<?xml version='1.0' encoding='utf-8'?> version="1.0" encoding="UTF-8"?>
<!DOCTYPE rfc [
  <!ENTITY nbsp    "&#160;">
  <!ENTITY zwsp   "&#8203;">
  <!ENTITY nbhy   "&#8209;">
  <!ENTITY wj     "&#8288;">
]>
<?xml-stylesheet type="text/xsl" href="rfc2629.xslt" ?>

<!-- generated by https://github.com/cabo/kramdown-rfc version 1.7.1 (Ruby 3.2.2) -->
<?rfc strict="yes"?>
<?rfc compact="yes"?>
<?rfc subcompact="no"?>

<rfc xmlns:xi="http://www.w3.org/2001/XInclude" ipr="trust200902" docName="draft-ietf-sedate-datetime-extended-11" number="9557" submissionType="IETF" category="std" consensus="true" submissionType="IETF" xml:lang="en" updates="3339" obsoletes="" tocDepth="4" tocInclude="true" sortRefs="true" symRefs="true" version="3">

  <!-- xml2rfc v2v3 conversion 3.18.1 -->
  <front>
    <title abbrev="Internet Extended Date/Time Fmt Format (IXDTF)">Date and Time on the Internet: Timestamps with additional information</title> Additional Information</title>
    <seriesInfo name="Internet-Draft" value="draft-ietf-sedate-datetime-extended-11"/> name="RFC" value="9557"/>
    <author initials="U." surname="Sharma" fullname="Ujjwal Sharma">
      <organization>Igalia, S.L.</organization>
      <address>
        <postal>
          <street>Bugallal Marchesi, 22, 1º</street>
          <city>A Coruña</city>
          <code>15008</code>
          <country>Spain</country>
        </postal>
        <email>ryzokuken@igalia.com</email>
      </address>
    </author>
    <author initials="C." surname="Bormann" fullname="Carsten Bormann">
      <organization>Universität Bremen TZI</organization>
      <address>
        <postal>
          <street>Postfach 330440</street>
          <city>Bremen</city>
          <code>D-28359</code>
          <country>Germany</country>
        </postal>
        <phone>+49-421-218-63921</phone>
        <email>cabo@tzi.org</email>
      </address>
    </author>
    <date year="2023" month="October" day="23"/>
    <workgroup>Serialising year="2024" month="March"/>
    <area>art</area>
    <workgroup>sedate</workgroup>
<keyword>Gregorian calendar</keyword>
<keyword>Calendar awareness</keyword>
<keyword>Time zone</keyword>
<keyword>ISO 8601</keyword>
<keyword>Temporal</keyword>
<keyword>RFC 3339</keyword>
<keyword>Extension</keyword>
<keyword>Internet Extended Data About Times and Events</workgroup> Date/Time Format</keyword>
<keyword>IXDTF</keyword>
    <abstract>
      <?line 158?>
<t>This document defines an extension to the timestamp format defined in
RFC3339
RFC 3339 for representing additional information information, including a time
zone.</t>
      <t>It updates RFC3339 RFC 3339 in the specific interpretation of the local offset
<tt>Z</tt>, which is no longer understood to "imply that UTC is the preferred
reference point for the specified time"; see <xref target="update"/>.</t>
      <t><cref anchor="status">(This "cref" paragraph will be removed by the RFC editor:)<br/>
The present version (-11) addresses comments received during IESG review.</cref></t> time".</t>
    </abstract>
    <note removeInRFC="true">
      <name>About This Document</name>
      <t>
        Status information for this document may be found at <eref target="https://datatracker.ietf.org/doc/draft-ietf-sedate-datetime-extended/"/>.
      </t>
      <t>
        Discussion of this document takes place on the
        Serialising Extended Data About Times and Events (SEDATE) Working Group mailing list (<eref target="mailto:sedate@ietf.org"/>),
        which is archived at <eref target="https://mailarchive.ietf.org/arch/browse/sedate/"/>.
        Subscribe at <eref target="https://www.ietf.org/mailman/listinfo/sedate/"/>.
      </t>
      <t>Source for this draft and an issue tracker can be found at
        <eref target="https://github.com/ietf-wg-sedate/draft-ietf-sedate-datetime-extended"/>.</t>
    </note>
  </front>
  <middle>
    <?line 175?>

<section anchor="intro">
      <name>Introduction</name>
      <t>Dates and times are used in a very diverse set of internet Internet
applications, all the way from server-side logging to calendaring and
scheduling.</t>
      <t>Each distinct instant in time can be represented in a descriptive text
format using a timestamp.
<xref target="ISO8601-2019"/> standardizes a widely-adopted widely adopted
timestamp format, an earlier version of which <xref target="ISO8601"/> formed the
basis of the Internet Date/Time Format <xref target="RFC3339"/>.
However, this format allows timestamps to contain only very little
additional relevant information.
Beyond that, any contextual
information related to a given timestamp needs to be either handled
separately or attached to it in a non-standard manner.</t>
      <t>This is a pressing issue for applications that handle each
such instant in time with an associated time zone name, name in order to take into account events
such as daylight saving time transitions.
Many of these applications attach the time zone to the timestamp in a
non-standard format, at least one of which is fairly well-adopted <xref target="JAVAZDT"/>.
Furthermore, applications might want to attach even more information to the
timestamp, including but not limited to the calendar system in which
      it should be represented.</t>
      <section anchor="scope">
        <name>Scope</name>
   <t>This document defines an extension syntax to the timestamp format defined in
   <xref target="RFC3339"/> for timestamps as specified representing additional information, including a time
   zone.</t>
   <t>It updates <xref target="RFC3339"/> in the specific interpretation of the local offset
   Z, which is no longer understood to "imply that UTC is the preferred
   reference point for the specified time"; see <xref target="update"/>8.</t>
      <section anchor="scope">
        <name>Scope</name>
        <t><xref target="RFC3339"/> defines a syntax for timestamps to represent date and time in the Internet.  For this, the present document defines an extension syntax that has achieves the following properties:</t>
        <ul spacing="normal">
          <li>
            <t>The extension suffix is completely optional, making existing
<xref target="RFC3339"/> timestamps compatible with this format.</t>
          </li>
          <li>
            <t>The format is compatible with the pre-existing popular syntax for attaching
time zone names to timestamps <xref target="JAVAZDT"/>.</t>
          </li>
          <li>
            <t>The format provides a generalized way to attach additional
information to the timestamp.</t>
          </li>
        </ul>
        <t>We refer to this format as the Internet Extended Date/Time Format (IXDTF).</t>
        <t>This document does not address extensions to the format where the
semantic result is no longer a fixed timestamp that is referenced to a
(past or future) UTC time.
For instance, it does not address:</t>
        <ul spacing="normal">
          <li>
            <t>Future
            <t>future time given as a local time in some specified time zone, where
changes to the definition of that time zone (such as a political
decision to enact or rescind daylight saving time) affect the
instant in time represented by the timestamp.</t> timestamp;</t>
          </li>
          <li>
            <t>"Floating
            <t>"floating time", i.e., a local time without information describing
the UTC offset or time zone in which it should be interpreted.</t> interpreted; and</t>
          </li>
          <li>
            <t>The
            <t>the use of timescales different from UTC, such as International Atomic
Time (TAI).</t>
          </li>
        </ul>
        <t>However, additional information augmenting a fixed timestamp may be
sufficient to detect an inconsistency between the intention and the actual
information in the timestamp, such as between the UTC offset and time zone
name.
For instance, inconsistencies might arise because of:</t>
        <ul spacing="normal">
          <li>
            <t>political decisions decisions, as discussed above, or</t> above,</t>
          </li>
          <li>
            <t>updates to time zone definitions being applied at different times
by timestamp producers and receivers, or</t>
          </li>
          <li>
            <t>errors in programs producing and consuming timestamps.</t>
          </li>
        </ul>
        <t>While the information available in an IXDTF string is not generally sufficient to resolve
an inconsistency, it may be used to initiate some out of band out-of-band
processing to obtain sufficient information for such a resolution.</t>
        <t>In order to address some of the requirements implied here, future
related specifications in the future might define syntax and semantics of strings
similar to those described in <xref target="RFC3339"/>.
Note that the extension syntax defined in the present document is
designed in such a way that it can be useful for such specifications
as well.</t>
      </section>
      <section anchor="definitions">
        <name>Definitions</name>
        <t>The
        <t>
    The key words "<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 "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as
    described in BCP 14 BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
    when, and only when, they appear in all capitals, as shown here.</t>
        <?line -18?> here.
        </t>
<dl>
          <dt>UTC:</dt>
          <dd>
            <t>Coordinated Universal Time, as maintained since 1988 by the Bureau
International des Poids et Mesures (BIPM) in conjunction with leap
seconds
seconds, as announced by the International Earth Rotation and
Reference Frames Systems Service <xref target="IERS"/>.
From 1972 through 1987, UTC was maintained entirely by the Bureau
International de l'Heure (BIH).
Before 1972, UTC was not generally recognized recognized, and civil time was
determined by individual jurisdictions using different techniques
for attempting to follow Universal Time based on measuring the
rotation of the earth.
</t>
            <t>UTC is often mistakenly referred to as GMT, GMT (Greenwich Mean Time), an earlier timescale
for which UTC was designed to be a useful successor.</t>
          </dd>
          <dt>ABNF:</dt>
          <dd>
            <t>Augmented Backus-Naur Form, a format used to represent permissible
strings in a protocol or language, as defined in <xref target="RFC5234"/>.
The rules defined in <xref section="B" sectionFormat="of" target="RFC5234"/> are imported implicitly.</t>
          </dd>
          <dt>Internet
          <dt>IXDTF:</dt>
          <dd>
            <t>Internet Extended Date/Time Format (IXDTF):</dt>
          <dd>
            <t>The Format, the date/time format defined in <xref target="extended-format"/> of this document.</t>
          </dd>
          <dt>Timestamp:</dt>
          <dd>
            <t>An unambiguous representation of a particular instant in time.</t>
          </dd>
          <dt>UTC Offset:</dt>
          <dd>
            <t>Difference between a given local time and UTC, usually given in
negative or positive hours and minutes. For example, local time in
the city of New York, NY, USA, USA in the wintertime in 2023, 2023 is 5 hours
behind UTC, so its UTC offset is "-05:00".</t> <tt>-05:00</tt>.</t>
          </dd>
          <dt>Z:</dt>
          <dd>
            <t>A suffix which, that, when applied to a time, denotes a UTC offset of
00:00;
<tt>00:00</tt>; often spoken pronounced "Zulu" from the ICAO phonetic alphabet
representation of the letter "Z".
(Definition
(The definition is from <xref section="2" sectionFormat="of" target="RFC3339"/>; see the International Civil Aviation Organization (ICAO) document <xref target="ICAO-PA"/> for the
phonetic alphabet.)</t> alphabet mentioned.)</t>
          </dd>
          <dt>Time Zone:</dt>
          <dd>
            <t>A set of rules representing the relationship of local time to UTC
for a particular place or region. Mathematically, a time zone can
be thought of as a function that maps timestamps to UTC offsets.
Time zones can deterministically convert a timestamp to local time.
They can also be used in the reverse direction to convert local time
to a timestamp, with the caveat that some local times may have zero
or multiple possible timestamps due to nearby daylight saving time
changes or other changes to the UTC offset of that time zone.
Unlike the UTC offset of a timestamp timestamp, which makes no claims about
the UTC offset of other related timestamps (and which is therefore
unsuitable for performing local-time operations operations, such as
"one day later"), a time zone also defines how to derive new
timestamps based on differences in local time.
For example, to calculate "one day later than this
timestamp in San Francisco, California", a time zone is required because the
UTC offset of local time in San Francisco can change from one day
to the next.</t>
          </dd>
          <dt>IANA Time Zone:</dt>
          <dd>
            <t>A named time zone that is included in the Time Zone Database (often
called <tt>tz</tt> or <tt>zoneinfo</tt>) maintained by IANA <xref target="TZDB"/><xref target="TZDB"/> <xref target="BCP175"/>.
Most IANA time zones Time Zones
are named for the largest city in a particular region that shares
the same time zone rules, e.g., <tt>Europe/Paris</tt> or <tt>Asia/Tokyo</tt> <xref target="TZDB-NAMING"/>.
</t>
            <t>The rules defined for a named IANA time zone Time Zone can change
over time.
The use of a named IANA time zone Time Zone implies that the intent is for the
rules to apply that are current at the time of interpretation: interpretation to apply:
the additional information conveyed by using that time zone name is
to change with any rule changes as recorded in the IANA time zone
database.</t> Time Zone
Database.</t>
          </dd>
          <dt>Offset Time Zone:</dt>
          <dd>
            <t>A time zone defined by a specific UTC offset, e.g. e.g., <tt>+08:45</tt>, and
serialized using as its name the same numeric UTC offset format used in an
RFC 3339 <xref target="RFC3339"/>
timestamp, for example:
</t>
            <artwork><![CDATA[
2022-07-08T00:14:07+08:45[+08:45]
]]></artwork>
            <t>An offset in the suffix that does not repeat the offset of the
timestamp is inconsistent (see <xref target="inconsistent"/>).</t>
            <t>Although serialization with offset time zones is
supported in this document for backwards compatibility with
<tt>java.time.ZonedDateTime</tt> <xref target="JAVAZDT"/>, use of offset time zones is
strongly discouraged.
In particular, programs <bcp14>MUST NOT</bcp14> copy the UTC
offset from a timestamp into an offset time zone in order to satisfy
another program which that requires a time zone suffix in its input.
Doing this will improperly assert that the UTC offset of timestamps
in that location will never change, which can result in incorrect
calculations in programs that add, subtract, or otherwise derive new
timestamps from the one provided. For example,
<tt>2020-01-01T00:00+01:00[Europe/Paris]</tt> will let programs add six
months to the timestamp while adjusting for Summer Time summer time (daylight saving time).
But
However, the same calculation applied to <tt>2020-01-01T00:00+01:00[+01:00]</tt>
will produce an incorrect result that will be off by one hour in the
timezone
time zone <tt>Europe/Paris</tt>.</t>
          </dd>
          <dt>CLDR:</dt>
          <dd>
            <t>Common locale data repository Locale Data Repository <xref target="CLDR"/>, a project of the Unicode
Consortium to provide locale data to applications.</t>
          </dd>
        </dl>
        <t>For more information about timescales, see <xref section="E" sectionFormat="of" target="RFC1305"/>,
Section 3 of <xref target="ISO8601"/>, and the appropriate ITU documents
<xref target="ITU-R-TF.460-6"/>.</t> target="ITU-R-TF.460-6"/>. (Note: <xref target="RFC1305"/> was obsoleted by <xref target="RFC5905"/>,
which no longer contains the Appendix <xref target="RFC1305" section="E" sectionFormat="bare"/> referenced here.)</t>
      </section>
    </section>
    <section anchor="update">
      <name>Updating RFC 3339</name>
      <section anchor="background">
        <name>Background</name>
        <t><xref section="4.3" sectionFormat="of" target="RFC3339"/> states that an offset given as <tt>Z</tt> or
<tt>+00:00</tt> implies that "UTC is the preferred reference point for the
specified time".  The offset <tt>-00:00</tt> is provided as a way to express
that "the time in UTC is known, but the offset to local time is
unknown".</t>
        <t>This convention mirrors a similar convention for date/time information
in email headers, headers that is described in <xref section="3.3" sectionFormat="of" target="RFC5322"/> and introduced
earlier in <xref section="3.3" sectionFormat="of" target="RFC2822"/>.
This email header convention is in actual use, while its adaptation into
<xref target="RFC3339"/> was always
compromised by the fact that <xref target="ISO8601-2000"/> and later versions do not actually allow <tt>-00:00</tt>.</t>
        <t>Implementations that needed to express the semantics of <tt>-00:00</tt>
therefore tended to use <tt>Z</tt> instead.</t>
      </section>
      <section anchor="update-to-rfc-3339">
        <name>Update to RFC 3339</name>
        <t>This specification updates <xref section="4.3" sectionFormat="of" target="RFC3339"/>, aligning it with the actual
practice of interpreting the offset <tt>Z</tt> to mean the same as<tt>-00:00</tt>: as <tt>-00:00</tt>:
"the time in UTC is known, but the offset to local time is unknown".</t>

<!-- [rfced] For clarity, would it be helpful to update "The original version
of this specification" to "[RFC3339]"?

Original:
   |  If the time in UTC is known, but the offset to local time is
   |  unknown, this can be represented with an offset of "Z".  (The
   |  original version of this specification provided "-00:00" for this
   |  purpose, which is not allowed by [ISO8601:2000] and therefore is
   |  less interoperable; Section 3.3 of [RFC5322] describes a related
   |  convention for email which does not have this problem).

Perhaps:
   |  If the time in UTC is known, but the offset to local time is
   |  unknown, this can be represented with an offset of "Z".
   |  ([RFC3339] provided "-00:00" for this
   |  purpose, which is not allowed by [ISO8601:2000] and therefore is
   |  less interoperable; Section 3.3 of [RFC5322] describes a related
   |  convention for email, which does not have this problem).
-->

<t><xref section="4.3" sectionFormat="of" target="RFC3339"/> is revised to read as follows:</t>
        <blockquote>
          <t>If the time in UTC is known, but the offset to local time is unknown,
   this can be represented with an offset of "Z".
   (The original version of this specification provided "-00:00" <tt>-00:00</tt> for
   this purpose, which is not allowed by <xref target="ISO8601-2000"/> and therefore
   is less interoperable; <xref section="3.3" sectionFormat="of" target="RFC5322"/> describes a related
   convention for email email, which does not have this problem).
   This differs semantically from an offset of "+00:00", <tt>+00:00</tt>, which implies
   that UTC is the preferred reference point for the specified time.</t>
        </blockquote>
      </section>
      <section anchor="notes">
        <name>Notes</name>
        <t>Note that the semantics of the local offset <tt>+00:00</tt> is not updated;
this retains the implication that UTC is the preferred reference point
for the specified time.</t>
        <t>Note also
        <t>Also note that the fact that <xref target="ISO8601-2000"/> and later do not allow <tt>-00:00</tt> as a
local offset reduces the level of interoperability that can be
achieved in using this feature; however, the present specification however does
not formally deprecate this syntax.
With the update to RFC 3339, <xref target="RFC3339"/>, the local offset <tt>Z</tt> should now be used in its
place.</t>
      </section>
    </section>
    <section anchor="date-time-format">
      <name>Internet Extended Date/Time format Format (IXDTF)</name>
      <t>This section discusses desirable qualities of formats for the
timestamp extension suffix and defines the IXDTF format, which extends
<xref target="RFC3339"/> for use in Internet protocols.</t>
      <section anchor="format-of-extended-information">
        <name>Format of Extended Information</name>
        <t>The format allows applications to specify additional
	important information in addition to a bare <xref target="RFC3339"/> timestamp.</t>
	<t>This is done by defining <em>tags</em>, each with a <em>key</em> and a <em>value</em>
separated by an equals sign.  The value of a tag can be one or more
items delimited by hyphen/minus signs.</t>
<t>Applications can build an informative timestamp <em>suffix</em> using any
   number of these tags.</t>
   <t>Keys are lower-case lowercase only.  Values are case-sensitive unless otherwise
   specified.</t>
	<t>See <xref target="optionally-critical"/> for the handling of inconsistent information
in a suffix.</t>
      </section>
      <section anchor="registered">
        <name>Registering Keys for Extended Information Tags</name>
        <t>Suffix tag keys are registered by supplying the information
specified in this section.  This information is modeled after that
specified for the media type "Media Types" registry <xref target="RFC6838"/>; if in doubt, the
	provisions of this registry should be applied analogously.</t>

        <dl>
          <dt>Key Identifier:</dt>
          <dd>
            <t>The key (conforming to <tt>suffix-key</tt> in <xref target="abnf"/>)</t>
          </dd>
          <dt>Registration status:</dt> Status:</dt>
          <dd>
            <t>"Provisional" or "Permanent"</t>
          </dd>
          <dt>Description:</dt>
          <dd>
            <t>A very brief description of the key.</t> key</t>
          </dd>
          <dt>Change controller:</dt> Controller:</dt>
          <dd>
            <t>Who is in control of evolving the specification governing values for
this key.  This information can include email addresses of contact
points and
points, discussion lists, and references to relevant web pages (URLs).</t>
          </dd>
          <dt>Reference:</dt>
          <dd>
            <t>A reference.
For permanent tag keys, this includes a full specification.
For provisional tag keys, there is an expectation that some
information is available even if that does not amount to a full
specification; in this case, the registrant is expected to improve this
information over time.</t>
          </dd>
        </dl>
        <t>Key names that start with an underscore are intended for experiments
in controlled environments and cannot be registered; such keys <bcp14>MUST
NOT</bcp14> be used for interchange and <bcp14>MUST</bcp14> be rejected by implementations
not specifically configured to take part in such an experiment.
See <xref target="BCP178"/> for a discussion about the danger of experimental keys
leaking out to general production and why that must be prevented.</t>
     </section>
     <section anchor="optionally-critical">
        <name>Optional Generation, Generation and Elective vs. Critical Consumption</name>
        <t>For the IXDTF format, suffix tags are always <em>optional</em>: <em>optional</em>. They
can be added or left out as desired by the generator of the string.
(An application might require the presence
of specific suffix tags, though.)</t>
        <t>Without further indication, suffix tags are also <em>elective</em>: <em>elective</em>.
The recipient is free to ignore any suffix tag included in an IXDTF
string.
Reasons might include that the recipient does
not implement (or know about) the specific suffix key, key or that it does
recognize the key but cannot act on the value provided.</t>
        <t>A suffix tag may also indicate that it is <em>critical</em>: The recipient is
advised that it <bcp14>MUST NOT</bcp14> act on the Internet Extended Date/Time Format (IXDTF) IXDTF string
unless it can process the suffix tag as specified.  A critical suffix
tag is indicated by following its opening bracket with an exclamation
mark (see <tt>critical-flag</tt> in <xref target="abnf"/>).</t>
        <t>For example, IXDTF strings such as:</t>
        <artwork><![CDATA[
2022-07-08T00:14:07+01:00[Europe/Paris]
]]></artwork>
        <t>are internally inconsistent (see <xref target="inconsistent"/>), because Europe/Paris <tt>Europe/Paris</tt> did not
use a time zone offset of <tt>+01:00</tt> in July 2022.
The
However, the time zone hint given in the suffix tag is elective, though, so the recipient is not
required to act on the inconsistency; it can treat the Internet
Date/Time Format string as if it were:</t>
        <artwork><![CDATA[
2022-07-08T00:14:07+01:00
]]></artwork>
        <aside>
          <t>Note that that, as per <xref target="update"/> (see also <xref target="inconsistent"/>), the IXDTF string:</t>
          <artwork><![CDATA[
2022-07-08T00:14:07Z[Europe/Paris]
]]></artwork>
          <t>does not exhibit such an inconsistency, as the local offset of <tt>Z</tt>
does not imply a specific preferred time zone of interpretation.
Using the Time Zone Database rules for Europe/Paris <tt>Europe/Paris</tt> in
the summer of 2022, it is equivalent to:</t>
          <artwork><![CDATA[
2022-07-08T02:14:07+02:00[Europe/Paris]
]]></artwork>
        </aside>
        <t>Similarly, an unknown suffix may be entirely ignored:</t>
        <artwork><![CDATA[
2022-07-08T00:14:07+01:00[knort=blargel]
]]></artwork>
        <t>(assuming that the recipient does not understand the suffix key <tt>knort</tt>).</t>
        <t>In contrast to this elective use of a suffix tag,</t>
        <artwork><![CDATA[
2022-07-08T00:14:07+01:00[!Europe/Paris]
2022-07-08T00:14:07Z[!u-ca=chinese][u-ca=japanese]
2022-07-08T00:14:07Z[u-ca=chinese][!u-ca=japanese]
2022-07-08T00:14:07Z[!knort=blargel]
]]></artwork>
        <t>each have an internal inconsistency or an unrecognized suffix key/value
that are is marked as critical, so a recipient <bcp14>MUST</bcp14> treat these IXDTF
strings as erroneous.
This means that the application <bcp14>MUST</bcp14> reject the data, data or perform some
other error handling, such as asking the user how to resolve the
inconsistency (see <xref target="inconsistent"/>).</t>
        <t>Note that applications <bcp14>MAY</bcp14> also perform additional processing on
inconsistent or unrecognized elective suffix tags, such as asking the
user how to resolve the inconsistency.
While they are not required to do so with elective suffix tags, they are
required to reject or perform some other error handling when
encountering inconsistent or unrecognized suffix tags marked as
critical.</t>
        <t>An application that encounters duplicate use of a suffix key in
elective suffixes and does not want to perform additional processing
on this inconsistency <bcp14>MUST</bcp14> choose the first suffix that has that key,
i.e.,</t>
that is,</t>
        <artwork><![CDATA[
2022-07-08T00:14:07Z[u-ca=chinese][u-ca=japanese]
2022-07-08T00:14:07Z[u-ca=chinese]
]]></artwork>
        <t>are then treated the same.</t>
      </section>
      <section anchor="inconsistent">
        <name>Inconsistent <tt>time-offset</tt>/Time-Zone <tt>time-offset</tt> and Time Zone Information</name>
        <t>An RFC 3339 <xref target="RFC3339"/> timestamp can contain a <tt>time-offset</tt> value that indicates
the offset between local time and UTC (see <xref section="4" sectionFormat="of" target="RFC3339"/>,
noting that <xref target="update"/> of the present specification updates <xref section="4.3" sectionFormat="of" target="RFC3339"/>).</t>
        <t>The information given in such a <tt>time-offset</tt> value can be
inconsistent with the information provided in a time zone suffix for an
IXDTF timestamp.</t>
        <t>For example, a calendar application could store an IXDTF string representing a
far-future meeting in a particular time zone. If that time zone's definition is
subsequently changed to abolish daylight saving time, IXDTF strings that were
originally consistent may now be inconsistent.</t>
        <t>In case of inconsistent an inconsistency between <tt>time-offset</tt> and time zone suffix, if the
critical flag is used on the time zone suffix, an application <bcp14>MUST</bcp14> act
on the inconsistency.
If the critical flag is not used, it <bcp14>MAY</bcp14> act on the inconsistency.
Acting on the inconsistency may involve rejecting the timestamp, timestamp or
resolving the inconsistency via additional information information, such as user input
and/or programmed behavior.</t>
        <t>For example, the IXDTF timestamps in <xref target="example-inconsistent"/> represent
00:14:07 UTC, indicating a local time with a <tt>time-offset</tt> of +00:00. <tt>+00:00</tt>.
However, because Europe/London <tt>Europe/London</tt> used offset +01:00 <tt>+01:00</tt> in July 2022, the
timestamps are inconsistent in <xref target="example-inconsistent"/>, where the first
case is one where the application <bcp14>MUST</bcp14> act on the inconsistency (the
time zone suffix is marked critical), critical) and the second case is one where
it <bcp14>MAY</bcp14> act on it (time the inconsistency (the time zone suffix is elective).</t>
        <figure anchor="example-inconsistent">
          <name>Inconsistent IXDTF timestamps</name> Timestamps</name>
          <artwork><![CDATA[
2022-07-08T00:14:07+00:00[!Europe/London]
2022-07-08T00:14:07+00:00[Europe/London]
]]></artwork>
        </figure>

        <t>As per <xref section="4.3" sectionFormat="of" target="RFC3339"/> as updated by <xref target="update"/>, IXDTF
timestamps may also forego indicating local time information in their
<xref target="RFC3339"/> part by using <tt>Z</tt> instead of a numeric time zone offset.
The IXDTF timestamps in <xref target="example-consistent"/> (which represent the same
instant in time as the strings in <xref target="example-inconsistent"/>) are not
inconsistent because they do not assert any particular local time nor
local offset in their <xref target="RFC3339"/> part.
Instead, applications that receive these strings can calculate the
local offset and local time using the rules of the time zone suffix,
such as Europe/London <tt>Europe/London</tt> in the example in <xref target="example-consistent"/>, which
like <xref target="example-inconsistent"/> has a case with a time zone suffix marked
critical, i.e.,
critical (i.e., the intention is that the application must understand
the time zone information, information) and one marked elective, which then only is
provided as additional information.</t>
        <figure anchor="example-consistent">
          <name>No inconsistency Inconsistency in IXDTF timestamps</name> Timestamps</name>
          <artwork><![CDATA[
2022-07-08T00:14:07Z[!Europe/London]
2022-07-08T00:14:07Z[Europe/London]
]]></artwork>
        </figure>
        <t>Note that <tt>-00:00</tt> may be used instead of <tt>Z</tt>, <tt>Z</tt> because they have the
same meaning according to <xref target="update"/>, but <tt>-00:00</tt> is not allowed by
<xref target="ISO8601-2000"/> and later so <tt>Z</tt> is preferred.</t>
      </section>
    </section>
    <section anchor="extended-format">
      <name>Syntax Extensions to RFC 3339</name>
      <section anchor="abnf">
        <name>ABNF</name>
        <t>The following rules extend the ABNF syntax defined in <xref target="RFC3339"/> in
order to allow the inclusion of an optional suffix.</t>
        <t>The Internet Extended Date/Time Format (IXDTF) is described by the
rule <tt>date-time-ext</tt>.</t>
        <t><tt>date-time</tt> and <tt>time-numoffset</tt> are imported from <xref section="5.6" sectionFormat="of" target="RFC3339"/>, and <tt>ALPHA</tt> and <tt>DIGIT</tt> are imported from <xref section="B.1" sectionFormat="of" target="RFC5234"/>.</t>
        <figure anchor="grammar">
          <name>ABNF grammar Grammar of extensions Extensions to RFC 3339</name>
          <sourcecode type="abnf" name="date-time-ext.abnf"><![CDATA[
time-zone-initial = ALPHA / "." / "_"
time-zone-char    = time-zone-initial / DIGIT / "-" / "+"
time-zone-part    = time-zone-initial *time-zone-char
                    ; but not "." or ".."
time-zone-name    = time-zone-part *("/" time-zone-part)
time-zone         = "[" critical-flag
                        time-zone-name / time-numoffset "]"

key-initial       = lcalpha / "_"
key-char          = key-initial / DIGIT / "-"
suffix-key        = key-initial *key-char

suffix-value      = 1*alphanum
suffix-values     = suffix-value *("-" suffix-value)
suffix-tag        = "[" critical-flag
                        suffix-key "=" suffix-values "]"
suffix            = [time-zone] *suffix-tag

date-time-ext     = date-time suffix

critical-flag     = [ "!" ]

alphanum          = ALPHA / DIGIT
lcalpha           = %x61-7A
]]></sourcecode>
        </figure>
        <t>Note that a <tt>time-zone</tt> is syntactically similar to a <tt>suffix-tag</tt>, <tt>suffix-tag</tt>
but does not include an equals sign.
This special case is only available for time zone tags.</t>
        <t>The ABNF definition of <tt>time-zone-part</tt> matches "." and "..", which
however
both are explicitly excluded (see also comment the note below on
<tt>time-zone-part</tt>).</t>
        <t><tt>time-zone-name</tt> is intended to be the name of an IANA Time Zone.
As a generator and recipient may be using different revisions of the
Time Zone Database, recipients may not be aware of such an IANA Time
Zone name and should treat such a situation as any other inconsistency.</t>
        <aside>
          <t>Note: At the time of writing, the length of each <tt>time-zone-part</tt> is
limited to a maximum of 14 characters by the rules in <xref target="TZDB-NAMING"/>.
One platform is known to enforce this limit, and an entry in a timezone
database Time Zone
Database on another platform is known to exceed this limit.
As the <tt>time-zone-name</tt> will ultimately have to be looked up in the
database, which therefore has control over the length, the
<tt>time-zone-part</tt> production in <xref target="grammar"/> is deliberately permissive.</t>
        </aside>
      </section>
      <section anchor="date-time-examples">
        <name>Examples</name>
        <t>Here are
        <t>This section contains some examples of Internet Extended Date/Time Format (IXDTF).</t>
        <figure anchor="rfc3339-datetime">
          <name>RFC 3339 date-time with time zone offset</name>
          <sourcecode type="ixdtf"><![CDATA[ Time Zone Offset</name>
          <artwork><![CDATA[
1996-12-19T16:39:57-08:00
]]></sourcecode>
]]></artwork>
        </figure>
        <t><xref target="rfc3339-datetime"/> represents 39 minutes and 57 seconds after the 16th hour of
December 19th, 1996 19, 1996, with an offset of -08:00 <tt>-08:00</tt> from UTC.
Note that this is the same instant in time as <tt>1996-12-20T00:39:57Z</tt>, expressed in UTC.</t>
        <figure anchor="datetime-tzname">
          <name>Adding a time zone name</name>
          <sourcecode type="ixdtf"><![CDATA[ Time Zone Name</name>
          <artwork><![CDATA[
1996-12-19T16:39:57-08:00[America/Los_Angeles]
]]></sourcecode>
]]></artwork>
        </figure>
        <t><xref target="datetime-tzname"/> represents the exact same instant in time as the previous example but
additionally specifies the human time zone associated with it
("Pacific Time") for time-zone-aware applications to take into
account.</t>
        <figure anchor="date-time-hebrew">
          <name>Projecting to the Hebrew calendar</name>
          <sourcecode type="ixdtf"><![CDATA[ Calendar</name>
          <artwork><![CDATA[
1996-12-19T16:39:57-08:00[America/Los_Angeles][u-ca=hebrew]
]]></sourcecode>
]]></artwork>
        </figure>
        <t><xref target="date-time-hebrew"/> represents the exact same instant in time, but it informs calendar-aware
applications (see <xref target="calendar"/>) that they should project it to the Hebrew calendar.</t>
        <figure anchor="date-time-private">
          <name>Adding experimental tags</name>
          <sourcecode type="ixdtf"><![CDATA[ Experimental Tags</name>
          <artwork><![CDATA[
1996-12-19T16:39:57-08:00[_foo=bar][_baz=bat]
]]></sourcecode>
]]></artwork>
        </figure>
        <t><xref target="date-time-private"/>, based on <xref target="rfc3339-datetime"/>, utilizes keys
identified as experimental by a leading underscore to declare two additional pieces of
information in the suffix; these can be interpreted by implementations
that take part in the controlled experiment making use of these tag keys.</t>
      </section>
    </section>
    <section anchor="calendar">
      <name>The u-ca Suffix Key: Calendar Awareness</name>
      <t>Out of the possible suffix keys, the suffix key <tt>u-ca</tt> is allocated to
indicate the calendar in which the date/time is preferably presented.</t>
      <t>A calendar is a set of rules defining how dates are counted and
consumed by implementations.
The set of suffix values allowed for this suffix key is the set of
values defined for the Unicode Calendar Identifier <xref target="TR35"/>.
A resource that has been built to provide

<xref target="CLDR-LINKS"/> provides links into
to the most recent
stable and development <xref target="CLDR"/> information about that is provided by <xref target="CLDR-LINKS"/>.</t> target="CLDR"/>, both stable and specific development stages.</t>
    </section>
    <section anchor="iana-cons">
      <name>IANA Considerations</name>
      <t><cref anchor="to-be-removed">RFC Editor: please replace RFCthis with the RFC
number of this RFC and remove this note.</cref></t>
      <t>IANA is requested to establish has created a registry called "Timestamp Suffix Tag
Keys" in a new registry group titled "Internet Date/Time Format".
Each entry in the registry shall consist of the information described in <xref target="registered"/>.
Initial
The initial contents of the registry are specified in <xref target="tab-registered"/>.</t>
      <table anchor="tab-registered">
        <name>Initial Content Contents of Timestamp Suffix Tag Keys registry</name> Registry</name>
        <thead>
          <tr>
            <th align="left">Key Identifier</th>
            <th align="left">Registration status</th> Status</th>
            <th align="left">Description:</th> align="left">Description</th>
            <th align="left">Change controller</th> Controller</th>
            <th align="left">Reference</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <td align="left">u-ca</td>
            <td align="left">Permanent</td>
            <td align="left">Preferred Calendar for Presentation</td>
            <td align="left">IESG</td> align="left">IETF</td>
            <td align="left">
              <xref target="calendar"/> of RFCthis</td> RFC 9557</td>
          </tr>
        </tbody>
      </table>
      <t>The registration policy <xref target="BCP26"/> is "Specification Required" for
permanent entries, entries and "Expert Review" for provisional ones.
In the second case, the expert is experts are instructed to ascertain that a basic
specification does exist, even if not complete or published yet.</t>
      <t anchor="de-instructions">The experts also are also instructed to be frugal in the allocation of
key identifiers that are suggestive of generally applicable semantics,
keeping them in reserve for suffix keys that are likely to enjoy wide
use and can make good use of the key identifier's conciseness.
If the experts become aware of key identifiers that are deployed and
in use, they may also initiate a registration on their own if
they deem such a registration can avert potential future collisions.</t>
    </section>
    <section anchor="security-considerations">
      <name>Security Considerations</name>
      <section anchor="excessive-disclosure">
        <name>Excessive Disclosure</name>
        <t>The ability to include various pieces of ancillary information with a
timestamp might lead to excessive disclosure.
An example for possibly excessive disclosure is given in <xref section="7" sectionFormat="of" target="RFC3339"/>.
Similarly, divulging information about the calendar system or the
language of choice may provide more information about the originator
of a timestamp than the data minimization principle would permit
<xref target="DATA-MINIMIZATION"/>. target="I-D.arkko-iab-data-minimization-principle"/>.
More generally speaking, generators of IXDTF timestamps need to
consider whether information to be added to the timestamp is
appropriate to divulge to the recipients of this information, information and need
to err on the side of minimizing such disclosure if the set of
recipients is not under control of the originator.</t>
      </section>
      <section anchor="data-format-implementation-vulnerabilities">
        <name>Data Format Implementation Vulnerabilities</name>
        <t>As usual when extending the syntax of a data format, this can lead to
new vulnerabilities in implementations parsing and processing the
format.
No considerations are known for the IXDTF syntax that would pose
concerns that are out of the ordinary.</t>
      </section>
      <section anchor="operating-with-inconsistent-data">
        <name>Operating with Inconsistent Data</name>
        <t>Information provided in the various parts of an IXDTF string may be
        inconsistent in interesting ways, both with the extensions defined in
        this specification (see for instance (for instance, see <xref target="inconsistent"/>)
        and with future extensions still to be defined.  Where consistent
        interpretation between multiple actors is required for security
        purposes (e.g., where timestamps are embedded as parameters in access
        control information), only those extensions can be
employed that have a well-understood and
        shared resolution of such inconsistent data.</t> data can be employed.</t>
      </section>
    </section>
  </middle>
  <back>
    <displayreference target="ISO8601" to="ISO8601:1988"/>
    <displayreference target="ISO8601-2000" to="ISO8601:2000"/>
    <displayreference target="ISO8601-2019" to="ISO8601-1:2019"/>
    <displayreference target="I-D.arkko-iab-data-minimization-principle" to="DATA-MINIMIZATION"/>

    <references>
      <name>References</name>
      <references anchor="sec-normative-references">
        <name>Normative References</name>
        <reference anchor="RFC3339">
          <front>
            <title>Date and Time on the Internet: Timestamps</title>
            <author fullname="G. Klyne" initials="G." surname="Klyne"/>
            <author fullname="C. Newman" initials="C." surname="Newman"/>
            <date month="July" year="2002"/>
            <abstract>
              <t>This document defines a date and time format for use in Internet protocols that is a profile of the ISO 8601 standard for representation of dates and times using the Gregorian calendar.</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="3339"/>
          <seriesInfo name="DOI" value="10.17487/RFC3339"/>
        </reference>
        <reference anchor="RFC5234">
          <front>
            <title>Augmented BNF for Syntax Specifications: ABNF</title>
            <author fullname="D. Crocker" initials="D." role="editor" surname="Crocker"/>
            <author fullname="P. Overell" initials="P." surname="Overell"/>
            <date month="January" year="2008"/>
            <abstract>
              <t>Internet technical specifications often need to define a formal syntax. Over the years, a modified version of Backus-Naur Form (BNF), called Augmented BNF (ABNF), has been popular among many Internet specifications. The current specification documents ABNF. It balances compactness and simplicity with reasonable representational power. The differences between standard BNF and ABNF involve naming rules, repetition, alternatives, order-independence, and value ranges. This specification also supplies additional rule definitions and encoding for a core lexical analyzer of the type common to several Internet specifications. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="STD" value="68"/>
          <seriesInfo name="RFC" value="5234"/>
          <seriesInfo name="DOI" value="10.17487/RFC5234"/>
        </reference>
        <reference anchor="RFC6838">
          <front>
            <title>Media Type Specifications and Registration Procedures</title>
            <author fullname="N. Freed" initials="N." surname="Freed"/>
            <author fullname="J. Klensin" initials="J." surname="Klensin"/>
            <author fullname="T. Hansen" initials="T." surname="Hansen"/>
            <date month="January" year="2013"/>
            <abstract>
              <t>This document defines procedures for the specification and registration of media types for use in HTTP, MIME, and other Internet protocols. This memo documents an Internet Best Current Practice.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="13"/>
          <seriesInfo name="RFC" value="6838"/>
          <seriesInfo name="DOI" value="10.17487/RFC6838"/>
        </reference>
        <reference anchor="BCP26">
          <front>
            <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
            <author fullname="M. Cotton" initials="M." surname="Cotton"/>
            <author fullname="B. Leiba" initials="B." surname="Leiba"/>
            <author fullname="T. Narten" initials="T." surname="Narten"/>
            <date month="June" year="2017"/>
            <abstract>
              <t>Many protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA).</t>
              <t>To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry.</t>
              <t>This is the third edition of this document; it obsoletes RFC 5226.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="26"/>
          <seriesInfo name="RFC" value="8126"/>
          <seriesInfo name="DOI" value="10.17487/RFC8126"/>
        </reference>
        <reference anchor="BCP178">
          <front>
            <title>Deprecating the "X-" Prefix and Similar Constructs in Application Protocols</title>
            <author fullname="P. Saint-Andre" initials="P." surname="Saint-Andre"/>
            <author fullname="D. Crocker" initials="D." surname="Crocker"/>
            <author fullname="M. Nottingham" initials="M." surname="Nottingham"/>
            <date month="June" year="2012"/>
            <abstract>
              <t>Historically, designers and implementers of application protocols have often distinguished between standardized and unstandardized parameters by prefixing the names of unstandardized parameters with the string "X-" or similar constructs. In practice, that convention causes more problems than it solves. Therefore, this document deprecates the convention for newly defined parameters with textual (as opposed to numerical) names in application protocols. This memo documents an Internet Best Current Practice.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="178"/>
          <seriesInfo name="RFC" value="6648"/>
          <seriesInfo name="DOI" value="10.17487/RFC6648"/>
        </reference>
        <reference anchor="BCP175">
          <front>
            <title>Procedures for Maintaining the Time Zone Database</title>
            <author fullname="E. Lear" initials="E." surname="Lear"/>
            <author fullname="P. Eggert" initials="P." surname="Eggert"/>
            <date month="February" year="2012"/>
            <abstract>
              <t>Time zone information serves as a basic protocol element in protocols, such as the calendaring suite and DHCP. The Time Zone (TZ) Database specifies the indices used in various protocols, as well as their semantic meanings, for all localities throughout the world. This database has been meticulously maintained and distributed free of charge by a group of volunteers, coordinated by a single volunteer who is now planning to retire. This memo specifies procedures involved with maintenance of the TZ database and associated code, including how to submit proposed updates, how decisions for inclusion of those updates are made, and the selection of a designated expert by and for the time zone community. The intent of this memo is, to the extent possible, to document existing practice and provide a means to ease succession of the database maintainers. This memo documents an Internet Best Current Practice.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="175"/>
          <seriesInfo name="RFC" value="6557"/>
          <seriesInfo name="DOI" value="10.17487/RFC6557"/>
        </reference>
        <reference anchor="RFC2119">
          <front>
            <title>Key words for use in RFCs to Indicate Requirement Levels</title>
            <author fullname="S. Bradner" initials="S." surname="Bradner"/>
            <date month="March" year="1997"/>
            <abstract>
              <t>In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="14"/>
          <seriesInfo name="RFC" value="2119"/>
          <seriesInfo name="DOI" value="10.17487/RFC2119"/>
        </reference>
        <reference anchor="RFC8174">
          <front>
            <title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</title>
            <author fullname="B. Leiba" initials="B." surname="Leiba"/>
            <date month="May" year="2017"/>
            <abstract>
              <t>RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.</t>
            </abstract>
          </front>
          <seriesInfo name="BCP" value="14"/>
          <seriesInfo name="RFC" value="8174"/>
          <seriesInfo name="DOI" value="10.17487/RFC8174"/>
        </reference>

<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3339.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5234.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6838.xml"/>

<referencegroup anchor="BCP26" target="https://www.rfc-editor.org/info/bcp26">
  <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8126.xml"/>
</referencegroup>

<referencegroup anchor="BCP178" target="https://www.rfc-editor.org/info/bcp178">
  <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6648.xml"/>
</referencegroup>

<referencegroup anchor="BCP175" target="https://www.rfc-editor.org/info/bcp175">
  <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6557.xml"/>
</referencegroup>

<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
  </references>

      <references anchor="sec-informative-references">
        <name>Informative References</name>
        <reference anchor="RFC2822">
          <front>
            <title>Internet Message Format</title>
            <author fullname="P. Resnick" initials="P." role="editor" surname="Resnick"/>
            <date month="April" year="2001"/>
            <abstract>
              <t>This document specifies a syntax for text messages that are sent between computer users, within the framework of "electronic mail" messages. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="2822"/>
          <seriesInfo name="DOI" value="10.17487/RFC2822"/>
        </reference>
        <reference anchor="RFC5322">
          <front>
            <title>Internet Message Format</title>
            <author fullname="P. Resnick" initials="P." role="editor" surname="Resnick"/>
            <date month="October" year="2008"/>
            <abstract>
              <t>This document specifies the Internet Message Format (IMF), a syntax for text messages that are sent between computer users, within the framework of "electronic mail" messages. This specification is a revision of Request For Comments (RFC) 2822, which itself superseded Request For Comments (RFC) 822, "Standard for the Format of ARPA Internet Text Messages", updating it to reflect current practice and incorporating incremental changes that were specified in other RFCs. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="5322"/>
          <seriesInfo name="DOI" value="10.17487/RFC5322"/>
        </reference>
        <reference anchor="RFC1305">
          <front>
            <title>Network Time Protocol (Version 3) Specification, Implementation and Analysis</title>
            <author fullname="D. Mills" initials="D." surname="Mills"/>
            <date month="March" year="1992"/>
            <abstract>
              <t>This document describes the Network Time Protocol (NTP), specifies its formal structure and summarizes information useful for its implementation. [STANDARDS-TRACK]</t>
            </abstract>
          </front>
          <seriesInfo name="RFC" value="1305"/>
          <seriesInfo name="DOI" value="10.17487/RFC1305"/>
        </reference>

<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2822.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5322.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.1305.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5905.xml"/>

        <reference anchor="ISO8601" target="https://www.iso.org/standard/15903.html">
          <front>
            <title>Data elements and interchange formats  -- Information interchange  -- Representation of dates and times</title>
            <author>
              <organization abbrev="ISO">International Organization for Standardization</organization>
            </author>
            <date year="1988" month="June"/>
          </front>
          <seriesInfo name="ISO" value="8601:1988"/>
          <annotation>Also available from &lt;⁠<eref target="https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub4-1-1991.pdf">https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub4-1-1991.pdf</eref>&gt;.</annotation> <eref target="https://nvlpubs.nist.gov/nistpubs/Legacy/FIPS/fipspub4-1-1991.pdf" brackets="angle"/>.</annotation>
        </reference>

        <reference anchor="ISO8601-2000" target="https://www.iso.org/standard/26780.html">
          <front>
            <title>Data elements and interchange formats  -- Information interchange  -- Representation of dates and times</title>
            <author>
              <organization abbrev="ISO">International Organization for Standardization</organization>
            </author>
            <date year="2000" month="December"/>
          </front>
          <seriesInfo name="ISO" value="8601:2000"/>
        </reference>

        <reference anchor="ISO8601-2019" target="https://www.iso.org/standard/70907.html">
          <front>
            <title>Date and time  -- Representations for information interchange  -- Part 1: Basic rules</title>
            <author>
              <organization abbrev="ISO">International Organization for Standardization</organization>
            </author>
            <date year="2019" month="February"/>
          </front>
          <seriesInfo name="ISO" value="8601-1:2019"/>
        </reference>

        <reference anchor="ITU-R-TF.460-6" target="https://www.itu.int/rec/R-REC-TF.460/en">
          <front>
            <title>ITU-R TF.460-6. Standard-frequency
            <title>Standard-frequency and time-signal emissions</title>
            <author>
              <organization/>
              <organization>ITU-R</organization>
            </author>
            <date year="2002" month="February"/>
          </front>
	  <seriesInfo name="ITU-R Recommendation" value="TF.460-6"/>
        </reference>

        <reference anchor="IERS" target="https://www.iers.org/IERS/EN/Publications/Bulletins/bulletins.html">
          <front>
            <title>International Earth Rotation Service Bulletins</title>
            <author>
              <organization/>
              <organization>IERS</organization>
            </author>
            <date/>
          </front>
        </reference>

        <reference anchor="JAVAZDT" target="https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html#ISO_ZONED_DATE_TIME">
          <front>
            <title>Java SE 8, java.time.format,
            <title>Class DateTimeFormatter: ISO_ZONED_DATE_TIME</title>
            <author>
              <organization/>
              <organization>Oracle</organization>
            </author>
            <date/>
          </front>
        </reference>

        <reference anchor="CLDR" target="https://cldr.unicode.org">
          <front>
            <title>Unicode CLDR Project</title>
            <author>
              <organization/>
              <organization>Unicode CLDR</organization>
            </author>
            <date/>
          </front>
        </reference>

        <reference anchor="CLDR-LINKS" target="https://cldr.unicode.org/stable-links-info">
          <front>
            <title>Stable Links Info</title>
            <author>
              <organization>Unicode CLDR</organization>
            </author>
            <date/>
          </front>
        </reference>

        <reference anchor="TZDB" target="https://data.iana.org/time-zones/tz-link.html">
          <front>
            <title>Sources for time
            <title>Time zone and daylight saving time data</title>
            <author>
              <organization/>
              <organization>IANA</organization>
            </author>
            <date/>
          </front>
        </reference>

        <reference anchor="TZDB-NAMING" target="https://data.iana.org/time-zones/theory.html">
          <front>
            <title>Theory and pragmatics of the tz code and data</title>
            <author>
              <organization/>
              <organization>IANA</organization>
            </author>
            <date/>
          </front>
        </reference>

        <reference anchor="TR35" target="https://www.unicode.org/reports/tr35/#UnicodeCalendarIdentifier">
          <front>
            <title>Unicode Technical Standard #35: Unicode Locale Data Markup Language (LDML)</title>
            <author>
            <author initials="M" surname="Davis" fullname="Mark Davis" role="editor">
              <organization/>
            </author>
            <date/>
          </front>
        </reference>

        <reference anchor="ICAO-PA" target="https://store.icao.int/annex-10-aeronautical-telecommunications-volume-ii-communication-procedures-including-those-with-pans-status">
          <front>
            <title>Annex 10 to the Convention on International Civil Aviation: Aeronautical Telecommunications; Volume II Communication Procedures including those with PANS status (7th ed.)</title> status</title>
            <author>
              <organization>International Civil Aviation Organization</organization>
            </author>
            <date year="2016" month="July"/>
          </front>
	  <refcontent>7th ed.</refcontent>
        </reference>
        <reference anchor="DATA-MINIMIZATION">
          <front>
            <title>Emphasizing data minimization among protocol participants</title>
            <author fullname="Jari Arkko" initials="J." surname="Arkko">
              <organization>Ericsson</organization>
            </author>
            <date day="10" month="July" year="2023"/>
            <abstract>
              <t>   Data minimization is an important privacy technique, as it can reduce
   the amount information exposed about a user.  This document
   emphasizes the need for data minimization among primary protocol
   participants, such as between clients and servers.  Avoiding data
   leakage to outside parties is of course very important as well, but
   both need to be considered in minimization.

   This is because is necessary to protect against endpoints that are
   compromised, malicious, or whose interests simply do not align with
   the interests of users.  It is important to consider the role of a
   participant and limit any data provided to it according to that role.

              </t>
            </abstract>
          </front>
          <seriesInfo name="Internet-Draft" value="draft-arkko-iab-data-minimization-principle-05"/>
        </reference>

<!-- [DATA-MINIMIZATION] [I-D.arkko-iab-data-minimization-principle] IAB state (None) -->

<xi:include href="https://datatracker.ietf.org/doc/bibxml3/reference.I-D.arkko-iab-data-minimization-principle.xml"/>

      </references>
    </references>
    <?line 828?>
<section numbered="false" anchor="acknowledgements">
      <name>Acknowledgements</name>
      <t>Richard Gibson
      <t>This specification benefits from work prepared by ECMA TC39,
   specifically in the Temporal proposal.</t>

   <t><contact fullname="Richard Gibson"/> and Justin Grant <contact fullname="Justin
   Grant"/> provided editorial improvements.  The SEDATE WG Chairs <contact
   fullname="Mark McFadden"/> and <contact fullname="Bron Gondwana"/>, the
   latter also in his role as CALEXT WG Chair, helped set up the structures
   needed to navigate the multi-SDO environment.  <contact fullname="John
   Klensin"/> critically accompanied the development of this specification,
   which led to significant improvements.  The authors would also like to
   especially thank Francesca Palombini <contact fullname="Francesca Palombini"/> for her AD review.</t>
   review and for her overall guidance during the development process.
      </t>
</section>
    <section anchor="contributors" numbered="false" toc="include" removeInRFC="false">
      <name>Contributors</name>
      <contact initials="J." surname="Grant" fullname="Justin Grant">
        <organization/>
        <address>
          <email>justingrant.ietf.public@gmail.com</email>
        </address>
      </contact>
    </section>
  </back>
  <!-- ##markdown-source:
H4sIAAAAAAAAA+V923IcR5bYe31FqhkOAZy+oEESJEFRO00ClDDDmwlwxqJW
FrKrs7uLrK7qqawC2ITosP/BH7AP/gG/+nH3T/ZLfG6ZldkXDrXrCD+sQiE1
6pJ58uS5X7J6vV5ydazuJMmkTAu9MMdqUulp3ctMPe1ZM9G16eF/6mxheuZj
bYqJmfRyuGLrJNX1sbL1JEnLwprCNvZY1VVjEtuMF5m1WVnUqyWMeXZ68SzJ
dTE7VqZIltlxouC9Kkvh/W9Xxn4Lf6flYqnDCzBIe60o8VJdphOzrOdw4S49
slpUZmqDd8qqDq/UWZ3D/N/DrROAWelioi5gKaosVD036qyoTVUYmAGv2lov
llZdZ/Vc6ckkq2EBOldZMS2rhca/Ej0eVwYw5l5Up4ITGn9AYz9b1Grv7L+c
XDzbT65hyeemynSe2ayYRY9rNRqXTc1TE2inV6aobdIsEeWwiDt37jxMErjY
GETZrCqb5e8fT+2dn56MLk73YYiFznLYM9rYP+Im98tqhkPDmpvxsaJ9v57J
1g++ghiSRDf1vKyOk55iCnr7/v01oO18rgFrMDbMAAibAci6q877z/u8+wbR
/qSB6zk8/UJX6dzYrKsOD7tq+M//B0kiq1fHaqSellXzL/9bE5E0RV3BxfOl
zgq6MIEZvx3eOzh4gARgeIHV6lP5oflgij9mNG8fKMnD91RXFmBXT3BXi8JB
+LbIrkxls/pf/letnlRmAY9cvDsLgH1d2nqq0znsy8HduwceQn7YQ3PSO3xw
597DENwfDE61gkvLeVnAM3+4+7B393DYOxw+6B3deXg4bGFP9bj8Y/0po51B
1gJGGTd1iOE/NbbOCvVDpYu6ffE9XZ3hxT5t7bIZ51n6xxneJgwkBRPyFZDT
LaXePHt6eHB4FPx+gGQGP5Hw5Oe9wzt3j5UeF1N57N7R3aNjdQvYQj15+vru
fX7s6MGdB8dqYSaZ7iHTW7gMt2F0vPtgeHiEr9MLx3xreP8B3Ts6uvvAXbnH
V+7du594rrsyAsnhg8NDB9Qd/nlLlWNb5qY2XQU4UoUxyAzwpsqA8EfLJdBo
9lGdynvDOwcwRVEve2U+gUtn568eHB0M8a5Sk8wucw275a4OHz54QHdqXc2Q
AOZ1vbTHg8H19XU/syXu0ACERjHR1WQwvPfw4E5/Xi9yfqcVPfgP8afJkVBq
Zs4MRUg6B6loFC/Vqn/97/8TRIsXN9EzcE/GemOWlQGBW/ND5VSRvKBRkTct
PefYEn/3hAlJammRa6+qmS6yTzwIouxcliLXZDYv8s5f0RUL4gcYFaA8lifg
DvCgR9m3jE0A6Vjh372DIwaoKICbc1sqfQUUqcc5LLwqF+q7f/0f//Sdw21x
lQPd2n6R2bo/K68G+AOvDJ6bmU5Xg2dnr88H02xp4eLd3rA3fPhw2F9Opt9/
3293tHd4cHCwtq3fun3Fe99+/cYeHt1/cPAffWNbnPHG4t+94WGE8eHDHRjv
4fvDh78D5/cPHh7c/xLOjUcK4TbGnGUJ8Hfx/VpXtRqCANc2S1XV5P8fMRzh
yOF4+LB3QDi+eNt707t41r97dNA7Og5xQreUu9X3kPSmlflbY4p05THVs9kM
oTdinG0u1u/tIc+7Y7fqpg8IHVQmHbzpvTl9KpANSAmenb45P979LqhY2mp8
bHD6cvCalBRv2+BJk4Mwz+DX2P3aIIJ4J05hC+fqTSksA7bRVZYa5QfascSp
zq2Bv/80+svo3cnFdnjBJkZYdZobVJ+D9yC3rBk8oBsDvczoygBRO2BSGyBl
ov31jP4EQAn8W7DNv7579fL05Fc0xH69OHtxuo2u/wTDqfNT9aCrcOQ+jtzn
kbtqY2iiq63D7l7v0+cnb7YvNs0nVb8pMrRhxCj08L3ly/S2el2V701abxk8
nBgf7T0/e/nnHbSwPh2yPiiEXp4VH2wPWSQE4Jxuqud4k+ToxjJbI85DugXC
i3cnT3bsNYjxfqYLTcAQt3wCS80O6k8E0wYZnpdNlRqWNCSG8HFitYle5dls
Xiurr9BGp7s4/g6Aei9HL85e/vB74ZqbslptgHVBlwmOZaVnKP5Si5oE3Z36
E5moAuV2gN7cuceW1Tokslk9gKPP7kI/K2kfB/lkkQ/q6s49cg+YZW+dN8sl
q0Wd//pU5wbF0q8nbtrNCVA8hBRRmSW4c5YGHuwUKDvfuCW04KY+mwAo2RQE
0DbWc4RzYdI5/ET/RQSpusUYCZ96XsIThnU/eC4fmqV6Drql0aBe9p6fvHi+
vwW1Z09Hr3qvR8fbph8Vhfmohgfg4tJOPS0L9N3ICijWRN7T7CrL1egqowsO
tJGp4G5TE+wXYJCAxFogcli0PpLH/lLmDZDj2RlMEdxHrk7NpAElCroyzZsJ
Ue68tIb94dejl+fgCOm6AX/yPlwwk/7+Li78EryR7gyw9KcmX6HGO9q60xb8
H9MHYEvSPBrR1Rse9HSw6l69sereFS23l2W96EZv6Zfb88vt0XJ7uNzeUsPL
vNwEHJdlmaF1B5vjABIOQLUQMAazwzgvxwNwuooBTloWg3G6vHt/kAoh9j8S
y4LIHvWA8c9enL0bXZy9egl46530gZo+lL1Mj5GXdG+RFdlCsAVQA7AZcFXS
7/eTpNfrgYkB3qkGcZwkF/PMKlBNDfKcmphpVpDtqMhVR4XvqKt2wQ6xT+Vh
NF0T8f5IrlXOqkJi2B4RCahF07gJiicA7qxWEsdwDiV6jDi7XZoU+DBlowxm
aM1dvJ0jb8EfU2vq5PLdZVddzzNwumFxRQl3wYSrVFNMwJCoy3KCa+pkiyVQ
Tz2Hpby9eIqP4kgw9NRUlZkk9ANsIcM7yUK7BcWwfdR5BBaaUTc3DPjnz7CM
n/8rU8Evwc9jpfYI2Z0UBu6opQZJW+nlHFglz9XYAOIW5RWMOl7RNIAA4JcM
ffj9f/xHIvALhg+RqyjsAAjY6w2H+4hnuG4Bb0g95FWAoWUyHA8oFjF9dnr+
A1y8ysw1gEh0sMgmE6ALoFVgvqqcNCnh9OZWhn9+TpKT2JNQujKqsbTnsHMA
wgrsdoQEsGJq3IxMYlyJBkHuOKqrNCwRF3WtV+y+gVUL74FxOcHNm81IcpTK
kTuRRjFJbDoHjgNdOgOYTzGMAn4CUFZaw0xo+NdEIKgsUyBawqJgyEE5MTat
siXGBFQNVJ0I+Ta2pT+i635ycxP6JZ8/K+stdFw87NTE5KuenpRLGD5Z54gu
8Y2uclAXfn8AJ0yKfnAYF59H+pmbZAxuhNe1PkIYBAYZ2psbYQgksB/LawPj
d+GdzDp2BBSX17ZdDkkejASBTAF9AKRO+5VnNSiRJGDMCiTgFWPSc2g/eWJW
Je77nNe1oqEAfY3Ok5CV4W2NuIbJtJoBkotAUmBoheCAjTEg/AAv4E4BzcHO
GuQAkL4rEP8KbFONW43PZjVvXAHCy22AwqAbGMYisDLcDdxn2kNwTBrymlVI
dMzZPB3sSjpPbIMSYY1sOHAL81lbphkvxVtmGDnr4qNlBaKDJKH+YJDIYbUp
ReqU4fgrDa7tdkMOpC3IUgKrn7xAbPKGA99EIDMavLhlIDbkL2InibDj6a9W
udEWOBHe85SHNKKzCjB9bfLckS+QlDgySFLPmgq3ZwEasxvDtKDVXCPOcNUM
IS5a4cORWGdIW77oBoKeIm0lwAeaSegFV+UYXtmVrc0C10ZAJ0AFdl42+WSN
qYEEbt1S52m5NF+lvewKOOCjt7iFNWCjvBgHcg7Zy9ENq4NpiWyFCwDtvzRV
Db74cZLcJlkczNJMp9lHxDSmHzC2iHS9ZA7rAvV+wCHMRxJe6CZFE7ZwUfKi
ztBvIcIMGLzvZhV+z7Y9Tfqh5+YBxbVsckKuRwJvIAMREzoxagBLRB/x3ICL
K5CFyIUzA3ypc5CQE5LuLY20Igam2iSTUPAmf8U9ngqLhULNxnJxW+aEn5Tk
SX+DKEpjifBERbabZh0gMtc10L8hArYGxE2N0R1jm7yOrQitYKdFSjA/EsFk
VnmDgaVhsrckVqzUtKnBatwnM4Pc8+QZhZqQf1MUMJtgEo09o/d4m1i0akQ5
Gzt0FUjXlot1m4T2tMsLwowChbD8colNstZ6AuBbQthzcgzkawm6Am1kGGIC
wztj0BRgOiqy9Gya7fBdwSSZTsHjJ3yqDakbammxdwJyuK06z/JS126wDqCo
b/rdeO1I8pi6CkmLlf1YyBtGRZSzWagin9vJGRXJGW9copxhigdzh9CE0KGw
AtLKprTPNVsyMENXOazFTsyoLhdZig4yzrt3MTpD+vTae4dxrJvZwpnPG7S2
ABYbY7IU5E2aGRbKEwAYUK3JsAbCzjBVleKD9bUxHMhkv5BMOVgV7OC6IhdD
OxDeblFumDV8+lgqIjRBCbJB1wE0IDdFlYB1Bzgdm1QzbonUPbF5UiMhDdZe
2li0OPUYjOMubCI87HwEkVe8oy1ZI8SEPVRj+God7JkLiSPVeawuyfgFi40W
JZZzZWU6cAfKCl1cfA5s9oWVF8RKRdPINgtHrSw+UajNs5wESry9Po+Behz8
dJRblNkmU4aEgAhV0CHxRgPPlPkVWG9rO00ihEmD7XM0oxAZGPMmAYGMAmQ8
RqOa/Fg2neC5ckwWYjBRCC2qDKYDnrxh6xBctcAocqKVZ2JTFgPJWSUZDnS1
cCdQIHVFHCbOcnSuXWRvsC53iguR7IQyGcuMLrC6wJpABQdARBbyy7I2Itpi
Pc3jta6r05mWdYUojcwmIEmymTwjCCD1RrK+dt4GIHva5C2W4rUkQMFocrHN
chIQ6M2tgFw/o84y6oMBAw1wCi7ii7fnFyD06P/q5Sv6/eb0P789e3N6gr/P
fxw9f+5/JPLE+Y+v3j4/aX+1bz599eLF6csTfhmuquhS0nkx+qnTJSx3Xr3G
sMLoeYeRE6pS9P7Ylg/kJHBpIlKXkfXk6et//qfhXdiPbzD/OiRHiv94MLx/
F/4AvVTwbOSW8J+wDyt0GsF/IsYAhzHVy6zWObqPFoX0dUEEhMbIz4gZ8Km/
G6fL4d3v5QIuOLrocBZdJJxtXtl4mZG45dKWaTw2o+trmI7hHf0U/e3wHlz8
7h9y5IHe8ME/fA8cl4DsPU6O1dMSiCQriHek/gCjdxm6KoAojCEhRyNnZRi9
wHSqU7JPgPF0g3HFSFGhKfe6zID0QK6/AKMHQ3p7T85ev9jHzQBJ874pODhA
hiY4GUuscTBwZ0KCGtwz8IbSVp1/MeOCUggzly7A8qwi+9MlYsBVPn1zjnys
4Bbo2OHD+4cwalU2szmu536XFNF1vFzUcRUa3gDCzoWq/NsfDVpVsLwf93GG
J2aKjgzO0Q4bS2HQCOWsIBuX5D0FJ9kI0ZbMI5hkQUDA3GATwQMTULDqfQPK
bpKlzPUccgh0EcWN/9aQQhLj3CyWtUhm9j3W9hhEOAp4QOICPD0O7bCNVZVx
TMwgzoFZlAtvlVOsYFmAzgAntqBlcaiLZLhVP7y4iEIY3uYR6NhgchjyApJF
gnayEOQgapcSnfXRk5fPkGRHbNLAw090+qGxvZe6qchyR5vOB2R4MG8bqiUi
FRTVmEAQmc/BAdBhdZmWOVp1uUTRifwD0U4aAUtRmJJQxlK6Nn7G13s8QcT5
N0jagd4qK4okoQJLszpfYZTyq70RXDtOS3VRRC8bsVOAwJfI8U2Ym3YwEL3o
1TjLgvBZqAYMrnE2a8rGthjz+68xvgjKkry/NeO7T5JEvSIrDkc7EYJMjTf1
XCgnMLeR8MnWbWxDTMFPUEVVYWZUdIO7sSwx0gG/waoWgwo4o8EUD2IHlLFG
D7kbuzFirmNtFML/0lyrn8rqQ1e9/AmY8nzUdbr6mnSPc34ODw7vdJG27/F0
aNiZeeZAtSWV9ARGKwZgewf3jg8OOoCHd4RM570TfZPbVHjbkcJaNcnWiQGh
QD5v6FRMYcqDAxjvkfCXXZbAXarzrsmbDrsIJA+fjl5xIRc6ljpfzjUgG9l2
Y/MooG0wWwujdJB091rbgUe8uTk3LI8PhWrZ8nHBaEkbcahR5MPG5P19Jiv1
DsvLGBMcxWU2iSL5bNPlbNjMsyU+Fuwg4Amw4sRYSH3LXKeG3cUZ2o7qhYax
KMeIZNQV/LIRD2YVbSFmkRq0A5GWEeVTp3/IAFvo5Xqks90T23ceFyU9yVRz
AhrjIjQt6jSQqnUYAMZh2iWJyFjR+xorkMZt8JuxwZHvCSid1AU23LDtOEjZ
ZThNtw3WpPrKkI0K/yHjuX3Nkj0/hwfUJ1Nh7hpQuGjyGlM5yGQkFkMkTBra
hgLENyihbU55EAuAwUqKx64FByLSXgsOIEbeFnn2wWx5NMQjK4oFaBkKnKS5
zsBn0lhousUtnwokPpLcLmkPpYcPYuJTpKthkAY8rowT/EhxoClQeOJCCYU9
AhoDduJViC8Lb3bIWQTc4mxVZz8mQNpoF0gEk5Pd6wrlWWGuJWYm0HlNPPEC
lLRTTEORzOMUBzIG+CcxJIhstrjDWXC8c7gOFhL40DYtu+qpzjNYbJHpTgw7
haDI65p495pZP0Z3HD+KRidid2VoKGgERCZi3LkCtBXqwNHLkVoTHhgCCKPn
Li7GQeCWcfxrlAtHLKo9kp1In8Cc8ORl/ekSafQSB0J/9HI/tPSAvgmAmxus
hfj8+eaGK0FZ0b8obc33PSyIU1ToDKLL5OWYMIZnSeuwWdHKLRZXwptzeNkK
7Vq9CMPzJCu7yvRn/a66PG0wTDx4jUEOXsHIZnpwUX5YlZcCr9RuUFh1m1nC
IpRBjZcRbA8KhCsx0px1I7GqHe+yE25bt5jDQiqzgZJgSFBgLX12FBGXNhWZ
rPIqs9d0LRt7LBjaEdgi2bji7WNTeC34iGArpv/SUaHkZ1YEmZdWmvKbGIDw
VBWvNqESASIuwDLbOuv0uhY7YsB0m2puuYa3V13+4eDB8d17l11xYCwX1aNb
INlES/YGrcOTSgEmXBUNF1m8FAVKqNKYavdDRTFtZcdxIsUSYPIc9g7u9w4e
XIDdMbx7fHCfwfqZ//cLPjgqvMEj+XM2cQjhPtYMCt7IhoYy38QCyIaxJjBt
2cIIr33+vE+kPMpZbXvE6NZllAlajuSNts3Smdjr4QZc/BjchWuNMRGX68hy
ZFYcEt6+bCvecFsnrtztMkxedB1f7AKhrspilq8o2AhGJHgSE6oKLgJx0G1j
fy7SACAtV06bITvK3qLY1JEER3YqNqaP8ooW1manKGd1wepQ5hP1J4LdRgLf
ZZ0KorqsWDY1An5SMm9llmsLgPEpdwVL1NaideJFwJq697qNQvb8GGoL2UYY
q0CjR9jQFVmgUHKZEg5MVhUX+zldRyo4jJ+yXJlMMMg8plqUrjdJrjE8vEvn
ensa1y9pqEnsWCBdAJMc9A6G8O8FGed/OBjCf38OpfMvl7wisLRbuAAkZbOP
MMSiLOq53chV4ZJzlHDSOMGFvM0CWFyi/FuzIRRnaOpWKASYCX2NXYDz/365
hGEIaAlYu5A/4dvtAeHWFZXA5qJUQ2yhgyTiQHBKRBSrLOBjLvc8plqvUqwZ
rkVEgYHeHRYL3tzgc8hd5IxjdafzXaTgDQs6Yd+Bu7NmgYuT7YpGFE3jIqYw
PW7lRmaZbMcgCdMVP6dt1hA3CJs1AKjEuUd38HpQetFtUyBL5IqKQuRnF2+9
3LFYBhKVTpOivqXeYtYBd9RL6ptbUvRD8V0MbWC3FaiGpPXP7vbvRB4a1cM5
LdxKBZ/eu3yHZkMCqga3/zLW2p1thUpqR6FSslao1GcjQSa87LkJrOcjdrUk
i2s+UoFFwhN7pQ8EJEB8KMrrgltoAg0S+VAoYJuCHuy4zGzaVikuMs6sgM6V
OH5wE1fRxk3CfjoAgbqX1NzoCaVpogB0i/s7HvfY+4MxHe60YOaZJC7QteMl
7B3CvSewwxlDMDMOSFE+DRVNVyQESmQ90cva9xKUSZj0xxCazgHXNkHVBmIt
s230dKpTYeSwJungQNbADoOUGKHK5NQxAYFSnuKGbofRWl+4qtqgNEb6ntqt
ZukUplncEIl3vZREvOAt1KpIrRheArRwkoOYhPxQxyWy7VFmxGfwdvMJ1oxl
s4KSYnXrMUvicokqA0PFoQ3qwhSOwgE2gGNhdNHKXW3dmo6TfztRq4Cov8Dq
5JBdZT6uqYnDOKyLGf6b4781JYoPqug9m6p/N0Co/FjzbymHc6VOrcKX8BJW
JmKIJptlaLMHpWv15tZ5YdFhRHaQU/20y6YCFWGi+kupTWPq3krPoWeP7+RI
jbSv5MKDl//oS2zt2N9SlpKiCDjQmjBhDma4vAlMARaGvCphngWpasU1JOTW
W88SxFts3kVIZFHd8Wtmic0o2VFcuktmrxVyME9hMtMmaznNiE/XS2BVqz54
mcxvk0cJLRX9taxgkDiyrdvY2teAm+wEl4CkIIqH9KtkmRNhkeQifZRECwNg
mtRYiZFemdxLAKYUdg9oNuaABKudzBWrBud1ossLnk9TAV2FCeCY0udcqEHE
kiB0pIKQCCbIVSkJOmIQyir3k786KdVsSMHulj0C+SSlJ8C6YXQRdEdCYdO+
1ObuTDdMo3QDppWx35o6PiSZ4MSv8I4rqOD8DbGW+htI1AwL2xCXrvnQGRGt
5btR7UYdIRIqIw+cKhlcLSIzA+c2bKT6cGhUHlnRrs3lcyyTvKRRAB6/6KAT
kvPlcd1rXPpZylauwio0zuasVbqS9pZnOFA7xnjH1vq8oPx0gqYzhlkpMA9E
dbvWM3u7S5WmImnV7Q9mdZtiBfD7SueNua1c3SsHG8CSQezD/oCu69Oy6DmJ
qOqZk+NU0OkM49oscP9cKSUMNF8t56YYYKKFx0I8jkKU0DhNlk/YZ/B90oFr
c5v39bYLZhQrjF2MgQPKacLVqrhIGPnPZsXF4CjWq16KITzM5YOJ+RcEn2/i
5R6e8cD5oKYgsd76eF54wIjnZM67isl81QOBTiK3TWFwLS9CRiwfhCTWjEMt
BMqk9MbM8DFKlBLcONw2qlIXsDhgoUpeMBNgnnOJm8BOfHCLbh9A1GMEI185
2yMEpRWOLrYhXNgXBRORoYXNhT1FK3wq4eA6GMIhgbrlFXbLCxzki0kzPSaA
MkQO0Cf41SR0ElLYbCg6je7fbEvffLEUoL+clY2lVCcgTLU9UC6diZUqe4B/
F3JHx5VR3oNbl2xPY/f/58/7ScIbwIF46QbCgTqvHVw67yBtd17TgQcwWSdJ
TlzVPkYVMVhHxevjKjPTtqK/TZfBtOi5csiQjj8AI4sB/uu8FCNdruM75qrM
r9yexVJ/hmFVYukrJmU2bwhvOM2WvUu1a2kxYmW0/RgwGRXhUzxEWoJIcLIg
xtdzQI/tSumZTySQxSiV+ddmrJYaA597b988txht88UTjB7/oks5LB0yPe1K
u4AAykm1PI9X799u9yZ6HytkM6mwhvfqwG7A/NVaoS8+6avdqGQ8m66FIPWC
iuhJ8CI4GI8LAXrkeQelSVcSb0xQHLtmQKTmDR0pMejWYAmC5UTVUvFMkNfY
0u2sY+4SSlHQUglAIZKCY7GA1oyjBC1B5VR7cpVVZdE29KdYEVOzCe7ExSNO
Q5EgwSgiFm55vc/d523HOQ5CoUYa4j2vEatLYl+ODBOPMslsTrNZI3Ud1LCA
ccy2kK0I1tEXyctna4iw1SF1SuiFqhioABrZx78P9IHLSXLDJe70bOlKZyRO
5UtPr+dimy0aS7hZVtQ+4cr6X4n8Vz/Q+/hHV53mKDVhV69sXz0VtUChpWax
lIalbYqDQ0mbhon1Ip3FOXvh6rYb4zYJuVUimhdYGbN8FZib05rWJ8UvVeuu
83LrsnLyiGtV+sneqAgtEylulGBuYHqmJsGqRpd5CEDsSiock/V/lYrnKTdr
UKFRKljaXBXY4LeN4O72MdkWYLRmy8wlfSpDJipYC0TsxSoYJErauSrVxC3r
jdG2rdV0os9b/O003nT2VKv2AEvoqzJh7UcS2AEAJEXxYFdtScP4Iiwn8ckp
Fj6jknT289mA8rFhsIPCdWFWnXAjyDN+EkDJbUc8TAMRvhI9EVdenvd5gGDu
ry8NEhJJxCqSklIpzY1SNnoWtauAAhopB6c8lNCOWb8mIsy2dQVjUeAekVIb
Vzr9YFpxZz6muRaDZaGrD5zfuXQT9Ka5nsUaXWK0PqcdFjD7RLukq7YmqzZD
8UniRG1FTPw1Gaeuz3GHQ4HkQneqTvBGmCtp/fVLhoAWJQ3Eh4dse7ePz9Ep
dxVO69uBWkcYy7En1RrV6yyGgPiUPPWMeUqJ6rcfuf2vK5eQc5SUbBCQlIpj
rnFKsTFQLX8P3UnynaZeS9ziSXldPO4MO9+HMQUYDmR60MfKaCdW2YL7Vqwy
OLsBeLe+1V73m4/zbIz9F6KV1krapfcn8plx+95dtkNwD2+Qs21DFuHWr+Wp
+8lb64y/LcUInAMnNyGkrKxImA4o2QOD4mK7Ijlwk6+wlw3V3xZkHLrdONxC
/N8NaHNgP845Dk5lUYUL6jnSkwJ/X+bKgnvyd1kNBqnqx2Oqdshhuj1tXbvC
donNISPulnbpklYyq0sa8HKfSiHZCMJGJ9e65VijLUdoWaf792D9JkbNTpr6
pgGv8zE2soH6/OVn+uu9Xmr6c/dr8VvffO1r36yjkLx8ih3qwsutte4bNKRw
D4Pi4RaJA9JSia+vQL7kBIyTvCRRdLAzpG+8gLAm0slUEoGNKoUB301yFhj6
Duo9QkOEBmOzUmy7WpPKlUoqNuc5E039L977bvuCtP3guAi2unLlUtKkQr5n
jJGdpQOBGApjFi9GP7EAckAFhSVBEwt5/YG+wPBSiHVPkJFZtbmKZMcq4n3t
t309K64pKr1FR0J+UuLOkX7dPrN7M1INshdrO6C27QBVqCYAC7pOHNj44vpD
09DTWeLoDA2k2EiljfDDY2Eh39vkaJQGIBbXlilHBnhJ4nqHv7iLSVl4/zQg
GaLTdF6WXMumphnIpKiahTt14QcajQn1CX5BF/0/EBtsrNRYJUzcaCY+vcRe
zFm4GZcUjGX1dUl6vEfaJgw84YELAUvQhmyWA3HxlzT063hgMXrZNBUj0CZB
wsgVdm8WdDuu9FmsOA2H1rtXFYF1II7O9sj51vReEo7Ljbpxkt+bW9JvtW2F
EtSP6N0nB8PBfJqKkLVRM0NubpGwCRMGeCPTVrf96SGDpBQ0o+NlNjr44uNP
kqmuetzvBtKYU5TrhYZtfS2nAMOSuG9t2K6b4TEDY0tHtNXo6VOkgC3LcZln
dr617HfdROcCEewNdik/jho4fKKdIRmJEM+i7rU1GwHYeKeixlBBeJdDP8aL
HYWOBWUupYi2juxv95YuNtUWxtK2WdH9RFKoG3OQPQPzkLVGWmWHId5PRmnN
OmXzJiEmK65IL7C8dvovqNkrq4R1RxsSDse4yvSu+kinkUgNUTVXAqgclL4W
bEGFvWB2ZNRdE1cWe4M8qJaS9hJ6pBer3ZZQEyfnuGfCBRWo/Xit3XqDKYEQ
ONMYHEqy5pY9L4sJigTaZhZGbOtF/lc3TjZZib1FQf6da+m2vfusIBKiUmx5
AlJq722jpO07veegiQvtvP50FLbf1hNxM5zamDmJSQ7+2ts2sNOhXEm5w0Q+
CE1kRuxOrSVPrz18c6xubUMiny32uBPprnV66qBqcn7izqoHpGBON3O+36kM
EUPhJvtgDOb+Z2VIe1GR+nqXelZFCUUKb/qi4qAmRaqhpQB3PRjAPv+XmSZi
mT1Xi+m0ntP7yfr5BuK7Bi1ru2h339mQsU4L6vdXPjnOxZsYqAvUR4AocFLi
bLnDllrHFohKxlB3y5k50v8uXoZbA1kfvncB+SOailL5LSiNd7DZmy6n2wW8
PzcnlhYScxGU7d4SSTMn1JSyU9TNqa6NOFOk2AYHMl8nrfPFB07Uvkxe8hlb
nSmKZrf+chKvNCBf1/Xs/b02jMSkRVYldUWDro/K8raqjN2y4t3Xiol3X5IQ
m/LhZbkmKbNiq5hoPTpfzBGeTxDwJ53WFpG71OSYhCq20IklZZSm1Pc842b/
VqpgFDisZowLjpIvFJ2A4CFhYduwEVVcnPMpAafRSTFB1ed6wyZZ/djr6goT
XOCVaZ8fJ6rBh7YcQhCyJ/hT7cEKVA4j6ilvXFUWlh+5TIlPdV/8vvBzZoOq
SU5jJNRicdmWkADgWD3YXmHbjk0AkKre4AtbZdf6E+/1j7B8IKjruxw9f/3j
SIY6Ofvh7OJy/aUn/WHUjAtA/Df4h0+Up9mRs3p8xEWuHisaUg1Up9/B//7a
CZ4CK7lC4n+sNt8cKAIA3+nRm38I3yS9suPN2/EE0pwR//PIn3qFcGGKu98P
x6c+kbXxac7be51BZ+3ifvuin+Cx6vzcUVGsfisgfHhoNO1AxbuoOr90kgR8
aL9CN0WeUsOo4BWfcBh1T4RvRRhN2qqA7U/fdsMl7lF28+TR4W2aGoCMblu5
Hb0COIMtDC/tu5cwZv9vwFgAfOdxPLQldInuCP55rH72eP7FFdTg/EkSsZU8
7K+5PE4SQeaGVJ1vOgrjDoKMcD5H+YT1xO1V+MR/+ng07N0fEQeRdCdXghxP
Eukkk9w1Su5uE3uwfjq8mE4tRQp63IlW1EfejCW/cxYQGSRlSfClrpIyOLtF
+/oRQNVlN0G2aWP8kl7cLJZytak6D8xuzAe0nwqIDn2S6qULJ4jjk7AuY35D
hVXj50WIeelsFOBeZ3C42sBxifZEhaaKOyGAUmqUOm0zKHIqJ4Yq16dBg/8y
Zs5LzuW1pdZj9l+IcVn+x/2XfTTL2yS0HGIkcWOvd+PDJ6gyua0KMm0ruM+E
dNtRrEQFKGuvr3HFmLCWzI2HJnnn+/jozB4uL+KgtUR1bFY30tRhyZYtJZcd
ueFAqJQTwdpopKhjNYo7D6+RUTAazZWgxYx6zLj8bmMnwZgKzh3UsJaP2QL4
CF4Y3sUwCpaTY6hT8vmst0kxrzVsvsK2I7AeKJDpyrP5VDS4lEpBKE3GZ2ng
t1zaGBS1JrrGREVVEdLttXXMj6mh6KIbkvYZAdwgGOr3we7wBZ+pyTYUUU5e
lmhqNkvX/DPx2+uNTinuR0PZV0lRwYxHLjvoG5gNCjwIXSJHuPgdSxTHRk75
dId5XEmU9JRtTBsVrYrhiUci/WikAofi4O4GbtnvOg2Q7Ibs46SeJsOHD496
w8Pe8OHF8Oj4zsPje2gJY3bUi8ZqmqKw818scjLSG3+txOao45pLiQLw5mZ9
lDDaYhWMIgdiEI/cu9+eoyOFf0YNj2BwatgC2+kE/DEqwxw+xH3AZWyp5eel
+DPp4jOwuGjVuatqi7t66bBzeIC+AWEHLXPpDWE7lcb9KpT+PCKfW4NbYX8d
FTNwdOwvLZ79F6HqT9wsK6poEhwK3fYEM1bX3omRKt5iWu9coESrrzI8McU5
lmOMsXnXCpWSlFnw8/NmoYvwdID2kFjagKxO9jqvNaeekf46+17lMJewqFwv
TvanyCZyiuy/B6ucnZibcWWu11DMTMW3HI7lUwziSOEqf+T7LtTdYjt8/feg
m32yzBXmWj80oyM6G9qlH9wjGBFxTravT3UNhlm9A+avxd+v07J8PNbVLz//
Otaf4Fe9FWPLKruiKEdEllHVG9oS65iS18gpdWdDbJMGXdXUWU6HSlPxXOYq
bMnVj6ahjvQcXGUEIChNpGMp0pwyUddllFLLTEpyctvpjmxlPZLQjlS4hae5
bSkw5N0Iywgpxh7UPnqA3UG37tBMVzNOyyTXGm0vpFclhdV/Niv8uJokWUZI
HgUWQN3c8gSRJK8a31vqDz5pM5CcUY0KFHAGMqLQgU7lfOokqPgKDh72J4FK
Gtw1HLqgANiRK+WbqKicrH2XehfDM3N8PwCmkeVDTFgKT7lUOj0s4dMit+Ka
I5IyoCxI/A0X0eA6cLR8gxSsa92j84jkhfA0ibrtym2R3dZ1o5nz5g6dnjGi
xHfDloxkV8eYOMTegTrq4qXvqlBzO9Wl46EbGDks6oQ/yyL9IVcmL5dEHK5l
eFtnrxwV4kNeFLhpvwcjLbhkZ2LlJzzjTna5uYVfOqFQ1Wc8b78ue2PTk8P0
f9m8Ql+LU6d8sj7YXYZKfgwfUwS3pG9eUopwgfxD3wjByMch2MpeuHpjNI6N
OxlFjmIxVkxOQyjBBJ1ui+/lrJPOhc/wClNcgL+IrQodNhwLEHT+Jfqeo+rs
PCm+0+dz8r3hGVRMozylgxXZ0nY8teUAXReWCnohPmPMmL12Ogoe1YA/61OG
J3Mt7Hq4uYF19+JRkt9U3FagflNbegTgatgEsMtJ/01tVP3TeK5fLXoWpibh
E77uuw7iq76OzPMLMtLr8Kiu3/ibCmvghKpMglhEHr+RjonR0WZdGLFPGbH4
2jai4P4Vh+2OnBtahbjDc3TTFRd0Hx6xGd45j5Lzb6TqhBs32z4BpJjMSCNC
5xSFeg0P4wcjOnzIUtAUgMdnIEGsp766YhrQy+TFAmiNq8/XNoXr2h0tgb1W
NkuTuHiAHH86wrzrmwbQ8XQnq1ONTEPcBKOuTC0uPU9q2eHm9GE49xhPNMIv
hzqmEN3A3n9CctSTpOvPR3puZnhIEJ1uNw3OhBQjhnSR68XswjBmKZkPOswe
6aW6MnJCrFdZ7fCYuci54b54X67oGxNcvMpNBHSMlprhR0tarapiaL8lry3N
LOlOnwZ3CBnjB24Cr33nUicgBcuVqClqlzRSrRRUTcupwjqmu9JlmtB1zahd
DJvjAAn+9ODgaTpSjc5JW5aUXMFcPVdJpMDCHJfos1GGIVfex4xF/C11btKm
wj7PWBWIW0kFRYDyk8ymeYlnmTJ9+ObQ0oeUrnRF7oC3mRSeg5WDWbWKpCJ7
W0EvJBe+o13m/HSec+Ln7GMRj3MzpnwuIlouq61PI6v48pc2Dn4/Cp33w/LQ
SXbV5DOuJ9nUppsfVpB2TndWJvUlzUtsoce9dUp918EbbXs4aM1k7bg3ObhM
TvQIPz6k/MeH1DUb8hgEqEG1b3zICJf3AmcPzr5eclNJtw1tsf+/nrEtDBt4
qZADJt4lqBR9dcB3c2x+UsMm4XkgaF0Tfv3XN4JAmLMBNvJ6CEaC5FBVrqqA
aq7hBUEKbhfxQ7jz09B4C+bJgjrcsHct3gw5WxoxL7GP+LAH9ZcmL1xnNLal
YwiJjvDkgy45OeVb4Tg1RRtMu+maZvyZAkLzCRolV/HQ1Lq8dtIEuAzWHZMe
njsOpDiVz1q8LFUam3QoizgINo06eAQ6rl9ieiqtwW0HtVIEgqxsHQY+K7la
uQYjmgRrKJGlo2oH+spccrajhqyeB+JCV7V1gdiw+EtO51+vWyEHy/B5Qdhr
1OWwsTcyg4h78FGtLWcvkK88Dc7Y36ym5T4rHFmOWQ8GBwjwO0zECDIRVrMa
ErsBwNEXtlzloD97Erx+Og6/PW2QjgOwTijLERDg2fOZeFJ/E5f2YEBrwrnt
BBuiF4bir3SUCnXAOIIPuGy/y+F9/sJcsC4pCjQLUV/iuWB1Nn/yJvjyF4el
NR9q4A60d7HseOfoM4r8pSw8hww1zyhFugSrfWbkrKDjpmDfgNqF32QYTJ6o
H7KxlZ638LvbLUXxl71Q70nPIg3H/h9/HM8KifN5m3SeQvGBT2rEQ5DUa52X
izHIFSIIlHajE/99r/8Lw9XEuqR/AAA=

-->
</rfc>