application/tzif"</xref> in its
      "capabilities" response
      (<xref target="RFC7808" section="5.1" format="default"/>).
      A TZDIST service MAY <bcp14>MAY</bcp14> also include the media type
      <xref target="tzif-leap" format="default">
        "application/tzif-leap"</xref> in its
      "capabilities" response if it is able to generate TZif files
      containing leap-second records.
      A TZDIST service MUST NOT <bcp14>MUST NOT</bcp14> advertise the "application/tzif-leap"
      media type without also advertising "application/tzif".</t>

      <t>TZDIST clients MUST <bcp14>MUST</bcp14> use the
      <xref target="RFC9110" section="12.5.1" sectionFormat="comma"
            format="default">HTTP HTTP "Accept"
      header field</xref> field (<xref target="RFC9110"
      section="12.5.1" sectionFormat="comma"/>) to indicate their preference to receive data in the
      "application/tzif" and/or "application/tzif-leap" formats.</t>

      <section anchor="truncation" numbered="true" toc="default">
        <name>Truncating TZif Files</name>

        <t>As described in
        <xref target="RFC7808" section="3.9" format="default"/>,
        a TZDIST service MAY <bcp14>MAY</bcp14> truncate time zone transition data.
        A truncated TZif file is valid from its first and up to, but
        not including, its last version 2+ transition time, if present.</t>

        <t>When truncating the start of a TZif file, the service MUST <bcp14>MUST</bcp14>
        supply in the version 2+ data a first transition time that is
        the start point of the truncation range.
        As with untruncated TZif files, time type 0 indicates local
        time immediately before the start point, and the time type of
        the first transition indicates local time thereafter.
        Time type 0 MUST <bcp14>MUST</bcp14> be a placeholder indicating that local time
        is unspecified, so that the reader is unambiguously informed
        of truncation at the start.</t>

        <t>When truncating the start of a TZif file containing
        leap-second records, the service MUST <bcp14>MUST</bcp14> keep all leap-second
        records governing timestamps within the truncation range,
        even if the first such record precedes the start point of
        the truncation range.
        If the truncated leap-second table is nonempty, non-empty,
        its first record MUST <bcp14>MUST</bcp14> have a positive correction
        if and only if it represents a positive leap second.</t>

        <t>When truncating the end of a TZif file, the service MUST <bcp14>MUST</bcp14>
        supply in the version 2+ data a last transition time that is
        the end point of the truncation range and MUST <bcp14>MUST</bcp14> supply an
        empty TZ string.
        As with untruncated TZif files with empty TZ strings, a
        truncated TZif file does not indicate local time after the
        last transition.
        To this end, the time type of the last transition MUST <bcp14>MUST</bcp14> be a
        placeholder indicating that local time is unspecified.</t>

        <t>All represented information that falls inside the
        truncation range MUST <bcp14>MUST</bcp14> be the same as that represented by a
        corresponding untruncated TZif file.</t>

        <t>TZDIST clients SHOULD NOT <bcp14>SHOULD NOT</bcp14> use a truncated TZif file (as
        described above) to interpret timestamps outside the
        truncation time range.</t>
      </section>

      <section numbered="true" toc="default">
        <name>Example TZDIST Request for TZif Data</name>

        <t>In this example, the client checks the server for the
          available formats and then requests that the time zone with a
          specific time zone identifier be returned in Time Zone
          Information Format.
        </t>

        <t keepWithNext="true">This example presumes that
        the time zone context path has been discovered
        (see <xref target="RFC7808" section="4.2.1"
        sectionFormat="comma" format="default"/>)
        to be "/tzdist".

        </t>

        <artwork type="ascii-art" name="" align="left" alt=""><![CDATA[
>> Request <<

GET /tzdist/capabilities HTTP/1.1
Host: tz.example.com

>> Response <<

HTTP/1.1 200 OK
Date: Fri, 01 Jun 2018 14:52:23 GMT
Content-Type: application/json
Content-Length: xxxx

{
  "version": 1,

  "info": {
    "primary-source": "IANA:2018e",
    "formats": [
      "text/calendar",
      "application/tzif",
      "application/tzif-leap"
    ],
...
  },
...
}

>> Request <<

GET /tzdist/zones/America%2FNew_York HTTP/1.1
Host: tz.example.com
Accept: application/tzif

>> Response <<

HTTP/1.1 200 OK
Date: Fri, 01 Jun 2018 14:52:24 GMT
Content-Type: application/tzif
Content-Length: xxxx
ETag: "123456789-000-111"

TZif2...[binary data without leap-second records]...
EST5EDT,M3.2.0,M11.1.0
]]></artwork>

      </section>
    </section>

    <section anchor="security" numbered="true" toc="default">
      <name>Security Considerations</name>

      <t>The Time Zone Information Format contains no executable
      code, and it does not define any extensible
      areas that could be used to store such code.</t>

      <t>TZif contains counted arrays of data elements.
      All counts should be checked when processing TZif objects, to
      guard against references past the end of the object.</t>

      <t>TZif provides no confidentiality or integrity protection.
      Time zone information is normally public and does not call
      for confidentiality protection.  Since time zone
      information is used in many critical applications,
      integrity protection may be required and must be provided
      externally.</t>

      <t>As discussed in <xref target="RFC7808" section="8"/>,
      transmission of time zone data over an insecure communication
      channel could result in tampered data, harming calendaring and
      scheduling operations. As such, TZif data transmitted over a
      public communications channel MUST <bcp14>MUST</bcp14> be protected with a security
      layer such as that provided by <xref target="RFC8446">
      Transport Layer Security (TLS)</xref>.</t>
    </section>

    <section anchor="privacy" numbered="true" toc="default">
      <name>Privacy Considerations</name>

      <t>The Time Zone Information Format contains publicly available
      data, and it does not define any extensible areas that
      could be used to store private data.</t>

      <t>As discussed in <xref target="RFC7808" section="9" format="default"/>,
      transmission of time zone data over an insecure communications
      channel could leak the past, current, or future location of a
      device or user.
      As such, TZif data transmitted over a public communications
      channel MUST <bcp14>MUST</bcp14> be protected with a confidentiality layer such as
      that provided by <xref target="RFC8446" format="default">
      Transport Layer Security (TLS)</xref>.</t>
    </section>

    <section anchor="iana" numbered="true" toc="default">
      <name>IANA Considerations</name>

      <t>The IANA is requested to update

      <t>IANA has updated the
      <eref target="https://www.iana.org/assignments/media-types/media-types.xhtml">Media Types Registry</eref> target="https://www.iana.org/assignments/media-types">"Media Types" registry</eref> as follows:</t> follows.</t>

      <t>This document defines two
      media types <xref target="RFC6838" format="default"/>
      for the exchange of data utilizing the Time Zone
      Information Format.</t>

      <section anchor="tzif" numbered="true" toc="default">
        <name>application/tzif</name>

        <dl newline="true" newline="false" spacing="normal">
          <dt>Type name:</dt>
          <dd>application</dd>
          <dt>Subtype name:</dt>
          <dd>tzif</dd>
          <dt>Required parameters:</dt>
          <dd>N/A</dd>
          <dt>Optional parameters:</dt>
          <dd>N/A</dd>
          <dt>Encoding considerations:</dt>
          <dd>binary</dd>
          <dt>Security considerations:</dt>
          <dd> See <xref target="security" format="default"/> of This Document.
          </dd> RFC 9636.</dd>
          <dt>Interoperability considerations:</dt>
          <dd>
            See
          <dd>See <xref target="interop" format="default"/> of This Document.
          </dd> RFC 9636.</dd>
          <dt>Published specification:</dt>
          <dd>
            This specification.
          </dd>
          <dd>RFC 9636.</dd>
          <dt>Applications that use this media type:</dt>
          <dd>
            This
          <dd>This media type is designed for widespread use by applications
          that need to use or exchange time zone information relative to UNIX Time,
          time, such as the <xref target="ZIC" format="default"> Time Zone
          Information Compiler (zic)</xref> 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> type.</dd>
          <dt>Fragment identifier considerations:</dt>
          <dd>N/A</dd>
          <dt>Additional information:</dt>
          <dd> information:</dt><dd>
	  <t><br/></t>
            <dl newline="false" spacing="normal"> spacing="compact">
              <dt>Magic number(s):</dt>
              <dd>
              The first 4 octets are 0x54, 0x5A, 0x69, 0x66</dd>
              <dt>File extensions(s):</dt>
              <dd>N/A</dd>
              <dt>Macintosh file type code(s):</dt>
              <dd>N/A</dd>
            </dl>
          </dd>
          <dt>Person &amp; email address to contact for further information:</dt>
          <dd>
            Time Zone Database mailing list &lt;tz@iana.org&gt;
          </dd>
          <dt>Intended usage:</dt>
          <dd>COMMON</dd>
          <dt>Restrictions on usage:</dt>
          <dd>N/A</dd>
          <dt>Author:</dt>
          <dd>
            See the "Authors' Addresses" section of This Document. RFC 9636.
          </dd>
          <dt>Change controller:</dt>
          <dd>IETF</dd>
        </dl>
      </section>

      <section anchor="tzif-leap" numbered="true" toc="default">
        <name>application/tzif-leap</name>

        <dl newline="true" newline="false" spacing="normal">
          <dt>Type name:</dt>
          <dd>application</dd>
          <dt>Subtype name:</dt>
          <dd>tzif-leap</dd>
          <dt>Required parameters:</dt>
          <dd>none</dd>
          <dt>Optional parameters:</dt>
          <dd>none</dd>
          <dt>Encoding considerations:</dt>
          <dd>binary</dd>
          <dt>Security considerations:</dt>
          <dd>
            See <xref target="security" format="default"/> of This Document. RFC 9636.
          </dd>
          <dt>Interoperability considerations:</dt>
          <dd>
            See <xref target="interop" format="default"/> of This Document. RFC 9636.
          </dd>
          <dt>Published specification:</dt>
          <dd>
            This specification.
            RFC 9636.
          </dd>
          <dt>Applications that use this media type:</dt>
          <dd>
            This media type is designed for widespread use by
            applications that need to use or exchange time zone
            information relative to UNIX Leap Time, leap time,
            such as the
            <xref target="ZIC" format="default">
              Time Zone Information Compiler (zic)
            </xref>
            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>
          <dd>N/A</dd>
          <dt>Additional information:</dt>
          <dd> information:</dt><dd>
          <t><br/></t>
            <dl newline="false" spacing="normal"> spacing="compact">
              <dt>Magic number(s):</dt>
              <dd>
              The first 4 octets are 0x54, 0x5A, 0x69, 0x66</dd>
              <dt>File extensions(s):</dt>
              <dd>N/A</dd>
              <dt>Macintosh file type code(s):</dt>
              <dd>N/A</dd>
            </dl>
          </dd>
          <dt>Person &amp; email address to contact for further information:</dt>
          <dd>
            Time Zone Database mailing list &lt;tz@iana.org&gt;
          </dd>
          <dt>Intended usage:</dt>
          <dd>COMMON</dd>
          <dt>Restrictions on usage:</dt>
          <dd>N/A</dd>
          <dt>Author:</dt>
          <dd>
            See the "Authors' Addresses" section of This Document. RFC 9636.
          </dd>
          <dt>Change controller:</dt>
          <dd>IETF</dd>
        </dl>
      </section>
    </section>
  </middle>

  <back>
    <references>
      <name>References</name>

      <references>
        <name>Normative References</name>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6838.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6838.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7808.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7808.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.9110.xml"/>
<!-- href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9110.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.0020.xml"/>-->

        <reference anchor="RFC20" target="https://www.rfc-editor.org/info/rfc20">
          <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> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.20.xml"/>
        <reference anchor="POSIX" target="https://pubs.opengroup.org/onlinepubs/9699919799/">
          <front>
            <title>Standard
            <title>IEEE Standard for Information Technology--Portable Operating
            System Interface (POSIX(R)) (POSIX(TM)) Base Specifications, Issue 7</title>
            <author>
              <organization>IEEE</organization>
            </author>
            <date day="31" month="January" year="2018"/>
          </front>
	  <refcontent>POSIX.1-2017</refcontent>
          <seriesInfo name="IEEE" name="IEEE Std" value="1003.1-2017"/>
          <seriesInfo name="DOI" value="10.1109/IEEESTD.2018.8277153"/>
        </reference>

        <reference anchor="ZIC" target="http://man7.org/linux/man-pages/man8/zic.8.html">
          <front>
            <title>ZIC(8)</title>
            <title>zic(8) - Linux manual page</title>
            <author initials="M" surname="Kerrisk" fullname="Michael Kerrisk">
              <organization/>
            </author>
          </front>
        </reference>

        <reference anchor="GNU-C" target="https://www.gnu.org/software/libc/">
          <front>
            <title>The GNU C Library (glibc)</title>
            <author initials="" surname="" fullname="">
              <organization/> Library</title>
            <author>
              <organization>Free Software Foundation</organization>
            </author>
          </front>
        </reference>

        <reference anchor="ITU-R-TF.460" target="https://www.itu.int/rec/R-REC-TF.460/en">
          <front>
            <title>Standard-frequency and time-signal emissions</title>
            <author>
              <organization>International Telecommunications Telecommunication Union</organization>
            </author>
            <date month="February" year="2002" />
          </front>
          <seriesInfo name="ITU-R" value="Recommendation TF.460" /> name="ITU-R Recommendation" value="TF.460"/>
        </reference>
      </references>

      <references>
        <name>Informative References</name>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5545.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5545.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6557.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6557.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8446.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8446.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8536.xml"/> href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8536.xml"/>

        <reference anchor="tz-link" target="https://www.iana.org/time-zones/repository/tz-link.html">
          <front>
            <title>
              Time
            <title>Time zone and daylight saving time data
            </title> data</title>
            <author initials="P." surname="Eggert" fullname="Paul Eggert"/>
            <author initials="A.D." initials="A." surname="Olson" fullname="Arthur David Olson"/>
          </front>
        </reference>

        <reference anchor="EGGERT-TZ" target="https://github.com/eggert/tz/commits/main/tzfile.5">
          <front>
            <title>History for tz</title>
            <author initials="" surname="" fullname="">
            <author>
              <organization/>
            </author>
	    <date month="June" year="2024"/>
          </front>
	  <refcontent>commit b5318b5</refcontent>
        </reference>

        <reference anchor="CGPM-2022-R4" target="https://www.bipm.org/en/cgpm-2022/resolution-4">
          <front>
            <title>Resolution 4 of the 27th CGPM (2022)</title>
            <author initials='' surname='' fullname=''>
            <author>
              <organization>General Conference on Weights and Measures</organization>
            </author>
            <date month='November' year='2022'/>
          </front>
	  <seriesInfo name="DOI" value="10.59161/CGPM2022RES4E"/>
        </reference>

        <reference anchor="CLDR" target="https://cldr.unicode.org/">
          <front>
            <title>Unicode CLDR Project</title>
            <author initials='' surname='' fullname=''>
            <author>
              <organization>Unicode, Inc.</organization>
            </author>
            <date month='' year='2024'/>
          </front>
        </reference>

        <reference anchor="Err6426" target="https://www.rfc-editor.org/errata/eid6426">
          <front>
            <title>Erratum ID 6426</title>
            <author initials='' surname='' fullname=''>
              <organization>RFC Errata</organization>
            </author>
            <date month='' year=''/>
          </front>
          <seriesInfo name="RFC" value="8536"/>
          <refcontent>RFC 8536</refcontent>
        </reference>

        <reference anchor="Err6435" target="https://www.rfc-editor.org/errata/eid6435">
          <front>
            <title>Erratum ID 6435</title>
            <author initials='' surname='' fullname=''>
              <organization>RFC Errata</organization>
            </author>
            <date month='' year=''/>
          </front>
          <seriesInfo name="RFC" value="8536"/>
          <refcontent>RFC 8536</refcontent>
        </reference>

        <reference anchor="Err6757" target="https://www.rfc-editor.org/errata/eid6757">
          <front>
            <title>Erratum ID 6757</title>
            <author initials='' surname='' fullname=''>
              <organization>RFC Errata</organization>
            </author>
            <date month='' year=''/>
          </front>
          <seriesInfo name="RFC" value="8536"/>
          <refcontent>RFC 8536</refcontent>
        </reference>

        <reference anchor="Err7681" target="https://www.rfc-editor.org/errata/eid7681">
          <front>
            <title>Erratum ID 7681</title>
            <author initials='' surname='' fullname=''>
              <organization>RFC Errata</organization>
            </author>
          </front>
          <refcontent>RFC 8536</refcontent>
        </reference>

      </references>
    </references>

    <section anchor="issues" numbered="true" toc="default">
      <name>Common Interoperability Issues</name>

      <t>This section documents common problems in implementing this
      specification.
      Most of these are problems in generating TZif files for use by
      readers conforming to
      <xref target="EGGERT-TZ" format="default">
        predecessors of this specification</xref>.
      The goals of this section are:</t> are to help:</t>

      <ol spacing="normal" type="1">
        <li>to help TZif
        <li>TZif writers output files that avoid common pitfalls in older or
        buggy TZif readers,</li>

        <li>to help TZif

        <li>TZif readers avoid common pitfalls when reading files generated by
        future TZif writers, and</li>

        <li>to help any

        <li>any future specification authors see what sort of problems arise
        when the TZif format is changed.</li>
      </ol>

      <t>When new versions of the TZif format have been defined, a
      design goal has been that a reader can successfully use a TZif
      file even if the file is of a later TZif version than what the
      reader was designed for.
      When complete compatibility was not achieved, an attempt was
      made to limit glitches to rarely used timestamps and allow
      simple partial workarounds in writers designed to generate
      new-version
      newer-version data useful even for older-version readers.
      This section attempts to document these compatibility issues and
      workarounds,
      workarounds as well as documenting other common bugs in readers.</t>
      <t>Interoperability problems with TZif include the following:</t>

      <ul spacing="normal">
        <li>Some readers examine only version 1 data.
        As a partial workaround, a writer can output as much version 1
        data as possible.
        However, a reader should ignore version 1 data and use
        version 2+ data, even if the reader's timestamps have only
        32 bits.</li>

        <li>Some readers designed for version 2 might mishandle
        timestamps after a version 3 or higher file's last transition, because
        they cannot parse extensions to POSIX in the TZ-like string.
        As a partial workaround, a writer can output more transitions
        than necessary, so that only far-future timestamps are
        mishandled by version 2 readers.</li>

        <li>Some readers designed for version 2 do not support permanent
        daylight saving time with transitions after 24:00 -- e.g., a TZ string
        "EST5EDT,0/0,J365/25" denoting permanent Eastern Daylight Time (-04).
        As a workaround, a writer can substitute standard time for two time
        zones east, e.g., "XXX3EDT4,0/0,J365/23" for a time zone with a
        never-used standard time (XXX, -03) and negative daylight saving time
        (EDT, -04) all year.  Alternatively, as a partial workaround 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, 3 and that require strict
        conformance to RFC 8536, <xref target="RFC8536"/> reject version 4 files whose
        leap-second tables are truncated at the start or that end in expiration
        times.</li>

        <li>Some readers ignore the footer and instead predict future
        timestamps from the time type of the last transition.  As a partial
        workaround, a writer can output more transitions than necessary.</li>

        <li>Some readers do not use time type 0 for timestamps before the
        first transition, in that they infer a time type using a heuristic
        that does not always select time type 0.  As a partial workaround, a
        writer can output a placeholder (no-op) first transition at an early
        time.</li>

        <li>Some readers mishandle timestamps before the first transition that
        has a timestamp that is not less than -2**31. -2<sup>31</sup>.  Readers that support
        only 32-bit timestamps are likely to be more prone to this problem,
        for example, when they process 64-bit transitions, only some of which
        are representable in 32 bits.  As a partial workaround, a writer can
        output a placeholder transition at timestamp -2**31.</li> -2<sup>31</sup>.</li>

        <li>Some readers mishandle a transition if its timestamp has the
        minimum possible signed 64-bit value.  Timestamps less than -2**59 -2<sup>59</sup> are
        not recommended.</li>

        <li>Some readers mishandle POSIX-style TZ strings that contain "&lt;"
        or "&gt;".  As a partial workaround, a writer can avoid using '&lt;' "&lt;"
        or '&gt;' "&gt;" for time zone abbreviations containing only alphabetic
        characters.</li>

        <li>Many readers mishandle time zone abbreviations that contain
        non-ASCII characters.  These characters are not recommended.</li>

        <li>Some readers may mishandle time zone abbreviations that contain
        fewer than 3 or more than 6 characters, characters or that contain ASCII
        characters other than alphanumerics, '-', "-", and
        '+'. "+".  These
        abbreviations are not recommended.</li>

        <li>This specification does not dictate how readers should deal with
        timestamps when local time is unspecified.  Common practice is for
        readers to report UT with designation string "-00".  A reader could
        return an error indication instead.</li>

        <li>Some readers mishandle TZif files that specify daylight saving
        time UT offsets that are less than the UT offsets for the
        corresponding standard time.  These readers do not support locations
        like Ireland, which uses the equivalent of the POSIX TZ string
        "IST-1GMT0,M10.5.0,M3.5.0/1", observing standard time (IST, +01) in
        summer and daylight saving time (GMT, +00) in winter.  As a partial
        workaround, a writer can output data for the equivalent of the POSIX
        TZ string "GMT0IST,M3.5.0/1,M10.5.0", thus swapping standard and
        daylight saving time.  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 leap
        seconds that occur when the UTC offset is not a multiple of 60
        seconds.  For example, in a timezone with UTC offset +01:23:45 and with
        a positive leap second 78796801 (1972-06-30 23:59:60 UTC), some
        readers will map both 78796800 and 78796801 to 01:23:45 local time the
        next day instead of mapping the latter to 01:23:46, and they will map
        78796815 to 01:23:59 instead of to 01:23:60.  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>

      <t>Some interoperability problems are reader bugs that
      are listed here mostly as warnings to developers of readers.</t>

      <ul spacing="normal">
        <li>Some readers do not support negative timestamps.  Developers of
        distributed applications should keep this in mind if they need to deal
        with pre-1970 data.</li>

        <li>Some readers mishandle timestamps before the first transition that
        has a nonnegative non-negative timestamp.  Readers that do not support negative
        timestamps are likely to be more prone to this problem.</li>

        <li>Some readers mishandle time zone abbreviations like "-08" that
        contain '+', '-', "+", "-", or digits.</li>

        <li>Some readers mishandle UT offsets that are out of the conventional
        range of -12 through +12 hours and so do not support locations like
        Kiritimati that are outside this range.</li>

        <li>Some readers mishandle UT offsets in the range [-3599, -1] seconds
        from UT, UT because they integer-divide the offset by 3600 to get 0 and
        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>
      </ul>
    </section>

    <section anchor="examples" numbered="true" toc="default">
      <name>Example TZif Files</name>

      <t>The following sections contain annotated hexadecimal dumps of example
      TZif files.</t>

      <t>These examples should only be considered informative.  Although the
      example data entries are current as of the publication date of this
      document, the data will likely change in the future as leap seconds are
      added and changes are made to civil time.</t>

      <section numbered="true" toc="default">
        <name>Version 1 File Representing UTC (with Leap Seconds)</name>

        <table align="center">
          <thead>
            <tr>
              <th align="left">File Offset</th>
              <th align="left">Hexadecimal Octets</th>
              <th align="left">Record Name / Field Name</th>
              <th align="left">Field Value</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">000</td>
              <td align="left">54 5a 69 66</td>
              <td align="left">magic</td>
              <td align="left">"TZif"</td>
            </tr>
            <tr>
              <td align="left">004</td>
              <td align="left">00</td>
              <td align="left">version</td>
              <td align="left">0 (1)</td>
            </tr>
            <tr>
              <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"></td>
              <td colspan="2" align="left"></td>
            </tr>
            <tr>
              <td align="left">020</td>
              <td align="left">00 00 00 01</td>
              <td align="left">isutcnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">024</td>
              <td align="left">00 00 00 01</td>
              <td align="left">isstdcnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">028</td>
              <td align="left">00 00 00 1b</td>
              <td align="left">leapcnt</td>
              <td align="left">27</td>
            </tr>
            <tr>
              <td align="left">032</td>
              <td align="left">00 00 00 00</td>
              <td align="left">timecnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">036</td>
              <td align="left">00 00 00 01</td>
              <td align="left">typecnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">040</td>
              <td align="left">00 00 00 04</td>
              <td align="left">charcnt</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">044</td>
              <td align="left">00 00 00 00</td>
              <td align="left">utoff</td>
              <td align="left">0 (+00:00)</td>
            </tr>
            <tr>
              <td align="left">048</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">049</td>
              <td align="left">00</td>
              <td align="left">desigidx</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">050</td>
              <td align="left">55 54 43 00</td>
              <td align="left">designations[0]</td>
              <td align="left">"UTC\0"</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">054</td>
              <td align="left">04 b2 58 00</td>
              <td align="left">occurrence</td>
              <td align="left">78796800 (1972-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">058</td>
              <td align="left">00 00 00 01</td>
              <td align="left">correction</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[1]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">062</td>
              <td align="left">05 a4 ec 01</td>
              <td align="left">occurrence</td>
              <td align="left">94694401 (1972-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">066</td>
              <td align="left">00 00 00 02</td>
              <td align="left">correction</td>
              <td align="left">2</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[2]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">070</td>
              <td align="left">07 86 1f 82</td>
              <td align="left">occurrence</td>
              <td align="left">126230402 (1973-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">074</td>
              <td align="left">00 00 00 03</td>
              <td align="left">correction</td>
              <td align="left">3</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[3]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">078</td>
              <td align="left">09 67 53 03</td>
              <td align="left">occurrence</td>
              <td align="left">157766403 (1974-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">082</td>
              <td align="left">00 00 00 04</td>
              <td align="left">correction</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[4]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">086</td>
              <td align="left">0b 48 86 84</td>
              <td align="left">occurrence</td>
              <td align="left">189302404 (1975-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">090</td>
              <td align="left">00 00 00 05</td>
              <td align="left">correction</td>
              <td align="left">5</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[5]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">094</td>
              <td align="left">0d 2b 0b 85</td>
              <td align="left">occurrence</td>
              <td align="left">220924805 (1976-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">098</td>
              <td align="left">00 00 00 06</td>
              <td align="left">correction</td>
              <td align="left">6</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[6]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">102</td>
              <td align="left">0f 0c 3f 06</td>
              <td align="left">occurrence</td>
              <td align="left">252460806 (1977-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">106</td>
              <td align="left">00 00 00 07</td>
              <td align="left">correction</td>
              <td align="left">7</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[7]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">110</td>
              <td align="left">10 ed 72 87</td>
              <td align="left">occurrence</td>
              <td align="left">283996807 (1978-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">114</td>
              <td align="left">00 00 00 08</td>
              <td align="left">correction</td>
              <td align="left">8</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[8]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">118</td>
              <td align="left">12 ce a6 08</td>
              <td align="left">occurrence</td>
              <td align="left">315532808 (1979-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">122</td>
              <td align="left">00 00 00 09</td>
              <td align="left">correction</td>
              <td align="left">9</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[9]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">126</td>
              <td align="left">15 9f ca 89</td>
              <td align="left">occurrence</td>
              <td align="left">362793609 (1981-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">130</td>
              <td align="left">00 00 00 0a</td>
              <td align="left">correction</td>
              <td align="left">10</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[10]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">134</td>
              <td align="left">17 80 fe 0a</td>
              <td align="left">occurrence</td>
              <td align="left">394329610 (1982-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">138</td>
              <td align="left">00 00 00 0b</td>
              <td align="left">correction</td>
              <td align="left">11</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[11]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">142</td>
              <td align="left">19 62 31 8b</td>
              <td align="left">occurrence</td>
              <td align="left">425865611 (1983-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">146</td>
              <td align="left">00 00 00 0c</td>
              <td align="left">correction</td>
              <td align="left">12</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[12]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">150</td>
              <td align="left">1d 25 ea 0c</td>
              <td align="left">occurrence</td>
              <td align="left">489024012 (1985-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">154</td>
              <td align="left">00 00 00 0d</td>
              <td align="left">correction</td>
              <td align="left">13</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[13]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">158</td>
              <td align="left">21 da e5 0d</td>
              <td align="left">occurrence</td>
              <td align="left">567993613 (1987-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">162</td>
              <td align="left">00 00 00 0e</td>
              <td align="left">correction</td>
              <td align="left">14</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[14]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">166</td>
              <td align="left">25 9e 9d 8e</td>
              <td align="left">occurrence</td>
              <td align="left">631152014 (1989-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">170</td>
              <td align="left">00 00 00 0f</td>
              <td align="left">correction</td>
              <td align="left">15</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[15]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">174</td>
              <td align="left">27 7f d1 0f</td>
              <td align="left">occurrence</td>
              <td align="left">662688015 (1990-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">178</td>
              <td align="left">00 00 00 10</td>
              <td align="left">correction</td>
              <td align="left">16</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[16]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">182</td>
              <td align="left">2a 50 f5 90</td>
              <td align="left">occurrence</td>
              <td align="left">709948816 (1992-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">186</td>
              <td align="left">00 00 00 11</td>
              <td align="left">correction</td>
              <td align="left">17</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[17]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">190</td>
              <td align="left">2c 32 29 11</td>
              <td align="left">occurrence</td>
              <td align="left">741484817 (1993-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">194</td>
              <td align="left">00 00 00 12</td>
              <td align="left">correction</td>
              <td align="left">18</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[18]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">198</td>
              <td align="left">2e 13 5c 92</td>
              <td align="left">occurrence</td>
              <td align="left">773020818 (1994-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">202</td>
              <td align="left">00 00 00 13</td>
              <td align="left">correction</td>
              <td align="left">19</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[19]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">206</td>
              <td align="left">30 e7 24 13</td>
              <td align="left">occurrence</td>
              <td align="left">820454419 (1995-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">210</td>
              <td align="left">00 00 00 14</td>
              <td align="left">correction</td>
              <td align="left">20</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[20]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">214</td>
              <td align="left">33 b8 48 94</td>
              <td align="left">occurrence</td>
              <td align="left">867715220 (1997-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">218</td>
              <td align="left">00 00 00 15</td>
              <td align="left">correction</td>
              <td align="left">21</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[21]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">222</td>
              <td align="left">36 8c 10 15</td>
              <td align="left">occurrence</td>
              <td align="left">915148821 (1998-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">226</td>
              <td align="left">00 00 00 16</td>
              <td align="left">correction</td>
              <td align="left">22</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[22]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">230</td>
              <td align="left">43 b7 1b 96</td>
              <td align="left">occurrence</td>
              <td align="left">1136073622 (2005-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">234</td>
              <td align="left">00 00 00 17</td>
              <td align="left">correction</td>
              <td align="left">23</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[23]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">238</td>
              <td align="left">49 5c 07 97</td>
              <td align="left">occurrence</td>
              <td align="left">1230768023 (2008-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">242</td>
              <td align="left">00 00 00 18</td>
              <td align="left">correction</td>
              <td align="left">24</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[24]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">246</td>
              <td align="left">4f ef 93 18</td>
              <td align="left">occurrence</td>
              <td align="left">1341100824 (2012-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">250</td>
              <td align="left">00 00 00 19</td>
              <td align="left">correction</td>
              <td align="left">25</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[25]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">254</td>
              <td align="left">55 93 2d 99</td>
              <td align="left">occurrence</td>
              <td align="left">1435708825 (2015-06-30T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">258</td>
              <td align="left">00 00 00 1a</td>
              <td align="left">correction</td>
              <td align="left">26</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[26]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">262</td>
              <td align="left">58 68 46 9a</td>
              <td align="left">occurrence</td>
              <td align="left">1483228826 (2016-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">266</td>
              <td align="left">00 00 00 1b</td>
              <td align="left">correction</td>
              <td align="left">27</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">270</td>
              <td align="left">00</td>
              <td align="left">standard/wall[0]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">271</td>
              <td align="left">00</td>
              <td align="left">UT/local[0]</td>
              <td align="left">0 (local)</td>
            </tr>
          </tbody>
        </table>

        <t>To determine TAI corresponding
        to 2000-01-01T00:00:00Z (UNIX&nbsp;time&nbsp;=&nbsp;946684800),
        the following procedure would be followed:</t>

        <ol spacing="normal" type="1">
          <li>Find the latest leap-second occurrence prior to the time of
          interest (leapsecond[21]) and note the correction value
          (LEAPCORR&nbsp;=&nbsp;22).</li>

          <li>Add LEAPCORR + 10 to the time of interest to yield TAI of
          2000-01-01T00:00:32.</li>
        </ol>
      </section>

      <section numbered="true" toc="default">
        <name>Version 2 File Representing Pacific/Honolulu</name>

        <table align="center">
          <thead>
            <tr>
              <th align="left">File Offset</th>
              <th align="left">Hexadecimal Octets</th>
              <th align="left">Record Name / Field Name</th>
              <th align="left">Field Value</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">000</td>
              <td align="left">54 5a 69 66</td>
              <td align="left">magic</td>
              <td align="left">"TZif"</td>
            </tr>
            <tr>
              <td align="left">004</td>
              <td align="left">32</td>
              <td align="left">version</td>
              <td align="left">'2' (2)</td>
            </tr>
            <tr>
              <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"></td>
              <td colspan="2" align="left"></td>
            </tr>
            <tr>
              <td align="left">020</td>
              <td align="left">00 00 00 06</td>
              <td align="left">isutcnt</td>
              <td align="left">6</td>
            </tr>
            <tr>
              <td align="left">024</td>
              <td align="left">00 00 00 06</td>
              <td align="left">isstdcnt</td>
              <td align="left">6</td>
            </tr>
            <tr>
              <td align="left">028</td>
              <td align="left">00 00 00 00</td>
              <td align="left">leapcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">032</td>
              <td align="left">00 00 00 07</td>
              <td align="left">timecnt</td>
              <td align="left">7</td>
            </tr>
            <tr>
              <td align="left">036</td>
              <td align="left">00 00 00 06</td>
              <td align="left">typecnt</td>
              <td align="left">6</td>
            </tr>
            <tr>
              <td align="left">040</td>
              <td align="left">00 00 00 14</td>
              <td align="left">charcnt</td>
              <td align="left">20</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">044</td>
              <td align="left">80 00 00 00</td>
              <td align="left">trans time[0]</td>
              <td align="left">-2147483648 (1901-12-13T20:45:52Z)</td>
            </tr>
            <tr>
              <td align="left">048</td>
              <td align="left">bb 05 43 48</td>
              <td align="left">trans time[1]</td>
              <td align="left">-1157283000 (1933-04-30T12:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">052</td>
              <td align="left">bb 21 71 58</td>
              <td align="left">trans time[2]</td>
              <td align="left">-1155436200 (1933-05-21T21:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">056</td>
              <td align="left">cb 89 3d c8</td>
              <td align="left">trans time[3]</td>
              <td align="left">-880198200 (1942-02-09T12:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">060</td>
              <td align="left">d2 23 f4 70</td>
              <td align="left">trans time[4]</td>
              <td align="left">-769395600 (1945-08-14T23:00:00Z)</td>
            </tr>
            <tr>
              <td align="left">064</td>
              <td align="left">d2 61 49 38</td>
              <td align="left">trans time[5]</td>
              <td align="left">-765376200 (1945-09-30T11:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">068</td>
              <td align="left">d5 8d 73 48</td>
              <td align="left">trans time[6]</td>
              <td align="left">-712150200 (1947-06-08T12:30:00Z)</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">072</td>
              <td align="left">01</td>
              <td align="left">trans type[0]</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">073</td>
              <td align="left">02</td>
              <td align="left">trans type[1]</td>
              <td align="left">2</td>
            </tr>
            <tr>
              <td align="left">074</td>
              <td align="left">01</td>
              <td align="left">trans type[2]</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">075</td>
              <td align="left">03</td>
              <td align="left">trans type[3]</td>
              <td align="left">3</td>
            </tr>
            <tr>
              <td align="left">076</td>
              <td align="left">04</td>
              <td align="left">trans type[4]</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td align="left">077</td>
              <td align="left">01</td>
              <td align="left">trans type[5]</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">078</td>
              <td align="left">05</td>
              <td align="left">trans type[6]</td>
              <td align="left">5</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">079</td>
              <td align="left">ff ff 6c 02</td>
              <td align="left">utoff</td>
              <td align="left">-37886 (-10:31:26)</td>
            </tr>
            <tr>
              <td align="left">083</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">084</td>
              <td align="left">00</td>
              <td align="left">desigidx</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[1]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">085</td>
              <td align="left">ff ff 6c 58</td>
              <td align="left">utoff</td>
              <td align="left">-37800 (-10:30)</td>
            </tr>
            <tr>
              <td align="left">089</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">090</td>
              <td align="left">04</td>
              <td align="left">desigidx</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[2]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">091</td>
              <td align="left">ff ff 7a 68</td>
              <td align="left">utoff</td>
              <td align="left">-34200 (-09:30)</td>
            </tr>
            <tr>
              <td align="left">095</td>
              <td align="left">01</td>
              <td align="left">isdst</td>
              <td align="left">1 (yes)</td>
            </tr>
            <tr>
              <td align="left">096</td>
              <td align="left">08</td>
              <td align="left">desigidx</td>
              <td align="left">8</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[3]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">097</td>
              <td align="left">ff ff 7a 68</td>
              <td align="left">utoff</td>
              <td align="left">-34200 (-09:30)</td>
            </tr>
            <tr>
              <td align="left">101</td>
              <td align="left">01</td>
              <td align="left">isdst</td>
              <td align="left">1 (yes)</td>
            </tr>
            <tr>
              <td align="left">102</td>
              <td align="left">0c</td>
              <td align="left">desigidx</td>
              <td align="left">12</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[4]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">103</td>
              <td align="left">ff ff 7a 68</td>
              <td align="left">utoff</td>
              <td align="left">-34200 (-09:30)</td>
            </tr>
            <tr>
              <td align="left">107</td>
              <td align="left">01</td>
              <td align="left">isdst</td>
              <td align="left">1 (yes)</td>
            </tr>
            <tr>
              <td align="left">108</td>
              <td align="left">10</td>
              <td align="left">desigidx</td>
              <td align="left">16</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[5]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">109</td>
              <td align="left">ff ff 73 60</td>
              <td align="left">utoff</td>
              <td align="left">-36000 (-10:00)</td>
            </tr>
            <tr>
              <td align="left">113</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">114</td>
              <td align="left">04</td>
              <td align="left">desigidx</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">115</td>
              <td align="left">4c 4d 54 00</td>
              <td align="left">designations[0]</td>
              <td align="left">"LMT\0"</td>
            </tr>
            <tr>
              <td align="left">119</td>
              <td align="left">48 53 54 00</td>
              <td align="left">designations[4]</td>
              <td align="left">"HST\0"</td>
            </tr>
            <tr>
              <td align="left">123</td>
              <td align="left">48 44 54 00</td>
              <td align="left">designations[8]</td>
              <td align="left">"HDT\0"</td>
            </tr>
            <tr>
              <td align="left">127</td>
              <td align="left">48 57 54 00</td>
              <td align="left">designations[12]</td>
              <td align="left">"HWT\0"</td>
            </tr>
            <tr>
              <td align="left">131</td>
              <td align="left">48 50 54 00</td>
              <td align="left">designations[16]</td>
              <td align="left">"HPT\0"</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">135</td>
              <td align="left">00</td>
              <td align="left">standard/wall[0]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td align="left">136</td>
              <td align="left">00</td>
              <td align="left">standard/wall[1]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td align="left">137</td>
              <td align="left">00</td>
              <td align="left">standard/wall[2]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td align="left">138</td>
              <td align="left">00</td>
              <td align="left">standard/wall[3]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td align="left">139</td>
              <td align="left">01</td>
              <td align="left">standard/wall[4]</td>
              <td align="left">1 (standard)</td>
            </tr>
            <tr>
              <td align="left">140</td>
              <td align="left">00</td>
              <td align="left">standard/wall[5]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">141</td>
              <td align="left">00</td>
              <td align="left">UT/local[0]</td>
              <td align="left">0 (local)</td>
            </tr>
            <tr>
              <td align="left">142</td>
              <td align="left">00</td>
              <td align="left">UT/local[1]</td>
              <td align="left">0 (local)</td>
            </tr>
            <tr>
              <td align="left">143</td>
              <td align="left">00</td>
              <td align="left">UT/local[2]</td>
              <td align="left">0 (local)</td>
            </tr>
            <tr>
              <td align="left">144</td>
              <td align="left">00</td>
              <td align="left">UT/local[3]</td>
              <td align="left">0 (local)</td>
            </tr>
            <tr>
              <td align="left">145</td>
              <td align="left">01</td>
              <td align="left">UT/local[4]</td>
              <td align="left">1 (UT)</td>
            </tr>
            <tr>
              <td align="left">146</td>
              <td align="left">00</td>
              <td align="left">UT/local[5]</td>
              <td align="left">0 (local)</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">147</td>
              <td align="left">54 5a 69 66</td>
              <td align="left">magic</td>
              <td align="left">"TZif"</td>
            </tr>
            <tr>
              <td align="left">151</td>
              <td align="left">32</td>
              <td align="left">version</td>
              <td align="left">'2' (2)</td>
            </tr>
            <tr>
              <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"></td>
              <td colspan="2" align="left"></td>
            </tr>
            <tr>
              <td align="left">167</td>
              <td align="left">00 00 00 06</td>
              <td align="left">isutcnt</td>
              <td align="left">6</td>
            </tr>
            <tr>
              <td align="left">171</td>
              <td align="left">00 00 00 06</td>
              <td align="left">isstdcnt</td>
              <td align="left">6</td>
            </tr>
            <tr>
              <td align="left">175</td>
              <td align="left">00 00 00 00</td>
              <td align="left">leapcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">179</td>
              <td align="left">00 00 00 07</td>
              <td align="left">timecnt</td>
              <td align="left">7</td>
            </tr>
            <tr>
              <td align="left">183</td>
              <td align="left">00 00 00 06</td>
              <td align="left">typecnt</td>
              <td align="left">6</td>
            </tr>
            <tr>
              <td align="left">187</td>
              <td align="left">00 00 00 14</td>
              <td align="left">charcnt</td>
              <td align="left">20</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">191</td>
              <td align="left">ff ff ff ff 74 e0 70 be</td>
              <td align="left">trans time[0]</td>
              <td align="left">-2334101314 (1896-01-13T22:31:26Z)</td>
            </tr>
            <tr>
              <td align="left">199</td>
              <td align="left">ff ff ff ff bb 05 43 48</td>
              <td align="left">trans time[1]</td>
              <td align="left">-1157283000 (1933-04-30T12:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">207</td>
              <td align="left">ff ff ff ff bb 21 71 58</td>
              <td align="left">trans time[2]</td>
              <td align="left">-1155436200 (1933-05-21T21:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">215</td>
              <td align="left">ff ff ff ff cb 89 3d c8</td>
              <td align="left">trans time[3]</td>
              <td align="left">-880198200 (1942-02-09T12:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">223</td>
              <td align="left">ff ff ff ff d2 23 f4 70</td>
              <td align="left">trans time[4]</td>
              <td align="left">-769395600 (1945-08-14T23:00:00Z)</td>
            </tr>
            <tr>
              <td align="left">231</td>
              <td align="left">ff ff ff ff d2 61 49 38</td>
              <td align="left">trans time[5]</td>
              <td align="left">-765376200 (1945-09-30T11:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">239</td>
              <td align="left">ff ff ff ff d5 8d 73 48</td>
              <td align="left">trans time[6]</td>
              <td align="left">-712150200 (1947-06-08T12:30:00Z)</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">247</td>
              <td align="left">01</td>
              <td align="left">trans type[0]</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">248</td>
              <td align="left">02</td>
              <td align="left">trans type[1]</td>
              <td align="left">2</td>
            </tr>
            <tr>
              <td align="left">249</td>
              <td align="left">01</td>
              <td align="left">trans type[2]</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">250</td>
              <td align="left">03</td>
              <td align="left">trans type[3]</td>
              <td align="left">3</td>
            </tr>
            <tr>
              <td align="left">251</td>
              <td align="left">04</td>
              <td align="left">trans type[4]</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td align="left">252</td>
              <td align="left">01</td>
              <td align="left">trans type[5]</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">253</td>
              <td align="left">05</td>
              <td align="left">trans type[6]</td>
              <td align="left">5</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">254</td>
              <td align="left">ff ff 6c 02</td>
              <td align="left">utoff</td>
              <td align="left">-37886 (-10:31:26)</td>
            </tr>
            <tr>
              <td align="left">258</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">259</td>
              <td align="left">00</td>
              <td align="left">desigidx</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[1]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">260</td>
              <td align="left">ff ff 6c 58</td>
              <td align="left">utoff</td>
              <td align="left">-37800 (-10:30)</td>
            </tr>
            <tr>
              <td align="left">264</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">265</td>
              <td align="left">04</td>
              <td align="left">desigidx</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[2]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">266</td>
              <td align="left">ff ff 7a 68</td>
              <td align="left">utoff</td>
              <td align="left">-34200 (-09:30)</td>
            </tr>
            <tr>
              <td align="left">270</td>
              <td align="left">01</td>
              <td align="left">isdst</td>
              <td align="left">1 (yes)</td>
            </tr>
            <tr>
              <td align="left">271</td>
              <td align="left">08</td>
              <td align="left">desigidx</td>
              <td align="left">8</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[3]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">272</td>
              <td align="left">ff ff 7a 68</td>
              <td align="left">utoff</td>
              <td align="left">-34200 (-09:30)</td>
            </tr>
            <tr>
              <td align="left">276</td>
              <td align="left">01</td>
              <td align="left">isdst</td>
              <td align="left">1 (yes)</td>
            </tr>
            <tr>
              <td align="left">277</td>
              <td align="left">0c</td>
              <td align="left">desigidx</td>
              <td align="left">12</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[4]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">278</td>
              <td align="left">ff ff 7a 68</td>
              <td align="left">utoff</td>
              <td align="left">-34200 (-09:30)</td>
            </tr>
            <tr>
              <td align="left">282</td>
              <td align="left">01</td>
              <td align="left">isdst</td>
              <td align="left">1 (yes)</td>
            </tr>
            <tr>
              <td align="left">283</td>
              <td align="left">10</td>
              <td align="left">desigidx</td>
              <td align="left">16</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[5]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">284</td>
              <td align="left">ff ff 73 60</td>
              <td align="left">utoff</td>
              <td align="left">-36000 (-10:00)</td>
            </tr>
            <tr>
              <td align="left">288</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">289</td>
              <td align="left">04</td>
              <td align="left">desigidx</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">290</td>
              <td align="left">4c 4d 54 00</td>
              <td align="left">designations[0]</td>
              <td align="left">"LMT\0"</td>
            </tr>
            <tr>
              <td align="left">294</td>
              <td align="left">48 53 54 00</td>
              <td align="left">designations[4]</td>
              <td align="left">"HST\0"</td>
            </tr>
            <tr>
              <td align="left">298</td>
              <td align="left">48 44 54 00</td>
              <td align="left">designations[8]</td>
              <td align="left">"HDT\0"</td>
            </tr>
            <tr>
              <td align="left">302</td>
              <td align="left">48 57 54 00</td>
              <td align="left">designations[12]</td>
              <td align="left">"HWT\0"</td>
            </tr>
            <tr>
              <td align="left">306</td>
              <td align="left">48 50 54 00</td>
              <td align="left">designations[16]</td>
              <td align="left">"HPT\0"</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">310</td>
              <td align="left">00</td>
              <td align="left">standard/wall[0]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td align="left">311</td>
              <td align="left">00</td>
              <td align="left">standard/wall[1]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td align="left">312</td>
              <td align="left">00</td>
              <td align="left">standard/wall[2]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td align="left">313</td>
              <td align="left">00</td>
              <td align="left">standard/wall[3]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td align="left">314</td>
              <td align="left">01</td>
              <td align="left">standard/wall[4]</td>
              <td align="left">1 (standard)</td>
            </tr>
            <tr>
              <td align="left">315</td>
              <td align="left">00</td>
              <td align="left">standard/wall[5]</td>
              <td align="left">0 (wall)</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">316</td>
              <td align="left">00</td>
              <td align="left">UT/local[0]</td>
              <td align="left">0 (local)</td>
            </tr>
            <tr>
              <td align="left">317</td>
              <td align="left">00</td>
              <td align="left">UT/local[1]</td>
              <td align="left">0 (local)</td>
            </tr>
            <tr>
              <td align="left">318</td>
              <td align="left">00</td>
              <td align="left">UT/local[2]</td>
              <td align="left">0 (local)</td>
            </tr>
            <tr>
              <td align="left">319</td>
              <td align="left">00</td>
              <td align="left">UT/local[3]</td>
              <td align="left">0 (local)</td>
            </tr>
            <tr>
              <td align="left">320</td>
              <td align="left">01</td>
              <td align="left">UT/local[4]</td>
              <td align="left">1 (UT)</td>
            </tr>
            <tr>
              <td align="left">321</td>
              <td align="left">00</td>
              <td align="left">UT/local[5]</td>
              <td align="left">0 (local)</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">322</td>
              <td align="left">0a</td>
              <td align="left">NL</td>
              <td align="left">'\n'</td>
            </tr>
            <tr>
              <td align="left">323</td>
              <td align="left">48 53 54 31 30</td>
              <td align="left">TZ string</td>
              <td align="left">"HST10"</td>
            </tr>
            <tr>
              <td align="left">328</td>
              <td align="left">0a</td>
              <td align="left">NL</td>
              <td align="left">'\n'</td>
            </tr>
          </tbody>
        </table>

        <t>To determine the local time in this time zone corresponding
        to 1933-05-04T12:00:00Z (UNIX time = -1156939200), the
        following procedure would be followed:</t>

        <ol spacing="normal" type="1">
          <li>Find the latest time transition prior to the time of
          interest (trans time[1]).</li>

          <li>Reference the corresponding transition type (trans
          type[1]) to determine the local time type index (2).</li>

          <li>Reference the corresponding local time type
          (localtimetype[2]) to determine the offset from UTC
          (-09:30), the daylight saving indicator (1 = yes), and the
          index into the time zone designation strings (8).</li>

          <li>Look up the corresponding time zone designation string
          (designations[8] = "HDT").</li>

          <li>Add the UTC offset to the time of interest to yield a
          local daylight saving time of 1933-05-04T02:30:00-09:30 (HDT).</li>
        </ol>

        <t>To determine the local time in this time zone corresponding
        to 2019-01-01T00:00:00Z (UNIX time = 1546300800), the following
        procedure would be followed:</t>

        <ol spacing="normal" type="1">
          <li>Find the latest time transition prior to the time of
          interest (there is no such transition).</li>

          <li>Look up the TZ string in the footer ("HST10"), which
          indicates that the time zone designation is "HST" year-round, year-round and
          the offset to UTC is 10:00.</li>

          <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>
        </ol>
      </section>

      <section anchor="v2truncated" numbered="true" toc="default">
        <name>Truncated Version 2 File Representing Pacific/Johnston</name>

        <t>The following TZif file has been truncated to end on
        2004-06-161T00:00:00Z (the atoll was abandoned sometime on
        2004-06-15).</t>

        <t>In this example:</t>

        <ul spacing="normal">
          <li>The version 1 header contains only the required
          minimum data, which will be ignored by readers.</li>

          <li>The version 2 header leverages the fact that that, by specifying
          'isutcnt' and 'isstdcnt' as zero, all transition times
          associated with local time types are assumed to be specified
          as local wall-clock time
          (see the definitions of UT/local indicators
          and standard/wall indicators in
          <xref target="data" format="default"/>).</li>

          <li>The time type of the last transition has designation "-00",
          indicating that local time is unspecified.</li>

          <li>The TZ string is empty, indicating that there are no
          known future transitions.</li>
        </ul>

        <table align="center">
          <thead>
            <tr>
              <th align="left">File Offset</th>
              <th align="left">Hexadecimal Octets</th>
              <th align="left">Record Name / Field Name</th>
              <th align="left">Field Value</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">000</td>
              <td align="left">54 5a 69 66</td>
              <td align="left">magic</td>
              <td align="left">"TZif"</td>
            </tr>
            <tr>
              <td align="left">004</td>
              <td align="left">32</td>
              <td align="left">version</td>
              <td align="left">'2' (2)</td>
            </tr>
            <tr>
              <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"></td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">020</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isutcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">024</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isstdcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">028</td>
              <td align="left">00 00 00 00</td>
              <td align="left">leapcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">032</td>
              <td align="left">00 00 00 00</td>
              <td align="left">timecnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">036</td>
              <td align="left">00 00 00 01</td>
              <td align="left">typecnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">040</td>
              <td align="left">00 00 00 01</td>
              <td align="left">charcnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">044</td>
              <td align="left">00 00 00 00</td>
              <td align="left">utoff</td>
              <td align="left">0 (+00:00)</td>
            </tr>
            <tr>
              <td align="left">048</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">049</td>
              <td align="left">00</td>
              <td align="left">desigidx</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">050</td>
              <td align="left">00</td>
              <td align="left">designations[0]</td>
              <td align="left">"\0"</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">051</td>
              <td align="left">54 5a 69 66</td>
              <td align="left">magic</td>
              <td align="left">"TZif"</td>
            </tr>
            <tr>
              <td align="left">055</td>
              <td align="left">32</td>
              <td align="left">version</td>
              <td align="left">'2' (2)</td>
            </tr>
            <tr>
              <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"></td>
              <td colspan="2" align="left"></td>
            </tr>
            <tr>
              <td align="left">071</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isutcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">075</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isstdcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">079</td>
              <td align="left">00 00 00 00</td>
              <td align="left">leapcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">083</td>
              <td align="left">00 00 00 08</td>
              <td align="left">timecnt</td>
              <td align="left">8</td>
            </tr>
            <tr>
              <td align="left">087</td>
              <td align="left">00 00 00 07</td>
              <td align="left">typecnt</td>
              <td align="left">7</td>
            </tr>
            <tr>
              <td align="left">091</td>
              <td align="left">00 00 00 18</td>
              <td align="left">charcnt</td>
              <td align="left">24</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">095</td>
              <td align="left">ff ff ff ff 74 e0 70 be</td>
              <td align="left">trans time[0]</td>
              <td align="left">-2334101314 (1896-01-13T22:31:26Z)</td>
            </tr>
            <tr>
              <td align="left">103</td>
              <td align="left">ff ff ff ff bb 05 43 48</td>
              <td align="left">trans time[1]</td>
              <td align="left">-1157283000 (1933-04-30T12:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">111</td>
              <td align="left">ff ff ff ff bb 21 71 58</td>
              <td align="left">trans time[2]</td>
              <td align="left">-1155436200 (1933-05-21T21:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">119</td>
              <td align="left">ff ff ff ff cb 89 3d c8</td>
              <td align="left">trans time[3]</td>
              <td align="left">-880198200 (1942-02-09T12:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">127</td>
              <td align="left">ff ff ff ff d2 23 f4 70</td>
              <td align="left">trans time[4]</td>
              <td align="left">-769395600 (1945-08-14T23:00:00Z)</td>
            </tr>
            <tr>
              <td align="left">135</td>
              <td align="left">ff ff ff ff d2 61 49 38</td>
              <td align="left">trans time[5]</td>
              <td align="left">-765376200 (1945-09-30T11:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">143</td>
              <td align="left">ff ff ff ff d5 8d 73 48</td>
              <td align="left">trans time[6]</td>
              <td align="left">-712150200 (1947-06-08T12:30:00Z)</td>
            </tr>
            <tr>
              <td align="left">151</td>
              <td align="left">00 00 00 00 40 cf 8d 80</td>
              <td align="left">trans time[7]</td>
              <td align="left">1087344000 (2004-06-16T00:00:00Z)</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">159</td>
              <td align="left">02</td>
              <td align="left">trans type[0]</td>
              <td align="left">2</td>
            </tr>
            <tr>
              <td align="left">160</td>
              <td align="left">03</td>
              <td align="left">trans type[1]</td>
              <td align="left">3</td>
            </tr>
            <tr>
              <td align="left">161</td>
              <td align="left">02</td>
              <td align="left">trans type[2]</td>
              <td align="left">2</td>
            </tr>
            <tr>
              <td align="left">162</td>
              <td align="left">04</td>
              <td align="left">trans type[3]</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td align="left">163</td>
              <td align="left">05</td>
              <td align="left">trans type[4]</td>
              <td align="left">5</td>
            </tr>
            <tr>
              <td align="left">164</td>
              <td align="left">02</td>
              <td align="left">trans type[5]</td>
              <td align="left">2</td>
            </tr>
            <tr>
              <td align="left">165</td>
              <td align="left">06</td>
              <td align="left">trans type[6]</td>
              <td align="left">6</td>
            </tr>
            <tr>
              <td align="left">166</td>
              <td align="left">01</td>
              <td align="left">trans type[7]</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">167</td>
              <td align="left">ff ff 6c 02</td>
              <td align="left">utoff</td>
              <td align="left">-37886 (-10:31:26)</td>
            </tr>
            <tr>
              <td align="left">171</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">172</td>
              <td align="left">04</td>
              <td align="left">desigidx</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[1]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">173</td>
              <td align="left">00 00 00 00</td>
              <td align="left">utoff</td>
              <td align="left">0 (+00:00)</td>
            </tr>
            <tr>
              <td align="left">177</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">178</td>
              <td align="left">00</td>
              <td align="left">desigidx</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[2]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">179</td>
              <td align="left">ff ff 6c 58</td>
              <td align="left">utoff</td>
              <td align="left">-37800 (-10:30)</td>
            </tr>
            <tr>
              <td align="left">183</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">184</td>
              <td align="left">08</td>
              <td align="left">desigidx</td>
              <td align="left">8</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[3]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">185</td>
              <td align="left">ff ff 7a 68</td>
              <td align="left">utoff</td>
              <td align="left">-34200 (-09:30)</td>
            </tr>
            <tr>
              <td align="left">189</td>
              <td align="left">01</td>
              <td align="left">isdst</td>
              <td align="left">1 (yes)</td>
            </tr>
            <tr>
              <td align="left">190</td>
              <td align="left">0c</td>
              <td align="left">desigidx</td>
              <td align="left">12</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[4]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">191</td>
              <td align="left">ff ff 7a 68</td>
              <td align="left">utoff</td>
              <td align="left">-34200 (-09:30)</td>
            </tr>
            <tr>
              <td align="left">195</td>
              <td align="left">01</td>
              <td align="left">isdst</td>
              <td align="left">1 (yes)</td>
            </tr>
            <tr>
              <td align="left">196</td>
              <td align="left">10</td>
              <td align="left">desigidx</td>
              <td align="left">16</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[5]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">197</td>
              <td align="left">ff ff 7a 68</td>
              <td align="left">utoff</td>
              <td align="left">-34200 (-09:30)</td>
            </tr>
            <tr>
              <td align="left">201</td>
              <td align="left">01</td>
              <td align="left">isdst</td>
              <td align="left">1 (yes)</td>
            </tr>
            <tr>
              <td align="left">202</td>
              <td align="left">14</td>
              <td align="left">desigidx</td>
              <td align="left">20</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[6]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">203</td>
              <td align="left">ff ff 73 60</td>
              <td align="left">utoff</td>
              <td align="left">-36000 (-10:00)</td>
            </tr>
            <tr>
              <td align="left">207</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">208</td>
              <td align="left">08</td>
              <td align="left">desigidx</td>
              <td align="left">8</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">209</td>
              <td align="left">2d 30 30 00</td>
              <td align="left">designations[0]</td>
              <td align="left">"-00\0"</td>
            </tr>
            <tr>
              <td align="left">213</td>
              <td align="left">4c 4d 54 00</td>
              <td align="left">designations[4]</td>
              <td align="left">"LMT\0"</td>
            </tr>
            <tr>
              <td align="left">217</td>
              <td align="left">48 53 54 00</td>
              <td align="left">designations[8]</td>
              <td align="left">"HST\0"</td>
            </tr>
            <tr>
              <td align="left">221</td>
              <td align="left">48 44 54 00</td>
              <td align="left">designations[12]</td>
              <td align="left">"HDT\0"</td>
            </tr>
            <tr>
              <td align="left">225</td>
              <td align="left">48 57 54 00</td>
              <td align="left">designations[16]</td>
              <td align="left">"HWT\0"</td>
            </tr>
            <tr>
              <td align="left">229</td>
              <td align="left">48 50 54 00</td>
              <td align="left">designations[20]</td>
              <td align="left">"HPT\0"</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">233</td>
              <td align="left">0a</td>
              <td align="left">NL</td>
              <td align="left">'\n'</td>
            </tr>
            <tr>
              <td align="left">234</td>
              <td align="left"></td>
              <td align="left">TZ string</td>
              <td align="left">""</td>
            </tr>
            <tr>
              <td align="left">234</td>
              <td align="left">0a</td>
              <td align="left">NL</td>
              <td align="left">'\n'</td>
            </tr>
          </tbody>
        </table>
      </section>

      <section anchor="v3example" numbered="true" toc="default">
        <name>Truncated Version 3 File Representing Asia/Jerusalem</name>

        <t>The following TZif file has been truncated to start on
        2038-01-01T00:00:00Z.</t>

        <t>In this example:</t>

        <ul spacing="normal">
          <li>The start time value can not cannot be represented using 32
          bits, so the version 1 header contains only the required
          minimum data, which will be ignored by readers.</li>

          <li>The version 3 header leverages the fact that that, by specifying
          'isutcnt' and 'isstdcnt' as zero, all transition times
          associated with local time types are assumed to be specified
          as local wall-clock time
          (see the definitions of UT/local indicators
          and standard/wall indicators in
          <xref target="data" format="default"/>).</li>

          <li>Time type 0 has designation "-00", indicating that local
          time is unspecified prior to the truncation time.</li>

          <li>The TZ string value has been line-wrapped for
          presentation purposes only.</li>
        </ul>

        <table align="center">
          <thead>
            <tr>
              <th align="left">File Offset</th>
              <th align="left">Hexadecimal Octets</th>
              <th align="left">Record Name / Field Name</th>
              <th align="left">Field Value</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">000</td>
              <td align="left">54 5a 69 66</td>
              <td align="left">magic</td>
              <td align="left">"TZif"</td>
            </tr>
            <tr>
              <td align="left">004</td>
              <td align="left">33</td>
              <td align="left">version</td>
              <td align="left">'3' (3)</td>
            </tr>
            <tr>
              <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"></td>
              <td colspan="2" align="left"></td>
            </tr>
            <tr>
              <td align="left">020</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isutcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">024</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isstdcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">028</td>
              <td align="left">00 00 00 00</td>
              <td align="left">leapcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">032</td>
              <td align="left">00 00 00 00</td>
              <td align="left">timecnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">036</td>
              <td align="left">00 00 00 01</td>
              <td align="left">typecnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">040</td>
              <td align="left">00 00 00 01</td>
              <td align="left">charcnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">044</td>
              <td align="left">00 00 00 00</td>
              <td align="left">utoff</td>
              <td align="left">0 (+00:00)</td>
            </tr>
            <tr>
              <td align="left">048</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">049</td>
              <td align="left">00</td>
              <td align="left">desigidx</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">050</td>
              <td align="left">00</td>
              <td align="left">designations[0]</td>
              <td align="left">"\0"</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">051</td>
              <td align="left">54 5a 69 66</td>
              <td align="left">magic</td>
              <td align="left">"TZif"</td>
            </tr>
            <tr>
              <td align="left">055</td>
              <td align="left">33</td>
              <td align="left">version</td>
              <td align="left">'3' (3)</td>
            </tr>
            <tr>
              <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"></td>
              <td colspan="2" align="left"></td>
            </tr>
            <tr>
              <td align="left">071</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isutcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">075</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isstdcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">079</td>
              <td align="left">00 00 00 00</td>
              <td align="left">leapcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">083</td>
              <td align="left">00 00 00 01</td>
              <td align="left">timecnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">087</td>
              <td align="left">00 00 00 02</td>
              <td align="left">typecnt</td>
              <td align="left">2</td>
            </tr>
            <tr>
              <td align="left">091</td>
              <td align="left">00 00 00 08</td>
              <td align="left">charcnt</td>
              <td align="left">8</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">095</td>
              <td align="left">00 00 00 00 7f e8 17 80</td>
              <td align="left">trans time[0]</td>
              <td align="left">2145916800 (2038-01-01T00:00:00Z)</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">103</td>
              <td align="left">01</td>
              <td align="left">trans type[0]</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">104</td>
              <td align="left">00 00 00 00</td>
              <td align="left">utoff</td>
              <td align="left">0 (+00:00)</td>
            </tr>
            <tr>
              <td align="left">108</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">109</td>
              <td align="left">00</td>
              <td align="left">desigidx</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[1]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">110</td>
              <td align="left">00 00 1c 20</td>
              <td align="left">utoff</td>
              <td align="left">7200 (+02:00)</td>
            </tr>
            <tr>
              <td align="left">114</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">115</td>
              <td align="left">04</td>
              <td align="left">desigidx</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">116</td>
              <td align="left">2d 30 30 00</td>
              <td align="left">designations[0]</td>
              <td align="left">"-00\0"</td>
            </tr>
            <tr>
              <td align="left">120</td>
              <td align="left">49 53 54 00</td>
              <td align="left">designations[4]</td>
              <td align="left">"IST\0"</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">124</td>
              <td align="left">0a</td>
              <td align="left">NL</td>
              <td align="left">'\n'</td>
            </tr>
            <tr>
              <td align="left">125</td>
              <td align="left">49 53 54 2d 32 49 44 54 2c 4d 33 2e 34
              2e 34 2f 32 36 2c 4d 31 30 2e 35 2e 30</td>
              <td align="left">TZ string</td>
              <td align="left">"IST-2IDT,M3.4.4/26,M10.5.0"</td>
            </tr>
            <tr>
              <td align="left">151</td>
              <td align="left">0a</td>
              <td align="left">NL</td>
              <td align="left">'\n'</td>
            </tr>
          </tbody>
        </table>
      </section>

      <section anchor="v4example" numbered="true" toc="default">
        <name>Truncated Version 4 File Representing Europe/London</name>

        <t>The following TZif file has been truncated to start on
        2022-01-01T00:00:00Z.</t>

        <t>In this example:</t>

        <ul spacing="normal">
          <li>The version 1 header contains only the required
          minimum data, which will be ignored by readers.</li>

          <li>The version 4 header leverages the fact that that, by specifying
          'isutcnt' and 'isstdcnt' as zero, all transition times
          associated with local time types are assumed to be specified
          as local wall-clock time
          (see the definitions of UT/local indicators
          and standard/wall indicators in
          <xref target="data" format="default"/>).</li>

          <li>Time type 0 has designation "-00", indicating that local
          time is unspecified prior to the truncation time.</li>

          <li>The first leap-second occurrence is the most recent one
          prior to the truncation time.</li>

          <li>The last leap-second correction matches the
          second-to-last leap-second correction, indicating the
          expiration time of the leap-second table.</li>

          <li>The TZ string value has been line-wrapped for
          presentation purposes only.</li>
        </ul>

        <table align="center">
          <thead>
            <tr>
              <th align="left">File Offset</th>
              <th align="left">Hexadecimal Octets</th>
              <th align="left">Record Name / Field Name</th>
              <th align="left">Field Value</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td align="left">000</td>
              <td align="left">54 5a 69 66</td>
              <td align="left">magic</td>
              <td align="left">"TZif"</td>
            </tr>
            <tr>
              <td align="left">004</td>
              <td align="left">34</td>
              <td align="left">version</td>
              <td align="left">'4' (4)</td>
            </tr>
            <tr>
              <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"></td>
              <td colspan="2" align="left"></td>
            </tr>
            <tr>
              <td align="left">020</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isutcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">024</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isstdcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">028</td>
              <td align="left">00 00 00 00</td>
              <td align="left">leapcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">032</td>
              <td align="left">00 00 00 00</td>
              <td align="left">timecnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">036</td>
              <td align="left">00 00 00 01</td>
              <td align="left">typecnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">040</td>
              <td align="left">00 00 00 01</td>
              <td align="left">charcnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">044</td>
              <td align="left">00 00 00 00</td>
              <td align="left">utoff</td>
              <td align="left">0 (+00:00)</td>
            </tr>
            <tr>
              <td align="left">048</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">049</td>
              <td align="left">00</td>
              <td align="left">desigidx</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">050</td>
              <td align="left">00</td>
              <td align="left">designations[0]</td>
              <td align="left">"\0"</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">051</td>
              <td align="left">54 5a 69 66</td>
              <td align="left">magic</td>
              <td align="left">"TZif"</td>
            </tr>
            <tr>
              <td align="left">055</td>
              <td align="left">34</td>
              <td align="left">version</td>
              <td align="left">'4' (4)</td>
            </tr>
            <tr>
              <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"></td>
              <td colspan="2" align="left"></td>
            </tr>
            <tr>
              <td align="left">071</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isutcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">075</td>
              <td align="left">00 00 00 00</td>
              <td align="left">isstdcnt</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td align="left">079</td>
              <td align="left">00 00 00 02</td>
              <td align="left">leapcnt</td>
              <td align="left">2</td>
            </tr>
            <tr>
              <td align="left">083</td>
              <td align="left">00 00 00 01</td>
              <td align="left">timecnt</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td align="left">087</td>
              <td align="left">00 00 00 02</td>
              <td align="left">typecnt</td>
              <td align="left">2</td>
            </tr>
            <tr>
              <td align="left">091</td>
              <td align="left">00 00 00 08</td>
              <td align="left">charcnt</td>
              <td align="left">8</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">095</td>
              <td align="left">00 00 00 00 61 cf 99 9b</td>
              <td align="left">trans time[0]</td>
              <td align="left">1640995227 (2022-01-01T00:00:27Z)</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">103</td>
              <td align="left">01</td>
              <td align="left">trans type[0]</td>
              <td align="left">1</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">104</td>
              <td align="left">00 00 00 00</td>
              <td align="left">utoff</td>
              <td align="left">0 (+00:00)</td>
            </tr>
            <tr>
              <td align="left">108</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">109</td>
              <td align="left">00</td>
              <td align="left">desigidx</td>
              <td align="left">0</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">localtimetype[1]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">110</td>
              <td align="left">00 00 00 00</td>
              <td align="left">utoff</td>
              <td align="left">0 (+00:00)</td>
            </tr>
            <tr>
              <td align="left">114</td>
              <td align="left">00</td>
              <td align="left">isdst</td>
              <td align="left">0 (no)</td>
            </tr>
            <tr>
              <td align="left">115</td>
              <td align="left">04</td>
              <td align="left">desigidx</td>
              <td align="left">4</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">116</td>
              <td align="left">2d 30 30 00</td>
              <td align="left">designations[0]</td>
              <td align="left">"-00\0"</td>
            </tr>
            <tr>
              <td align="left">120</td>
              <td align="left">47 4d 54 00</td>
              <td align="left">designations[4]</td>
              <td align="left">"GMT\0"</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[0]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">124</td>
              <td align="left">00 00 00 00 58 68 46 9a</td>
              <td align="left">occurrence</td>
              <td align="left">1483228826 (2016-12-31T23:59:60Z)</td>
            </tr>
            <tr>
              <td align="left">132</td>
              <td align="left">00 00 00 1b</td>
              <td align="left">correction</td>
              <td align="left">27</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left"></td>
              <td colspan="2" align="left"></td>
              <td align="left">leapsecond[1]</td>
              <td align="left"></td>
            </tr>
            <tr>
              <td align="left">136</td>
              <td align="left">00 00 00 00 66 7d fd 1b</td>
              <td align="left">occurrence</td>
              <td align="left">1719532827 (2024-06-28T00:00:01Z)</td>
            </tr>
            <tr>
              <td align="left">144</td>
              <td align="left">00 00 00 1b</td>
              <td align="left">correction</td>
              <td align="left">27</td>
            </tr>
            <tr>
              <td colspan="4"/>
            </tr>
            <tr>
              <td align="left">148</td>
              <td align="left">0a</td>
              <td align="left">NL</td>
              <td align="left">'\n'</td>
            </tr>
            <tr>
              <td align="left">149</td>
              <td align="left">47 4d 54 30 42 53 54 2c 4d 33 2e 35 2e
              30 2f 31 2c 4d 31 30 2e 35 2e 30</td>
              <td align="left">TZ string</td>
              <td align="left">"GMT0BST,M3.5.0/1,M10.5.0"</td>
            </tr>
            <tr>
              <td align="left">173</td>
              <td align="left">0a</td>
              <td align="left">NL</td>
              <td align="left">'\n'</td>
            </tr>
          </tbody>
        </table>
      </section>
    </section>

    <section anchor="changes" numbered="true" toc="default">
      <name>Changes from RFC 8536</name>

      <ul spacing="normal">
        <li>Added definition of Leap Second.</li>

        <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>Documented the longstanding practice that UT with
        designation string "-00" denotes unspecified local time.
        Added recommendation that this designation string should be
        used for timestamps excluded by TZif file truncation.</li>

        <li>Required support in version 2 files for all-year daylight
        saving time, using POSIX TZ strings with negative DST, as this
        is not an extension to POSIX (<xref target="permdst"/>).</li>

        <li>Applied erratum <xref target="Err6435" format="default"/>.</li>

        <li>Addressed errata <xref target="Err6426" format="default"/>
        and format="default"/>,
        <xref target="Err6757" format="default"/>, and
        <xref target="Err7681" format="default"/>
        as well as several other errors in the examples.</li>

        <li>Added additional interoperabilty interoperability considerations and common
        issues.</li>

        <li>Added an <xref target="v2truncated" format="default">
        example of a TZif file truncated at the end.</xref></li>

        <li>Added informational notes to
        <xref target="v3example" format="default"/>.</li>

        <li>Miscellaneous editorial changes.</li>
      </ul>
    </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> end</xref>.</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">
      <name>Acknowledgments</name>

      <t>The authors would like to thank the following individuals for
      contributing their ideas and support for writing this specification: Michael Douglass, Ned Freed, Guy Harris,
      Eliot Lear, Alexey Melnikov, and Tim Parenti.</t>
      <contact fullname="Michael Douglass"/>, <contact fullname="Ned Freed"/>,
      <contact fullname="Guy Harris"/>, <contact fullname="Eliot Lear"/>,
      <contact fullname="Alexey Melnikov"/>, and <contact fullname="Tim
      Parenti"/>.</t>
    </section>
  </back>
</rfc>