/[pcre]/code/trunk/doc/pcre.txt

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-revision 259 by ph10,
Wed Sep 19 09:52:44 2007 UTC
+revision 416 by ph10,
Sat Apr 11 14:34:02 2009 UTC
 Line 18 
 INTRODUCTION
         The  PCRE  library is a set of functions that implement regular expres-
         sion pattern matching using the same syntax and semantics as Perl, with
-        just  a  few differences. (Certain features that appeared in Python and
+        just  a  few  differences. Certain features that appeared in Python and
         PCRE before they appeared in Perl are also available using  the  Python
-        syntax.)
+        syntax.  There is also some support for certain .NET and Oniguruma syn-
+        tax items, and there is an option for  requesting  some  minor  changes
+        that give better JavaScript compatibility.
         The  current  implementation of PCRE (release 7.x) corresponds approxi-
         mately with Perl 5.10, including support for UTF-8 encoded strings  and
         Unicode general category properties. However, UTF-8 and Unicode support
         has to be explicitly enabled; it is not the default. The Unicode tables
-        correspond to Unicode release 5.0.0.
+        correspond to Unicode release 5.1.
         In  addition to the Perl-compatible matching function, PCRE contains an
         alternative matching function that matches the same  compiled  patterns
-Line 92 
 USER DOCUMENTATION
+Line 94 
 USER DOCUMENTATION
           pcrestack         discussion of stack usage
           pcretest          description of the pcretest testing command
-        In  addition,  in the "man" and HTML formats, there is a short page for
+        In addition, in the "man" and HTML formats, there is a short  page  for
         each C library function, listing its arguments and results.
  LIMITATIONS
-        There are some size limitations in PCRE but it is hoped that they  will
+        There  are some size limitations in PCRE but it is hoped that they will
         never in practice be relevant.
-        The  maximum  length of a compiled pattern is 65539 (sic) bytes if PCRE
+        The maximum length of a compiled pattern is 65539 (sic) bytes  if  PCRE
         is compiled with the default internal linkage size of 2. If you want to
-        process  regular  expressions  that are truly enormous, you can compile
+        process regular expressions that are truly enormous,  you  can  compile
-        PCRE with an internal linkage size of 3 or 4 (see the  README  file  in
+        PCRE  with  an  internal linkage size of 3 or 4 (see the README file in
-        the  source  distribution and the pcrebuild documentation for details).
+        the source distribution and the pcrebuild documentation  for  details).
-        In these cases the limit is substantially larger.  However,  the  speed
+        In  these  cases the limit is substantially larger.  However, the speed
         of execution is slower.
         All values in repeating quantifiers must be less than 65536.
-Line 117 
 LIMITATIONS
+Line 119 
 LIMITATIONS
         The maximum length of name for a named subpattern is 32 characters, and
         the maximum number of named subpatterns is 10000.
-        The  maximum  length of a subject string is the largest positive number
+        The maximum length of a subject string is the largest  positive  number
-        that an integer variable can hold. However, when using the  traditional
+        that  an integer variable can hold. However, when using the traditional
         matching function, PCRE uses recursion to handle subpatterns and indef-
-        inite repetition.  This means that the available stack space may  limit
+        inite  repetition.  This means that the available stack space may limit
         the size of a subject string that can be processed by certain patterns.
         For a discussion of stack issues, see the pcrestack documentation.
  UTF-8 AND UNICODE PROPERTY SUPPORT
-        From release 3.3, PCRE has  had  some  support  for  character  strings
+        From  release  3.3,  PCRE  has  had  some support for character strings
-        encoded  in the UTF-8 format. For release 4.0 this was greatly extended
+        encoded in the UTF-8 format. For release 4.0 this was greatly  extended
-        to cover most common requirements, and in release 5.0  additional  sup-
+        to  cover  most common requirements, and in release 5.0 additional sup-
         port for Unicode general category properties was added.
-        In  order  process  UTF-8 strings, you must build PCRE to include UTF-8
+        In order process UTF-8 strings, you must build PCRE  to  include  UTF-8
-        support in the code, and, in addition,  you  must  call  pcre_compile()
+        support  in  the  code,  and, in addition, you must call pcre_compile()
-        with  the PCRE_UTF8 option flag. When you do this, both the pattern and
+        with the PCRE_UTF8 option flag, or the  pattern  must  start  with  the
-        any subject strings that are matched against it are  treated  as  UTF-8
+        sequence  (*UTF8).  When  either of these is the case, both the pattern
-        strings instead of just strings of bytes.
+        and any subject strings that are matched  against  it  are  treated  as
+        UTF-8 strings instead of just strings of bytes.
         If  you compile PCRE with UTF-8 support, but do not use it at run time,
         the library will be a bit bigger, but the additional run time  overhead
-Line 222 
 UTF-8 AND UNICODE PROPERTY SUPPORT
+Line 225 
 UTF-8 AND UNICODE PROPERTY SUPPORT
         includes Unicode property support, because to do otherwise  would  slow
         down  PCRE in many common cases. If you really want to test for a wider
         sense of, say, "digit", you must use Unicode  property  tests  such  as
-        \p{Nd}.
+        \p{Nd}.  Note  that  this  also applies to \b, because it is defined in
+        terms of \w and \W.
-.  Similarly,  characters that match the POSIX named character classes
+. Similarly, characters that match the POSIX named  character  classes
         are all low-valued characters.
-. However, the Perl 5.10 horizontal and vertical  whitespace  matching
+.  However,  the Perl 5.10 horizontal and vertical whitespace matching
         escapes (\h, \H, \v, and \V) do match all the appropriate Unicode char-
         acters.
-. Case-insensitive matching applies only to  characters  whose  values
+.  Case-insensitive  matching  applies only to characters whose values
-        are  less than 128, unless PCRE is built with Unicode property support.
+        are less than 128, unless PCRE is built with Unicode property  support.
-        Even when Unicode property support is available, PCRE  still  uses  its
+        Even  when  Unicode  property support is available, PCRE still uses its
-        own  character  tables when checking the case of low-valued characters,
+        own character tables when checking the case of  low-valued  characters,
-        so as not to degrade performance.  The Unicode property information  is
+        so  as not to degrade performance.  The Unicode property information is
         used only for characters with higher values. Even when Unicode property
         support is available, PCRE supports case-insensitive matching only when
-        there  is  a  one-to-one  mapping between a letter's cases. There are a
+        there is a one-to-one mapping between a letter's  cases.  There  are  a
-        small number of many-to-one mappings in Unicode;  these  are  not  sup-
+        small  number  of  many-to-one  mappings in Unicode; these are not sup-
         ported by PCRE.
-Line 249 
 AUTHOR
+Line 253 
 AUTHOR
         University Computing Service
         Cambridge CB2 3QH, England.
-        Putting  an actual email address here seems to have been a spam magnet,
+        Putting an actual email address here seems to have been a spam  magnet,
-        so I've taken it away. If you want to email me, use  my  two  initials,
+        so  I've  taken  it away. If you want to email me, use my two initials,
         followed by the two digits 10, at the domain cam.ac.uk.
  REVISION
-        Last updated: 09 August 2007
+        Last updated: 11 April 2009
-        Copyright (c) 1997-2007 University of Cambridge.
+        Copyright (c) 1997-2009 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 271 
 NAME
+Line 275 
 NAME
  PCRE BUILD-TIME OPTIONS
         This  document  describes  the  optional  features  of PCRE that can be
-        selected when the library is compiled. They are all selected, or  dese-
+        selected when the library is compiled. It assumes use of the  configure
-        lected, by providing options to the configure script that is run before
+        script,  where the optional features are selected or deselected by pro-
-        the make command. The complete list of  options  for  configure  (which
+        viding options to configure before running the make  command.  However,
-        includes  the  standard  ones such as the selection of the installation
+        the  same  options  can be selected in both Unix-like and non-Unix-like
-        directory) can be obtained by running
+        environments using the GUI facility of  CMakeSetup  if  you  are  using
+        CMake instead of configure to build PCRE.
+        The complete list of options for configure (which includes the standard
+        ones such as the  selection  of  the  installation  directory)  can  be
+        obtained by running
           ./configure --help
-        The following sections include  descriptions  of  options  whose  names
+        The  following  sections  include  descriptions  of options whose names
         begin with --enable or --disable. These settings specify changes to the
-        defaults for the configure command. Because of the way  that  configure
+        defaults  for  the configure command. Because of the way that configure
-        works,  --enable  and --disable always come in pairs, so the complemen-
+        works, --enable and --disable always come in pairs, so  the  complemen-
-        tary option always exists as well, but as it specifies the default,  it
+        tary  option always exists as well, but as it specifies the default, it
         is not described.
-Line 300 
 C++ SUPPORT
+Line 309 
 C++ SUPPORT
  UTF-8 SUPPORT
-        To build PCRE with support for UTF-8 character strings, add
+        To build PCRE with support for UTF-8 Unicode character strings, add
           --enable-utf8
-        to  the  configure  command.  Of  itself, this does not make PCRE treat
+        to the configure command. Of itself, this  does  not  make  PCRE  treat
-        strings as UTF-8. As well as compiling PCRE with this option, you  also
+        strings  as UTF-8. As well as compiling PCRE with this option, you also
-        have  have to set the PCRE_UTF8 option when you call the pcre_compile()
+        have have to set the PCRE_UTF8 option when you call the  pcre_compile()
         function.
+        If  you set --enable-utf8 when compiling in an EBCDIC environment, PCRE
+        expects its input to be either ASCII or UTF-8 (depending on the runtime
+        option).  It  is not possible to support both EBCDIC and UTF-8 codes in
+        the same  version  of  the  library.  Consequently,  --enable-utf8  and
+        --enable-ebcdic are mutually exclusive.
  UNICODE CHARACTER PROPERTY SUPPORT
-        UTF-8 support allows PCRE to process character values greater than  255
+        UTF-8  support allows PCRE to process character values greater than 255
-        in  the  strings that it handles. On its own, however, it does not pro-
+        in the strings that it handles. On its own, however, it does  not  pro-
         vide any facilities for accessing the properties of such characters. If
-        you  want  to  be able to use the pattern escapes \P, \p, and \X, which
+        you want to be able to use the pattern escapes \P, \p,  and  \X,  which
         refer to Unicode character properties, you must add
           --enable-unicode-properties
-        to the configure command. This implies UTF-8 support, even if you  have
+        to  the configure command. This implies UTF-8 support, even if you have
         not explicitly requested it.
-        Including  Unicode  property  support  adds around 30K of tables to the
+        Including Unicode property support adds around 30K  of  tables  to  the
-        PCRE library. Only the general category properties such as  Lu  and  Nd
+        PCRE  library.  Only  the general category properties such as Lu and Nd
         are supported. Details are given in the pcrepattern documentation.
  CODE VALUE OF NEWLINE
-        By  default,  PCRE interprets character 10 (linefeed, LF) as indicating
+        By default, PCRE interprets the linefeed (LF) character  as  indicating
-        the end of a line. This is the normal newline  character  on  Unix-like
+        the  end  of  a line. This is the normal newline character on Unix-like
-        systems. You can compile PCRE to use character 13 (carriage return, CR)
+        systems. You can compile PCRE to use carriage return (CR)  instead,  by
-        instead, by adding
+        adding
           --enable-newline-is-cr
-        to the  configure  command.  There  is  also  a  --enable-newline-is-lf
+        to  the  configure  command.  There  is  also  a --enable-newline-is-lf
         option, which explicitly specifies linefeed as the newline character.
         Alternatively, you can specify that line endings are to be indicated by
-Line 349 
 CODE VALUE OF NEWLINE
+Line 364 
 CODE VALUE OF NEWLINE
           --enable-newline-is-anycrlf
-        which causes PCRE to recognize any of the three sequences  CR,  LF,  or
+        which  causes  PCRE  to recognize any of the three sequences CR, LF, or
         CRLF as indicating a line ending. Finally, a fifth option, specified by
           --enable-newline-is-any
-Line 509 
 USING EBCDIC CODE
+Line 524 
 USING EBCDIC CODE
         to the configure command. This setting implies --enable-rebuild-charta-
         bles.  You  should  only  use  it if you know that you are in an EBCDIC
-        environment (for example, an IBM mainframe operating system).
+        environment (for example,  an  IBM  mainframe  operating  system).  The
+        --enable-ebcdic option is incompatible with --enable-utf8.
+ PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT
+        By default, pcregrep reads all files as plain text. You can build it so
+        that it recognizes files whose names end in .gz or .bz2, and reads them
+        with libz or libbz2, respectively, by adding one or both of
+          --enable-pcregrep-libz
+          --enable-pcregrep-libbz2
+        to the configure command. These options naturally require that the rel-
+        evant libraries are installed on your system. Configuration  will  fail
+        if they are not.
+ PCRETEST OPTION FOR LIBREADLINE SUPPORT
+        If you add
+          --enable-pcretest-libreadline
+        to  the  configure  command,  pcretest  is  linked with the libreadline
+        library, and when its input is from a terminal, it reads it  using  the
+        readline() function. This provides line-editing and history facilities.
+        Note that libreadline is GPL-licenced, so if you distribute a binary of
+        pcretest linked in this way, there may be licensing issues.
+        Setting  this  option  causes  the -lreadline option to be added to the
+        pcretest build. In many operating environments with  a  sytem-installed
+        libreadline this is sufficient. However, in some environments (e.g.  if
+        an unmodified distribution version of readline is in use),  some  extra
+        configuration  may  be necessary. The INSTALL file for libreadline says
+        this:
+          "Readline uses the termcap functions, but does not link with the
+          termcap or curses library itself, allowing applications which link
+          with readline the to choose an appropriate library."
+        If your environment has not been set up so that an appropriate  library
+        is automatically included, you may need to add something like
+          LIBS="-ncurses"
+        immediately before the configure command.
  SEE ALSO
-Line 526 
 AUTHOR
+Line 587 
 AUTHOR
  REVISION
-        Last updated: 11 September 2007
+        Last updated: 17 March 2009
-        Copyright (c) 1997-2007 University of Cambridge.
+        Copyright (c) 1997-2009 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 675 
 THE ALTERNATIVE MATCHING ALGORITHM
+Line 736 
 THE ALTERNATIVE MATCHING ALGORITHM
         tive algorithm moves through the subject  string  one  character  at  a
         time, for all active paths through the tree.
-.  None  of  the  backtracking control verbs such as (*PRUNE) are sup-
+.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
-        ported.
+        are not supported. (*FAIL) is supported, and  behaves  like  a  failing
+        negative assertion.
  ADVANTAGES OF THE ALTERNATIVE ALGORITHM
-        Using the alternative matching algorithm provides the following  advan-
+        Using  the alternative matching algorithm provides the following advan-
         tages:
 . All possible matches (at a single point in the subject) are automat-
-        ically found, and in particular, the longest match is  found.  To  find
+        ically  found,  and  in particular, the longest match is found. To find
         more than one match using the standard algorithm, you have to do kludgy
         things with callouts.
-. There is much better support for partial matching. The  restrictions
+.  There is much better support for partial matching. The restrictions
-        on  the content of the pattern that apply when using the standard algo-
+        on the content of the pattern that apply when using the standard  algo-
-        rithm for partial matching do not apply to the  alternative  algorithm.
+        rithm  for  partial matching do not apply to the alternative algorithm.
-        For  non-anchored patterns, the starting position of a partial match is
+        For non-anchored patterns, the starting position of a partial match  is
         available.
-. Because the alternative algorithm  scans  the  subject  string  just
+.  Because  the  alternative  algorithm  scans the subject string just
-        once,  and  never  needs to backtrack, it is possible to pass very long
+        once, and never needs to backtrack, it is possible to  pass  very  long
-        subject strings to the matching function in  several  pieces,  checking
+        subject  strings  to  the matching function in several pieces, checking
         for partial matching each time.
-Line 705 
 DISADVANTAGES OF THE ALTERNATIVE ALGORIT
+Line 767 
 DISADVANTAGES OF THE ALTERNATIVE ALGORIT
         The alternative algorithm suffers from a number of disadvantages:
-.  It  is  substantially  slower  than the standard algorithm. This is
+. It is substantially slower than  the  standard  algorithm.  This  is
-        partly because it has to search for all possible matches, but  is  also
+        partly  because  it has to search for all possible matches, but is also
         because it is less susceptible to optimization.
 . Capturing parentheses and back references are not supported.
-Line 724 
 AUTHOR
+Line 786 
 AUTHOR
  REVISION
-        Last updated: 08 August 2007
+        Last updated: 19 April 2008
-        Copyright (c) 1997-2007 University of Cambridge.
+        Copyright (c) 1997-2008 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 837 
 PCRE API OVERVIEW
+Line 899 
 PCRE API OVERVIEW
         a  Perl-compatible  manner. A sample program that demonstrates the sim-
         plest way of using them is provided in the file  called  pcredemo.c  in
         the  source distribution. The pcresample documentation describes how to
-        run it.
+        compile and run it.
         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
         ble,  is  also provided. This uses a different algorithm for the match-
-Line 946 
 MULTITHREADING
+Line 1008 
 MULTITHREADING
         pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the
         callout function pointed to by pcre_callout, are shared by all threads.
-        The compiled form of a regular expression is not altered during  match-
+        The  compiled form of a regular expression is not altered during match-
         ing, so the same compiled pattern can safely be used by several threads
         at once.
-Line 954 
 MULTITHREADING
+Line 1016 
 MULTITHREADING
  SAVING PRECOMPILED PATTERNS FOR LATER USE
         The compiled form of a regular expression can be saved and re-used at a
-        later  time,  possibly by a different program, and even on a host other
+        later time, possibly by a different program, and even on a  host  other
-        than the one on which  it  was  compiled.  Details  are  given  in  the
+        than  the  one  on  which  it  was  compiled.  Details are given in the
-        pcreprecompile  documentation.  However, compiling a regular expression
+        pcreprecompile documentation. However, compiling a  regular  expression
-        with one version of PCRE for use with a different version is not  guar-
+        with  one version of PCRE for use with a different version is not guar-
         anteed to work and may cause crashes.
-Line 965 
 CHECKING BUILD-TIME OPTIONS
+Line 1027 
 CHECKING BUILD-TIME OPTIONS
         int pcre_config(int what, void *where);
-        The  function pcre_config() makes it possible for a PCRE client to dis-
+        The function pcre_config() makes it possible for a PCRE client to  dis-
         cover which optional features have been compiled into the PCRE library.
-        The  pcrebuild documentation has more details about these optional fea-
+        The pcrebuild documentation has more details about these optional  fea-
         tures.
-        The first argument for pcre_config() is an  integer,  specifying  which
+        The  first  argument  for pcre_config() is an integer, specifying which
         information is required; the second argument is a pointer to a variable
-        into which the information is  placed.  The  following  information  is
+        into  which  the  information  is  placed. The following information is
         available:
           PCRE_CONFIG_UTF8
-        The  output is an integer that is set to one if UTF-8 support is avail-
+        The output is an integer that is set to one if UTF-8 support is  avail-
         able; otherwise it is set to zero.
           PCRE_CONFIG_UNICODE_PROPERTIES
-        The output is an integer that is set to  one  if  support  for  Unicode
+        The  output  is  an  integer  that is set to one if support for Unicode
         character properties is available; otherwise it is set to zero.
           PCRE_CONFIG_NEWLINE
-        The  output  is  an integer whose value specifies the default character
+        The output is an integer whose value specifies  the  default  character
-        sequence that is recognized as meaning "newline". The four values  that
+        sequence  that is recognized as meaning "newline". The four values that
         are supported are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF,
-        and -1 for ANY. The default should normally be  the  standard  sequence
+        and  -1  for  ANY.  Though they are derived from ASCII, the same values
-        for your operating system.
+        are returned in EBCDIC environments. The default should normally corre-
+        spond to the standard sequence for your operating system.
           PCRE_CONFIG_BSR
-Line 1018 
 CHECKING BUILD-TIME OPTIONS
+Line 1081 
 CHECKING BUILD-TIME OPTIONS
           PCRE_CONFIG_MATCH_LIMIT
-        The output is an integer that gives the default limit for the number of
+        The output is a long integer that gives the default limit for the  num-
-        internal  matching  function  calls in a pcre_exec() execution. Further
+        ber  of  internal  matching  function calls in a pcre_exec() execution.
-        details are given with pcre_exec() below.
+        Further details are given with pcre_exec() below.
           PCRE_CONFIG_MATCH_LIMIT_RECURSION
-        The output is an integer that gives the default limit for the depth  of
+        The output is a long integer that gives the default limit for the depth
-        recursion  when calling the internal matching function in a pcre_exec()
+        of   recursion  when  calling  the  internal  matching  function  in  a
-        execution. Further details are given with pcre_exec() below.
+        pcre_exec() execution.  Further  details  are  given  with  pcre_exec()
+        below.
           PCRE_CONFIG_STACKRECURSE
-        The output is an integer that is set to one if internal recursion  when
+        The  output is an integer that is set to one if internal recursion when
         running pcre_exec() is implemented by recursive function calls that use
-        the stack to remember their state. This is the usual way that  PCRE  is
+        the  stack  to remember their state. This is the usual way that PCRE is
         compiled. The output is zero if PCRE was compiled to use blocks of data
-        on the  heap  instead  of  recursive  function  calls.  In  this  case,
+        on  the  heap  instead  of  recursive  function  calls.  In  this case,
-        pcre_stack_malloc  and  pcre_stack_free  are  called  to  manage memory
+        pcre_stack_malloc and  pcre_stack_free  are  called  to  manage  memory
         blocks on the heap, thus avoiding the use of the stack.
-Line 1052 
 COMPILING A PATTERN
+Line 1116 
 COMPILING A PATTERN
         Either of the functions pcre_compile() or pcre_compile2() can be called
         to compile a pattern into an internal form. The only difference between
-        the two interfaces is that pcre_compile2() has an additional  argument,
+        the  two interfaces is that pcre_compile2() has an additional argument,
         errorcodeptr, via which a numerical error code can be returned.
         The pattern is a C string terminated by a binary zero, and is passed in
-        the pattern argument. A pointer to a single block  of  memory  that  is
+        the  pattern  argument.  A  pointer to a single block of memory that is
-        obtained  via  pcre_malloc is returned. This contains the compiled code
+        obtained via pcre_malloc is returned. This contains the  compiled  code
         and related data. The pcre type is defined for the returned block; this
         is a typedef for a structure whose contents are not externally defined.
         It is up to the caller to free the memory (via pcre_free) when it is no
         longer required.
-        Although  the compiled code of a PCRE regex is relocatable, that is, it
+        Although the compiled code of a PCRE regex is relocatable, that is,  it
         does not depend on memory location, the complete pcre data block is not
-        fully  relocatable, because it may contain a copy of the tableptr argu-
+        fully relocatable, because it may contain a copy of the tableptr  argu-
         ment, which is an address (see below).
         The options argument contains various bit settings that affect the com-
-        pilation.  It  should be zero if no options are required. The available
+        pilation. It should be zero if no options are required.  The  available
-        options are described below. Some of them, in  particular,  those  that
+        options  are  described  below. Some of them (in particular, those that
-        are  compatible  with  Perl,  can also be set and unset from within the
+        are compatible with Perl, but also some others) can  also  be  set  and
-        pattern (see the detailed description  in  the  pcrepattern  documenta-
+        unset  from  within  the  pattern  (see the detailed description in the
-        tion).  For  these options, the contents of the options argument speci-
+        pcrepattern documentation). For those options that can be different  in
-        fies their initial settings at the start of compilation and  execution.
+        different  parts  of  the pattern, the contents of the options argument
-        The  PCRE_ANCHORED  and PCRE_NEWLINE_xxx options can be set at the time
+        specifies their initial settings at the start of compilation and execu-
-        of matching as well as at compile time.
+        tion.  The PCRE_ANCHORED and PCRE_NEWLINE_xxx options can be set at the
+        time of matching as well as at compile time.
         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and
-Line 1212 
 COMPILING A PATTERN
+Line 1277 
 COMPILING A PATTERN
         before or at the first  newline  in  the  subject  string,  though  the
         matched text may continue over the newline.
+          PCRE_JAVASCRIPT_COMPAT
+        If this option is set, PCRE's behaviour is changed in some ways so that
+        it is compatible with JavaScript rather than Perl. The changes  are  as
+        follows:
+        (1)  A  lone  closing square bracket in a pattern causes a compile-time
+        error, because this is illegal in JavaScript (by default it is  treated
+        as a data character). Thus, the pattern AB]CD becomes illegal when this
+        option is set.
+        (2) At run time, a back reference to an unset subpattern group  matches
+        an  empty  string (by default this causes the current matching alterna-
+        tive to fail). A pattern such as (\1)(a) succeeds when this  option  is
+        set  (assuming  it can find an "a" in the subject), whereas it fails by
+        default, for Perl compatibility.
           PCRE_MULTILINE
-        By  default,  PCRE  treats the subject string as consisting of a single
+        By default, PCRE treats the subject string as consisting  of  a  single
-        line of characters (even if it actually contains newlines). The  "start
+        line  of characters (even if it actually contains newlines). The "start
-        of  line"  metacharacter  (^)  matches only at the start of the string,
+        of line" metacharacter (^) matches only at the  start  of  the  string,
-        while the "end of line" metacharacter ($) matches only at  the  end  of
+        while  the  "end  of line" metacharacter ($) matches only at the end of
         the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY
         is set). This is the same as Perl.
-        When PCRE_MULTILINE it is set, the "start of line" and  "end  of  line"
+        When  PCRE_MULTILINE  it  is set, the "start of line" and "end of line"
-        constructs  match  immediately following or immediately before internal
+        constructs match immediately following or immediately  before  internal
-        newlines in the subject string, respectively, as well as  at  the  very
+        newlines  in  the  subject string, respectively, as well as at the very
-        start  and  end.  This is equivalent to Perl's /m option, and it can be
+        start and end. This is equivalent to Perl's /m option, and  it  can  be
         changed within a pattern by a (?m) option setting. If there are no new-
-        lines  in  a  subject string, or no occurrences of ^ or $ in a pattern,
+        lines in a subject string, or no occurrences of ^ or $  in  a  pattern,
         setting PCRE_MULTILINE has no effect.
           PCRE_NEWLINE_CR
-Line 1235 
 COMPILING A PATTERN
+Line 1317 
 COMPILING A PATTERN
           PCRE_NEWLINE_ANYCRLF
           PCRE_NEWLINE_ANY
-        These options override the default newline definition that  was  chosen
+        These  options  override the default newline definition that was chosen
-        when  PCRE  was built. Setting the first or the second specifies that a
+        when PCRE was built. Setting the first or the second specifies  that  a
-        newline is indicated by a single character (CR  or  LF,  respectively).
+        newline  is  indicated  by a single character (CR or LF, respectively).
-        Setting  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the
+        Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the
-        two-character CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF  specifies
+        two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies
         that any of the three preceding sequences should be recognized. Setting
-        PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should  be
+        PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be
         recognized. The Unicode newline sequences are the three just mentioned,
-        plus the single characters VT (vertical  tab,  U+000B),  FF  (formfeed,
+        plus  the  single  characters  VT (vertical tab, U+000B), FF (formfeed,
-        U+000C),  NEL  (next line, U+0085), LS (line separator, U+2028), and PS
+        U+000C), NEL (next line, U+0085), LS (line separator, U+2028),  and  PS
-        (paragraph separator, U+2029). The last  two  are  recognized  only  in
+        (paragraph  separator,  U+2029).  The  last  two are recognized only in
         UTF-8 mode.
-        The  newline  setting  in  the  options  word  uses three bits that are
+        The newline setting in the  options  word  uses  three  bits  that  are
         treated as a number, giving eight possibilities. Currently only six are
-        used  (default  plus the five values above). This means that if you set
+        used (default plus the five values above). This means that if  you  set
-        more than one newline option, the combination may or may not be  sensi-
+        more  than one newline option, the combination may or may not be sensi-
         ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to
-        PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and
+        PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and
         cause an error.
-        The  only time that a line break is specially recognized when compiling
+        The only time that a line break is specially recognized when  compiling
-        a pattern is if PCRE_EXTENDED is set, and  an  unescaped  #  outside  a
+        a  pattern  is  if  PCRE_EXTENDED  is set, and an unescaped # outside a
-        character  class  is  encountered.  This indicates a comment that lasts
+        character class is encountered. This indicates  a  comment  that  lasts
-        until after the next line break sequence. In other circumstances,  line
+        until  after the next line break sequence. In other circumstances, line
-        break   sequences   are   treated  as  literal  data,  except  that  in
+        break  sequences  are  treated  as  literal  data,   except   that   in
         PCRE_EXTENDED mode, both CR and LF are treated as whitespace characters
         and are therefore ignored.
         The newline option that is set at compile time becomes the default that
-        is used for pcre_exec() and pcre_dfa_exec(), but it can be  overridden.
+        is used for pcre_exec() and pcre_dfa_exec(), but it can be overridden.
           PCRE_NO_AUTO_CAPTURE
-Line 1324 
 COMPILATION ERROR CODES
+Line 1406 
 COMPILATION ERROR CODES
  nothing to repeat
  [this code is not in use]
  internal error: unexpected repeat
- unrecognized character after (?
+ unrecognized character after (? or (?-
  POSIX named classes are supported only within a class
  missing )
  reference to non-existent subpattern
-Line 1332 
 COMPILATION ERROR CODES
+Line 1414 
 COMPILATION ERROR CODES
  unknown option bit(s) set
  missing ) after comment
  [this code is not in use]
- regular expression too large
+ regular expression is too large
  failed to get memory
  unmatched parentheses
  internal error: code overflow
-Line 1361 
 COMPILATION ERROR CODES
+Line 1443 
 COMPILATION ERROR CODES
  malformed \P or \p sequence
  unknown property name after \P or \p
  subpattern name is too long (maximum 32 characters)
- too many named subpatterns (maximum 10,000)
+ too many named subpatterns (maximum 10000)
  [this code is not in use]
  octal value is greater than \377 (not in UTF-8 mode)
  internal error: overran compiling workspace
-Line 1370 
 COMPILATION ERROR CODES
+Line 1452 
 COMPILATION ERROR CODES
  DEFINE group contains more than one branch
  repeating a DEFINE group is not allowed
  inconsistent NEWLINE options
- \g is not followed by a braced name or an optionally braced
+ \g is not followed by a braced, angle-bracketed, or quoted
-                non-zero number
+                name/number or by a plain number
- (?+ or (?- or (?(+ or (?(- must be followed by a non-zero number
+ a numbered reference must not be zero
+ (*VERB) with an argument is not supported
+ (*VERB) not recognized
+ number is too big
+ subpattern name expected
+ digit expected after (?+
+ ] is an invalid data character in JavaScript compatibility mode
+        The numbers 32 and 10000 in errors 48 and 49  are  defaults;  different
+        values may be used if the limits were changed when PCRE was built.
  STUDYING A PATTERN
-Line 1380 
 STUDYING A PATTERN
+Line 1471 
 STUDYING A PATTERN
         pcre_extra *pcre_study(const pcre *code, int options
              const char **errptr);
-        If a compiled pattern is going to be used several times,  it  is  worth
+        If  a  compiled  pattern is going to be used several times, it is worth
         spending more time analyzing it in order to speed up the time taken for
-        matching. The function pcre_study() takes a pointer to a compiled  pat-
+        matching.  The function pcre_study() takes a pointer to a compiled pat-
         tern as its first argument. If studying the pattern produces additional
-        information that will help speed up matching,  pcre_study()  returns  a
+        information  that  will  help speed up matching, pcre_study() returns a
-        pointer  to a pcre_extra block, in which the study_data field points to
+        pointer to a pcre_extra block, in which the study_data field points  to
         the results of the study.
         The  returned  value  from  pcre_study()  can  be  passed  directly  to
-        pcre_exec().  However,  a  pcre_extra  block also contains other fields
+        pcre_exec(). However, a pcre_extra block  also  contains  other  fields
-        that can be set by the caller before the block  is  passed;  these  are
+        that  can  be  set  by the caller before the block is passed; these are
         described below in the section on matching a pattern.
-        If  studying  the  pattern  does not produce any additional information
+        If studying the pattern does not  produce  any  additional  information
         pcre_study() returns NULL. In that circumstance, if the calling program
-        wants  to  pass  any of the other fields to pcre_exec(), it must set up
+        wants to pass any of the other fields to pcre_exec(), it  must  set  up
         its own pcre_extra block.
-        The second argument of pcre_study() contains option bits.  At  present,
+        The  second  argument of pcre_study() contains option bits. At present,
         no options are defined, and this argument should always be zero.
-        The  third argument for pcre_study() is a pointer for an error message.
+        The third argument for pcre_study() is a pointer for an error  message.
-        If studying succeeds (even if no data is  returned),  the  variable  it
+        If  studying  succeeds  (even  if no data is returned), the variable it
-        points  to  is  set  to NULL. Otherwise it is set to point to a textual
+        points to is set to NULL. Otherwise it is set to  point  to  a  textual
         error message. This is a static string that is part of the library. You
-        must  not  try  to  free it. You should test the error pointer for NULL
+        must not try to free it. You should test the  error  pointer  for  NULL
         after calling pcre_study(), to be sure that it has run successfully.
         This is a typical call to pcre_study():
-Line 1417 
 STUDYING A PATTERN
+Line 1508 
 STUDYING A PATTERN
             &error);        /* set to NULL or points to a message */
         At present, studying a pattern is useful only for non-anchored patterns
-        that  do not have a single fixed starting character. A bitmap of possi-
+        that do not have a single fixed starting character. A bitmap of  possi-
         ble starting bytes is created.
  LOCALE SUPPORT
-        PCRE handles caseless matching, and determines whether  characters  are
+        PCRE  handles  caseless matching, and determines whether characters are
-        letters,  digits, or whatever, by reference to a set of tables, indexed
+        letters, digits, or whatever, by reference to a set of tables,  indexed
-        by character value. When running in UTF-8 mode, this  applies  only  to
+        by  character  value.  When running in UTF-8 mode, this applies only to
-        characters  with  codes  less than 128. Higher-valued codes never match
+        characters with codes less than 128. Higher-valued  codes  never  match
-        escapes such as \w or \d, but can be tested with \p if  PCRE  is  built
+        escapes  such  as  \w or \d, but can be tested with \p if PCRE is built
-        with  Unicode  character property support. The use of locales with Uni-
+        with Unicode character property support. The use of locales  with  Uni-
-        code is discouraged. If you are handling characters with codes  greater
+        code  is discouraged. If you are handling characters with codes greater
-        than  128, you should either use UTF-8 and Unicode, or use locales, but
+        than 128, you should either use UTF-8 and Unicode, or use locales,  but
         not try to mix the two.
-        PCRE contains an internal set of tables that are used  when  the  final
+        PCRE  contains  an  internal set of tables that are used when the final
-        argument  of  pcre_compile()  is  NULL.  These  are sufficient for many
+        argument of pcre_compile() is  NULL.  These  are  sufficient  for  many
         applications.  Normally, the internal tables recognize only ASCII char-
         acters. However, when PCRE is built, it is possible to cause the inter-
         nal tables to be rebuilt in the default "C" locale of the local system,
         which may cause them to be different.
-        The  internal tables can always be overridden by tables supplied by the
+        The internal tables can always be overridden by tables supplied by  the
         application that calls PCRE. These may be created in a different locale
-        from  the  default.  As more and more applications change to using Uni-
+        from the default. As more and more applications change  to  using  Uni-
         code, the need for this locale support is expected to die away.
-        External tables are built by calling  the  pcre_maketables()  function,
+        External  tables  are  built by calling the pcre_maketables() function,
-        which  has no arguments, in the relevant locale. The result can then be
+        which has no arguments, in the relevant locale. The result can then  be
-        passed to pcre_compile() or pcre_exec()  as  often  as  necessary.  For
+        passed  to  pcre_compile()  or  pcre_exec()  as often as necessary. For
-        example,  to  build  and use tables that are appropriate for the French
+        example, to build and use tables that are appropriate  for  the  French
-        locale (where accented characters with  values  greater  than  128  are
+        locale  (where  accented  characters  with  values greater than 128 are
         treated as letters), the following code could be used:
           setlocale(LC_CTYPE, "fr_FR");
           tables = pcre_maketables();
           re = pcre_compile(..., tables);
-        The  locale  name "fr_FR" is used on Linux and other Unix-like systems;
+        The locale name "fr_FR" is used on Linux and other  Unix-like  systems;
         if you are using Windows, the name for the French locale is "french".
-        When pcre_maketables() runs, the tables are built  in  memory  that  is
+        When  pcre_maketables()  runs,  the  tables are built in memory that is
-        obtained  via  pcre_malloc. It is the caller's responsibility to ensure
+        obtained via pcre_malloc. It is the caller's responsibility  to  ensure
-        that the memory containing the tables remains available for as long  as
+        that  the memory containing the tables remains available for as long as
         it is needed.
         The pointer that is passed to pcre_compile() is saved with the compiled
-        pattern, and the same tables are used via this pointer by  pcre_study()
+        pattern,  and the same tables are used via this pointer by pcre_study()
         and normally also by pcre_exec(). Thus, by default, for any single pat-
         tern, compilation, studying and matching all happen in the same locale,
         but different patterns can be compiled in different locales.
-        It  is  possible to pass a table pointer or NULL (indicating the use of
+        It is possible to pass a table pointer or NULL (indicating the  use  of
-        the internal tables) to pcre_exec(). Although  not  intended  for  this
+        the  internal  tables)  to  pcre_exec(). Although not intended for this
-        purpose,  this facility could be used to match a pattern in a different
+        purpose, this facility could be used to match a pattern in a  different
         locale from the one in which it was compiled. Passing table pointers at
         run time is discussed below in the section on matching a pattern.
-Line 1482 
 INFORMATION ABOUT A PATTERN
+Line 1573 
 INFORMATION ABOUT A PATTERN
         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
              int what, void *where);
-        The  pcre_fullinfo() function returns information about a compiled pat-
+        The pcre_fullinfo() function returns information about a compiled  pat-
         tern. It replaces the obsolete pcre_info() function, which is neverthe-
         less retained for backwards compability (and is documented below).
-        The  first  argument  for  pcre_fullinfo() is a pointer to the compiled
+        The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
-        pattern. The second argument is the result of pcre_study(), or NULL  if
+        pattern.  The second argument is the result of pcre_study(), or NULL if
-        the  pattern  was not studied. The third argument specifies which piece
+        the pattern was not studied. The third argument specifies  which  piece
-        of information is required, and the fourth argument is a pointer  to  a
+        of  information  is required, and the fourth argument is a pointer to a
-        variable  to  receive  the  data. The yield of the function is zero for
+        variable to receive the data. The yield of the  function  is  zero  for
         success, or one of the following negative numbers:
           PCRE_ERROR_NULL       the argument code was NULL
-Line 1498 
 INFORMATION ABOUT A PATTERN
+Line 1589 
 INFORMATION ABOUT A PATTERN
           PCRE_ERROR_BADMAGIC   the "magic number" was not found
           PCRE_ERROR_BADOPTION  the value of what was invalid
-        The "magic number" is placed at the start of each compiled  pattern  as
+        The  "magic  number" is placed at the start of each compiled pattern as
-        an  simple check against passing an arbitrary memory pointer. Here is a
+        an simple check against passing an arbitrary memory pointer. Here is  a
-        typical call of pcre_fullinfo(), to obtain the length of  the  compiled
+        typical  call  of pcre_fullinfo(), to obtain the length of the compiled
         pattern:
           int rc;
-Line 1511 
 INFORMATION ABOUT A PATTERN
+Line 1602 
 INFORMATION ABOUT A PATTERN
             PCRE_INFO_SIZE,   /* what is required */
             &length);         /* where to put the data */
-        The  possible  values for the third argument are defined in pcre.h, and
+        The possible values for the third argument are defined in  pcre.h,  and
         are as follows:
           PCRE_INFO_BACKREFMAX
-        Return the number of the highest back reference  in  the  pattern.  The
+        Return  the  number  of  the highest back reference in the pattern. The
-        fourth  argument  should  point to an int variable. Zero is returned if
+        fourth argument should point to an int variable. Zero  is  returned  if
         there are no back references.
           PCRE_INFO_CAPTURECOUNT
-        Return the number of capturing subpatterns in the pattern.  The  fourth
+        Return  the  number of capturing subpatterns in the pattern. The fourth
         argument should point to an int variable.
           PCRE_INFO_DEFAULT_TABLES
-        Return  a pointer to the internal default character tables within PCRE.
+        Return a pointer to the internal default character tables within  PCRE.
-        The fourth argument should point to an unsigned char *  variable.  This
+        The  fourth  argument should point to an unsigned char * variable. This
         information call is provided for internal use by the pcre_study() func-
-        tion. External callers can cause PCRE to use  its  internal  tables  by
+        tion.  External  callers  can  cause PCRE to use its internal tables by
         passing a NULL table pointer.
           PCRE_INFO_FIRSTBYTE
-        Return  information  about  the first byte of any matched string, for a
+        Return information about the first byte of any matched  string,  for  a
-        non-anchored pattern. The fourth argument should point to an int  vari-
+        non-anchored  pattern. The fourth argument should point to an int vari-
-        able.  (This option used to be called PCRE_INFO_FIRSTCHAR; the old name
+        able. (This option used to be called PCRE_INFO_FIRSTCHAR; the old  name
         is still recognized for backwards compatibility.)
-        If there is a fixed first byte, for example, from  a  pattern  such  as
+        If  there  is  a  fixed first byte, for example, from a pattern such as
         (cat|cow|coyote), its value is returned. Otherwise, if either
-        (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
+        (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
         branch starts with "^", or
         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
         set (if it were set, the pattern would be anchored),
-        -1  is  returned, indicating that the pattern matches only at the start
+        -1 is returned, indicating that the pattern matches only at  the  start
-        of a subject string or after any newline within the  string.  Otherwise
+        of  a  subject string or after any newline within the string. Otherwise
         -2 is returned. For anchored patterns, -2 is returned.
           PCRE_INFO_FIRSTTABLE
-        If  the pattern was studied, and this resulted in the construction of a
+        If the pattern was studied, and this resulted in the construction of  a
 -bit table indicating a fixed set of bytes for the first byte in any
-        matching  string, a pointer to the table is returned. Otherwise NULL is
+        matching string, a pointer to the table is returned. Otherwise NULL  is
-        returned. The fourth argument should point to an unsigned char *  vari-
+        returned.  The fourth argument should point to an unsigned char * vari-
         able.
           PCRE_INFO_HASCRORLF
-        Return  1  if  the  pattern  contains any explicit matches for CR or LF
+        Return 1 if the pattern contains any explicit  matches  for  CR  or  LF
-        characters, otherwise 0. The fourth argument should  point  to  an  int
+        characters,  otherwise  0.  The  fourth argument should point to an int
-        variable.  An explicit match is either a literal CR or LF character, or
+        variable. An explicit match is either a literal CR or LF character,  or
         \r or \n.
           PCRE_INFO_JCHANGED
-        Return 1 if the (?J) option setting is used in the  pattern,  otherwise
+        Return  1  if  the (?J) or (?-J) option setting is used in the pattern,
-. The fourth argument should point to an int variable. The (?J) inter-
+        otherwise 0. The fourth argument should point to an int variable.  (?J)
-        nal option setting changes the local PCRE_DUPNAMES option.
+        and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
           PCRE_INFO_LASTLITERAL
-        Return the value of the rightmost literal byte that must exist  in  any
+        Return  the  value of the rightmost literal byte that must exist in any
-        matched  string,  other  than  at  its  start,  if such a byte has been
+        matched string, other than at its  start,  if  such  a  byte  has  been
         recorded. The fourth argument should point to an int variable. If there
-        is  no such byte, -1 is returned. For anchored patterns, a last literal
+        is no such byte, -1 is returned. For anchored patterns, a last  literal
-        byte is recorded only if it follows something of variable  length.  For
+        byte  is  recorded only if it follows something of variable length. For
         example, for the pattern /^a\d+z\d+/ the returned value is "z", but for
         /^a\dz\d/ the returned value is -1.
-Line 1588 
 INFORMATION ABOUT A PATTERN
+Line 1679 
 INFORMATION ABOUT A PATTERN
           PCRE_INFO_NAMEENTRYSIZE
           PCRE_INFO_NAMETABLE
-        PCRE supports the use of named as well as numbered capturing  parenthe-
+        PCRE  supports the use of named as well as numbered capturing parenthe-
-        ses.  The names are just an additional way of identifying the parenthe-
+        ses. The names are just an additional way of identifying the  parenthe-
         ses, which still acquire numbers. Several convenience functions such as
-        pcre_get_named_substring()  are  provided  for extracting captured sub-
+        pcre_get_named_substring() are provided for  extracting  captured  sub-
-        strings by name. It is also possible to extract the data  directly,  by
+        strings  by  name. It is also possible to extract the data directly, by
-        first  converting  the  name to a number in order to access the correct
+        first converting the name to a number in order to  access  the  correct
         pointers in the output vector (described with pcre_exec() below). To do
-        the  conversion,  you  need  to  use  the  name-to-number map, which is
+        the conversion, you need  to  use  the  name-to-number  map,  which  is
         described by these three values.
         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT
         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
-        of each entry; both of these  return  an  int  value.  The  entry  size
+        of  each  entry;  both  of  these  return  an int value. The entry size
-        depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns
+        depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns
-        a pointer to the first entry of the table  (a  pointer  to  char).  The
+        a  pointer  to  the  first  entry of the table (a pointer to char). The
         first two bytes of each entry are the number of the capturing parenthe-
-        sis, most significant byte first. The rest of the entry is  the  corre-
+        sis,  most  significant byte first. The rest of the entry is the corre-
-        sponding  name,  zero  terminated. The names are in alphabetical order.
+        sponding name, zero terminated. The names are  in  alphabetical  order.
         When PCRE_DUPNAMES is set, duplicate names are in order of their paren-
-        theses  numbers.  For  example,  consider the following pattern (assume
+        theses numbers. For example, consider  the  following  pattern  (assume
-        PCRE_EXTENDED is  set,  so  white  space  -  including  newlines  -  is
+        PCRE_EXTENDED  is  set,  so  white  space  -  including  newlines  - is
         ignored):
           (?<date> (?<year>(\d\d)?\d\d) -
           (?<month>\d\d) - (?<day>\d\d) )
-        There  are  four  named subpatterns, so the table has four entries, and
+        There are four named subpatterns, so the table has  four  entries,  and
-        each entry in the table is eight bytes long. The table is  as  follows,
+        each  entry  in the table is eight bytes long. The table is as follows,
         with non-printing bytes shows in hexadecimal, and undefined bytes shown
         as ??:
-Line 1624 
 INFORMATION ABOUT A PATTERN
+Line 1715 
 INFORMATION ABOUT A PATTERN
 04 m  o  n  t  h  00
 02 y  e  a  r  00 ??
-        When writing code to extract data  from  named  subpatterns  using  the
+        When  writing  code  to  extract  data from named subpatterns using the
-        name-to-number  map,  remember that the length of the entries is likely
+        name-to-number map, remember that the length of the entries  is  likely
         to be different for each compiled pattern.
           PCRE_INFO_OKPARTIAL
-        Return 1 if the pattern can be used for partial matching, otherwise  0.
+        Return  1 if the pattern can be used for partial matching, otherwise 0.
-        The  fourth  argument  should point to an int variable. The pcrepartial
+        The fourth argument should point to an int  variable.  The  pcrepartial
-        documentation lists the restrictions that apply to patterns  when  par-
+        documentation  lists  the restrictions that apply to patterns when par-
         tial matching is used.
           PCRE_INFO_OPTIONS
-        Return  a  copy of the options with which the pattern was compiled. The
+        Return a copy of the options with which the pattern was  compiled.  The
-        fourth argument should point to an unsigned long  int  variable.  These
+        fourth  argument  should  point to an unsigned long int variable. These
         option bits are those specified in the call to pcre_compile(), modified
         by any top-level option settings at the start of the pattern itself. In
-        other  words,  they are the options that will be in force when matching
+        other words, they are the options that will be in force  when  matching
-        starts. For example, if the pattern /(?im)abc(?-i)d/ is  compiled  with
+        starts.  For  example, if the pattern /(?im)abc(?-i)d/ is compiled with
-        the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
+        the PCRE_EXTENDED option, the result is PCRE_CASELESS,  PCRE_MULTILINE,
         and PCRE_EXTENDED.
-        A pattern is automatically anchored by PCRE if  all  of  its  top-level
+        A  pattern  is  automatically  anchored by PCRE if all of its top-level
         alternatives begin with one of the following:
           ^     unless PCRE_MULTILINE is set
-Line 1660 
 INFORMATION ABOUT A PATTERN
+Line 1751 
 INFORMATION ABOUT A PATTERN
           PCRE_INFO_SIZE
-        Return the size of the compiled pattern, that is, the  value  that  was
+        Return  the  size  of the compiled pattern, that is, the value that was
         passed as the argument to pcre_malloc() when PCRE was getting memory in
         which to place the compiled data. The fourth argument should point to a
         size_t variable.
-Line 1668 
 INFORMATION ABOUT A PATTERN
+Line 1759 
 INFORMATION ABOUT A PATTERN
           PCRE_INFO_STUDYSIZE
         Return the size of the data block pointed to by the study_data field in
-        a pcre_extra block. That is,  it  is  the  value  that  was  passed  to
+        a  pcre_extra  block.  That  is,  it  is  the  value that was passed to
         pcre_malloc() when PCRE was getting memory into which to place the data
-        created by pcre_study(). The fourth argument should point to  a  size_t
+        created  by  pcre_study(). The fourth argument should point to a size_t
         variable.
-Line 1678 
 OBSOLETE INFO FUNCTION
+Line 1769 
 OBSOLETE INFO FUNCTION
         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);
-        The  pcre_info()  function is now obsolete because its interface is too
+        The pcre_info() function is now obsolete because its interface  is  too
-        restrictive to return all the available data about a compiled  pattern.
+        restrictive  to return all the available data about a compiled pattern.
-        New   programs   should  use  pcre_fullinfo()  instead.  The  yield  of
+        New  programs  should  use  pcre_fullinfo()  instead.  The   yield   of
-        pcre_info() is the number of capturing subpatterns, or one of the  fol-
+        pcre_info()  is the number of capturing subpatterns, or one of the fol-
         lowing negative numbers:
           PCRE_ERROR_NULL       the argument code was NULL
           PCRE_ERROR_BADMAGIC   the "magic number" was not found
-        If  the  optptr  argument is not NULL, a copy of the options with which
+        If the optptr argument is not NULL, a copy of the  options  with  which
-        the pattern was compiled is placed in the integer  it  points  to  (see
+        the  pattern  was  compiled  is placed in the integer it points to (see
         PCRE_INFO_OPTIONS above).
-        If  the  pattern  is  not anchored and the firstcharptr argument is not
+        If the pattern is not anchored and the  firstcharptr  argument  is  not
-        NULL, it is used to pass back information about the first character  of
+        NULL,  it is used to pass back information about the first character of
         any matched string (see PCRE_INFO_FIRSTBYTE above).
-Line 1700 
 REFERENCE COUNTS
+Line 1791 
 REFERENCE COUNTS
         int pcre_refcount(pcre *code, int adjust);
-        The  pcre_refcount()  function is used to maintain a reference count in
+        The pcre_refcount() function is used to maintain a reference  count  in
         the data block that contains a compiled pattern. It is provided for the
-        benefit  of  applications  that  operate  in an object-oriented manner,
+        benefit of applications that  operate  in  an  object-oriented  manner,
         where different parts of the application may be using the same compiled
         pattern, but you want to free the block when they are all done.
         When a pattern is compiled, the reference count field is initialized to
-        zero.  It is changed only by calling this function, whose action is  to
+        zero.   It is changed only by calling this function, whose action is to
-        add  the  adjust  value  (which may be positive or negative) to it. The
+        add the adjust value (which may be positive or  negative)  to  it.  The
         yield of the function is the new value. However, the value of the count
-        is  constrained to lie between 0 and 65535, inclusive. If the new value
+        is constrained to lie between 0 and 65535, inclusive. If the new  value
         is outside these limits, it is forced to the appropriate limit value.
-        Except when it is zero, the reference count is not correctly  preserved
+        Except  when it is zero, the reference count is not correctly preserved
-        if  a  pattern  is  compiled on one host and then transferred to a host
+        if a pattern is compiled on one host and then  transferred  to  a  host
         whose byte-order is different. (This seems a highly unlikely scenario.)
-Line 1808 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 1899 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
         the  total number of calls, because not all calls to match() are recur-
         sive.  This limit is of use only if it is set smaller than match_limit.
-        Limiting  the  recursion  depth  limits the amount of stack that can be
+        Limiting the recursion depth limits the amount of  stack  that  can  be
         used, or, when PCRE has been compiled to use memory on the heap instead
         of the stack, the amount of heap memory that can be used.
-        The  default  value  for  match_limit_recursion can be set when PCRE is
+        The default value for match_limit_recursion can be  set  when  PCRE  is
-        built; the default default  is  the  same  value  as  the  default  for
+        built;  the  default  default  is  the  same  value  as the default for
-        match_limit.  You can override the default by suppling pcre_exec() with
+        match_limit. You can override the default by suppling pcre_exec()  with
-        a  pcre_extra  block  in  which  match_limit_recursion  is   set,   and
+        a   pcre_extra   block  in  which  match_limit_recursion  is  set,  and
-        PCRE_EXTRA_MATCH_LIMIT_RECURSION  is  set  in  the  flags field. If the
+        PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in  the  flags  field.  If  the
         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
-        The pcre_callout field is used in conjunction with the  "callout"  fea-
+        The  pcre_callout  field is used in conjunction with the "callout" fea-
         ture, which is described in the pcrecallout documentation.
-        The  tables  field  is  used  to  pass  a  character  tables pointer to
+        The tables field  is  used  to  pass  a  character  tables  pointer  to
-        pcre_exec(); this overrides the value that is stored with the  compiled
+        pcre_exec();  this overrides the value that is stored with the compiled
-        pattern.  A  non-NULL value is stored with the compiled pattern only if
+        pattern. A non-NULL value is stored with the compiled pattern  only  if
-        custom tables were supplied to pcre_compile() via  its  tableptr  argu-
+        custom  tables  were  supplied to pcre_compile() via its tableptr argu-
         ment.  If NULL is passed to pcre_exec() using this mechanism, it forces
-        PCRE's internal tables to be used. This facility is  helpful  when  re-
+        PCRE's  internal  tables  to be used. This facility is helpful when re-
-        using  patterns  that  have been saved after compiling with an external
+        using patterns that have been saved after compiling  with  an  external
-        set of tables, because the external tables  might  be  at  a  different
+        set  of  tables,  because  the  external tables might be at a different
-        address  when  pcre_exec() is called. See the pcreprecompile documenta-
+        address when pcre_exec() is called. See the  pcreprecompile  documenta-
         tion for a discussion of saving compiled patterns for later use.
     Option bits for pcre_exec()
-        The unused bits of the options argument for pcre_exec() must  be  zero.
+        The  unused  bits of the options argument for pcre_exec() must be zero.
-        The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,
+        The only bits that may  be  set  are  PCRE_ANCHORED,  PCRE_NEWLINE_xxx,
-        PCRE_NOTBOL,   PCRE_NOTEOL,   PCRE_NOTEMPTY,   PCRE_NO_UTF8_CHECK   and
+        PCRE_NOTBOL,    PCRE_NOTEOL,   PCRE_NOTEMPTY,   PCRE_NO_START_OPTIMIZE,
-        PCRE_PARTIAL.
+        PCRE_NO_UTF8_CHECK and PCRE_PARTIAL.
           PCRE_ANCHORED
-        The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first
+        The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first
-        matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or
+        matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or
-        turned  out to be anchored by virtue of its contents, it cannot be made
+        turned out to be anchored by virtue of its contents, it cannot be  made
         unachored at matching time.
           PCRE_BSR_ANYCRLF
           PCRE_BSR_UNICODE
         These options (which are mutually exclusive) control what the \R escape
-        sequence  matches.  The choice is either to match only CR, LF, or CRLF,
+        sequence matches. The choice is either to match only CR, LF,  or  CRLF,
-        or to match any Unicode newline sequence. These  options  override  the
+        or  to  match  any Unicode newline sequence. These options override the
         choice that was made or defaulted when the pattern was compiled.
           PCRE_NEWLINE_CR
-Line 1861 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 1952 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
           PCRE_NEWLINE_ANYCRLF
           PCRE_NEWLINE_ANY
-        These  options  override  the  newline  definition  that  was chosen or
+        These options override  the  newline  definition  that  was  chosen  or
-        defaulted when the pattern was compiled. For details, see the  descrip-
+        defaulted  when the pattern was compiled. For details, see the descrip-
-        tion  of  pcre_compile()  above.  During  matching,  the newline choice
+        tion of pcre_compile()  above.  During  matching,  the  newline  choice
-        affects the behaviour of the dot, circumflex,  and  dollar  metacharac-
+        affects  the  behaviour  of the dot, circumflex, and dollar metacharac-
-        ters.  It may also alter the way the match position is advanced after a
+        ters. It may also alter the way the match position is advanced after  a
         match failure for an unanchored pattern.
-        When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is
+        When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is
-        set,  and a match attempt for an unanchored pattern fails when the cur-
+        set, and a match attempt for an unanchored pattern fails when the  cur-
-        rent position is at a  CRLF  sequence,  and  the  pattern  contains  no
+        rent  position  is  at  a  CRLF  sequence,  and the pattern contains no
-        explicit  matches  for  CR  or  LF  characters,  the  match position is
+        explicit matches for  CR  or  LF  characters,  the  match  position  is
         advanced by two characters instead of one, in other words, to after the
         CRLF.
         The above rule is a compromise that makes the most common cases work as
-        expected. For example, if the  pattern  is  .+A  (and  the  PCRE_DOTALL
+        expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL
         option is not set), it does not match the string "\r\nA" because, after
-        failing at the start, it skips both the CR and the LF before  retrying.
+        failing  at the start, it skips both the CR and the LF before retrying.
-        However,  the  pattern  [\r\n]A does match that string, because it con-
+        However, the pattern [\r\n]A does match that string,  because  it  con-
         tains an explicit CR or LF reference, and so advances only by one char-
         acter after the first failure.
         An explicit match for CR of LF is either a literal appearance of one of
-        those characters, or one of the \r or  \n  escape  sequences.  Implicit
+        those  characters,  or  one  of the \r or \n escape sequences. Implicit
-        matches  such  as [^X] do not count, nor does \s (which includes CR and
+        matches such as [^X] do not count, nor does \s (which includes  CR  and
         LF in the characters that it matches).
-        Notwithstanding the above, anomalous effects may still occur when  CRLF
+        Notwithstanding  the above, anomalous effects may still occur when CRLF
         is a valid newline sequence and explicit \r or \n escapes appear in the
         pattern.
           PCRE_NOTBOL
         This option specifies that first character of the subject string is not
-        the  beginning  of  a  line, so the circumflex metacharacter should not
+        the beginning of a line, so the  circumflex  metacharacter  should  not
-        match before it. Setting this without PCRE_MULTILINE (at compile  time)
+        match  before it. Setting this without PCRE_MULTILINE (at compile time)
-        causes  circumflex  never to match. This option affects only the behav-
+        causes circumflex never to match. This option affects only  the  behav-
         iour of the circumflex metacharacter. It does not affect \A.
           PCRE_NOTEOL
         This option specifies that the end of the subject string is not the end
-        of  a line, so the dollar metacharacter should not match it nor (except
+        of a line, so the dollar metacharacter should not match it nor  (except
-        in multiline mode) a newline immediately before it. Setting this  with-
+        in  multiline mode) a newline immediately before it. Setting this with-
         out PCRE_MULTILINE (at compile time) causes dollar never to match. This
-        option affects only the behaviour of the dollar metacharacter. It  does
+        option  affects only the behaviour of the dollar metacharacter. It does
         not affect \Z or \z.
           PCRE_NOTEMPTY
         An empty string is not considered to be a valid match if this option is
-        set. If there are alternatives in the pattern, they are tried.  If  all
+        set.  If  there are alternatives in the pattern, they are tried. If all
-        the  alternatives  match  the empty string, the entire match fails. For
+        the alternatives match the empty string, the entire  match  fails.  For
         example, if the pattern
           a?b?
-        is applied to a string not beginning with "a" or "b",  it  matches  the
+        is  applied  to  a string not beginning with "a" or "b", it matches the
-        empty  string at the start of the subject. With PCRE_NOTEMPTY set, this
+        empty string at the start of the subject. With PCRE_NOTEMPTY set,  this
         match is not valid, so PCRE searches further into the string for occur-
         rences of "a" or "b".
         Perl has no direct equivalent of PCRE_NOTEMPTY, but it does make a spe-
-        cial case of a pattern match of the empty  string  within  its  split()
+        cial  case  of  a  pattern match of the empty string within its split()
-        function,  and  when  using  the /g modifier. It is possible to emulate
+        function, and when using the /g modifier. It  is  possible  to  emulate
         Perl's behaviour after matching a null string by first trying the match
         again at the same offset with PCRE_NOTEMPTY and PCRE_ANCHORED, and then
-        if that fails by advancing the starting offset (see below)  and  trying
+        if  that  fails by advancing the starting offset (see below) and trying
         an ordinary match again. There is some code that demonstrates how to do
         this in the pcredemo.c sample program.
+          PCRE_NO_START_OPTIMIZE
+        There  are a number of optimizations that pcre_exec() uses at the start
+        of a match, in order to speed up the process. For  example,  if  it  is
+        known  that  a  match must start with a specific character, it searches
+        the subject for that character, and fails immediately if it cannot find
+        it,  without actually running the main matching function. When callouts
+        are in use, these optimizations can cause  them  to  be  skipped.  This
+        option  disables  the  "start-up" optimizations, causing performance to
+        suffer, but ensuring that the callouts do occur.
           PCRE_NO_UTF8_CHECK
         When PCRE_UTF8 is set at compile time, the validity of the subject as a
-Line 1968 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 2070 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
     The string to be matched by pcre_exec()
         The  subject string is passed to pcre_exec() as a pointer in subject, a
-        length in length, and a starting byte offset in startoffset.  In  UTF-8
+        length (in bytes) in length, and a starting byte offset in startoffset.
-        mode,  the  byte  offset  must point to the start of a UTF-8 character.
+        In UTF-8 mode, the byte offset must point to the start of a UTF-8 char-
-        Unlike the pattern string, the subject may contain binary  zero  bytes.
+        acter. Unlike the pattern string, the subject may contain  binary  zero
-        When  the starting offset is zero, the search for a match starts at the
+        bytes.  When the starting offset is zero, the search for a match starts
-        beginning of the subject, and this is by far the most common case.
+        at the beginning of the subject, and this is by  far  the  most  common
+        case.
-        A non-zero starting offset is useful when searching for  another  match
-        in  the same subject by calling pcre_exec() again after a previous suc-
+        A  non-zero  starting offset is useful when searching for another match
-        cess.  Setting startoffset differs from just passing over  a  shortened
+        in the same subject by calling pcre_exec() again after a previous  suc-
-        string  and  setting  PCRE_NOTBOL  in the case of a pattern that begins
+        cess.   Setting  startoffset differs from just passing over a shortened
+        string and setting PCRE_NOTBOL in the case of  a  pattern  that  begins
         with any kind of lookbehind. For example, consider the pattern
           \Biss\B
-        which finds occurrences of "iss" in the middle of  words.  (\B  matches
+        which  finds  occurrences  of "iss" in the middle of words. (\B matches
-        only  if  the  current position in the subject is not a word boundary.)
+        only if the current position in the subject is not  a  word  boundary.)
-        When applied to the string "Mississipi" the first call  to  pcre_exec()
+        When  applied  to the string "Mississipi" the first call to pcre_exec()
-        finds  the  first  occurrence. If pcre_exec() is called again with just
+        finds the first occurrence. If pcre_exec() is called  again  with  just
-        the remainder of the subject,  namely  "issipi",  it  does  not  match,
+        the  remainder  of  the  subject,  namely  "issipi", it does not match,
         because \B is always false at the start of the subject, which is deemed
-        to be a word boundary. However, if pcre_exec()  is  passed  the  entire
+        to  be  a  word  boundary. However, if pcre_exec() is passed the entire
         string again, but with startoffset set to 4, it finds the second occur-
-        rence of "iss" because it is able to look behind the starting point  to
+        rence  of "iss" because it is able to look behind the starting point to
         discover that it is preceded by a letter.
-        If  a  non-zero starting offset is passed when the pattern is anchored,
+        If a non-zero starting offset is passed when the pattern  is  anchored,
         one attempt to match at the given offset is made. This can only succeed
-        if  the  pattern  does  not require the match to be at the start of the
+        if the pattern does not require the match to be at  the  start  of  the
         subject.
     How pcre_exec() returns captured substrings
-        In general, a pattern matches a certain portion of the subject, and  in
+        In  general, a pattern matches a certain portion of the subject, and in
-        addition,  further  substrings  from  the  subject may be picked out by
+        addition, further substrings from the subject  may  be  picked  out  by
-        parts of the pattern. Following the usage  in  Jeffrey  Friedl's  book,
+        parts  of  the  pattern.  Following the usage in Jeffrey Friedl's book,
-        this  is  called "capturing" in what follows, and the phrase "capturing
+        this is called "capturing" in what follows, and the  phrase  "capturing
-        subpattern" is used for a fragment of a pattern that picks out  a  sub-
+        subpattern"  is  used for a fragment of a pattern that picks out a sub-
-        string.  PCRE  supports several other kinds of parenthesized subpattern
+        string. PCRE supports several other kinds of  parenthesized  subpattern
         that do not cause substrings to be captured.
-        Captured substrings are returned to the caller via a vector of  integer
+        Captured substrings are returned to the caller via a vector of integers
-        offsets  whose  address is passed in ovector. The number of elements in
+        whose address is passed in ovector. The number of elements in the  vec-
-        the vector is passed in ovecsize, which must be a non-negative  number.
+        tor  is  passed in ovecsize, which must be a non-negative number. Note:
-        Note: this argument is NOT the size of ovector in bytes.
+        this argument is NOT the size of ovector in bytes.
-        The  first  two-thirds of the vector is used to pass back captured sub-
+        The first two-thirds of the vector is used to pass back  captured  sub-
-        strings, each substring using a pair of integers. The  remaining  third
+        strings,  each  substring using a pair of integers. The remaining third
-        of  the  vector is used as workspace by pcre_exec() while matching cap-
+        of the vector is used as workspace by pcre_exec() while  matching  cap-
-        turing subpatterns, and is not available for passing back  information.
+        turing  subpatterns, and is not available for passing back information.
-        The  length passed in ovecsize should always be a multiple of three. If
+        The number passed in ovecsize should always be a multiple of three.  If
         it is not, it is rounded down.
-        When a match is successful, information about  captured  substrings  is
+        When  a  match  is successful, information about captured substrings is
-        returned  in  pairs  of integers, starting at the beginning of ovector,
+        returned in pairs of integers, starting at the  beginning  of  ovector,
-        and continuing up to two-thirds of its length at the  most.  The  first
+        and  continuing  up  to two-thirds of its length at the most. The first
-        element of a pair is set to the offset of the first character in a sub-
+        element of each pair is set to the byte offset of the  first  character
-        string, and the second is set to the  offset  of  the  first  character
+        in  a  substring, and the second is set to the byte offset of the first
-        after  the  end  of  a  substring. The first pair, ovector[0] and ovec-
+        character after the end of a substring. Note: these values  are  always
-        tor[1], identify the portion of  the  subject  string  matched  by  the
+        byte offsets, even in UTF-8 mode. They are not character counts.
-        entire  pattern.  The next pair is used for the first capturing subpat-
-        tern, and so on. The value returned by pcre_exec() is one more than the
+        The  first  pair  of  integers, ovector[0] and ovector[1], identify the
-        highest numbered pair that has been set. For example, if two substrings
+        portion of the subject string matched by the entire pattern.  The  next
-        have been captured, the returned value is 3. If there are no  capturing
+        pair  is  used for the first capturing subpattern, and so on. The value
-        subpatterns,  the return value from a successful match is 1, indicating
+        returned by pcre_exec() is one more than the highest numbered pair that
-        that just the first pair of offsets has been set.
+        has  been  set.  For example, if two substrings have been captured, the
+        returned value is 3. If there are no capturing subpatterns, the  return
+        value from a successful match is 1, indicating that just the first pair
+        of offsets has been set.
         If a capturing subpattern is matched repeatedly, it is the last portion
         of the string that it matched that is returned.
         If  the vector is too small to hold all the captured substring offsets,
         it is used as far as possible (up to two-thirds of its length), and the
-        function  returns a value of zero. In particular, if the substring off-
+        function  returns  a value of zero. If the substring offsets are not of
-        sets are not of interest, pcre_exec() may be called with ovector passed
+        interest, pcre_exec() may be called with ovector  passed  as  NULL  and
-        as  NULL  and  ovecsize  as zero. However, if the pattern contains back
+        ovecsize  as zero. However, if the pattern contains back references and
-        references and the ovector is not big enough to  remember  the  related
+        the ovector is not big enough to remember the related substrings,  PCRE
-        substrings,  PCRE has to get additional memory for use during matching.
+        has  to  get additional memory for use during matching. Thus it is usu-
-        Thus it is usually advisable to supply an ovector.
+        ally advisable to supply an ovector.
         The pcre_info() function can be used to find  out  how  many  capturing
         subpatterns  there  are  in  a  compiled pattern. The smallest size for
-Line 2156 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
+Line 2262 
 MATCHING A PATTERN: THE TRADITIONAL FUNC
           PCRE_ERROR_BADCOUNT       (-15)
-        This error is given if the value of the ovecsize argument is  negative.
+        This error is given if the value of the ovecsize argument is negative.
           PCRE_ERROR_RECURSIONLIMIT (-21)
         The internal recursion limit, as specified by the match_limit_recursion
-        field in a pcre_extra structure (or defaulted)  was  reached.  See  the
+        field  in  a  pcre_extra  structure (or defaulted) was reached. See the
         description above.
           PCRE_ERROR_BADNEWLINE     (-23)
-Line 2184 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
+Line 2290 
 EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
         int pcre_get_substring_list(const char *subject,
              int *ovector, int stringcount, const char ***listptr);
-        Captured  substrings  can  be  accessed  directly  by using the offsets
+        Captured substrings can be  accessed  directly  by  using  the  offsets
-        returned by pcre_exec() in  ovector.  For  convenience,  the  functions
+        returned  by  pcre_exec()  in  ovector.  For convenience, the functions
         pcre_copy_substring(),    pcre_get_substring(),    and    pcre_get_sub-
-        string_list() are provided for extracting captured substrings  as  new,
+        string_list()  are  provided for extracting captured substrings as new,
-        separate,  zero-terminated strings. These functions identify substrings
+        separate, zero-terminated strings. These functions identify  substrings
-        by number. The next section describes functions  for  extracting  named
+        by  number.  The  next section describes functions for extracting named
         substrings.
-        A  substring that contains a binary zero is correctly extracted and has
+        A substring that contains a binary zero is correctly extracted and  has
-        a further zero added on the end, but the result is not, of course, a  C
+        a  further zero added on the end, but the result is not, of course, a C
-        string.   However,  you  can  process such a string by referring to the
+        string.  However, you can process such a string  by  referring  to  the
-        length that is  returned  by  pcre_copy_substring()  and  pcre_get_sub-
+        length  that  is  returned  by  pcre_copy_substring() and pcre_get_sub-
         string().  Unfortunately, the interface to pcre_get_substring_list() is
-        not adequate for handling strings containing binary zeros, because  the
+        not  adequate for handling strings containing binary zeros, because the
         end of the final string is not independently indicated.
-        The  first  three  arguments  are the same for all three of these func-
+        The first three arguments are the same for all  three  of  these  func-
-        tions: subject is the subject string that has  just  been  successfully
+        tions:  subject  is  the subject string that has just been successfully
         matched, ovector is a pointer to the vector of integer offsets that was
         passed to pcre_exec(), and stringcount is the number of substrings that
-        were  captured  by  the match, including the substring that matched the
+        were captured by the match, including the substring  that  matched  the
         entire regular expression. This is the value returned by pcre_exec() if
-        it  is greater than zero. If pcre_exec() returned zero, indicating that
+        it is greater than zero. If pcre_exec() returned zero, indicating  that
-        it ran out of space in ovector, the value passed as stringcount  should
+        it  ran out of space in ovector, the value passed as stringcount should
         be the number of elements in the vector divided by three.
-        The  functions pcre_copy_substring() and pcre_get_substring() extract a
+        The functions pcre_copy_substring() and pcre_get_substring() extract  a
-        single substring, whose number is given as  stringnumber.  A  value  of
+        single  substring,  whose  number  is given as stringnumber. A value of
-        zero  extracts  the  substring that matched the entire pattern, whereas
+        zero extracts the substring that matched the  entire  pattern,  whereas
-        higher values  extract  the  captured  substrings.  For  pcre_copy_sub-
+        higher  values  extract  the  captured  substrings.  For pcre_copy_sub-
-        string(),  the  string  is  placed  in buffer, whose length is given by
+        string(), the string is placed in buffer,  whose  length  is  given  by
-        buffersize, while for pcre_get_substring() a new  block  of  memory  is
+        buffersize,  while  for  pcre_get_substring()  a new block of memory is
-        obtained  via  pcre_malloc,  and its address is returned via stringptr.
+        obtained via pcre_malloc, and its address is  returned  via  stringptr.
-        The yield of the function is the length of the  string,  not  including
+        The  yield  of  the function is the length of the string, not including
         the terminating zero, or one of these error codes:
           PCRE_ERROR_NOMEMORY       (-6)
-        The  buffer  was too small for pcre_copy_substring(), or the attempt to
+        The buffer was too small for pcre_copy_substring(), or the  attempt  to
         get memory failed for pcre_get_substring().
           PCRE_ERROR_NOSUBSTRING    (-7)
         There is no substring whose number is stringnumber.
-        The pcre_get_substring_list()  function  extracts  all  available  sub-
+        The  pcre_get_substring_list()  function  extracts  all  available sub-
-        strings  and  builds  a list of pointers to them. All this is done in a
+        strings and builds a list of pointers to them. All this is  done  in  a
         single block of memory that is obtained via pcre_malloc. The address of
-        the  memory  block  is returned via listptr, which is also the start of
+        the memory block is returned via listptr, which is also  the  start  of
-        the list of string pointers. The end of the list is marked  by  a  NULL
+        the  list  of  string pointers. The end of the list is marked by a NULL
-        pointer.  The  yield  of  the function is zero if all went well, or the
+        pointer. The yield of the function is zero if all  went  well,  or  the
         error code
           PCRE_ERROR_NOMEMORY       (-6)
         if the attempt to get the memory block failed.
-        When any of these functions encounter a substring that is unset,  which
+        When  any of these functions encounter a substring that is unset, which
-        can  happen  when  capturing subpattern number n+1 matches some part of
+        can happen when capturing subpattern number n+1 matches  some  part  of
-        the subject, but subpattern n has not been used at all, they return  an
+        the  subject, but subpattern n has not been used at all, they return an
         empty string. This can be distinguished from a genuine zero-length sub-
-        string by inspecting the appropriate offset in ovector, which is  nega-
+        string  by inspecting the appropriate offset in ovector, which is nega-
         tive for unset substrings.
-        The  two convenience functions pcre_free_substring() and pcre_free_sub-
+        The two convenience functions pcre_free_substring() and  pcre_free_sub-
-        string_list() can be used to free the memory  returned  by  a  previous
+        string_list()  can  be  used  to free the memory returned by a previous
         call  of  pcre_get_substring()  or  pcre_get_substring_list(),  respec-
-        tively. They do nothing more than  call  the  function  pointed  to  by
+        tively.  They  do  nothing  more  than  call the function pointed to by
-        pcre_free,  which  of course could be called directly from a C program.
+        pcre_free, which of course could be called directly from a  C  program.
-        However, PCRE is used in some situations where it is linked via a  spe-
+        However,  PCRE is used in some situations where it is linked via a spe-
-        cial   interface  to  another  programming  language  that  cannot  use
+        cial  interface  to  another  programming  language  that  cannot   use
-        pcre_free directly; it is for these cases that the functions  are  pro-
+        pcre_free  directly;  it is for these cases that the functions are pro-
         vided.
-Line 2274 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
+Line 2380 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
              int stringcount, const char *stringname,
              const char **stringptr);
-        To  extract a substring by name, you first have to find associated num-
+        To extract a substring by name, you first have to find associated  num-
         ber.  For example, for this pattern
           (a+)b(?<xxx>\d+)...
-Line 2283 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
+Line 2389 
 EXTRACTING CAPTURED SUBSTRINGS BY NAME
         be unique (PCRE_DUPNAMES was not set), you can find the number from the
         name by calling pcre_get_stringnumber(). The first argument is the com-
         piled pattern, and the second is the name. The yield of the function is
-        the subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if  there  is  no
+        the  subpattern  number,  or PCRE_ERROR_NOSUBSTRING (-7) if there is no
         subpattern of that name.
         Given the number, you can extract the substring directly, or use one of
         the functions described in the previous section. For convenience, there
         are also two functions that do the whole job.
-        Most    of    the    arguments   of   pcre_copy_named_substring()   and
+        Most   of   the   arguments    of    pcre_copy_named_substring()    and
-        pcre_get_named_substring() are the same  as  those  for  the  similarly
+        pcre_get_named_substring()  are  the  same  as  those for the similarly
-        named  functions  that extract by number. As these are described in the
+        named functions that extract by number. As these are described  in  the
-        previous section, they are not re-described here. There  are  just  two
+        previous  section,  they  are not re-described here. There are just two
         differences:
-        First,  instead  of a substring number, a substring name is given. Sec-
+        First, instead of a substring number, a substring name is  given.  Sec-
         ond, there is an extra argument, given at the start, which is a pointer
-        to  the compiled pattern. This is needed in order to gain access to the
+        to the compiled pattern. This is needed in order to gain access to  the
         name-to-number translation table.
-        These functions call pcre_get_stringnumber(), and if it succeeds,  they
+        These  functions call pcre_get_stringnumber(), and if it succeeds, they
-        then  call  pcre_copy_substring() or pcre_get_substring(), as appropri-
+        then call pcre_copy_substring() or pcre_get_substring(),  as  appropri-
-        ate. NOTE: If PCRE_DUPNAMES is set and there are duplicate  names,  the
+        ate.  NOTE:  If PCRE_DUPNAMES is set and there are duplicate names, the
         behaviour may not be what you want (see the next section).
+        Warning: If the pattern uses the "(?|" feature to set up multiple  sub-
+        patterns  with  the  same  number,  you cannot use names to distinguish
+        them, because names are not included in the compiled code. The matching
+        process uses only numbers.
  DUPLICATE SUBPATTERN NAMES
-Line 2513 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
+Line 2624 
 MATCHING A PATTERN: THE ALTERNATIVE FUNC
  SEE ALSO
         pcrebuild(3), pcrecallout(3), pcrecpp(3)(3), pcrematching(3),  pcrepar-
-        tial(3),  pcreposix(3), pcreprecompile(3), pcresample(3), pcrestack(3).
+        tial(3), pcreposix(3), pcreprecompile(3), pcresample(3), pcrestack(3).
  AUTHOR
-Line 2525 
 AUTHOR
+Line 2636 
 AUTHOR
  REVISION
-        Last updated: 11 September 2007
+        Last updated: 11 April 2009
-        Copyright (c) 1997-2007 University of Cambridge.
+        Copyright (c) 1997-2009 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 2577 
 PCRE CALLOUTS
+Line 2688 
 PCRE CALLOUTS
  MISSING CALLOUTS
         You  should  be  aware  that,  because of optimizations in the way PCRE
-        matches patterns, callouts sometimes do not happen. For example, if the
+        matches patterns by default, callouts  sometimes  do  not  happen.  For
-        pattern is
+        example, if the pattern is
           ab(?C4)cd
-Line 2587 
 MISSING CALLOUTS
+Line 2698 
 MISSING CALLOUTS
         ever  start,  and  the  callout is never reached. However, with "abyd",
         though the result is still no match, the callout is obeyed.
+        You can disable these optimizations by passing the  PCRE_NO_START_OPTI-
+        MIZE  option  to  pcre_exec()  or  pcre_dfa_exec(). This slows down the
+        matching process, but does ensure that callouts  such  as  the  example
+        above are obeyed.
  THE CALLOUT INTERFACE
-        During matching, when PCRE reaches a callout point, the external  func-
+        During  matching, when PCRE reaches a callout point, the external func-
-        tion  defined by pcre_callout is called (if it is set). This applies to
+        tion defined by pcre_callout is called (if it is set). This applies  to
-        both the pcre_exec() and the pcre_dfa_exec()  matching  functions.  The
+        both  the  pcre_exec()  and the pcre_dfa_exec() matching functions. The
-        only  argument  to  the callout function is a pointer to a pcre_callout
+        only argument to the callout function is a pointer  to  a  pcre_callout
         block. This structure contains the following fields:
           int          version;
-Line 2609 
 THE CALLOUT INTERFACE
+Line 2725 
 THE CALLOUT INTERFACE
           int          pattern_position;
           int          next_item_length;
-        The version field is an integer containing the version  number  of  the
+        The  version  field  is an integer containing the version number of the
-        block  format. The initial version was 0; the current version is 1. The
+        block format. The initial version was 0; the current version is 1.  The
-        version number will change again in future  if  additional  fields  are
+        version  number  will  change  again in future if additional fields are
         added, but the intention is never to remove any of the existing fields.
         The callout_number field contains the number of the  callout,  as  com-
-Line 2696 
 AUTHOR
+Line 2812 
 AUTHOR
  REVISION
-        Last updated: 29 May 2007
+        Last updated: 15 March 2009
-        Copyright (c) 1997-2007 University of Cambridge.
+        Copyright (c) 1997-2009 University of Cambridge.
  ------------------------------------------------------------------------------
-Line 2853 
 PCRE REGULAR EXPRESSION DETAILS
+Line 2969 
 PCRE REGULAR EXPRESSION DETAILS
         The  syntax and semantics of the regular expressions that are supported
         by PCRE are described in detail below. There is a quick-reference  syn-
-        tax  summary  in  the  pcresyntax  page. Perl's regular expressions are
+        tax summary in the pcresyntax page. PCRE tries to match Perl syntax and
-        described in its own documentation, and regular expressions in  general
+        semantics as closely as it can. PCRE  also  supports  some  alternative
-        are  covered in a number of books, some of which have copious examples.
+        regular  expression  syntax (which does not conflict with the Perl syn-
-        Jeffrey  Friedl's  "Mastering  Regular   Expressions",   published   by
+        tax) in order to provide some compatibility with regular expressions in
-        O'Reilly,  covers regular expressions in great detail. This description
+        Python, .NET, and Oniguruma.
-        of PCRE's regular expressions is intended as reference material.
+        Perl's  regular expressions are described in its own documentation, and
+        regular expressions in general are covered in a number of  books,  some
+        of  which  have  copious  examples. Jeffrey Friedl's "Mastering Regular
+        Expressions", published by  O'Reilly,  covers  regular  expressions  in
+        great  detail.  This  description  of  PCRE's  regular  expressions  is
+        intended as reference material.
         The original operation of PCRE was on strings of  one-byte  characters.
         However,  there is now also support for UTF-8 character strings. To use
         this, you must build PCRE to  include  UTF-8  support,  and  then  call
-        pcre_compile()  with  the  PCRE_UTF8  option.  How this affects pattern
+        pcre_compile()  with  the  PCRE_UTF8  option.  There  is also a special
-        matching is mentioned in several places below. There is also a  summary
+        sequence that can be given at the start of a pattern:
-        of  UTF-8  features  in  the  section on UTF-8 support in the main pcre
-        page.
+          (*UTF8)
+        Starting a pattern with this sequence  is  equivalent  to  setting  the
+        PCRE_UTF8  option.  This  feature  is  not Perl-compatible. How setting
+        UTF-8 mode affects pattern matching  is  mentioned  in  several  places
+        below.  There  is  also  a  summary of UTF-8 features in the section on
+        UTF-8 support in the main pcre page.
         The remainder of this document discusses the  patterns  that  are  sup-
         ported  by  PCRE when its main matching function, pcre_exec(), is used.
-Line 2970 
 CHARACTERS AND METACHARACTERS
+Line 3098 
 CHARACTERS AND METACHARACTERS
                    syntax)
           ]      terminates the character class
-        The  following sections describe the use of each of the metacharacters.
+        The following sections describe the use of each of the metacharacters.
  BACKSLASH
         The backslash character has several uses. Firstly, if it is followed by
-        a  non-alphanumeric  character,  it takes away any special meaning that
+        a non-alphanumeric character, it takes away any  special  meaning  that
-        character may have. This  use  of  backslash  as  an  escape  character
+        character  may  have.  This  use  of  backslash  as an escape character
         applies both inside and outside character classes.
-        For  example,  if  you want to match a * character, you write \* in the
+        For example, if you want to match a * character, you write  \*  in  the
-        pattern.  This escaping action applies whether  or  not  the  following
+        pattern.   This  escaping  action  applies whether or not the following
-        character  would  otherwise be interpreted as a metacharacter, so it is
+        character would otherwise be interpreted as a metacharacter, so  it  is
-        always safe to precede a non-alphanumeric  with  backslash  to  specify
+        always  safe  to  precede  a non-alphanumeric with backslash to specify
-        that  it stands for itself. In particular, if you want to match a back-
+        that it stands for itself. In particular, if you want to match a  back-
         slash, you write \\.
-        If a pattern is compiled with the PCRE_EXTENDED option,  whitespace  in
+        If  a  pattern is compiled with the PCRE_EXTENDED option, whitespace in
-        the  pattern (other than in a character class) and characters between a
+        the pattern (other than in a character class) and characters between  a
         # outside a character class and the next newline are ignored. An escap-
-        ing  backslash  can  be  used to include a whitespace or # character as
+        ing backslash can be used to include a whitespace  or  #  character  as
         part of the pattern.
-        If you want to remove the special meaning from a  sequence  of  charac-
+        If  you  want  to remove the special meaning from a sequence of charac-
-        ters,  you can do so by putting them between \Q and \E. This is differ-
+        ters, you can do so by putting them between \Q and \E. This is  differ-
-        ent from Perl in that $ and  @  are  handled  as  literals  in  \Q...\E
+        ent  from  Perl  in  that  $  and  @ are handled as literals in \Q...\E
-        sequences  in  PCRE, whereas in Perl, $ and @ cause variable interpola-
+        sequences in PCRE, whereas in Perl, $ and @ cause  variable  interpola-
         tion. Note the following examples:
           Pattern            PCRE matches   Perl matches
-Line 3006 
 BACKSLASH
+Line 3134 
 BACKSLASH
           \Qabc\$xyz\E       abc\$xyz       abc\$xyz
           \Qabc\E\$\Qxyz\E   abc$xyz        abc$xyz
-        The \Q...\E sequence is recognized both inside  and  outside  character
+        The  \Q...\E  sequence  is recognized both inside and outside character
         classes.
     Non-printing characters
         A second use of backslash provides a way of encoding non-printing char-
-        acters in patterns in a visible manner. There is no restriction on  the
+        acters  in patterns in a visible manner. There is no restriction on the
-        appearance  of non-printing characters, apart from the binary zero that
+        appearance of non-printing characters, apart from the binary zero  that
-        terminates a pattern, but when a pattern  is  being  prepared  by  text
+        terminates  a  pattern,  but  when  a pattern is being prepared by text
-        editing,  it  is  usually  easier  to  use  one of the following escape
+        editing, it is usually easier  to  use  one  of  the  following  escape
         sequences than the binary character it represents:
           \a        alarm, that is, the BEL character (hex 07)
-Line 3029 
 BACKSLASH
+Line 3157 
 BACKSLASH
           \xhh      character with hex code hh
           \x{hhh..} character with hex code hhh..
-        The precise effect of \cx is as follows: if x is a lower  case  letter,
+        The  precise  effect of \cx is as follows: if x is a lower case letter,
-        it  is converted to upper case. Then bit 6 of the character (hex 40) is
+        it is converted to upper case. Then bit 6 of the character (hex 40)  is
-        inverted.  Thus \cz becomes hex 1A, but \c{ becomes hex 3B,  while  \c;
+        inverted.   Thus  \cz becomes hex 1A, but \c{ becomes hex 3B, while \c;
         becomes hex 7B.
-        After  \x, from zero to two hexadecimal digits are read (letters can be
+        After \x, from zero to two hexadecimal digits are read (letters can  be
-        in upper or lower case). Any number of hexadecimal  digits  may  appear
+        in  upper  or  lower case). Any number of hexadecimal digits may appear
-        between  \x{  and  },  but the value of the character code must be less
+        between \x{ and }, but the value of the character  code  must  be  less
         than 256 in non-UTF-8 mode, and less than 2**31 in UTF-8 mode. That is,
-        the  maximum value in hexadecimal is 7FFFFFFF. Note that this is bigger
+        the maximum value in hexadecimal is 7FFFFFFF. Note that this is  bigger
         than the largest Unicode code point, which is 10FFFF.
-        If characters other than hexadecimal digits appear between \x{  and  },
+        If  characters  other than hexadecimal digits appear between \x{ and },
         or if there is no terminating }, this form of escape is not recognized.
-        Instead, the initial \x will be  interpreted  as  a  basic  hexadecimal
+        Instead,  the  initial  \x  will  be interpreted as a basic hexadecimal
-        escape,  with  no  following  digits, giving a character whose value is
+        escape, with no following digits, giving a  character  whose  value  is
         zero.
         Characters whose value is less than 256 can be defined by either of the
-        two  syntaxes  for  \x. There is no difference in the way they are han-
+        two syntaxes for \x. There is no difference in the way  they  are  han-
         dled. For example, \xdc is exactly the same as \x{dc}.
-        After \0 up to two further octal digits are read. If  there  are  fewer
+        After  \0  up  to two further octal digits are read. If there are fewer
-        than  two  digits,  just  those  that  are  present  are used. Thus the
+        than two digits, just  those  that  are  present  are  used.  Thus  the
         sequence \0\x\07 specifies two binary zeros followed by a BEL character
-        (code  value 7). Make sure you supply two digits after the initial zero
+        (code value 7). Make sure you supply two digits after the initial  zero
         if the pattern character that follows is itself an octal digit.
         The handling of a backslash followed by a digit other than 0 is compli-
         cated.  Outside a character class, PCRE reads it and any following dig-
-        its as a decimal number. If the number is less than  10,  or  if  there
+        its  as  a  decimal  number. If the number is less than 10, or if there
         have been at least that many previous capturing left parentheses in the
-        expression, the entire  sequence  is  taken  as  a  back  reference.  A
+        expression,  the  entire  sequence  is  taken  as  a  back reference. A
-        description  of how this works is given later, following the discussion
+        description of how this works is given later, following the  discussion
         of parenthesized subpatterns.
-        Inside a character class, or if the decimal number is  greater  than  9
+        Inside  a  character  class, or if the decimal number is greater than 9
-        and  there have not been that many capturing subpatterns, PCRE re-reads
+        and there have not been that many capturing subpatterns, PCRE  re-reads
         up to three octal digits following the backslash, and uses them to gen-
-        erate  a data character. Any subsequent digits stand for themselves. In
+        erate a data character. Any subsequent digits stand for themselves.  In
-        non-UTF-8 mode, the value of a character specified  in  octal  must  be
+        non-UTF-8  mode,  the  value  of a character specified in octal must be
-        less  than  \400.  In  UTF-8 mode, values up to \777 are permitted. For
+        less than \400. In UTF-8 mode, values up to  \777  are  permitted.  For
         example:
           \040   is another way of writing a space
-Line 3088 
 BACKSLASH
+Line 3216 
 BACKSLASH
           \81    is either a back reference, or a binary zero
                     followed by the two characters "8" and "1"
-        Note that octal values of 100 or greater must not be  introduced  by  a
+        Note  that  octal  values of 100 or greater must not be introduced by a
         leading zero, because no more than three octal digits are ever read.
         All the sequences that define a single character value can be used both
-        inside and outside character classes. In addition, inside  a  character
+        inside  and  outside character classes. In addition, inside a character
-        class,  the  sequence \b is interpreted as the backspace character (hex
+        class, the sequence \b is interpreted as the backspace  character  (hex
-), and the sequences \R and \X are interpreted as the characters  "R"
+),  and the sequences \R and \X are interpreted as the characters "R"
-        and  "X", respectively. Outside a character class, these sequences have
+        and "X", respectively. Outside a character class, these sequences  have
         different meanings (see below).
     Absolute and relative back references
-        The sequence \g followed by an unsigned or a negative  number,  option-
+        The  sequence  \g followed by an unsigned or a negative number, option-
-        ally  enclosed  in braces, is an absolute or relative back reference. A
+        ally enclosed in braces, is an absolute or relative back  reference.  A
         named back reference can be coded as \g{name}. Back references are dis-
         cussed later, following the discussion of parenthesized subpatterns.
+    Absolute and relative subroutine calls
+        For compatibility with Oniguruma, the non-Perl syntax \g followed by  a
+        name or a number enclosed either in angle brackets or single quotes, is
+        an alternative syntax for referencing a subpattern as  a  "subroutine".
+        Details  are  discussed  later.   Note  that  \g{...} (Perl syntax) and
+        \g<...> (Oniguruma syntax) are not synonymous. The  former  is  a  back
+        reference; the latter is a subroutine call.
     Generic character types
         Another use of backslash is for specifying generic character types. The
-Line 3140 
 BACKSLASH
+Line 3277 
 BACKSLASH
         \s, or \w, and always match \D, \S, and \W. This is true even when Uni-
         code  character  property  support is available. These sequences retain
         their original meanings from before UTF-8 support was available, mainly
-        for efficiency reasons.
+        for  efficiency  reasons. Note that this also affects \b, because it is
+        defined in terms of \w and \W.
         The sequences \h, \H, \v, and \V are Perl 5.10 features. In contrast to
-        the other sequences, these do match certain high-valued  codepoints  in
+        the  other  sequences, these do match certain high-valued codepoints in
         UTF-8 mode.  The horizontal space characters are:
           U+0009     Horizontal tab
-Line 3177 
 BACKSLASH
+Line 3315 
 BACKSLASH
           U+2029     Paragraph separator
         A "word" character is an underscore or any character less than 256 that
-        is a letter or digit. The definition of  letters  and  digits  is  con-
+        is  a  letter  or  digit.  The definition of letters and digits is con-
-        trolled  by PCRE's low-valued character tables, and may vary if locale-
+        trolled by PCRE's low-valued character tables, and may vary if  locale-
-        specific matching is taking place (see "Locale support" in the  pcreapi
+        specific  matching is taking place (see "Locale support" in the pcreapi
-        page).  For  example,  in  a French locale such as "fr_FR" in Unix-like
+        page). For example, in a French locale such  as  "fr_FR"  in  Unix-like
-        systems, or "french" in Windows, some character codes greater than  128
+        systems,  or "french" in Windows, some character codes greater than 128
-        are  used for accented letters, and these are matched by \w. The use of
+        are used for accented letters, and these are matched by \w. The use  of
         locales with Unicode is discouraged.
     Newline sequences
-        Outside a character class, by default, the escape sequence  \R  matches
+        Outside  a  character class, by default, the escape sequence \R matches
         any Unicode newline sequence. This is a Perl 5.10 feature. In non-UTF-8
         mode \R is equivalent to the following:
           (?>\r\n|\n|\x0b|\f|\r|\x85)
-        This is an example of an "atomic group", details  of  which  are  given
+        This  is  an  example  of an "atomic group", details of which are given
         below.  This particular group matches either the two-character sequence
-        CR followed by LF, or  one  of  the  single  characters  LF  (linefeed,
+        CR  followed  by  LF,  or  one  of  the single characters LF (linefeed,
         U+000A), VT (vertical tab, U+000B), FF (formfeed, U+000C), CR (carriage
         return, U+000D), or NEL (next line, U+0085). The two-character sequence
         is treated as a single unit that cannot be split.
-        In  UTF-8  mode, two additional characters whose codepoints are greater
+        In UTF-8 mode, two additional characters whose codepoints  are  greater
         than 255 are added: LS (line separator, U+2028) and PS (paragraph sepa-
-        rator,  U+2029).   Unicode character property support is not needed for
+        rator, U+2029).  Unicode character property support is not  needed  for
         these characters to be recognized.
         It is possible to restrict \R to match only CR, LF, or CRLF (instead of
-        the  complete  set  of  Unicode  line  endings)  by  setting the option
+        the complete set  of  Unicode  line  endings)  by  setting  the  option
         PCRE_BSR_ANYCRLF either at compile time or when the pattern is matched.
         (BSR is an abbrevation for "backslash R".) This can be made the default
-        when PCRE is built; if this is the case, the  other  behaviour  can  be
+        when  PCRE  is  built;  if this is the case, the other behaviour can be
-        requested  via  the  PCRE_BSR_UNICODE  option.   It is also possible to
+        requested via the PCRE_BSR_UNICODE option.   It  is  also  possible  to
-        specify these settings by starting a pattern string  with  one  of  the
+        specify  these  settings  by  starting a pattern string with one of the
         following sequences:
           (*BSR_ANYCRLF)   CR, LF, or CRLF only
-Line 3220 
 BACKSLASH
+Line 3358 
 BACKSLASH
         These override the default and the options given to pcre_compile(), but
         they can be overridden by options given to pcre_exec(). Note that these
         special settings, which are not Perl-compatible, are recognized only at
-        the very start of a pattern, and that they must be in  upper  case.  If
+        the  very  start  of a pattern, and that they must be in upper case. If
-        more  than  one  of  them is present, the last one is used. They can be
+        more than one of them is present, the last one is  used.  They  can  be
-        combined with a change of newline convention, for  example,  a  pattern
+        combined  with  a  change of newline convention, for example, a pattern
         can start with:
           (*ANY)(*BSR_ANYCRLF)
-Line 3232 
 BACKSLASH
+Line 3370 
 BACKSLASH
     Unicode character properties
         When PCRE is built with Unicode character property support, three addi-
-        tional escape sequences that match characters with specific  properties
+        tional  escape sequences that match characters with specific properties
-        are  available.   When not in UTF-8 mode, these sequences are of course
+        are available.  When not in UTF-8 mode, these sequences are  of  course
-        limited to testing characters whose codepoints are less than  256,  but
+        limited  to  testing characters whose codepoints are less than 256, but
         they do work in this mode.  The extra escape sequences are:
           \p{xx}   a character with the xx property
           \P{xx}   a character without the xx property
           \X       an extended Unicode sequence
-        The  property  names represented by xx above are limited to the Unicode
+        The property names represented by xx above are limited to  the  Unicode
         script names, the general category properties, and "Any", which matches
         any character (including newline). Other properties such as "InMusical-
-        Symbols" are not currently supported by PCRE. Note  that  \P{Any}  does
+        Symbols"  are  not  currently supported by PCRE. Note that \P{Any} does
         not match any characters, so always causes a match failure.
         Sets of Unicode characters are defined as belonging to certain scripts.
-        A character from one of these sets can be matched using a script  name.
+        A  character from one of these sets can be matched using a script name.
         For example:
           \p{Greek}
           \P{Han}
-        Those  that are not part of an identified script are lumped together as
+        Those that are not part of an identified script are lumped together  as
         "Common". The current list of scripts is:
         Arabic,  Armenian,  Balinese,  Bengali,  Bopomofo,  Braille,  Buginese,
-        Buhid,   Canadian_Aboriginal,   Cherokee,  Common,  Coptic,  Cuneiform,
+        Buhid,  Canadian_Aboriginal,  Cherokee,  Common,   Coptic,   Cuneiform,
         Cypriot, Cyrillic, Deseret, Devanagari, Ethiopic, Georgian, Glagolitic,
-        Gothic,  Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew, Hira-
+        Gothic, Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew,  Hira-
-        gana, Inherited, Kannada,  Katakana,  Kharoshthi,  Khmer,  Lao,  Latin,
+        gana,  Inherited,  Kannada,  Katakana,  Kharoshthi,  Khmer, Lao, Latin,
         Limbu,  Linear_B,  Malayalam,  Mongolian,  Myanmar,  New_Tai_Lue,  Nko,
-        Ogham, Old_Italic, Old_Persian, Oriya, Osmanya,  Phags_Pa,  Phoenician,
+        Ogham,  Old_Italic,  Old_Persian, Oriya, Osmanya, Phags_Pa, Phoenician,
         Runic,  Shavian,  Sinhala,  Syloti_Nagri,  Syriac,  Tagalog,  Tagbanwa,
         Tai_Le, Tamil, Telugu, Thaana, Thai, Tibetan, Tifinagh, Ugaritic, Yi.
-        Each character has exactly one general category property, specified  by
+        Each  character has exactly one general category 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
+        specified  by  including a circumflex between the opening brace and the
         property name. For example, \p{^Lu} is the same as \P{Lu}.
         If only one letter is specified with \p or \P, it includes all the gen-
-        eral category properties that start with that letter. In this case,  in
+        eral  category properties that start with that letter. In this case, in
-        the  absence of negation, the curly brackets in the escape sequence are
+        the absence of negation, the curly brackets in the escape sequence  are
         optional; these two examples have the same effect:
           \p{L}
-Line 3326 
 BACKSLASH
+Line 3464 
 BACKSLASH
           Zp    Paragraph separator
           Zs    Space separator
-        The special property L& is also supported: it matches a character  that
+        The  special property L& is also supported: it matches a character that
-        has  the  Lu,  Ll, or Lt property, in other words, a letter that is not
+        has the Lu, Ll, or Lt property, in other words, a letter  that  is  not
         classified as a modifier or "other".
-        The Cs (Surrogate) property applies only to  characters  in  the  range
+        The  Cs  (Surrogate)  property  applies only to characters in the range
-        U+D800  to  U+DFFF. Such characters are not valid in UTF-8 strings (see
+        U+D800 to U+DFFF. Such characters are not valid in UTF-8  strings  (see
         RFC 3629) and so cannot be tested by PCRE, unless UTF-8 validity check-
-        ing  has  been  turned off (see the discussion of PCRE_NO_UTF8_CHECK in
+        ing has been turned off (see the discussion  of  PCRE_NO_UTF8_CHECK  in
         the pcreapi page).
-        The long synonyms for these properties  that  Perl  supports  (such  as
+        The  long  synonyms  for  these  properties that Perl supports (such as
-        \p{Letter})  are  not  supported by PCRE, nor is it permitted to prefix
+        \p{Letter}) are not supported by PCRE, nor is it  permitted  to  prefix
         any of these properties with "Is".
         No character that is in the Unicode table has the Cn (unassigned) prop-
         erty.  Instead, this property is assumed for any code point that is not
         in the Unicode table.
-        Specifying caseless matching does not affect  these  escape  sequences.
+        Specifying  caseless  matching  does not affect these escape sequences.
         For example, \p{Lu} always matches only upper case letters.
-        The  \X  escape  matches  any number of Unicode characters that form an
+        The \X escape matches any number of Unicode  characters  that  form  an
         extended Unicode sequence. \X is equivalent to
           (?>\PM\pM*)
-        That is, it matches a character without the "mark"  property,  followed
+        That  is,  it matches a character without the "mark" property, followed
-        by  zero  or  more  characters with the "mark" property, and treats the
+        by zero or more characters with the "mark"  property,  and  treats  the
-        sequence as an atomic group (see below).  Characters  with  the  "mark"
+        sequence  as  an  atomic group (see below).  Characters with the "mark"
-        property  are  typically  accents  that affect the preceding character.
+        property are typically accents that  affect  the  preceding  character.
-        None of them have codepoints less than 256, so  in  non-UTF-8  mode  \X
+        None  of  them  have  codepoints less than 256, so in non-UTF-8 mode \X
         matches any one character.
-        Matching  characters  by Unicode property is not fast, because PCRE has
+        Matching characters by Unicode property is not fast, because  PCRE  has
-        to search a structure that contains  data  for  over  fifteen  thousand
+        to  search  a  structure  that  contains data for over fifteen thousand
         characters. That is why the traditional escape sequences such as \d and
         \w do not use Unicode properties in PCRE.
     Resetting the match start
         The escape sequence \K, which is a Perl 5.10 feature, causes any previ-
-        ously  matched  characters  not  to  be  included  in the final matched
+        ously matched characters not  to  be  included  in  the  final  matched
         sequence. For example, the pattern:
           foo\Kbar
-        matches "foobar", but reports that it has matched "bar".  This  feature
+        matches  "foobar",  but reports that it has matched "bar". This feature
-        is  similar  to  a lookbehind assertion (described below).  However, in
+        is similar to a lookbehind assertion (described  below).   However,  in
-        this case, the part of the subject before the real match does not  have
+        this  case, the part of the subject before the real match does not have
-        to  be of fixed length, as lookbehind assertions do. The use of \K does
+        to be of fixed length, as lookbehind assertions do. The use of \K  does
-        not interfere with the setting of captured  substrings.   For  example,
+        not  interfere  with  the setting of captured substrings.  For example,
         when the pattern
           (foo)\Kbar
-Line 3385 
 BACKSLASH
+Line 3523 
 BACKSLASH
     Simple assertions
-        The  final use of backslash is for certain simple assertions. An asser-
+        The final use of backslash is for certain simple assertions. An  asser-
-        tion specifies a condition that has to be met at a particular point  in
+        tion  specifies a condition that has to be met at a particular point in
-        a  match, without consuming any characters from the subject string. The
+        a match, without consuming any characters from the subject string.  The
-        use of subpatterns for more complicated assertions is described  below.
+        use  of subpatterns for more complicated assertions is described below.
         The backslashed assertions are:
           \b     matches at a word boundary
-Line 3399 
 BACKSLASH
+Line 3537 
 BACKSLASH
           \z     matches only at the end of the subject
           \G     matches at the first matching position in the subject
-        These  assertions may not appear in character classes (but note that \b
+        These assertions may not appear in character classes (but note that  \b
         has a different meaning, namely the backspace character, inside a char-
         acter class).
-        A  word  boundary is a position in the subject string where the current
+        A word boundary is a position in the subject string where  the  current
-        character and the previous character do not both match \w or  \W  (i.e.
+        character  and  the previous character do not both match \w or \W (i.e.
-        one  matches  \w  and the other matches \W), or the start or end of the
+        one matches \w and the other matches \W), or the start or  end  of  the
         string if the first or last character matches \w, respectively.
-        The \A, \Z, and \z assertions differ from  the  traditional  circumflex
+        The  \A,  \Z,  and \z assertions differ from the traditional circumflex
         and dollar (described in the next section) in that they only ever match
-        at the very start and end of the subject string, whatever  options  are
+        at  the  very start and end of the subject string, whatever options are
-        set.  Thus,  they are independent of multiline mode. These three asser-
+        set. Thus, they are independent of multiline mode. These  three  asser-
         tions are not affected by the PCRE_NOTBOL or PCRE_NOTEOL options, which
-        affect  only the behaviour of the circumflex and dollar metacharacters.
+        affect only the behaviour of the circumflex and dollar  metacharacters.
-        However, if the startoffset argument of pcre_exec() is non-zero,  indi-
+        However,  if the startoffset argument of pcre_exec() is non-zero, indi-
         cating that matching is to start at a point other than the beginning of
-        the subject, \A can never match. The difference between \Z  and  \z  is
+        the  subject,  \A  can never match. The difference between \Z and \z is
         that \Z matches before a newline at the end of the string as well as at
         the very end, whereas \z matches only at the end.
-        The \G assertion is true only when the current matching position is  at
+        The  \G assertion is true only when the current matching position is at
-        the  start point of the match, as specified by the startoffset argument
+        the start point of the match, as specified by the startoffset  argument
-        of pcre_exec(). It differs from \A when the  value  of  startoffset  is
+        of  pcre_exec().  It  differs  from \A when the value of startoffset is
-        non-zero.  By calling pcre_exec() multiple times with appropriate argu-
+        non-zero. By calling pcre_exec() multiple times with appropriate  argu-
         ments, you can mimic Perl's /g option, and it is in this kind of imple-
         mentation where \G can be useful.
-        Note,  however,  that  PCRE's interpretation of \G, as the start of the
+        Note, however, that PCRE's interpretation of \G, as the  start  of  the
         current match, is subtly different from Perl's, which defines it as the
-        end  of  the  previous  match. In Perl, these can be different when the
+        end of the previous match. In Perl, these can  be  different  when  the
-        previously matched string was empty. Because PCRE does just  one  match
+        previously  matched  string was empty. Because PCRE does just one match
         at a time, it cannot reproduce this behaviour.
-        If  all  the alternatives of a pattern begin with \G, the expression is
+        If all the alternatives of a pattern begin with \G, the  expression  is
         anchored to the starting match position, and the "anchored" flag is set
         in the compiled regular expression.
-Line 3441 
 BACKSLASH
+Line 3579 
 BACKSLASH
  CIRCUMFLEX AND DOLLAR
         Outside a character class, in the default matching mode, the circumflex
-        character is an assertion that is true only  if  the  current  matching
+        character  is  an  assertion  that is true only if the current matching
-        point  is  at the start of the subject string. If the startoffset argu-
+        point is at the start of the subject string. If the  startoffset  argu-
-        ment of pcre_exec() is non-zero, circumflex  can  never  match  if  the
+        ment  of  pcre_exec()  is  non-zero,  circumflex can never match if the
-        PCRE_MULTILINE  option  is  unset. Inside a character class, circumflex
+        PCRE_MULTILINE option is unset. Inside a  character  class,  circumflex
         has an entirely different meaning (see below).
-        Circumflex need not be the first character of the pattern if  a  number
+        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
+        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
+        alternative  in  which  it appears if the pattern is ever to match that
-        branch.  If all possible alternatives start with a circumflex, that is,
+        branch. If all possible alternatives start with a circumflex, that  is,
-        if the pattern is constrained to match only at the start  of  the  sub-
+        if  the  pattern  is constrained to match only at the start of the sub-
-        ject,  it  is  said  to be an "anchored" pattern. (There are also other
+        ject, it is said to be an "anchored" pattern.  (There  are  also  other
         constructs that can cause a pattern to be anchored.)
-        A dollar character is an assertion that is true  only  if  the  current
+        A  dollar  character  is  an assertion that is true only if the current
-        matching  point  is  at  the  end of the subject string, or immediately
+        matching point is at the end of  the  subject  string,  or  immediately
         before a newline at the end of the string (by default). Dollar need not
-        be  the  last  character of the pattern if a number of alternatives are
+        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
+        involved,  but  it  should  be  the last item in any branch in which it
         appears. Dollar has no special meaning in a character class.
-        The  meaning  of  dollar  can be changed so that it matches only at the
+        The meaning of dollar can be changed so that it  matches  only  at  the
-        very end of the string, by setting the  PCRE_DOLLAR_ENDONLY  option  at
+        very  end  of  the string, by setting the PCRE_DOLLAR_ENDONLY option at
         compile time. This does not affect the \Z assertion.
         The meanings of the circumflex and dollar characters are changed if the
-        PCRE_MULTILINE option is set. When  this  is  the  case,  a  circumflex
+        PCRE_MULTILINE  option  is  set.  When  this  is the case, a circumflex
-        matches  immediately after internal newlines as well as at the start of
+        matches immediately after internal newlines as well as at the start  of
-        the subject string. It does not match after a  newline  that  ends  the
+        the  subject  string.  It  does not match after a newline that ends the
-        string.  A dollar matches before any newlines in the string, as well as
+        string. A dollar matches before any newlines in the string, as well  as
-        at the very end, when PCRE_MULTILINE is set. When newline is  specified
+        at  the very end, when PCRE_MULTILINE is set. When newline is specified
-        as  the  two-character  sequence CRLF, isolated CR and LF characters do
+        as the two-character sequence CRLF, isolated CR and  LF  characters  do
         not indicate newlines.
-        For example, the pattern /^abc$/ matches the subject string  "def\nabc"
+        For  example, the pattern /^abc$/ matches the subject string "def\nabc"
-        (where  \n  represents a newline) in multiline mode, but not otherwise.
+        (where \n represents a newline) in multiline mode, but  not  otherwise.
-        Consequently, patterns that are anchored in single  line  mode  because
+        Consequently,  patterns  that  are anchored in single line mode because
-        all  branches  start  with  ^ are not anchored in multiline mode, and a
+        all branches start with ^ are not anchored in  multiline  mode,  and  a
-        match for circumflex is  possible  when  the  startoffset  argument  of
+        match  for  circumflex  is  possible  when  the startoffset argument of
-        pcre_exec()  is  non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if
+        pcre_exec() is non-zero. The PCRE_DOLLAR_ENDONLY option is  ignored  if
         PCRE_MULTILINE is set.
-        Note that the sequences \A, \Z, and \z can be used to match  the  start
+        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
+        and end of the subject in both modes, and if all branches of a  pattern
-        start with \A it is always anchored, whether or not  PCRE_MULTILINE  is
+        start  with  \A it is always anchored, whether or not PCRE_MULTILINE is
         set.
  FULL STOP (PERIOD, DOT)
         Outside a character class, a dot in the pattern matches any one charac-
-        ter in the subject string except (by default) a character  that  signi-
+        ter  in  the subject string except (by default) a character that signi-
-        fies  the  end  of  a line. In UTF-8 mode, the matched character may be
+        fies the end of a line. In UTF-8 mode, the  matched  character  may  be
         more than one byte long.
-        When a line ending is defined as a single character, dot never  matches
+        When  a line ending is defined as a single character, dot never matches
-        that  character; when the two-character sequence CRLF is used, dot does
+        that character; when the two-character sequence CRLF is used, dot  does
-        not match CR if it is immediately followed  by  LF,  but  otherwise  it
+        not  match  CR  if  it  is immediately followed by LF, but otherwise it
-        matches  all characters (including isolated CRs and LFs). When any Uni-
+        matches all characters (including isolated CRs and LFs). When any  Uni-
-        code line endings are being recognized, dot does not match CR or LF  or
+        code  line endings are being recognized, dot does not match CR or LF or
         any of the other line ending characters.
-        The  behaviour  of  dot  with regard to newlines can be changed. If the
+        The behaviour of dot with regard to newlines can  be  changed.  If  the
-        PCRE_DOTALL option is set, a dot matches  any  one  character,  without
+        PCRE_DOTALL  option  is  set,  a dot matches any one character, without
         exception. If the two-character sequence CRLF is present in the subject
         string, it takes two dots to match it.
-        The handling of dot is entirely independent of the handling of  circum-
+        The  handling of dot is entirely independent of the handling of circum-
-        flex  and  dollar,  the  only relationship being that they both involve
+        flex and dollar, the only relationship being  that  they  both  involve
         newlines. Dot has no special meaning in a character class.
  MATCHING A SINGLE BYTE
         Outside a character class, the escape sequence \C matches any one byte,
-        both  in  and  out  of  UTF-8 mode. Unlike a dot, it always matches any
+        both in and out of UTF-8 mode. Unlike a  dot,  it  always  matches  any
-        line-ending characters. The feature is provided in  Perl  in  order  to
+        line-ending  characters.  The  feature  is provided in Perl in order to
-        match  individual bytes in UTF-8 mode. Because it breaks up UTF-8 char-
+        match individual bytes in UTF-8 mode. Because it breaks up UTF-8  char-
-        acters into individual bytes, what remains in the string may be a  mal-
+        acters  into individual bytes, what remains in the string may be a mal-
-        formed  UTF-8  string.  For this reason, the \C escape sequence is best
+        formed UTF-8 string. For this reason, the \C escape  sequence  is  best
         avoided.
-        PCRE does not allow \C to appear in  lookbehind  assertions  (described
+        PCRE  does  not  allow \C to appear in lookbehind assertions (described
-        below),  because  in UTF-8 mode this would make it impossible to calcu-
+        below), because in UTF-8 mode this would make it impossible  to  calcu-
         late the length of the lookbehind.
-Line 3533 
 SQUARE BRACKETS AND CHARACTER CLASSES
+Line 3671 
 SQUARE BRACKETS AND CHARACTER CLASSES
         An opening square bracket introduces a character class, terminated by a
         closing square bracket. A closing square bracket on its own is not spe-
         cial. If a closing square bracket is required as a member of the class,
-        it  should  be  the first data character in the class (after an initial
+        it should be the first data character in the class  (after  an  initial
         circumflex, if present) or escaped with a backslash.
-        A character class matches a single character in the subject.  In  UTF-8
+        A  character  class matches a single character in the subject. In UTF-8
-        mode,  the character may occupy more than one byte. A matched character
+        mode, the character may occupy more than one byte. A matched  character
         must be in the set of characters defined by the class, unless the first
-        character  in  the  class definition is a circumflex, in which case the
+        character in the class definition is a circumflex, in  which  case  the
-        subject character must not be in the set defined by  the  class.  If  a
+        subject  character  must  not  be in the set defined by the class. If a
-        circumflex  is actually required as a member of the class, ensure it is
+        circumflex is actually required as a member of the class, ensure it  is
         not the first character, or escape it with a backslash.
-        For example, the character class [aeiou] matches any lower case  vowel,
+        For  example, the character class [aeiou] matches any lower case vowel,
-        while  [^aeiou]  matches  any character that is not a lower case vowel.
+        while [^aeiou] matches any character that is not a  lower  case  vowel.
         Note that a circumflex is just a convenient notation for specifying the
-        characters  that  are in the class by enumerating those that are not. A
+        characters that are in the class by enumerating those that are  not.  A
-        class that starts with a circumflex is not an assertion: it still  con-
+        class  that starts with a circumflex is not an assertion: it still con-
-        sumes  a  character  from the subject string, and therefore it fails if
+        sumes a character from the subject string, and therefore  it  fails  if
         the current pointer is at the end of the string.
-        In UTF-8 mode, characters with values greater than 255 can be  included
+        In  UTF-8 mode, characters with values greater than 255 can be included
-        in  a  class as a literal string of bytes, or by using the \x{ escaping
+        in a class as a literal string of bytes, or by using the  \x{  escaping
         mechanism.
-        When caseless matching is set, any letters in a  class  represent  both
+        When  caseless  matching  is set, any letters in a class represent both
-        their  upper  case  and lower case versions, so for example, a caseless
+        their upper case and lower case versions, so for  example,  a  caseless
-        [aeiou] matches "A" as well as "a", and a caseless  [^aeiou]  does  not
+        [aeiou]  matches  "A"  as well as "a", and a caseless [^aeiou] does not
-        match  "A", whereas a caseful version would. In UTF-8 mode, PCRE always
+        match "A", whereas a caseful version would. In UTF-8 mode, PCRE  always
-        understands the concept of case for characters whose  values  are  less
+        understands  the  concept  of case for characters whose values are less
-        than  128, so caseless matching is always possible. For characters with
+        than 128, so caseless matching is always possible. For characters  with
-        higher values, the concept of case is supported  if  PCRE  is  compiled
+        higher  values,  the  concept  of case is supported if PCRE is compiled
-        with  Unicode  property support, but not otherwise.  If you want to use
+        with Unicode property support, but not otherwise.  If you want  to  use
-        caseless matching for characters 128 and above, you  must  ensure  that
+        caseless  matching  for  characters 128 and above, you must ensure that
-        PCRE  is  compiled  with Unicode property support as well as with UTF-8
+        PCRE is compiled with Unicode property support as well  as  with  UTF-8
         support.
-        Characters that might indicate line breaks are  never  treated  in  any
+        Characters  that  might  indicate  line breaks are never treated in any
-        special  way  when  matching  character  classes,  whatever line-ending
+        special way  when  matching  character  classes,  whatever  line-ending
-        sequence is in  use,  and  whatever  setting  of  the  PCRE_DOTALL  and
+        sequence  is  in  use,  and  whatever  setting  of  the PCRE_DOTALL and
         PCRE_MULTILINE options is used. A class such as [^a] always matches one
         of these characters.
-        The minus (hyphen) character can be used to specify a range of  charac-
+        The  minus (hyphen) character can be used to specify a range of charac-
-        ters  in  a  character  class.  For  example,  [d-m] matches any letter
+        ters in a character  class.  For  example,  [d-m]  matches  any  letter
-        between d and m, inclusive. If a  minus  character  is  required  in  a
+        between  d  and  m,  inclusive.  If  a minus character is required in a
-        class,  it  must  be  escaped  with a backslash or appear in a position
+        class, it must be escaped with a backslash  or  appear  in  a  position
-        where it cannot be interpreted as indicating a range, typically as  the
+        where  it cannot be interpreted as indicating a range, typically as the
         first or last character in the class.
         It is not possible to have the literal character "]" as the end charac-
-        ter of a range. A pattern such as [W-]46] is interpreted as a class  of
+        ter  of a range. A pattern such as [W-]46] is interpreted as a class of
-        two  characters ("W" and "-") followed by a literal string "46]", so it
+        two characters ("W" and "-") followed by a literal string "46]", so  it
-        would match "W46]" or "-46]". However, if the "]"  is  escaped  with  a
+        would  match  "W46]"  or  "-46]". However, if the "]" is escaped with a
-        backslash  it is interpreted as the end of range, so [W-\]46] is inter-
+        backslash it is interpreted as the end of range, so [W-\]46] is  inter-
-        preted as a class containing a range followed by two other  characters.
+        preted  as a class containing a range followed by two other characters.
-        The  octal or hexadecimal representation of "]" can also be used to end
+        The octal or hexadecimal representation of "]" can also be used to  end
         a range.
-        Ranges operate in the collating sequence of character values. They  can
+        Ranges  operate in the collating sequence of character values. They can
-        also   be  used  for  characters  specified  numerically,  for  example
+        also  be  used  for  characters  specified  numerically,  for   example
-        [\000-\037]. In UTF-8 mode, ranges can include characters whose  values
+        [\000-\037].  In UTF-8 mode, ranges can include characters whose values
         are greater than 255, for example [\x{100}-\x{2ff}].
         If a range that includes letters is used when caseless matching is set,
         it matches the letters in either case. For example, [W-c] is equivalent
-        to  [][\\^_`wxyzabc],  matched  caselessly,  and  in non-UTF-8 mode, if
+        to [][\\^_`wxyzabc], matched caselessly,  and  in  non-UTF-8  mode,  if
-        character tables for a French locale are in  use,  [\xc8-\xcb]  matches
+        character  tables  for  a French locale are in use, [\xc8-\xcb] matches
-        accented  E  characters in both cases. In UTF-8 mode, PCRE supports the
+        accented E characters in both cases. In UTF-8 mode, PCRE  supports  the
-        concept of case for characters with values greater than 128  only  when
+        concept  of  case for characters with values greater than 128 only when
         it is compiled with Unicode property support.
-        The  character types \d, \D, \p, \P, \s, \S, \w, and \W may also appear
+        The character types \d, \D, \p, \P, \s, \S, \w, and \W may also  appear
-        in a character class, and add the characters that  they  match  to  the
+        in  a  character  class,  and add the characters that they match to the
         class. For example, [\dABCDEF] matches any hexadecimal digit. A circum-
-        flex can conveniently be used with the upper case  character  types  to
+        flex  can  conveniently  be used with the upper case character types to
-        specify  a  more  restricted  set of characters than the matching lower
+        specify a more restricted set of characters  than  the  matching  lower
-        case type. For example, the class [^\W_] matches any letter  or  digit,
+        case  type.  For example, the class [^\W_] matches any letter or digit,
         but not underscore.
-        The  only  metacharacters  that are recognized in character classes are
+        The only metacharacters that are recognized in  character  classes  are
-        backslash, hyphen (only where it can be  interpreted  as  specifying  a
+        backslash,  hyphen  (only  where  it can be interpreted as specifying a
-        range),  circumflex  (only  at the start), opening square bracket (only
+        range), circumflex (only at the start), opening  square  bracket  (only
-        when it can be interpreted as introducing a POSIX class name - see  the
+        when  it can be interpreted as introducing a POSIX class name - see the
-        next  section),  and  the  terminating closing square bracket. However,
+        next section), and the terminating  closing  square  bracket.  However,
         escaping other non-alphanumeric characters does no harm.
  POSIX CHARACTER CLASSES
         Perl supports the POSIX notation for character classes. This uses names
-        enclosed  by  [: and :] within the enclosing square brackets. PCRE also
+        enclosed by [: and :] within the enclosing square brackets.  PCRE  also
         supports this notation. For example,
           [01[:alpha:]%]
-Line 3645 
 POSIX CHARACTER CLASSES
+Line 3783 
 POSIX CHARACTER CLASSES
           word     "word" characters (same as \w)
           xdigit   hexadecimal digits
-        The  "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13),
+        The "space" characters are HT (9), LF (10), VT (11), FF (12), CR  (13),
-        and space (32). Notice that this list includes the VT  character  (code
+        and  space  (32). Notice that this list includes the VT character (code
 ). This makes "space" different to \s, which does not include VT (for
         Perl compatibility).
-        The name "word" is a Perl extension, and "blank"  is  a  GNU  extension
+        The  name  "word"  is  a Perl extension, and "blank" is a GNU extension
-        from  Perl  5.8. Another Perl extension is negation, which is indicated
+        from Perl 5.8. Another Perl extension is negation, which  is  indicated
         by a ^ character after the colon. For example,
           [12[:^digit:]]
-        matches "1", "2", or any non-digit. PCRE (and Perl) also recognize  the
+        matches  "1", "2", or any non-digit. PCRE (and Perl) also recognize the
         POSIX syntax [.ch.] and [=ch=] where "ch" is a "collating element", but
         these are not supported, and an error is given if they are encountered.
-Line 3676 
 VERTICAL BAR
+Line 3814 
 VERTICAL BAR
         string). The matching process tries each alternative in turn, from left
         to right, and the first one that succeeds is used. If the  alternatives
         are  within a subpattern (defined below), "succeeds" means matching the
-        rest of the main pattern as well as the alternative in the  subpattern.
+        rest of the main pattern as well as the alternative in the subpattern.
  INTERNAL OPTION SETTING
-        The  settings  of  the  PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and
+        The settings of the  PCRE_CASELESS,  PCRE_MULTILINE,  PCRE_DOTALL,  and
-        PCRE_EXTENDED options (which are Perl-compatible) can be  changed  from
+        PCRE_EXTENDED  options  (which are Perl-compatible) can be changed from
-        within  the  pattern  by  a  sequence  of  Perl option letters enclosed
+        within the pattern by  a  sequence  of  Perl  option  letters  enclosed
         between "(?" and ")".  The option letters are
           i  for PCRE_CASELESS
-Line 3693 
 INTERNAL OPTION SETTING
+Line 3831 
 INTERNAL OPTION SETTING
         For example, (?im) sets caseless, multiline matching. It is also possi-
         ble to unset these options by preceding the letter with a hyphen, and a
-        combined setting and unsetting such as (?im-sx), which sets  PCRE_CASE-
+        combined  setting and unsetting such as (?im-sx), which sets PCRE_CASE-
-        LESS  and PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED,
+        LESS and PCRE_MULTILINE while unsetting PCRE_DOTALL and  PCRE_EXTENDED,
-        is also permitted. If a  letter  appears  both  before  and  after  the
+        is  also  permitted.  If  a  letter  appears  both before and after the
         hyphen, the option is unset.
-        The  PCRE-specific options PCRE_DUPNAMES, PCRE_UNGREEDY, and PCRE_EXTRA
+        The PCRE-specific options PCRE_DUPNAMES, PCRE_UNGREEDY, and  PCRE_EXTRA
-        can be changed in the same way as the Perl-compatible options by  using
+        can  be changed in the same way as the Perl-compatible options by using
         the characters J, U and X respectively.
-        When  an option change occurs at top level (that is, not inside subpat-
+        When one of these option changes occurs at  top  level  (that  is,  not
-        tern parentheses), the change applies to the remainder of  the  pattern
+        inside  subpattern parentheses), the change applies to the remainder of
-        that follows.  If the change is placed right at the start of a pattern,
+        the pattern that follows. If the change is placed right at the start of
-        PCRE extracts it into the global options (and it will therefore show up
+        a pattern, PCRE extracts it into the global options (and it will there-
-        in data extracted by the pcre_fullinfo() function).
+        fore show up in data extracted by the pcre_fullinfo() function).
-        An  option  change  within a subpattern (see below for a description of
+        An option change within a subpattern (see below for  a  description  of
         subpatterns) affects only that part of the current pattern that follows
         it, so
           (a(?i)b)c
         matches abc and aBc and no other strings (assuming PCRE_CASELESS is not
-        used).  By this means, options can be made to have  different  settings
+        used).   By  this means, options can be made to have different settings
-        in  different parts of the pattern. Any changes made in one alternative
+        in different parts of the pattern. Any changes made in one  alternative
-        do carry on into subsequent branches within the  same  subpattern.  For
+        do  carry  on  into subsequent branches within the same subpattern. For
         example,
           (a(?i)b|c)
-        matches  "ab",  "aB",  "c",  and "C", even though when matching "C" the
+        matches "ab", "aB", "c", and "C", even though  when  matching  "C"  the
-        first branch is abandoned before the option setting.  This  is  because
+        first  branch  is  abandoned before the option setting. This is because
-        the  effects  of option settings happen at compile time. There would be
+        the effects of option settings happen at compile time. There  would  be
         some very weird behaviour otherwise.
-        Note: There are other PCRE-specific options that  can  be  set  by  the
+        Note:  There  are  other  PCRE-specific  options that can be set by the
-        application  when  the  compile  or match functions are called. In some
+        application when the compile or match functions  are  called.  In  some
-        cases the pattern can contain special  leading  sequences  to  override
+        cases the pattern can contain special leading sequences such as (*CRLF)
-        what  the  application  has set or what has been defaulted. Details are
+        to override what the application has set or what  has  been  defaulted.
-        given in the section entitled "Newline sequences" above.
+        Details  are  given  in the section entitled "Newline sequences" above.
+        There is also the (*UTF8) leading sequence that  can  be  used  to  set
+        UTF-8 mode; this is equivalent to setting the PCRE_UTF8 option.
  SUBPATTERNS
-Line 3743 
 SUBPATTERNS
+Line 3883 
 SUBPATTERNS
           cat(aract|erpillar|)
-        matches  one  of the words "cat", "cataract", or "caterpillar". Without
+        matches one of the words "cat", "cataract", or  "caterpillar".  Without
-        the parentheses, it would match  "cataract",  "erpillar"  or  an  empty
+        the  parentheses,  it  would  match  "cataract", "erpillar" or an empty
         string.
-.  It  sets  up  the  subpattern as a capturing subpattern. This means
+. It sets up the subpattern as  a  capturing  subpattern.  This  means
-        that, when the whole pattern  matches,  that  portion  of  the  subject
+        that,  when  the  whole  pattern  matches,  that portion of the subject
         string that matched the subpattern is passed back to the caller via the
-        ovector argument of pcre_exec(). Opening parentheses are  counted  from
+        ovector  argument  of pcre_exec(). Opening parentheses are counted from
-        left  to  right  (starting  from 1) to obtain numbers for the capturing
+        left to right (starting from 1) to obtain  numbers  for  the  capturing
         subpatterns.
-        For example, if the string "the red king" is matched against  the  pat-
+        For  example,  if the string "the red king" is matched against the pat-
         tern
           the ((red|white) (king|queen))
-Line 3762 
 SUBPATTERNS
+Line 3902 
 SUBPATTERNS
         the captured substrings are "red king", "red", and "king", and are num-
         bered 1, 2, and 3, respectively.
-        The fact that plain parentheses fulfil  two  functions  is  not  always
+        The  fact  that  plain  parentheses  fulfil two functions is not always
-        helpful.   There are often times when a grouping subpattern is required
+        helpful.  There are often times when a grouping subpattern is  required
-        without a capturing requirement. If an opening parenthesis is  followed
+        without  a capturing requirement. If an opening parenthesis is followed
-        by  a question mark and a colon, the subpattern does not do any captur-
+        by a question mark and a colon, the subpattern does not do any  captur-
-        ing, and is not counted when computing the  number  of  any  subsequent
+        ing,  and  is  not  counted when computing the number of any subsequent
-        capturing  subpatterns. For example, if the string "the white queen" is
+        capturing subpatterns. For example, if the string "the white queen"  is
         matched against the pattern
           the ((?:red|white) (king|queen))
-Line 3775 
 SUBPATTERNS
+Line 3915 
 SUBPATTERNS
         the captured substrings are "white queen" and "queen", and are numbered
 and 2. The maximum number of capturing subpatterns is 65535.
-        As  a  convenient shorthand, if any option settings are required at the
+        As a convenient shorthand, if any option settings are required  at  the
-        start of a non-capturing subpattern,  the  option  letters  may  appear
+        start  of  a  non-capturing  subpattern,  the option letters may appear
         between the "?" and the ":". Thus the two patterns
           (?i:saturday|sunday)
           (?:(?i)saturday|sunday)
         match exactly the same set of strings. Because alternative branches are
-        tried from left to right, and options are not reset until  the  end  of
+        tried  from  left  to right, and options are not reset until the end of
-        the  subpattern is reached, an option setting in one branch does affect
+        the subpattern is reached, an option setting in one branch does  affect
-        subsequent branches, so the above patterns match "SUNDAY"  as  well  as
+        subsequent  branches,  so  the above patterns match "SUNDAY" as well as
         "Saturday".
  DUPLICATE SUBPATTERN NUMBERS
         Perl 5.10 introduced a feature whereby each alternative in a subpattern
-        uses the same numbers for its capturing parentheses. Such a  subpattern
+        uses  the same numbers for its capturing parentheses. Such a subpattern
-        starts  with (?| and is itself a non-capturing subpattern. For example,
+        starts with (?| and is itself a non-capturing subpattern. For  example,
         consider this pattern:
           (?|(Sat)ur|(Sun))day
-        Because the two alternatives are inside a (?| group, both sets of  cap-
+        Because  the two alternatives are inside a (?| group, both sets of cap-
-        turing  parentheses  are  numbered one. Thus, when the pattern matches,
+        turing parentheses are numbered one. Thus, when  the  pattern  matches,
-        you can look at captured substring number  one,  whichever  alternative
+        you  can  look  at captured substring number one, whichever alternative
-        matched.  This  construct  is useful when you want to capture part, but
+        matched. This construct is useful when you want to  capture  part,  but
         not all, of one of a number of alternatives. Inside a (?| group, paren-
-        theses  are  numbered as usual, but the number is reset at the start of
+        theses are numbered as usual, but the number is reset at the  start  of
-        each branch. The numbers of any capturing buffers that follow the  sub-
+        each  branch. The numbers of any capturing buffers that follow the sub-
-        pattern  start after the highest number used in any branch. The follow-
+        pattern start after the highest number used in any branch. The  follow-
-        ing example is taken from the Perl documentation.  The  numbers  under-
+        ing  example  is taken from the Perl documentation.  The numbers under-
         neath show in which buffer the captured content will be stored.
           # before  ---------------branch-reset----------- after
           / ( a )  (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x
           # 1            2         2  3        2     3     4
-        A  backreference  or  a  recursive call to a numbered subpattern always
+        A backreference or a recursive call to  a  numbered  subpattern  always
         refers to the first one in the pattern with the given number.
-        An alternative approach to using this "branch reset" feature is to  use
+        An  alternative approach to using this "branch reset" feature is to use
         duplicate named subpatterns, as described in the next section.
  NAMED SUBPATTERNS
-        Identifying  capturing  parentheses  by number is simple, but it can be
+        Identifying capturing parentheses by number is simple, but  it  can  be
-        very hard to keep track of the numbers in complicated  regular  expres-
+        very  hard  to keep track of the numbers in complicated regular expres-
-        sions.  Furthermore,  if  an  expression  is  modified, the numbers may
+        sions. Furthermore, if an  expression  is  modified,  the  numbers  may
-        change. To help with this difficulty, PCRE supports the naming of  sub-
+        change.  To help with this difficulty, PCRE supports the naming of sub-
         patterns. This feature was not added to Perl until release 5.10. Python
-        had the feature earlier, and PCRE introduced it at release  4.0,  using
+        had  the  feature earlier, and PCRE introduced it at release 4.0, using
-        the  Python syntax. PCRE now supports both the Perl and the Python syn-
+        the Python syntax. PCRE now supports both the Perl and the Python  syn-
         tax.
-        In PCRE, a subpattern can be named in one of three  ways:  (?<name>...)
+        In  PCRE,  a subpattern can be named in one of three ways: (?<name>...)
-        or  (?'name'...)  as in Perl, or (?P<name>...) as in Python. References
+        or (?'name'...) as in Perl, or (?P<name>...) as in  Python.  References
         to capturing parentheses from other parts of the pattern, such as back-
-        references,  recursion,  and conditions, can be made by name as well as
+        references, recursion, and conditions, can be made by name as  well  as
         by number.
-        Names consist of up to  32  alphanumeric  characters  and  underscores.
+        Names  consist  of  up  to  32 alphanumeric characters and underscores.
-        Named  capturing  parentheses  are  still  allocated numbers as well as
+        Named capturing parentheses are still  allocated  numbers  as  well  as
-        names, exactly as if the names were not present. The PCRE API  provides
+        names,  exactly as if the names were not present. The PCRE API provides
         function calls for extracting the name-to-number translation table from
         a compiled pattern. There is also a convenience function for extracting
         a captured substring by name.
-        By  default, a name must be unique within a pattern, but it is possible
+        By default, a name must be unique within a pattern, but it is  possible
         to relax this constraint by setting the PCRE_DUPNAMES option at compile
-        time.  This  can  be useful for patterns where only one instance of the
+        time. This can be useful for patterns where only one  instance  of  the
-        named parentheses can match. Suppose you want to match the  name  of  a
+        named  parentheses  can  match. Suppose you want to match the name of a
-        weekday,  either as a 3-letter abbreviation or as the full name, and in
+        weekday, either as a 3-letter abbreviation or as the full name, and  in
         both cases you want to extract the abbreviation. This pattern (ignoring
         the line breaks) does the job:
-Line 3858 
 NAMED SUBPATTERNS
+Line 3998 
 NAMED SUBPATTERNS
           (?<DN>Thu)(?:rsday)?|
           (?<DN>Sat)(?:urday)?
-        There  are  five capturing substrings, but only one is ever set after a
+        There are five capturing substrings, but only one is ever set  after  a
         match.  (An alternative way of solving this problem is to use a "branch
         reset" subpattern, as described in the previous section.)
-        The  convenience  function  for extracting the data by name returns the
+        The convenience function for extracting the data by  name  returns  the
-        substring for the first (and in this example, the only)  subpattern  of
+        substring  for  the first (and in this example, the only) subpattern of
-        that  name  that  matched.  This saves searching to find which numbered
+        that name that matched. This saves searching  to  find  which  numbered
-        subpattern it was. If you make a reference to a non-unique  named  sub-
+        subpattern  it  was. If you make a reference to a non-unique named sub-
-        pattern  from elsewhere in the pattern, the one that corresponds to the
+        pattern from elsewhere in the pattern, the one that corresponds to  the
-        lowest number is used. For further details of the interfaces  for  han-
+        lowest  number  is used. For further details of the interfaces for han-
         dling named subpatterns, see the pcreapi documentation.
+        Warning: You cannot use different names to distinguish between two sub-
+        patterns  with  the same number (see the previous section) because PCRE
+        uses only the numbers when matching.
  REPETITION
-        Repetition  is  specified  by  quantifiers, which can follow any of the
+        Repetition is specified by quantifiers, which can  follow  any  of  the
         following items:
           a literal data character
-Line 3886 
 REPETITION
+Line 4030 
 REPETITION
           a back reference (see next section)
           a parenthesized subpattern (unless it is an assertion)
-        The general repetition quantifier specifies a minimum and maximum  num-
+        The  general repetition quantifier specifies a minimum and maximum num-
-        ber  of  permitted matches, by giving the two numbers in curly brackets
+        ber of permitted matches, by giving the two numbers in  curly  brackets
-        (braces), separated by a comma. The numbers must be  less  than  65536,
+        (braces),  separated  by  a comma. The numbers must be less than 65536,
         and the first must be less than or equal to the second. For example:
           z{2,4}
-        matches  "zz",  "zzz",  or  "zzzz". A closing brace on its own is not a
+        matches "zz", "zzz", or "zzzz". A closing brace on its  own  is  not  a
-        special character. If the second number is omitted, but  the  comma  is
+        special  character.  If  the second number is omitted, but the comma is
-        present,  there  is  no upper limit; if the second number and the comma
+        present, there is no upper limit; if the second number  and  the  comma
-        are both omitted, the quantifier specifies an exact number of  required
+        are  both omitted, the quantifier specifies an exact number of required
         matches. Thus
           [aeiou]{3,}
-Line 3905 
 REPETITION
+Line 4049 
 REPETITION
           \d{8}
-        matches  exactly  8  digits. An opening curly bracket that appears in a
+        matches exactly 8 digits. An opening curly bracket that  appears  in  a
-        position where a quantifier is not allowed, or one that does not  match
+        position  where a quantifier is not allowed, or one that does not match
-        the  syntax of a quantifier, is taken as a literal character. For exam-
+        the syntax of a quantifier, is taken as a literal character. For  exam-
         ple, {,6} is not a quantifier, but a literal string of four characters.
         In  UTF-8  mode,  quantifiers  apply to UTF-8 characters rather than to
-Line 3918 
 REPETITION
+Line 4062 
 REPETITION
         may be of different lengths).
         The quantifier {0} is permitted, causing the expression to behave as if
-        the previous item and the quantifier were not present.
+        the previous item and the quantifier were not present. This may be use-
+        ful for subpatterns that are referenced as subroutines  from  elsewhere
+        in the pattern. Items other than subpatterns that have a {0} quantifier
+        are omitted from the compiled pattern.
-        For  convenience, the three most common quantifiers have single-charac-
+        For convenience, the three most common quantifiers have  single-charac-
         ter abbreviations:
           *    is equivalent to {0,}
           +    is equivalent to {1,}
           ?    is equivalent to {0,1}
-        It is possible to construct infinite loops by  following  a  subpattern
+        It  is  possible  to construct infinite loops by following a subpattern
         that can match no characters with a quantifier that has no upper limit,
         for example:
           (a?)*
         Earlier versions of Perl and PCRE used to give an error at compile time
-        for  such  patterns. However, because there are cases where this can be
+        for such patterns. However, because there are cases where this  can  be
-        useful, such patterns are now accepted, but if any  repetition  of  the
+        useful,  such  patterns  are now accepted, but if any repetition of the
-        subpattern  does in fact match no characters, the loop is forcibly bro-
+        subpattern does in fact match no characters, the loop is forcibly  bro-
         ken.
-        By default, the quantifiers are "greedy", that is, they match  as  much
+        By  default,  the quantifiers are "greedy", that is, they match as much
-        as  possible  (up  to  the  maximum number of permitted times), without
+        as possible (up to the maximum  number  of  permitted  times),  without
-        causing the rest of the pattern to fail. The classic example  of  where
+        causing  the  rest of the pattern to fail. The classic example of where
         this gives problems is in trying to match comments in C programs. These
-        appear between /* and */ and within the comment,  individual  *  and  /
+        appear  between  /*  and  */ and within the comment, individual * and /
-        characters  may  appear. An attempt to match C comments by applying the
+        characters may appear. An attempt to match C comments by  applying  the
         pattern
           /\*.*\*/
-Line 3953 
 REPETITION
+Line 4100 
 REPETITION
           /* first comment */  not comment  /* second comment */
-        fails, because it matches the entire string owing to the greediness  of
+        fails,  because it matches the entire string owing to the greediness of
         the .*  item.
-        However,  if  a quantifier is followed by a question mark, it ceases to
+        However, if a quantifier is followed by a question mark, it  ceases  to
         be greedy, and instead matches the minimum number of times possible, so
         the pattern
           /\*.*?\*/
-        does  the  right  thing with the C comments. The meaning of the various
+        does the right thing with the C comments. The meaning  of  the  various
-        quantifiers is not otherwise changed,  just  the  preferred  number  of
+        quantifiers  is  not  otherwise  changed,  just the preferred number of
-        matches.   Do  not  confuse this use of question mark with its use as a
+        matches.  Do not confuse this use of question mark with its  use  as  a
-        quantifier in its own right. Because it has two uses, it can  sometimes
+        quantifier  in its own right. Because it has two uses, it can sometimes
         appear doubled, as in
           \d??\d
-Line 3973 
 REPETITION
+Line 4120 
 REPETITION
         which matches one digit by preference, but can match two if that is the
         only way the rest of the pattern matches.
-        If the PCRE_UNGREEDY option is set (an option that is not available  in
+        If  the PCRE_UNGREEDY option is set (an option that is not available in
-        Perl),  the  quantifiers are not greedy by default, but individual ones
+        Perl), the quantifiers are not greedy by default, but  individual  ones
-        can be made greedy by following them with a  question  mark.  In  other
+        can  be  made  greedy  by following them with a question mark. In other
         words, it inverts the default behaviour.
-        When  a  parenthesized  subpattern  is quantified with a minimum repeat
+        When a parenthesized subpattern is quantified  with  a  minimum  repeat
-        count that is greater than 1 or with a limited maximum, more memory  is
+        count  that is greater than 1 or with a limited maximum, more memory is
-        required  for  the  compiled  pattern, in proportion to the size of the
+        required for the compiled pattern, in proportion to  the  size  of  the
         minimum or maximum.
         If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equiv-
-        alent  to  Perl's  /s) is set, thus allowing the dot to match newlines,
+        alent to Perl's /s) is set, thus allowing the dot  to  match  newlines,
-        the pattern is implicitly anchored, because whatever  follows  will  be
+        the  pattern  is  implicitly anchored, because whatever follows will be
-        tried  against every character position in the subject string, so there
+        tried against every character position in the subject string, so  there
-        is no point in retrying the overall match at  any  position  after  the
+        is  no  point  in  retrying the overall match at any position after the
-        first.  PCRE  normally treats such a pattern as though it were preceded
+        first. PCRE normally treats such a pattern as though it  were  preceded
         by \A.
-        In cases where it is known that the subject  string  contains  no  new-
+        In  cases  where  it  is known that the subject string contains no new-
-        lines,  it  is  worth setting PCRE_DOTALL in order to obtain this opti-
+        lines, it is worth setting PCRE_DOTALL in order to  obtain  this  opti-
         mization, or alternatively using ^ to indicate anchoring explicitly.
-        However, there is one situation where the optimization cannot be  used.
+        However,  there is one situation where the optimization cannot be used.
-        When  .*   is  inside  capturing  parentheses that are the subject of a
+        When .*  is inside capturing parentheses that  are  the  subject  of  a
-        backreference elsewhere in the pattern, a match at the start  may  fail
+        backreference  elsewhere  in the pattern, a match at the start may fail
         where a later one succeeds. Consider, for example:
           (.*)abc\1
-        If  the subject is "xyz123abc123" the match point is the fourth charac-
+        If the subject is "xyz123abc123" the match point is the fourth  charac-
         ter. For this reason, such a pattern is not implicitly anchored.
         When a capturing subpattern is repeated, the value captured is the sub-
-Line 4011 
 REPETITION
+Line 4158 
 REPETITION
           (tweedle[dume]{3}\s*)+
         has matched "tweedledum tweedledee" the value of the captured substring
-        is "tweedledee". However, if there are  nested  capturing  subpatterns,
+        is  "tweedledee".  However,  if there are nested capturing subpatterns,
-        the  corresponding captured values may have been set in previous itera-
+        the corresponding captured values may have been set in previous  itera-
         tions. For example, after
           /(a|(b))+/
-Line 4022 
 REPETITION
+Line 4169 
 REPETITION
  ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS
-        With both maximizing ("greedy") and minimizing ("ungreedy"  or  "lazy")
+        With  both  maximizing ("greedy") and minimizing ("ungreedy" or "lazy")
-        repetition,  failure  of what follows normally causes the repeated item
+        repetition, failure of what follows normally causes the  repeated  item
-        to be re-evaluated to see if a different number of repeats  allows  the
+        to  be  re-evaluated to see if a different number of repeats allows the
-        rest  of  the pattern to match. Sometimes it is useful to prevent this,
+        rest of the pattern to match. Sometimes it is useful to  prevent  this,
-        either to change the nature of the match, or to cause it  fail  earlier
+        either  to  change the nature of the match, or to cause it fail earlier
-        than  it otherwise might, when the author of the pattern knows there is
+        than it otherwise might, when the author of the pattern knows there  is
         no point in carrying on.
-        Consider, for example, the pattern \d+foo when applied to  the  subject
+        Consider,  for  example, the pattern \d+foo when applied to the subject
         line
 bar
         After matching all 6 digits and then failing to match "foo", the normal
-        action of the matcher is to try again with only 5 digits  matching  the
+        action  of  the matcher is to try again with only 5 digits matching the
-        \d+  item,  and  then  with  4,  and  so on, before ultimately failing.
+        \d+ item, and then with  4,  and  so  on,  before  ultimately  failing.
-        "Atomic grouping" (a term taken from Jeffrey  Friedl's  book)  provides
+        "Atomic  grouping"  (a  term taken from Jeffrey Friedl's book) provides
-        the  means for specifying that once a subpattern has matched, it is not
+        the means for specifying that once a subpattern has matched, it is  not
         to be re-evaluated in this way.
-        If we use atomic grouping for the previous example, the  matcher  gives
+        If  we  use atomic grouping for the previous example, the matcher gives
-        up  immediately  on failing to match "foo" the first time. The notation
+        up immediately on failing to match "foo" the first time.  The  notation
         is a kind of special parenthesis, starting with (?> as in this example:
           (?>\d+)foo
-Line 4121 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIE
+Line 4268 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIE
           ((?>\D+)|<\d+>)*[!?]
-        sequences of non-digits cannot be broken, and failure happens  quickly.
+        sequences of non-digits cannot be broken, and failure happens quickly.
  BACK REFERENCES
         Outside a character class, a backslash followed by a digit greater than
 (and possibly further digits) is a back reference to a capturing sub-
-        pattern  earlier  (that is, to its left) in the pattern, provided there
+        pattern earlier (that is, to its left) in the pattern,  provided  there
         have been that many previous capturing left parentheses.
         However, if the decimal number following the backslash is less than 10,
-        it  is  always  taken  as a back reference, and causes an error only if
+        it is always taken as a back reference, and causes  an  error  only  if
-        there are not that many capturing left parentheses in the  entire  pat-
+        there  are  not that many capturing left parentheses in the entire pat-
-        tern.  In  other words, the parentheses that are referenced need not be
+        tern. In other words, the parentheses that are referenced need  not  be
-        to the left of the reference for numbers less than 10. A "forward  back
+        to  the left of the reference for numbers less than 10. A "forward back
-        reference"  of  this  type can make sense when a repetition is involved
+        reference" of this type can make sense when a  repetition  is  involved
-        and the subpattern to the right has participated in an  earlier  itera-
+        and  the  subpattern to the right has participated in an earlier itera-
         tion.
-        It  is  not  possible to have a numerical "forward back reference" to a
+        It is not possible to have a numerical "forward back  reference"  to  a
-        subpattern whose number is 10 or  more  using  this  syntax  because  a
+        subpattern  whose  number  is  10  or  more using this syntax because a
-        sequence  such  as  \50 is interpreted as a character defined in octal.
+        sequence such as \50 is interpreted as a character  defined  in  octal.
         See the subsection entitled "Non-printing characters" above for further
-        details  of  the  handling of digits following a backslash. There is no
+        details of the handling of digits following a backslash.  There  is  no
-        such problem when named parentheses are used. A back reference  to  any
+        such  problem  when named parentheses are used. A back reference to any
         subpattern is possible using named parentheses (see below).
-        Another  way  of  avoiding  the ambiguity inherent in the use of digits
+        Another way of avoiding the ambiguity inherent in  the  use  of  digits
         following a backslash is to use the \g escape sequence, which is a fea-
-        ture  introduced  in  Perl  5.10.  This  escape  must be followed by an
+        ture introduced in Perl 5.10.  This  escape  must  be  followed  by  an
-        unsigned number or a negative number, optionally  enclosed  in  braces.
+        unsigned  number  or  a negative number, optionally enclosed in braces.
         These examples are all identical:
           (ring), \1
           (ring), \g1
           (ring), \g{1}
-        An  unsigned number specifies an absolute reference without the ambigu-
+        An unsigned number specifies an absolute reference without the  ambigu-
         ity that is present in the older syntax. It is also useful when literal
         digits follow the reference. A negative number is a relative reference.
         Consider this example:
-Line 4166 
 BACK REFERENCES
+Line 4313 
 BACK REFERENCES
           (abc(def)ghi)\g{-1}
         The sequence \g{-1} is a reference to the most recently started captur-
-        ing  subpattern  before \g, that is, is it equivalent to \2. Similarly,
+        ing subpattern before \g, that is, is it equivalent to  \2.  Similarly,
         \g{-2} would be equivalent to \1. The use of relative references can be
-        helpful  in  long  patterns,  and  also in patterns that are created by
+        helpful in long patterns, and also in  patterns  that  are  created  by
         joining together fragments that contain references within themselves.
-        A back reference matches whatever actually matched the  capturing  sub-
+        A  back  reference matches whatever actually matched the capturing sub-
-        pattern  in  the  current subject string, rather than anything matching
+        pattern in the current subject string, rather  than  anything  matching
         the subpattern itself (see "Subpatterns as subroutines" below for a way
         of doing that). So the pattern
           (sens|respons)e and \1ibility
-        matches  "sense and sensibility" and "response and responsibility", but
+        matches "sense and sensibility" and "response and responsibility",  but
-        not "sense and responsibility". If caseful matching is in force at  the
+        not  "sense and responsibility". If caseful matching is in force at the
-        time  of the back reference, the case of letters is relevant. For exam-
+        time of the back reference, the case of letters is relevant. For  exam-
         ple,
           ((?i)rah)\s+\1
-        matches "rah rah" and "RAH RAH", but not "RAH  rah",  even  though  the
+        matches  "rah  rah"  and  "RAH RAH", but not "RAH rah", even though the
         original capturing subpattern is matched caselessly.
-        There  are  several  different ways of writing back references to named
+        There are several different ways of writing back  references  to  named
-        subpatterns. The .NET syntax \k{name} and the Perl syntax  \k<name>  or
+        subpatterns.  The  .NET syntax \k{name} and the Perl syntax \k<name> or
-        \k'name'  are supported, as is the Python syntax (?P=name). Perl 5.10's
+        \k'name' are supported, as is the Python syntax (?P=name). Perl  5.10's
         unified back reference syntax, in which \g can be used for both numeric
-        and  named  references,  is  also supported. We could rewrite the above
+        and named references, is also supported. We  could  rewrite  the  above
         example in any of the following ways:
           (?<p1>(?i)rah)\s+\k<p1>
-Line 4200 
 BACK REFERENCES
+Line 4347 
 BACK REFERENCES
           (?P<p1>(?i)rah)\s+(?P=p1)
           (?<p1>(?i)rah)\s+\g{p1}
-        A subpattern that is referenced by  name  may  appear  in  the  pattern
+        A  subpattern  that  is  referenced  by  name may appear in the pattern
         before or after the reference.
-        There  may be more than one back reference to the same subpattern. If a
+        There may be more than one back reference to the same subpattern. If  a
-        subpattern has not actually been used in a particular match,  any  back
+        subpattern  has  not actually been used in a particular match, any back
         references to it always fail. For example, the pattern
           (a|(bc))\2
-        always  fails if it starts to match "a" rather than "bc". Because there
+        always fails if it starts to match "a" rather than "bc". Because  there
-        may be many capturing parentheses in a pattern,  all  digits  following
+        may  be  many  capturing parentheses in a pattern, all digits following
-        the  backslash  are taken as part of a potential back reference number.
+        the backslash are taken as part of a potential back  reference  number.
         If the pattern continues with a digit character, some delimiter must be
-        used  to  terminate  the back reference. If the PCRE_EXTENDED option is
+        used to terminate the back reference. If the  PCRE_EXTENDED  option  is
-        set, this can be whitespace.  Otherwise an  empty  comment  (see  "Com-
+        set,  this  can  be  whitespace.  Otherwise an empty comment (see "Com-
         ments" below) can be used.
-        A  back reference that occurs inside the parentheses to which it refers
+        A back reference that occurs inside the parentheses to which it  refers
-        fails when the subpattern is first used, so, for example,  (a\1)  never
+        fails  when  the subpattern is first used, so, for example, (a\1) never
-        matches.   However,  such references can be useful inside repeated sub-
+        matches.  However, such references can be useful inside  repeated  sub-
         patterns. For example, the pattern
           (a|b\1)+
         matches any number of "a"s and also "aba", "ababbaa" etc. At each iter-
-        ation  of  the  subpattern,  the  back  reference matches the character
+        ation of the subpattern,  the  back  reference  matches  the  character
-        string corresponding to the previous iteration. In order  for  this  to
+        string  corresponding  to  the previous iteration. In order for this to
-        work,  the  pattern must be such that the first iteration does not need
+        work, the pattern must be such that the first iteration does  not  need
-        to match the back reference. This can be done using alternation, as  in
+        to  match the back reference. This can be done using alternation, as in
         the example above, or by a quantifier with a minimum of zero.
  ASSERTIONS
-        An  assertion  is  a  test on the characters following or preceding the
+        An assertion is a test on the characters  following  or  preceding  the
-        current matching point that does not actually consume  any  characters.
+        current  matching  point that does not actually consume any characters.
-        The  simple  assertions  coded  as  \b, \B, \A, \G, \Z, \z, ^ and $ are
+        The simple assertions coded as \b, \B, \A, \G, \Z,  \z,  ^  and  $  are
         described above.
-        More complicated assertions are coded as  subpatterns.  There  are  two
+        More  complicated  assertions  are  coded as subpatterns. There are two
-        kinds:  those  that  look  ahead of the current position in the subject
+        kinds: those that look ahead of the current  position  in  the  subject
-        string, and those that look  behind  it.  An  assertion  subpattern  is
+        string,  and  those  that  look  behind  it. An assertion subpattern is
-        matched  in  the  normal way, except that it does not cause the current
+        matched in the normal way, except that it does not  cause  the  current
         matching position to be changed.
-        Assertion subpatterns are not capturing subpatterns,  and  may  not  be
+        Assertion  subpatterns  are  not  capturing subpatterns, and may not be
-        repeated,  because  it  makes no sense to assert the same thing several
+        repeated, because it makes no sense to assert the  same  thing  several
-        times. If any kind of assertion contains capturing  subpatterns  within
+        times.  If  any kind of assertion contains capturing subpatterns within
-        it,  these are counted for the purposes of numbering the capturing sub-
+        it, these are counted for the purposes of numbering the capturing  sub-
         patterns in the whole pattern.  However, substring capturing is carried
-        out  only  for  positive assertions, because it does not make sense for
+        out only for positive assertions, because it does not  make  sense  for
         negative assertions.
     Lookahead assertions
-Line 4260 
 ASSERTIONS
+Line 4407 
 ASSERTIONS
           \w+(?=;)
-        matches  a word followed by a semicolon, but does not include the semi-
+        matches a word followed by a semicolon, but does not include the  semi-
         colon in the match, and
           foo(?!bar)
-        matches any occurrence of "foo" that is not  followed  by  "bar".  Note
+        matches  any  occurrence  of  "foo" that is not followed by "bar". Note
         that the apparently similar pattern
           (?!foo)bar
-        does  not  find  an  occurrence  of "bar" that is preceded by something
+        does not find an occurrence of "bar"  that  is  preceded  by  something
-        other than "foo"; it finds any occurrence of "bar" whatsoever,  because
+        other  than "foo"; it finds any occurrence of "bar" whatsoever, because
         the assertion (?!foo) is always true when the next three characters are
         "bar". A lookbehind assertion is needed to achieve the other effect.
         If you want to force a matching failure at some point in a pattern, the
-        most  convenient  way  to  do  it  is with (?!) because an empty string
+        most convenient way to do it is  with  (?!)  because  an  empty  string
-        always matches, so an assertion that requires there not to be an  empty
+        always  matches, so an assertion that requires there not to be an empty
         string must always fail.
     Lookbehind assertions
-        Lookbehind  assertions start with (?<= for positive assertions and (?<!
+        Lookbehind assertions start with (?<= for positive assertions and  (?<!
         for negative assertions. For example,
           (?<!foo)bar
-        does find an occurrence of "bar" that is not  preceded  by  "foo".  The
+        does  find  an  occurrence  of "bar" that is not preceded by "foo". The
-        contents  of  a  lookbehind  assertion are restricted such that all the
+        contents of a lookbehind assertion are restricted  such  that  all  the
         strings it matches must have a fixed length. However, if there are sev-
-        eral  top-level  alternatives,  they  do  not all have to have the same
+        eral top-level alternatives, they do not all  have  to  have  the  same
         fixed length. Thus
           (?<=bullock|donkey)
-Line 4299 
 ASSERTIONS
+Line 4446 
 ASSERTIONS
           (?<!dogs?|cats?)
-        causes an error at compile time. Branches that match  different  length
+        causes  an  error at compile time. Branches that match different length
-        strings  are permitted only at the top level of a lookbehind assertion.
+        strings are permitted only at the top level of a lookbehind  assertion.
-        This is an extension compared with  Perl  (at  least  for  5.8),  which
+        This  is  an  extension  compared  with  Perl (at least for 5.8), which
-        requires  all branches to match the same length of string. An assertion
+        requires all branches to match the same length of string. An  assertion
         such as
           (?<=ab(c|de))
-        is not permitted, because its single top-level  branch  can  match  two
+        is  not  permitted,  because  its single top-level branch can match two
-        different  lengths,  but  it is acceptable if rewritten to use two top-
+        different lengths, but it is acceptable if rewritten to  use  two  top-
         level branches:
           (?<=abc|abde)
         In some cases, the Perl 5.10 escape sequence \K (see above) can be used
-        instead  of  a lookbehind assertion; this is not restricted to a fixed-
+        instead of a lookbehind assertion; this is not restricted to  a  fixed-
         length.
-        The implementation of lookbehind assertions is, for  each  alternative,
+        The  implementation  of lookbehind assertions is, for each alternative,
-        to  temporarily  move the current position back by the fixed length and
+        to temporarily move the current position back by the fixed  length  and
         then try to match. If there are insufficient characters before the cur-
         rent position, the assertion fails.
         PCRE does not allow the \C escape (which matches a single byte in UTF-8
-        mode) to appear in lookbehind assertions, because it makes it  impossi-
+        mode)  to appear in lookbehind assertions, because it makes it impossi-
-        ble  to  calculate the length of the lookbehind. The \X and \R escapes,
+        ble to calculate the length of the lookbehind. The \X and  \R  escapes,
         which can match different numbers of bytes, are also not permitted.
-        Possessive quantifiers can  be  used  in  conjunction  with  lookbehind
+        Possessive  quantifiers  can  be  used  in  conjunction with lookbehind
-        assertions  to  specify  efficient  matching  at the end of the subject
+        assertions to specify efficient matching at  the  end  of  the  subject
         string. Consider a simple pattern such as
           abcd$
-        when applied to a long string that does  not  match.  Because  matching
+        when  applied  to  a  long string that does not match. Because matching
         proceeds from left to right, PCRE will look for each "a" in the subject
-        and then see if what follows matches the rest of the  pattern.  If  the
+        and  then  see  if what follows matches the rest of the pattern. If the
         pattern is specified as
           ^.*abcd$
-        the  initial .* matches the entire string at first, but when this fails
+        the initial .* matches the entire string at first, but when this  fails
         (because there is no following "a"), it backtracks to match all but the
-        last  character,  then all but the last two characters, and so on. Once
+        last character, then all but the last two characters, and so  on.  Once
-        again the search for "a" covers the entire string, from right to  left,
+        again  the search for "a" covers the entire string, from right to left,
         so we are no better off. However, if the pattern is written as
           ^.*+(?<=abcd)
-        there  can  be  no backtracking for the .*+ item; it can match only the
+        there can be no backtracking for the .*+ item; it can  match  only  the
-        entire string. The subsequent lookbehind assertion does a  single  test
+        entire  string.  The subsequent lookbehind assertion does a single test
-        on  the last four characters. If it fails, the match fails immediately.
+        on the last four characters. If it fails, the match fails  immediately.
-        For long strings, this approach makes a significant difference  to  the
+        For  long  strings, this approach makes a significant difference to the
         processing time.
     Using multiple assertions
-Line 4360 
 ASSERTIONS
+Line 4507 
 ASSERTIONS
           (?<=\d{3})(?<!999)foo
-        matches  "foo" preceded by three digits that are not "999". Notice that
+        matches "foo" preceded by three digits that are not "999". Notice  that
-        each of the assertions is applied independently at the  same  point  in
+        each  of  the  assertions is applied independently at the same point in
-        the  subject  string.  First  there  is a check that the previous three
+        the subject string. First there is a  check  that  the  previous  three
-        characters are all digits, and then there is  a  check  that  the  same
+        characters  are  all  digits,  and  then there is a check that the same
         three characters are not "999".  This pattern does not match "foo" pre-
-        ceded by six characters, the first of which are  digits  and  the  last
+        ceded  by  six  characters,  the first of which are digits and the last
-        three  of  which  are not "999". For example, it doesn't match "123abc-
+        three of which are not "999". For example, it  doesn't  match  "123abc-
         foo". A pattern to do that is
           (?<=\d{3}...)(?<!999)foo
-        This time the first assertion looks at the  preceding  six  characters,
+        This  time  the  first assertion looks at the preceding six characters,
         checking that the first three are digits, and then the second assertion
         checks that the preceding three characters are not "999".
-Line 4379 
 ASSERTIONS
+Line 4526 
 ASSERTIONS
           (?<=(?<!foo)bar)baz
-        matches an occurrence of "baz" that is preceded by "bar" which in  turn
+        matches  an occurrence of "baz" that is preceded by "bar" which in turn
         is not preceded by "foo", while
           (?<=\d{3}(?!999)...)foo
-        is  another pattern that matches "foo" preceded by three digits and any
+        is another pattern that matches "foo" preceded by three digits and  any
         three characters that are not "999".
  CONDITIONAL SUBPATTERNS
-        It is possible to cause the matching process to obey a subpattern  con-
+        It  is possible to cause the matching process to obey a subpattern con-
-        ditionally  or to choose between two alternative subpatterns, depending
+        ditionally or to choose between two alternative subpatterns,  depending
-        on the result of an assertion, or whether a previous capturing  subpat-
+        on  the result of an assertion, or whether a previous capturing subpat-
-        tern  matched  or not. The two possible forms of conditional subpattern
+        tern matched or not. The two possible forms of  conditional  subpattern
         are
           (?(condition)yes-pattern)
           (?(condition)yes-pattern|no-pattern)
-        If the condition is satisfied, the yes-pattern is used;  otherwise  the
+        If  the  condition is satisfied, the yes-pattern is used; otherwise the
-        no-pattern  (if  present)  is used. If there are more than two alterna-
+        no-pattern (if present) is used. If there are more  than  two  alterna-
         tives in the subpattern, a compile-time error occurs.
-        There are four kinds of condition: references  to  subpatterns,  refer-
+        There  are  four  kinds of condition: references to subpatterns, refer-
         ences to recursion, a pseudo-condition called DEFINE, and assertions.
     Checking for a used subpattern by number
-        If  the  text between the parentheses consists of a sequence of digits,
+        If the text between the parentheses consists of a sequence  of  digits,
-        the condition is true if the capturing subpattern of  that  number  has
+        the  condition  is  true if the capturing subpattern of that number has
-        previously  matched.  An  alternative notation is to precede the digits
+        previously matched. An alternative notation is to  precede  the  digits
         with a plus or minus sign. In this case, the subpattern number is rela-
         tive rather than absolute.  The most recently opened parentheses can be
-        referenced by (?(-1), the next most recent by (?(-2),  and  so  on.  In
+        referenced  by  (?(-1),  the  next most recent by (?(-2), and so on. In
         looping constructs it can also make sense to refer to subsequent groups
         with constructs such as (?(+2).
-        Consider the following pattern, which  contains  non-significant  white
+        Consider  the  following  pattern, which contains non-significant white
         space to make it more readable (assume the PCRE_EXTENDED option) and to
         divide it into three parts for ease of discussion:
           ( \( )?    [^()]+    (?(1) \) )
-        The first part matches an optional opening  parenthesis,  and  if  that
+        The  first  part  matches  an optional opening parenthesis, and if that
         character is present, sets it as the first captured substring. The sec-
-        ond part matches one or more characters that are not  parentheses.  The
+        ond  part  matches one or more characters that are not parentheses. The
         third part is a conditional subpattern that tests whether the first set
         of parentheses matched or not. If they did, that is, if subject started
         with an opening parenthesis, the condition is true, and so the yes-pat-
-        tern is executed and a  closing  parenthesis  is  required.  Otherwise,
+        tern  is  executed  and  a  closing parenthesis is required. Otherwise,
-        since  no-pattern  is  not  present, the subpattern matches nothing. In
+        since no-pattern is not present, the  subpattern  matches  nothing.  In
-        other words,  this  pattern  matches  a  sequence  of  non-parentheses,
+        other  words,  this  pattern  matches  a  sequence  of non-parentheses,
         optionally enclosed in parentheses.
-        If  you  were  embedding  this pattern in a larger one, you could use a
+        If you were embedding this pattern in a larger one,  you  could  use  a
         relative reference:
           ...other stuff... ( \( )?    [^()]+    (?(-1) \) ) ...
-        This makes the fragment independent of the parentheses  in  the  larger
+        This  makes  the  fragment independent of the parentheses in the larger
         pattern.
     Checking for a used subpattern by name
-        Perl  uses  the  syntax  (?(<name>)...) or (?('name')...) to test for a
+        Perl uses the syntax (?(<name>)...) or (?('name')...)  to  test  for  a
-        used subpattern by name. For compatibility  with  earlier  versions  of
+        used  subpattern  by  name.  For compatibility with earlier versions of
-        PCRE,  which  had this facility before Perl, the syntax (?(name)...) is
+        PCRE, which had this facility before Perl, the syntax  (?(name)...)  is
-        also recognized. However, there is a possible ambiguity with this  syn-
+        also  recognized. However, there is a possible ambiguity with this syn-
-        tax,  because  subpattern  names  may  consist entirely of digits. PCRE
+        tax, because subpattern names may  consist  entirely  of  digits.  PCRE
-        looks first for a named subpattern; if it cannot find one and the  name
+        looks  first for a named subpattern; if it cannot find one and the name
-        consists  entirely  of digits, PCRE looks for a subpattern of that num-
+        consists entirely of digits, PCRE looks for a subpattern of  that  num-
-        ber, which must be greater than zero. Using subpattern names that  con-
+        ber,  which must be greater than zero. Using subpattern names that con-
         sist entirely of digits is not recommended.
         Rewriting the above example to use a named subpattern gives this:
-Line 4462 
 CONDITIONAL SUBPATTERNS
+Line 4609 
 CONDITIONAL SUBPATTERNS
     Checking for pattern recursion
         If the condition is the string (R), and there is no subpattern with the
-        name R, the condition is true if a recursive call to the whole  pattern
+        name  R, the condition is true if a recursive call to the whole pattern
         or any subpattern has been made. If digits or a name preceded by amper-
         sand follow the letter R, for example:
           (?(R3)...) or (?(R&name)...)
-        the condition is true if the most recent recursion is into the  subpat-
+        the  condition is true if the most recent recursion is into the subpat-
-        tern  whose  number or name is given. This condition does not check the
+        tern whose number or name is given. This condition does not  check  the
         entire recursion stack.
-        At "top level", all these recursion test conditions are  false.  Recur-
+        At  "top  level", all these recursion test conditions are false. Recur-
         sive patterns are described below.
     Defining subpatterns for use by reference only
-        If  the  condition  is  the string (DEFINE), and there is no subpattern
+        If the condition is the string (DEFINE), and  there  is  no  subpattern
-        with the name DEFINE, the condition is  always  false.  In  this  case,
+        with  the  name  DEFINE,  the  condition is always false. In this case,
-        there  may  be  only  one  alternative  in the subpattern. It is always
+        there may be only one alternative  in  the  subpattern.  It  is  always
-        skipped if control reaches this point  in  the  pattern;  the  idea  of
+        skipped  if  control  reaches  this  point  in the pattern; the idea of
-        DEFINE  is that it can be used to define "subroutines" that can be ref-
+        DEFINE is that it can be used to define "subroutines" that can be  ref-
-        erenced from elsewhere. (The use of "subroutines" is described  below.)
+        erenced  from elsewhere. (The use of "subroutines" is described below.)
-        For  example,  a pattern to match an IPv4 address could be written like
+        For example, a pattern to match an IPv4 address could be  written  like
         this (ignore whitespace and line breaks):
           (?(DEFINE) (?<byte> 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d) )
           \b (?&byte) (\.(?&byte)){3} \b
-        The first part of the pattern is a DEFINE group inside which a  another
+        The  first part of the pattern is a DEFINE group inside which a another
-        group  named "byte" is defined. This matches an individual component of
+        group named "byte" is defined. This matches an individual component  of
-        an IPv4 address (a number less than 256). When  matching  takes  place,
+        an  IPv4  address  (a number less than 256). When matching takes place,
-        this  part  of  the pattern is skipped because DEFINE acts like a false
+        this part of the pattern is skipped because DEFINE acts  like  a  false
         condition.
         The rest of the pattern uses references to the named group to match the
-        four  dot-separated  components of an IPv4 address, insisting on a word
+        four dot-separated components of an IPv4 address, insisting on  a  word
         boundary at each end.
     Assertion conditions
-        If the condition is not in any of the above  formats,  it  must  be  an
+        If  the  condition  is  not  in any of the above formats, it must be an
-        assertion.   This may be a positive or negative lookahead or lookbehind
+        assertion.  This may be a positive or negative lookahead or  lookbehind
-        assertion. Consider  this  pattern,  again  containing  non-significant
+        assertion.  Consider  this  pattern,  again  containing non-significant
         white space, and with the two alternatives on the second line:
           (?(?=[^a-z]*[a-z])
           \d{2}-[a-z]{3}-\d{2}  |  \d{2}-\d{2}-\d{2} )
-        The  condition  is  a  positive  lookahead  assertion  that  matches an
+        The condition  is  a  positive  lookahead  assertion  that  matches  an
-        optional sequence of non-letters followed by a letter. In other  words,
+        optional  sequence of non-letters followed by a letter. In other words,
-        it  tests  for the presence of at least one letter in the subject. If a
+        it tests for the presence of at least one letter in the subject.  If  a
-        letter is found, the subject is matched against the first  alternative;
+        letter  is found, the subject is matched against the first alternative;
-        otherwise  it  is  matched  against  the  second.  This pattern matches
+        otherwise it is  matched  against  the  second.  This  pattern  matches
-        strings in one of the two forms dd-aaa-dd or dd-dd-dd,  where  aaa  are
+        strings  in  one  of the two forms dd-aaa-dd or dd-dd-dd, where aaa are
         letters and dd are digits.
  COMMENTS
-        The  sequence (?# marks the start of a comment that continues up to the
+        The sequence (?# marks the start of a comment that continues up to  the
-        next closing parenthesis. Nested parentheses  are  not  permitted.  The
+        next  closing  parenthesis.  Nested  parentheses are not permitted. The
-        characters  that make up a comment play no part in the pattern matching
+        characters that make up a comment play no part in the pattern  matching
         at all.
-        If the PCRE_EXTENDED option is set, an unescaped # character outside  a
+        If  the PCRE_EXTENDED option is set, an unescaped # character outside a
-        character  class  introduces  a  comment  that continues to immediately
+        character class introduces a  comment  that  continues  to  immediately
         after the next newline in the pattern.
  RECURSIVE PATTERNS