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214 lines
8 KiB
XML
214 lines
8 KiB
XML
<reference id="ref.http">
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<title>HTTP functions</title>
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<titleabbrev>HTTP</titleabbrev>
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<partintro>
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<simpara>
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These functions let you manipulate the output sent back to the
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remote browser right down to the HTTP protocol level.
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</simpara>
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</partintro>
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<refentry id="function.header">
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<refnamediv>
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<refname>header</refname>
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<refpurpose>Send a raw HTTP header</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>int <function>header</function></funcdef>
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<paramdef>string <parameter>string</parameter></paramdef>
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</funcsynopsis>
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<para>
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The <function>Header</function> function is used at the top of an
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<acronym>HTML</acronym> file to send raw <acronym>HTTP</acronym>
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header strings. See the <ulink url="&spec.http1.1;">HTTP 1.1
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Specification</ulink> for more information on raw http headers.
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<emphasis>Note:</emphasis> Remember that the
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<function>Header</function> function must be called before any
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actual output is sent either by normal HTML tags or from PHP. It
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is a very common error to read code with
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<function>include</function> or with auto_prepend and have spaces
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or empty lines in this code that force output before
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<function>header</function> is called.
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</para>
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<para>
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There are two special-case header calls. The first is the
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"Location" header. Not only does it send this header
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back to the browser, it also returns a REDIRECT status code to
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Apache. From a script writer's point of view this should not be
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important, but for people who understand Apache internals it is
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important to understand.
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<informalexample>
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<programlisting role="php">
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header ("Location: http://www.php.net"); /* Redirect browser
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to PHP web site */
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exit; /* Make sure that code below does
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not get executed when we redirect. */
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</programlisting>
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</informalexample>
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</para>
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<para>
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The second special-case is any header that starts with the
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string, "HTTP/" (case is not significant). For
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example, if you have your ErrorDocument 404 Apache directive
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pointed to a PHP script, it would be a good idea to make sure
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that your PHP script is actually generating a 404. The first
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thing you do in your script should then be:
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<informalexample>
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<programlisting role="php">
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header ("http/1.0 404 Not Found");
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</programlisting>
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</informalexample>
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</para>
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<para>
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PHP scripts often generate dynamic HTML that must not be cached
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by the client browser or any proxy caches between the server and the
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client browser. Many proxies and clients can be forced to disable
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caching with
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<informalexample>
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<programlisting role="php">
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header ("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); // Date in the past
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header ("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
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// always modified
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header ("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
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header ("Pragma: no-cache"); // HTTP/1.0
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</programlisting>
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</informalexample>
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.setcookie">
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<refnamediv>
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<refname>setcookie</refname>
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<refpurpose>Send a cookie</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcdef>int <function>setcookie</function></funcdef>
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<paramdef>string <parameter>name</parameter></paramdef>
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<paramdef>string <parameter>value</parameter></paramdef>
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<paramdef>int <parameter>expire</parameter></paramdef>
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<paramdef>string <parameter>path</parameter></paramdef>
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<paramdef>string <parameter>domain</parameter></paramdef>
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<paramdef>int <parameter>secure</parameter></paramdef>
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</funcsynopsis>
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<para>
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<function>setcookie</function> defines a cookie to be sent along
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with the rest of the header information. Cookies must be sent
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<emphasis>before</emphasis> any other headers are sent (this is a
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restriction of cookies, not PHP). This requires you to place
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calls to this function before any <literal><html></literal> or
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<literal><head></literal> tags.
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</para>
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<para>
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All the arguments except the <parameter>name</parameter> argument
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are optional. If only the name argument is present, the cookie
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by that name will be deleted from the remote client. You may
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also replace any argument with an empty string
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(<emphasis>""</emphasis>) in order to skip that
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argument. The <parameter>expire</parameter> and
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<parameter>secure</parameter> arguments are integers and cannot
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be skipped with an empty string. Use a zero
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(<emphasis>0</emphasis>) instead. The
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<parameter>expire</parameter> argument is a regular Unix time
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integer as returned by the <function>time</function> or
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<function>mktime</function> functions. The
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<parameter>secure</parameter> indicates that the cookie should
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only be transmitted over a secure HTTPS connection.
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</para>
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<para>
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Common Pitfalls:
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</para>
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<simpara>
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Cookies will not become visible until the next loading of a page that
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the cookie should be visible for.
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</simpara>
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<simpara>
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Multiple calls to <function>setcookie</function> in the same
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script will be performed in reverse order. If you are trying to
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delete one cookie before inserting another you should put the
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insert before the delete.
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</simpara>
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<para>
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Some examples follow:
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<example>
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<title><function>setcookie</function> examples</title>
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<programlisting role="php">
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setcookie ("TestCookie", "Test Value");
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setcookie ("TestCookie", $value,time()+3600); /* expire in 1 hour */
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setcookie ("TestCookie", $value,time()+3600, "/~rasmus/", ".utoronto.ca", 1);
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</programlisting>
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</example>
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</para>
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<para>
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Note that the value portion of the cookie will automatically be
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urlencoded when you send the cookie, and when it is received, it
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is automatically decoded and assigned to a variable by the same
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name as the cookie name. To see the contents of our test
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cookie in a script, simply use one of the following examples:
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<informalexample>
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<programlisting role="php">
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echo $TestCookie;
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echo $HTTP_COOKIE_VARS["TestCookie"];
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</programlisting>
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</informalexample>
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</para>
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<para>
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You may also set array cookies by using array notation in the
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cookie name. This has the effect of setting as many cookies as
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you have array elements, but when the cookie is received by your
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script, the values are all placed in an array with the cookie's
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name:
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<informalexample>
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<programlisting role="php">
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setcookie ("cookie[three]", "cookiethree");
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setcookie ("cookie[two]", "cookietwo");
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setcookie ("cookie[one]", "cookieone");
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if (isset ($cookie)) {
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while (list ($name, $value) = each ($cookie)) {
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echo "$name == $value<br>\n";
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}
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}
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</programlisting>
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</informalexample>
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</para>
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<para>
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For more information on cookies, see Netscape's cookie
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specification at <ulink
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url="&spec.cookies;">&spec.cookies;</ulink>.
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</para>
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<simpara>
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Microsoft Internet Explorer 4 with Service Pack 1 applied does
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not correctly deal with cookies that have their path parameter
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set.
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</simpara>
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<simpara>
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Netscape Communicator 4.05 and Microsoft Internet Explorer 3.x
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appear to handle cookies incorrectly when the path and time
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are not set.
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</simpara>
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</refsect1>
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</refentry>
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</reference>
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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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sgml-parent-document:nil
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sgml-default-dtd-file:"../../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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-->
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