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4754397753
Document false and null return types Cf. <https://news-web.php.net/php.doc.cvs/17645>. git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@351729 c90b9560-bf6c-de11-be94-00142212c4b1
206 lines
6.4 KiB
XML
206 lines
6.4 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<!-- splitted from ./en/functions/datetime.xml, last change in rev 1.8 -->
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<refentry xml:id="function.strtotime" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<refnamediv>
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<refname>strtotime</refname>
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<refpurpose>Parse about any English textual datetime description into a Unix timestamp</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type>int</type><methodname>strtotime</methodname>
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<methodparam><type>string</type><parameter>datetime</parameter></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>now</parameter><initializer>time()</initializer></methodparam>
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</methodsynopsis>
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<simpara>
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The function expects to be given a string containing an English date format
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and will try to parse that format into a Unix timestamp (the number of
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seconds since January 1 1970 00:00:00 UTC), relative to the timestamp given
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in <parameter>now</parameter>, or the current time if
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<parameter>now</parameter> is not supplied.
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</simpara>
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<warning>
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<para>
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The Unix timestamp that this function returns does not contain information
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about time zones. In order to do calculations with date/time information,
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you should use the more capable <classname>DateTimeImmutable</classname>.
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</para>
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</warning>
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<para>
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Each parameter of this function uses the default time zone unless a
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time zone is specified in that parameter. Be careful not to use
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different time zones in each parameter unless that is intended.
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See <function>date_default_timezone_get</function> on the various
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ways to define the default time zone.
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</para>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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<para>
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<variablelist>
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<varlistentry>
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<term><parameter>datetime</parameter></term>
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<listitem>
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<para>&date.formats.parameter;</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>now</parameter></term>
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<listitem>
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<para>
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The timestamp which is used as a base for the calculation of relative
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dates.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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Returns a timestamp on success, &false; otherwise.
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</para>
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</refsect1>
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<refsect1 role="errors">
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&reftitle.errors;
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&date.timezone.errors.description;
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<para>
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<example>
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<title>A <function>strtotime</function> example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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echo strtotime("now"), "\n";
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echo strtotime("10 September 2000"), "\n";
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echo strtotime("+1 day"), "\n";
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echo strtotime("+1 week"), "\n";
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echo strtotime("+1 week 2 days 4 hours 2 seconds"), "\n";
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echo strtotime("next Thursday"), "\n";
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echo strtotime("last Monday"), "\n";
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?>
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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<example>
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<title>Checking for failure</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$str = 'Not Good';
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// previous to PHP 5.1.0 you would compare with -1, instead of false
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if (($timestamp = strtotime($str)) === false) {
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echo "The string ($str) is bogus";
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} else {
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echo "$str == " . date('l dS \o\f F Y h:i:s A', $timestamp);
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}
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?>
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]]>
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</programlisting>
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</example>
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</para>
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</refsect1>
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<refsect1 role="notes">
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&reftitle.notes;
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<note>
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<para>
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If the number of the year is specified in a two digit format, the values
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between 00-69 are mapped to 2000-2069 and 70-99 to 1970-1999. See the notes
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below for possible differences on 32bit systems (possible dates might end on
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2038-01-19 03:14:07).
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</para>
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</note>
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<note>
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<para>
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The valid range of a timestamp is typically from Fri, 13 Dec
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1901 20:45:54 UTC to Tue, 19 Jan 2038 03:14:07 UTC. (These are
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the dates that correspond to the minimum and maximum values for
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a 32-bit signed integer.)
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</para>
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<para>
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Prior to PHP 5.1.0, not all platforms support negative timestamps, therefore
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your date range may be limited to no earlier than the Unix epoch. This
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means that e.g. dates prior to Jan 1, 1970 will not work on Windows,
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some Linux distributions, and a few other operating systems.
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</para>
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<para>
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For 64-bit versions of PHP, the valid range of a timestamp is effectively
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infinite, as 64 bits can represent approximately 293 billion years in either
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direction.
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</para>
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</note>
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<note>
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<para>
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Dates in the <literal>m/d/y</literal> or <literal>d-m-y</literal> formats
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are disambiguated by looking at the separator between the various
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components: if the separator is a slash (<literal>/</literal>), then the
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American <literal>m/d/y</literal> is assumed; whereas if the separator is a
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dash (<literal>-</literal>) or a dot (<literal>.</literal>), then the
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European <literal>d-m-y</literal> format is assumed.
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If, however, the year is given in a two digit format and the separator is a
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dash (<literal>-</literal>), the date string is parsed as
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<literal>y-m-d</literal>.
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</para>
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<para>
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To avoid potential ambiguity, it's best to use ISO 8601
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(<literal>YYYY-MM-DD</literal>) dates or
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<methodname>DateTime::createFromFormat</methodname> when possible.
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</para>
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</note>
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<note>
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<para>
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Using this function for mathematical operations is not advisable.
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It is better to use <methodname>DateTime::add</methodname> and
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<methodname>DateTime::sub</methodname> in PHP 5.3 and later, or
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<methodname>DateTime::modify</methodname> in PHP 5.2.
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</para>
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</note>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member><link linkend="datetime.formats">Date and Time Formats</link></member>
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<member><methodname>DateTime::createFromFormat</methodname></member>
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<member><function>checkdate</function></member>
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<member><function>strptime</function></member>
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</simplelist>
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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