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      <dt>

       <span class="term"><em class="emphasis">\Z</em></span>

       <dd>

        <span class="simpara">
         end of subject or newline at end (independent of
         multiline mode)
        </span>
       </dd>

      </dt>

      <dt>

       <span class="term"><em class="emphasis">\z</em></span>

       <dd>
<span class="simpara">end of subject (independent of multiline mode)</span></dd>

      </dt>

      <dt>

       <span class="term"><em class="emphasis">\G</em></span>

       <dd>
<span class="simpara">first matching position in subject</span></dd>

      </dt>

     </dl>

    </p>
    <p class="para">
     These assertions may not appear in  character  classes  (but
     note that &quot;<i>\b</i>&quot; has a different meaning, namely the backspace
     character, inside a character class).
    </p>
    <p class="para">
     A word boundary is a position in the subject string where
     the current character and the previous character do not both
     match <i>\w</i> or <i>\W</i> (i.e. one matches 
     <i>\w</i> and  the  other  matches
     <i>\W</i>), or the start or end of the string if the first
     or last character matches <i>\w</i>, respectively.
    </p>
    <p class="para">
     The <i>\A</i>, <i>\Z</i>, and
     <i>\z</i> assertions differ  from  the  traditional
     circumflex  and  dollar  (described below) in that they only
     ever match at the very start and end of the subject  string,
     whatever  options  are  set.  They  are  not affected by the
     <a href="reference.pcre.pattern.modifiers.html" class="link">PCRE_MULTILINE</a> or
     <a href="reference.pcre.pattern.modifiers.html" class="link">PCRE_DOLLAR_ENDONLY</a>
     options. The  difference  between <i>\Z</i> and
     <i>\z</i>  is that <i>\Z</i> matches before a
     newline that is the last character of the string as well as at the end of
     the string, whereas <i>\z</i> matches only at the end.
     </p>
     <p class="para">
      The <i>\G</i> assertion is true only when the current
      matching position is at the start point of the match, as specified by
      the <i><tt class="parameter">offset</tt></i>
 argument of
      <a href="function.preg-match.html" class="function">preg_match()</a>. It differs from <i>\A</i>
      when the value of <i><tt class="parameter">offset</tt></i>
 is non-zero.
      It is available since PHP 4.3.3.
     </p>
     
     <p class="para">
      <i>\Q</i> and <i>\E</i> can be used to ignore
      regexp metacharacters in the pattern since PHP 4.3.3. For example:
      <i>\w+\Q.$.\E$</i> will match one or more word characters,
      followed by literals <i>.$.</i> and anchored at the end of
      the string.
     </p>
     
     <p class="para">
      <i>\K</i> can be used to reset the match start since
      PHP 5.2.4. For example, the pattern <i>foo\Kbar</i> matches
      &quot;foobar&quot;, but reports that it has matched &quot;bar&quot;. The use of
      <i>\K</i> does not interfere with the setting of captured
      substrings. For example, when the pattern <i>(foo)\Kbar</i>
      matches &quot;foobar&quot;, the first substring is still set to &quot;foo&quot;.
     </p>
     
    </div>
 
    <div id="regexp.reference.unicode" class="section">
     <h2 class="title">Unicode character properties</h2>
     <p class="para">
      Since PHP 4.4.0 and 5.1.0, three
      additional escape sequences to match generic character types are available
      when <em class="emphasis">UTF-8 mode</em> is selected. They are:
     </p>
     <dl>

      <dt>

       <span class="term"><em class="emphasis">\p{xx}</em></span>

       <dd>
<span class="simpara">a character with the xx property</span></dd>

      </dt>

      <dt>

       <span class="term"><em class="emphasis">\P{xx}</em></span>

       <dd>
<span class="simpara">a character without the xx property</span></dd>

      </dt>

      <dt>

       <span class="term"><em class="emphasis">\X</em></span>

       <dd>
<span class="simpara">an extended Unicode sequence</span></dd>

      </dt>

     </dl>

     <p class="para">
      The property names represented by <i>xx</i> above are limited 
      to the Unicode general category properties. Each character has exactly one 
      such property, specified by a two-letter abbreviation. For compatibility with
      Perl, negation can be specified by including a circumflex between the
      opening brace and the property name. For example, <i>\p{^Lu}</i> 
      is the same as <i>\P{Lu}</i>.
     </p>
     <p class="para">
      If only one letter is specified with <i>\p</i> or 
      <i>\P</i>, it includes all the properties that start with that
      letter. In this case, in the absence of negation, the curly brackets in the 
      escape sequence are optional; these two examples have the same effect:
     </p>
     <pre class="literallayout">
      \p{L}
      \pL
     </pre>
     <table border="5">
      <caption><b>Supported property codes</b></caption>
      <colgroup>

       <tbody valign="middle" class="tbody">
        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>C</i></td><td colspan="1" rowspan="1" align="left">Other</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Cc</i></td><td colspan="1" rowspan="1" align="left">Control</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Cf</i></td><td colspan="1" rowspan="1" align="left">Format</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Cn</i></td><td colspan="1" rowspan="1" align="left">Unassigned</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Co</i></td><td colspan="1" rowspan="1" align="left">Private use</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Cs</i></td><td colspan="1" rowspan="1" align="left">Surrogate</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>L</i></td><td colspan="1" rowspan="1" align="left">Letter</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Ll</i></td><td colspan="1" rowspan="1" align="left">Lower case letter</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Lm</i></td><td colspan="1" rowspan="1" align="left">Modifier letter</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Lo</i></td><td colspan="1" rowspan="1" align="left">Other letter</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Lt</i></td><td colspan="1" rowspan="1" align="left">Title case letter</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Lu</i></td><td colspan="1" rowspan="1" align="left">Upper case letter</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>M</i></td><td colspan="1" rowspan="1" align="left">Mark</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Mc</i></td><td colspan="1" rowspan="1" align="left">Spacing mark</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Me</i></td><td colspan="1" rowspan="1" align="left">Enclosing mark</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Mn</i></td><td colspan="1" rowspan="1" align="left">Non-spacing mark</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>N</i></td><td colspan="1" rowspan="1" align="left">Number</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Nd</i></td><td colspan="1" rowspan="1" align="left">Decimal number</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Nl</i></td><td colspan="1" rowspan="1" align="left">Letter number</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>No</i></td><td colspan="1" rowspan="1" align="left">Other number</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>P</i></td><td colspan="1" rowspan="1" align="left">Punctuation</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Pc</i></td><td colspan="1" rowspan="1" align="left">Connector punctuation</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Pd</i></td><td colspan="1" rowspan="1" align="left">Dash punctuation</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Pe</i></td><td colspan="1" rowspan="1" align="left">Close punctuation</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Pf</i></td><td colspan="1" rowspan="1" align="left">Final punctuation</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Pi</i></td><td colspan="1" rowspan="1" align="left">Initial punctuation</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Po</i></td><td colspan="1" rowspan="1" align="left">Other punctuation</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Ps</i></td><td colspan="1" rowspan="1" align="left">Open punctuation</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>S</i></td><td colspan="1" rowspan="1" align="left">Symbol</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Sc</i></td><td colspan="1" rowspan="1" align="left">Currency symbol</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Sk</i></td><td colspan="1" rowspan="1" align="left">Modifier symbol</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Sm</i></td><td colspan="1" rowspan="1" align="left">Mathematical symbol</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>So</i></td><td colspan="1" rowspan="1" align="left">Other symbol</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Z</i></td><td colspan="1" rowspan="1" align="left">Separator</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Zl</i></td><td colspan="1" rowspan="1" align="left">Line separator</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Zp</i></td><td colspan="1" rowspan="1" align="left">Paragraph separator</td></tr>

        <tr valign="middle"><td colspan="1" rowspan="1" align="left"><i>Zs</i></td><td colspan="1" rowspan="1" align="left">Space separator</td></tr>

       </tbody>
      </colgroup>

     </table>

     <p class="para">
      Extended properties such as &quot;Greek&quot; or &quot;InMusicalSymbols&quot; are not
      supported by PCRE.
     </p>
     <p class="para">
      Specifying caseless matching does not affect these escape sequences.
      For example, <i>\p{Lu}</i> always matches only upper case letters.
     </p>
     <p class="para">
      The <i>\X</i> escape matches any number of Unicode characters 
      that form an extended Unicode sequence. <i>\X</i> is equivalent 
      to <i>(?&gt;\PM\pM*)</i>.
     </p>
     <p class="para">
      That is, it matches a character without the &quot;mark&quot; property, followed
      by zero or more characters with the &quot;mark&quot; property, and treats the
      sequence as an atomic group (see below). Characters with the &quot;mark&quot;
      property are typically accents that affect the preceding character.
     </p>
     <p class="para">
      Matching characters by Unicode property is not fast, because PCRE has
      to search a structure that contains data for over fifteen thousand
      characters. That is why the traditional escape sequences such as 
      <i>\d</i> and <i>\w</i> do not use Unicode properties 
      in PCRE.
     </p>
    </div>

    <div id="regexp.reference.circudollar" class="section">
     <h2 class="title">Circumflex and dollar</h2>
     <p class="para">
      Outside a character class, in the default matching mode, the
      circumflex  character  is an assertion which is true only if
      the current matching point is at the start  of  the  subject
      string. Inside a character class, circumflex has an entirely
      different meaning (see below).
     </p>
     <p class="para">
      Circumflex need not be the first character of the pattern if
      a number of alternatives are involved, but it should be the
      first thing in each alternative in which it appears  if  the
      pattern is ever to match that branch. If all possible
      alternatives start with a circumflex, that is, if the pattern is
      constrained to match only at the start of the subject, it is
      said to be an &quot;anchored&quot; pattern. (There are also other
      constructs that can cause a pattern to be anchored.)
     </p>
     <p class="para">
      A dollar character is an assertion which is <b><tt>TRUE</tt></b> only if the
      current  matching point is at the end of the subject string,
      or immediately before a newline character that is  the  last
      character in the string (by default). Dollar need not be the
      last character of the pattern if a  number  of  alternatives
      are  involved,  but it should be the last item in any branch
      in which it appears.  Dollar has no  special  meaning  in  a
      character class.
     </p>
     <p class="para">
      The meaning of dollar can be changed so that it matches only
      at the very end of the string, by setting the
      <a href="reference.pcre.pattern.modifiers.html" class="link">PCRE_DOLLAR_ENDONLY</a>
      option at compile or matching time. This does not affect the \Z assertion.
     </p>
     <p class="para">
      The meanings of the circumflex and dollar characters are
      changed if the
      <a href="reference.pcre.pattern.modifiers.html" class="link">PCRE_MULTILINE</a> option
      is set. When this is the case, they match immediately after and
      immediately before an internal &quot;\n&quot; character, respectively, in addition
      to matching at the start and end of the subject string. For example, the
      pattern /^abc$/ matches the subject string &quot;def\nabc&quot; in multiline mode,
      but not otherwise. Consequently, patterns that are anchored in single
      line mode because all branches start with &quot;^&quot; are not anchored in
      multiline mode. The
      <a href="reference.pcre.pattern.modifiers.html" class="link">PCRE_DOLLAR_ENDONLY</a>
      option is ignored if
      <a href="reference.pcre.pattern.modifiers.html" class="link">PCRE_MULTILINE</a> is
      set.
     </p>
     <p class="para">
      Note that the sequences \A, \Z, and \z can be used to  match
      the  start  and end of the subject in both modes, and if all
      branches of a pattern start with \A is it  always  anchored,
      whether <a href="reference.pcre.pattern.modifiers.html" class="link">PCRE_MULTILINE</a>  
      is set or not.
     </p>
    </div>

    <div id="regexp.reference.dot" class="section">
     <h2 class="title">Full stop</h2>
     <p class="para">
     Outside a character class, a dot in the pattern matches  any
     one  character  in  the  subject,  including  a non-printing
     character, but not (by default) newline.  If the
     <a href="reference.pcre.pattern.modifiers.html" class="link">PCRE_DOTALL</a> 
     option  is  set,  then dots match newlines as well. The
     handling of dot is entirely independent of the handling of
     circumflex  and  dollar,  the only relationship being that they
     both involve newline characters.  Dot has no special meaning
     in a character class.
     </p>
     <p class="para">
      <em class="emphasis">\C</em> can be used to match single byte. It makes sense
      in <em class="emphasis">UTF-8 mode</em> where full stop matches the whole
      character which can consist of multiple bytes.
     </p>
    </div>

    <div id="regexp.reference.squarebrackets" class="section">