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c030e2adf7
- All id attributes are now xml:id - Add docbook namespace to all root elements - Replace <ulink /> with <link xlink:href /> - Minor markup fixes here and there git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@238160 c90b9560-bf6c-de11-be94-00142212c4b1
220 lines
6.5 KiB
XML
220 lines
6.5 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.10 $ -->
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<refentry xml:id="function.pack" xmlns="http://docbook.org/ns/docbook">
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<refnamediv>
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<refname>pack</refname>
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<refpurpose>Pack data into binary string</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>string</type><methodname>pack</methodname>
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<methodparam><type>string</type><parameter>format</parameter></methodparam>
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<methodparam choice="opt"><type>mixed</type><parameter>args</parameter></methodparam>
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<methodparam choice="opt"><type>mixed</type><parameter>...</parameter></methodparam>
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</methodsynopsis>
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<para>
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Pack given arguments into binary string according to
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<parameter>format</parameter>.
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</para>
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<para>
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The idea to this function was taken from Perl and all formatting codes
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work the same as there, however, there are some formatting codes that are
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missing such as Perl's "u" format code.
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</para>
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<para>
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Note that the distinction between signed and unsigned values only
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affects the function <function>unpack</function>, where as
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function <function>pack</function> gives the same result for
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signed and unsigned format codes.
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</para>
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<para>
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Also note that PHP internally stores <type>integer</type> values as
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signed values of a machine dependent size. If you give it an unsigned
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integer value too large to be stored that way it is converted to a
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<type>float</type> which often yields an undesired result.
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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>format</parameter></term>
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<listitem>
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<para>
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The <parameter>format</parameter> string consists of format codes
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followed by an optional repeater argument. The repeater argument can
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be either an integer value or <literal>*</literal> for repeating to
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the end of the input data. For a, A, h, H the repeat count specifies
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how many characters of one data argument are taken, for @ it is the
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absolute position where to put the next data, for everything else the
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repeat count specifies how many data arguments are consumed and packed
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into the resulting binary string.
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</para>
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<para>
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Currently implemented formats are:
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<table>
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<title><function>pack</function> format characters</title>
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<tgroup cols="2">
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<thead>
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<row>
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<entry>Code</entry>
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<entry>Description</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>a</entry>
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<entry>NUL-padded string</entry>
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</row>
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<row>
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<entry>A</entry>
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<entry>SPACE-padded string</entry></row>
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<row>
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<entry>h</entry>
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<entry>Hex string, low nibble first</entry></row>
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<row>
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<entry>H</entry>
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<entry>Hex string, high nibble first</entry></row>
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<row><entry>c</entry><entry>signed char</entry></row>
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<row>
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<entry>C</entry>
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<entry>unsigned char</entry></row>
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<row>
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<entry>s</entry>
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<entry>signed short (always 16 bit, machine byte order)</entry>
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</row>
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<row>
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<entry>S</entry>
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<entry>unsigned short (always 16 bit, machine byte order)</entry>
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</row>
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<row>
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<entry>n</entry>
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<entry>unsigned short (always 16 bit, big endian byte order)</entry>
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</row>
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<row>
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<entry>v</entry>
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<entry>unsigned short (always 16 bit, little endian byte order)</entry>
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</row>
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<row>
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<entry>i</entry>
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<entry>signed integer (machine dependent size and byte order)</entry>
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</row>
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<row>
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<entry>I</entry>
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<entry>unsigned integer (machine dependent size and byte order)</entry>
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</row>
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<row>
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<entry>l</entry>
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<entry>signed long (always 32 bit, machine byte order)</entry>
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</row>
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<row>
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<entry>L</entry>
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<entry>unsigned long (always 32 bit, machine byte order)</entry>
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</row>
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<row>
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<entry>N</entry>
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<entry>unsigned long (always 32 bit, big endian byte order)</entry>
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</row>
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<row>
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<entry>V</entry>
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<entry>unsigned long (always 32 bit, little endian byte order)</entry>
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</row>
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<row>
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<entry>f</entry>
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<entry>float (machine dependent size and representation)</entry>
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</row>
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<row>
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<entry>d</entry>
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<entry>double (machine dependent size and representation)</entry>
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</row>
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<row>
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<entry>x</entry>
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<entry>NUL byte</entry>
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</row>
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<row>
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<entry>X</entry>
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<entry>Back up one byte</entry>
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</row>
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<row>
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<entry>@</entry>
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<entry>NUL-fill to absolute position</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>args</parameter></term>
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<listitem>
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<para>
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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 binary string containing data.
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</para>
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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><function>pack</function> example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$binarydata = pack("nvc*", 0x1234, 0x5678, 65, 66);
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?>
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]]>
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</programlisting>
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<para>
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The resulting binary string will be 6 bytes long and contain
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the byte sequence 0x12, 0x34, 0x78, 0x56, 0x41, 0x42.
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</para>
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</example>
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</para>
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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><function>unpack</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:"../../../../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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