From dc426be88eec9f13e25858f077b0eaf029c1e682 Mon Sep 17 00:00:00 2001 From: "Philip.Hazel" Date: Wed, 4 Nov 2020 17:01:13 +0000 Subject: [PATCH] Documentation update --- doc/html/pcre2api.html | 46 +- doc/pcre2.txt | 2546 ++++++++++++++++++++-------------------- doc/pcre2api.3 | 47 +- 3 files changed, 1364 insertions(+), 1275 deletions(-) diff --git a/doc/html/pcre2api.html b/doc/html/pcre2api.html index 5cd7ae0..e456647 100644 --- a/doc/html/pcre2api.html +++ b/doc/html/pcre2api.html @@ -626,14 +626,15 @@ documentation for more details.

In a more complicated situation, where patterns are compiled only when they are first needed, but are still shared between threads, pointers to compiled -patterns must be protected from simultaneous writing by multiple threads, at -least until a pattern has been compiled. The logic can be something like this: +patterns must be protected from simultaneous writing by multiple threads. This +is somewhat tricky to do correctly. If you know that writing to a pointer is +atomic in your environment, you can use logic like this: 

   Get a read-only (shared) lock (mutex) for pointer
   if (pointer == NULL)
     {
     Get a write (unique) lock for pointer
-    pointer = pcre2_compile(...
+    if (pointer == NULL) pointer = pcre2_compile(...
     }
   Release the lock
   Use pointer in pcre2_match()
@@ -641,10 +642,39 @@ least until a pattern has been compiled. The logic can be something like this:
 Of course, testing for compilation errors should also be included in the code.
 

 

-If JIT is being used, but the JIT compilation is not being done immediately,
-(perhaps waiting to see if the pattern is used often enough) similar logic is
-required. JIT compilation updates a pointer within the compiled code block, so
-a thread must gain unique write access to the pointer before calling
+The reason for checking the pointer a second time is as follows: Several
+threads may have acquired the shared lock and tested the pointer for being
+NULL, but only one of them will be given the write lock, with the rest kept
+waiting. The winning thread will compile the pattern and store the result.
+After this thread releases the write lock, another thread will get it, and if
+it does not retest pointer for being NULL, will recompile the pattern and
+overwrite the pointer, creating a memory leak and possibly causing other
+issues.
+

+

+In an environment where writing to a pointer may not be atomic, the above logic
+is not sufficient. The thread that is doing the compiling may be descheduled
+after writing only part of the pointer, which could cause other threads to use
+an invalid value. Instead of checking the pointer itself, a separate "pointer
+is valid" flag (that can be updated atomically) must be used:
+
+  Get a read-only (shared) lock (mutex) for pointer
+  if (!pointer_is_valid)
+    {
+    Get a write (unique) lock for pointer
+    if (!pointer_is_valid) 
+      {
+      pointer = pcre2_compile(...
+      pointer_is_valid = TRUE
+      }  
+    }
+  Release the lock
+  Use pointer in pcre2_match()
+

+If JIT is being used, but the JIT compilation is not being done immediately
+(perhaps waiting to see if the pattern is used often enough), similar logic is
+required. JIT compilation updates a value within the compiled code block, so a
+thread must gain unique write access to the pointer before calling
 pcre2_jit_compile(). Alternatively, pcre2_code_copy() or
 pcre2_code_copy_with_tables() can be used to obtain a private copy of the
 compiled code before calling the JIT compiler.
@@ -3959,7 +3989,7 @@ Cambridge, England.
 

 
REVISION

 

-Last updated: 05 October 2020
+Last updated: 04 November 2020
 

 Copyright © 1997-2020 University of Cambridge.
 

diff --git a/doc/pcre2.txt b/doc/pcre2.txt
index 0d8e5ac..5027bfd 100644
--- a/doc/pcre2.txt
+++ b/doc/pcre2.txt
@@ -683,84 +683,114 @@ MULTITHREADING
        In  a more complicated situation, where patterns are compiled only when
        they are first needed, but are still shared between  threads,  pointers
        to  compiled  patterns  must  be protected from simultaneous writing by
-       multiple threads, at least until a pattern has been compiled. The logic
-       can be something like this:
+       multiple threads. This is somewhat tricky to do correctly. If you  know
+       that  writing  to  a pointer is atomic in your environment, you can use
+       logic like this:
 
          Get a read-only (shared) lock (mutex) for pointer
          if (pointer == NULL)
            {
            Get a write (unique) lock for pointer
-           pointer = pcre2_compile(...
+           if (pointer == NULL) pointer = pcre2_compile(...
            }
          Release the lock
          Use pointer in pcre2_match()
 
-       Of  course,  testing  for compilation errors should also be included in
+       Of course, testing for compilation errors should also  be  included  in
        the code.
 
+       The  reason  for checking the pointer a second time is as follows: Sev-
+       eral threads may have acquired the shared lock and tested  the  pointer
+       for being NULL, but only one of them will be given the write lock, with
+       the rest kept waiting. The winning thread will compile the pattern  and
+       store  the  result.  After this thread releases the write lock, another
+       thread will get it, and if it does not retest pointer for  being  NULL,
+       will recompile the pattern and overwrite the pointer, creating a memory
+       leak and possibly causing other issues.
+
+       In an environment where writing to a pointer may  not  be  atomic,  the
+       above  logic  is not sufficient. The thread that is doing the compiling
+       may be descheduled after writing only part of the pointer, which  could
+       cause  other  threads  to use an invalid value. Instead of checking the
+       pointer itself, a separate "pointer is valid" flag (that can be updated
+       atomically) must be used:
+
+         Get a read-only (shared) lock (mutex) for pointer
+         if (!pointer_is_valid)
+           {
+           Get a write (unique) lock for pointer
+           if (!pointer_is_valid)
+             {
+             pointer = pcre2_compile(...
+             pointer_is_valid = TRUE
+             }
+           }
+         Release the lock
+         Use pointer in pcre2_match()
+
        If JIT is being used, but the JIT compilation is not being done immedi-
-       ately,  (perhaps  waiting  to  see if the pattern is used often enough)
-       similar logic is required. JIT compilation updates a pointer within the
-       compiled  code  block, so a thread must gain unique write access to the
-       pointer    before    calling    pcre2_jit_compile().     Alternatively,
-       pcre2_code_copy()  or  pcre2_code_copy_with_tables() can be used to ob-
-       tain a private copy of the compiled code before calling  the  JIT  com-
+       ately (perhaps waiting to see if the pattern  is  used  often  enough),
+       similar  logic  is required. JIT compilation updates a value within the
+       compiled code block, so a thread must gain unique write access  to  the
+       pointer     before    calling    pcre2_jit_compile().    Alternatively,
+       pcre2_code_copy() or pcre2_code_copy_with_tables() can be used  to  ob-
+       tain  a  private  copy of the compiled code before calling the JIT com-
        piler.
 
    Context blocks
 
-       The  next main section below introduces the idea of "contexts" in which
+       The next main section below introduces the idea of "contexts" in  which
        PCRE2 functions are called. A context is nothing more than a collection
        of parameters that control the way PCRE2 operates. Grouping a number of
        parameters together in a context is a convenient way of passing them to
-       a  PCRE2  function without using lots of arguments. The parameters that
-       are stored in contexts are in some sense  "advanced  features"  of  the
+       a PCRE2 function without using lots of arguments. The  parameters  that
+       are  stored  in  contexts  are in some sense "advanced features" of the
        API. Many straightforward applications will not need to use contexts.
 
        In a multithreaded application, if the parameters in a context are val-
-       ues that are never changed, the same context can be  used  by  all  the
+       ues  that  are  never  changed, the same context can be used by all the
        threads. However, if any thread needs to change any value in a context,
        it must make its own thread-specific copy.
 
    Match blocks
 
-       The matching functions need a block of memory for storing  the  results
+       The  matching  functions need a block of memory for storing the results
        of a match. This includes details of what was matched, as well as addi-
-       tional information such as the name of a (*MARK) setting.  Each  thread
+       tional  information  such as the name of a (*MARK) setting. Each thread
        must provide its own copy of this memory.
 
 
 PCRE2 CONTEXTS
 
-       Some  PCRE2  functions have a lot of parameters, many of which are used
-       only by specialist applications, for example,  those  that  use  custom
-       memory  management  or  non-standard character tables. To keep function
-       argument lists at a reasonable size, and at the same time to  keep  the
-       API  extensible,  "uncommon" parameters are passed to certain functions
-       in a context instead of directly. A context is just a block  of  memory
-       that  holds the parameter values.  Applications that do not need to ad-
+       Some PCRE2 functions have a lot of parameters, many of which  are  used
+       only  by  specialist  applications,  for example, those that use custom
+       memory management or non-standard character tables.  To  keep  function
+       argument  lists  at a reasonable size, and at the same time to keep the
+       API extensible, "uncommon" parameters are passed to  certain  functions
+       in  a  context instead of directly. A context is just a block of memory
+       that holds the parameter values.  Applications that do not need to  ad-
        just any of the context parameters can pass NULL when a context pointer
        is required.
 
-       There  are  three different types of context: a general context that is
-       relevant for several PCRE2 operations, a compile-time  context,  and  a
+       There are three different types of context: a general context  that  is
+       relevant  for  several  PCRE2 operations, a compile-time context, and a
        match-time context.
 
    The general context
 
-       At  present,  this context just contains pointers to (and data for) ex-
-       ternal memory management functions that are called from several  places
-       in  the  PCRE2  library.  The  context  is  named `general' rather than
-       specifically `memory' because in future other fields may be  added.  If
-       you  do not want to supply your own custom memory management functions,
-       you do not need to bother with a general context. A general context  is
+       At present, this context just contains pointers to (and data  for)  ex-
+       ternal  memory management functions that are called from several places
+       in the PCRE2 library.  The  context  is  named  `general'  rather  than
+       specifically  `memory'  because in future other fields may be added. If
+       you do not want to supply your own custom memory management  functions,
+       you  do not need to bother with a general context. A general context is
        created by:
 
        pcre2_general_context *pcre2_general_context_create(
          void *(*private_malloc)(PCRE2_SIZE, void *),
          void (*private_free)(void *, void *), void *memory_data);
 
-       The  two  function pointers specify custom memory management functions,
+       The two function pointers specify custom memory  management  functions,
        whose prototypes are:
 
          void *private_malloc(PCRE2_SIZE, void *);
@@ -768,16 +798,16 @@ PCRE2 CONTEXTS
 
        Whenever code in PCRE2 calls these functions, the final argument is the
        value of memory_data. Either of the first two arguments of the creation
-       function may be NULL, in which case the system memory management  func-
-       tions  malloc()  and free() are used. (This is not currently useful, as
-       there are no other fields in a general context,  but  in  future  there
-       might  be.)  The private_malloc() function is used (if supplied) to ob-
-       tain memory for storing the context, and all three values are saved  as
+       function  may be NULL, in which case the system memory management func-
+       tions malloc() and free() are used. (This is not currently  useful,  as
+       there  are  no  other  fields in a general context, but in future there
+       might be.)  The private_malloc() function is used (if supplied) to  ob-
+       tain  memory for storing the context, and all three values are saved as
        part of the context.
 
-       Whenever  PCRE2  creates a data block of any kind, the block contains a
-       pointer to the free() function that matches the malloc() function  that
-       was  used.  When  the  time  comes  to free the block, this function is
+       Whenever PCRE2 creates a data block of any kind, the block  contains  a
+       pointer  to the free() function that matches the malloc() function that
+       was used. When the time comes to  free  the  block,  this  function  is
        called.
 
        A general context can be copied by calling:
@@ -789,13 +819,13 @@ PCRE2 CONTEXTS
 
        void pcre2_general_context_free(pcre2_general_context *gcontext);
 
-       If this function is passed a  NULL  argument,  it  returns  immediately
+       If  this  function  is  passed  a NULL argument, it returns immediately
        without doing anything.
 
    The compile context
 
-       A  compile context is required if you want to provide an external func-
-       tion for stack checking during compilation or  to  change  the  default
+       A compile context is required if you want to provide an external  func-
+       tion  for  stack  checking  during compilation or to change the default
        values of any of the following compile-time parameters:
 
          What \R matches (Unicode newlines or CR, LF, CRLF only)
@@ -805,11 +835,11 @@ PCRE2 CONTEXTS
          The maximum length of the pattern string
          The extra options bits (none set by default)
 
-       A  compile context is also required if you are using custom memory man-
-       agement.  If none of these apply, just pass NULL as the  context  argu-
+       A compile context is also required if you are using custom memory  man-
+       agement.   If  none of these apply, just pass NULL as the context argu-
        ment of pcre2_compile().
 
-       A  compile context is created, copied, and freed by the following func-
+       A compile context is created, copied, and freed by the following  func-
        tions:
 
        pcre2_compile_context *pcre2_compile_context_create(
@@ -820,91 +850,91 @@ PCRE2 CONTEXTS
 
        void pcre2_compile_context_free(pcre2_compile_context *ccontext);
 
-       A compile context is created with default values  for  its  parameters.
+       A  compile  context  is created with default values for its parameters.
        These can be changed by calling the following functions, which return 0
        on success, or PCRE2_ERROR_BADDATA if invalid data is detected.
 
        int pcre2_set_bsr(pcre2_compile_context *ccontext,
          uint32_t value);
 
-       The value must be PCRE2_BSR_ANYCRLF, to specify that  \R  matches  only
-       CR,  LF,  or CRLF, or PCRE2_BSR_UNICODE, to specify that \R matches any
+       The  value  must  be PCRE2_BSR_ANYCRLF, to specify that \R matches only
+       CR, LF, or CRLF, or PCRE2_BSR_UNICODE, to specify that \R  matches  any
        Unicode line ending sequence. The value is used by the JIT compiler and
-       by   the   two   interpreted   matching  functions,  pcre2_match()  and
+       by  the  two  interpreted   matching   functions,   pcre2_match()   and
        pcre2_dfa_match().
 
        int pcre2_set_character_tables(pcre2_compile_context *ccontext,
          const uint8_t *tables);
 
-       The value must be the result of a  call  to  pcre2_maketables(),  whose
+       The  value  must  be  the result of a call to pcre2_maketables(), whose
        only argument is a general context. This function builds a set of char-
        acter tables in the current locale.
 
        int pcre2_set_compile_extra_options(pcre2_compile_context *ccontext,
          uint32_t extra_options);
 
-       As PCRE2 has developed, almost all the 32 option bits that  are  avail-
-       able  in  the options argument of pcre2_compile() have been used up. To
-       avoid running out, the compile context contains a set of  extra  option
-       bits  which are used for some newer, assumed rarer, options. This func-
-       tion sets those bits. It always sets all the bits (either on  or  off).
-       It  does not modify any existing setting. The available options are de-
+       As  PCRE2  has developed, almost all the 32 option bits that are avail-
+       able in the options argument of pcre2_compile() have been used  up.  To
+       avoid  running  out, the compile context contains a set of extra option
+       bits which are used for some newer, assumed rarer, options. This  func-
+       tion  sets  those bits. It always sets all the bits (either on or off).
+       It does not modify any existing setting. The available options are  de-
        fined in the section entitled "Extra compile options" below.
 
        int pcre2_set_max_pattern_length(pcre2_compile_context *ccontext,
          PCRE2_SIZE value);
 
-       This sets a maximum length, in code units, for any pattern string  that
-       is  compiled  with  this context. If the pattern is longer, an error is
-       generated.  This facility is provided so that applications that  accept
+       This  sets a maximum length, in code units, for any pattern string that
+       is compiled with this context. If the pattern is longer,  an  error  is
+       generated.   This facility is provided so that applications that accept
        patterns from external sources can limit their size. The default is the
-       largest number that a PCRE2_SIZE variable can  hold,  which  is  effec-
+       largest  number  that  a  PCRE2_SIZE variable can hold, which is effec-
        tively unlimited.
 
        int pcre2_set_newline(pcre2_compile_context *ccontext,
          uint32_t value);
 
        This specifies which characters or character sequences are to be recog-
-       nized as newlines. The value must be one of PCRE2_NEWLINE_CR  (carriage
+       nized  as newlines. The value must be one of PCRE2_NEWLINE_CR (carriage
        return only), PCRE2_NEWLINE_LF (linefeed only), PCRE2_NEWLINE_CRLF (the
-       two-character sequence CR followed by LF),  PCRE2_NEWLINE_ANYCRLF  (any
-       of  the  above),  PCRE2_NEWLINE_ANY  (any Unicode newline sequence), or
+       two-character  sequence  CR followed by LF), PCRE2_NEWLINE_ANYCRLF (any
+       of the above), PCRE2_NEWLINE_ANY (any  Unicode  newline  sequence),  or
        PCRE2_NEWLINE_NUL (the NUL character, that is a binary zero).
 
        A pattern can override the value set in the compile context by starting
        with a sequence such as (*CRLF). See the pcre2pattern page for details.
 
-       When  a  pattern  is  compiled  with  the  PCRE2_EXTENDED  or PCRE2_EX-
-       TENDED_MORE option, the newline convention affects the  recognition  of
-       the  end  of internal comments starting with #. The value is saved with
-       the compiled pattern for subsequent use by the JIT compiler and by  the
-       two     interpreted     matching     functions,    pcre2_match()    and
+       When a  pattern  is  compiled  with  the  PCRE2_EXTENDED  or  PCRE2_EX-
+       TENDED_MORE  option,  the newline convention affects the recognition of
+       the end of internal comments starting with #. The value is  saved  with
+       the  compiled pattern for subsequent use by the JIT compiler and by the
+       two    interpreted    matching     functions,     pcre2_match()     and
        pcre2_dfa_match().
 
        int pcre2_set_parens_nest_limit(pcre2_compile_context *ccontext,
          uint32_t value);
 
-       This parameter adjusts the limit, set  when  PCRE2  is  built  (default
-       250),  on  the  depth  of  parenthesis nesting in a pattern. This limit
-       stops rogue patterns using up too much system  stack  when  being  com-
-       piled.  The limit applies to parentheses of all kinds, not just captur-
+       This  parameter  adjusts  the  limit,  set when PCRE2 is built (default
+       250), on the depth of parenthesis nesting  in  a  pattern.  This  limit
+       stops  rogue  patterns  using  up too much system stack when being com-
+       piled. The limit applies to parentheses of all kinds, not just  captur-
        ing parentheses.
 
        int pcre2_set_compile_recursion_guard(pcre2_compile_context *ccontext,
          int (*guard_function)(uint32_t, void *), void *user_data);
 
-       There is at least one application that runs PCRE2 in threads with  very
-       limited  system  stack,  where running out of stack is to be avoided at
-       all costs. The parenthesis limit above cannot take account of how  much
-       stack  is  actually  available during compilation. For a finer control,
-       you can supply a  function  that  is  called  whenever  pcre2_compile()
-       starts  to compile a parenthesized part of a pattern. This function can
-       check the actual stack size (or anything else  that  it  wants  to,  of
+       There  is at least one application that runs PCRE2 in threads with very
+       limited system stack, where running out of stack is to  be  avoided  at
+       all  costs. The parenthesis limit above cannot take account of how much
+       stack is actually available during compilation. For  a  finer  control,
+       you  can  supply  a  function  that  is called whenever pcre2_compile()
+       starts to compile a parenthesized part of a pattern. This function  can
+       check  the  actual  stack  size  (or anything else that it wants to, of
        course).
 
-       The  first  argument to the callout function gives the current depth of
-       nesting, and the second is user data that is set up by the  last  argu-
-       ment   of  pcre2_set_compile_recursion_guard().  The  callout  function
+       The first argument to the callout function gives the current  depth  of
+       nesting,  and  the second is user data that is set up by the last argu-
+       ment  of  pcre2_set_compile_recursion_guard().  The  callout   function
        should return zero if all is well, or non-zero to force an error.
 
    The match context
@@ -918,10 +948,10 @@ PCRE2 CONTEXTS
          Change the backtracking depth limit
          Set custom memory management specifically for the match
 
-       If none of these apply, just pass  NULL  as  the  context  argument  of
+       If  none  of  these  apply,  just  pass NULL as the context argument of
        pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match().
 
-       A  match  context  is created, copied, and freed by the following func-
+       A match context is created, copied, and freed by  the  following  func-
        tions:
 
        pcre2_match_context *pcre2_match_context_create(
@@ -932,7 +962,7 @@ PCRE2 CONTEXTS
 
        void pcre2_match_context_free(pcre2_match_context *mcontext);
 
-       A match context is created with  default  values  for  its  parameters.
+       A  match  context  is  created  with default values for its parameters.
        These can be changed by calling the following functions, which return 0
        on success, or PCRE2_ERROR_BADDATA if invalid data is detected.
 
@@ -940,7 +970,7 @@ PCRE2 CONTEXTS
          int (*callout_function)(pcre2_callout_block *, void *),
          void *callout_data);
 
-       This sets up a callout function for PCRE2 to call at  specified  points
+       This  sets  up a callout function for PCRE2 to call at specified points
        during a matching operation. Details are given in the pcre2callout doc-
        umentation.
 
@@ -948,34 +978,34 @@ PCRE2 CONTEXTS
          int (*callout_function)(pcre2_substitute_callout_block *, void *),
          void *callout_data);
 
-       This sets up a callout function for PCRE2 to call after each  substitu-
+       This  sets up a callout function for PCRE2 to call after each substitu-
        tion made by pcre2_substitute(). Details are given in the section enti-
        tled "Creating a new string with substitutions" below.
 
        int pcre2_set_offset_limit(pcre2_match_context *mcontext,
          PCRE2_SIZE value);
 
-       The offset_limit parameter limits how far an unanchored search can  ad-
-       vance  in  the  subject  string.  The default value is PCRE2_UNSET. The
-       pcre2_match() and pcre2_dfa_match()  functions  return  PCRE2_ERROR_NO-
+       The  offset_limit parameter limits how far an unanchored search can ad-
+       vance in the subject string. The  default  value  is  PCRE2_UNSET.  The
+       pcre2_match()  and  pcre2_dfa_match()  functions return PCRE2_ERROR_NO-
        MATCH if a match with a starting point before or at the given offset is
        not found. The pcre2_substitute() function makes no more substitutions.
 
-       For example, if the pattern /abc/ is matched against "123abc"  with  an
-       offset  limit  less  than 3, the result is PCRE2_ERROR_NOMATCH. A match
-       can never be  found  if  the  startoffset  argument  of  pcre2_match(),
-       pcre2_dfa_match(),  or  pcre2_substitute()  is  greater than the offset
+       For  example,  if the pattern /abc/ is matched against "123abc" with an
+       offset limit less than 3, the result is  PCRE2_ERROR_NOMATCH.  A  match
+       can  never  be  found  if  the  startoffset  argument of pcre2_match(),
+       pcre2_dfa_match(), or pcre2_substitute() is  greater  than  the  offset
        limit set in the match context.
 
-       When using this facility, you must set the  PCRE2_USE_OFFSET_LIMIT  op-
+       When  using  this facility, you must set the PCRE2_USE_OFFSET_LIMIT op-
        tion when calling pcre2_compile() so that when JIT is in use, different
-       code can be compiled. If a match is started with  a  non-default  match
+       code  can  be  compiled. If a match is started with a non-default match
        limit when PCRE2_USE_OFFSET_LIMIT is not set, an error is generated.
 
-       The  offset limit facility can be used to track progress when searching
-       large subject strings or to limit the extent of  global  substitutions.
-       See  also  the  PCRE2_FIRSTLINE option, which requires a match to start
-       before or at the first newline that follows the start  of  matching  in
+       The offset limit facility can be used to track progress when  searching
+       large  subject  strings or to limit the extent of global substitutions.
+       See also the PCRE2_FIRSTLINE option, which requires a  match  to  start
+       before  or  at  the first newline that follows the start of matching in
        the subject. If this is set with an offset limit, a match must occur in
        the first line and also within the offset limit. In other words, which-
        ever limit comes first is used.
@@ -984,15 +1014,15 @@ PCRE2 CONTEXTS
          uint32_t value);
 
        The heap_limit parameter specifies, in units of kibibytes (1024 bytes),
-       the maximum amount of heap memory that pcre2_match() may  use  to  hold
+       the  maximum  amount  of heap memory that pcre2_match() may use to hold
        backtracking information when running an interpretive match. This limit
        also applies to pcre2_dfa_match(), which may use the heap when process-
-       ing  patterns  with a lot of nested pattern recursion or lookarounds or
+       ing patterns with a lot of nested pattern recursion or  lookarounds  or
        atomic groups. This limit does not apply to matching with the JIT opti-
-       mization,  which  has  its  own  memory  control  arrangements (see the
-       pcre2jit documentation for more details). If the limit is reached,  the
-       negative  error  code  PCRE2_ERROR_HEAPLIMIT  is  returned. The default
-       limit can be set when PCRE2 is built; if it is not, the default is  set
+       mization, which has  its  own  memory  control  arrangements  (see  the
+       pcre2jit  documentation for more details). If the limit is reached, the
+       negative error code  PCRE2_ERROR_HEAPLIMIT  is  returned.  The  default
+       limit  can be set when PCRE2 is built; if it is not, the default is set
        very large and is essentially "unlimited".
 
        A value for the heap limit may also be supplied by an item at the start
@@ -1000,101 +1030,101 @@ PCRE2 CONTEXTS
 
          (*LIMIT_HEAP=ddd)
 
-       where ddd is a decimal number. However, such a setting is  ignored  un-
-       less  ddd is less than the limit set by the caller of pcre2_match() or,
+       where  ddd  is a decimal number. However, such a setting is ignored un-
+       less ddd is less than the limit set by the caller of pcre2_match()  or,
        if no such limit is set, less than the default.
 
-       The pcre2_match() function starts out using a 20KiB vector on the  sys-
+       The  pcre2_match() function starts out using a 20KiB vector on the sys-
        tem stack for recording backtracking points. The more nested backtrack-
-       ing points there are (that is, the deeper the search  tree),  the  more
-       memory  is  needed.   Heap memory is used only if the initial vector is
+       ing  points  there  are (that is, the deeper the search tree), the more
+       memory is needed.  Heap memory is used only if the  initial  vector  is
        too small. If the heap limit is set to a value less than 21 (in partic-
-       ular,  zero)  no  heap memory will be used. In this case, only patterns
-       that do not have a lot of nested backtracking can be successfully  pro-
+       ular, zero) no heap memory will be used. In this  case,  only  patterns
+       that  do not have a lot of nested backtracking can be successfully pro-
        cessed.
 
-       Similarly,  for pcre2_dfa_match(), a vector on the system stack is used
-       when processing pattern recursions, lookarounds, or atomic groups,  and
-       only  if this is not big enough is heap memory used. In this case, too,
+       Similarly, for pcre2_dfa_match(), a vector on the system stack is  used
+       when  processing pattern recursions, lookarounds, or atomic groups, and
+       only if this is not big enough is heap memory used. In this case,  too,
        setting a value of zero disables the use of the heap.
 
        int pcre2_set_match_limit(pcre2_match_context *mcontext,
          uint32_t value);
 
        The match_limit parameter provides a means of preventing PCRE2 from us-
-       ing  up  too many computing resources when processing patterns that are
+       ing up too many computing resources when processing patterns  that  are
        not going to match, but which have a very large number of possibilities
-       in  their  search  trees.  The  classic  example is a pattern that uses
+       in their search trees. The classic  example  is  a  pattern  that  uses
        nested unlimited repeats.
 
-       There is an internal counter in pcre2_match() that is incremented  each
-       time  round  its  main  matching  loop. If this value reaches the match
+       There  is an internal counter in pcre2_match() that is incremented each
+       time round its main matching loop. If  this  value  reaches  the  match
        limit, pcre2_match() returns the negative value PCRE2_ERROR_MATCHLIMIT.
-       This  has  the  effect  of limiting the amount of backtracking that can
+       This has the effect of limiting the amount  of  backtracking  that  can
        take place. For patterns that are not anchored, the count restarts from
-       zero  for  each position in the subject string. This limit also applies
+       zero for each position in the subject string. This limit  also  applies
        to pcre2_dfa_match(), though the counting is done in a different way.
 
-       When pcre2_match() is called with a pattern that was successfully  pro-
+       When  pcre2_match() is called with a pattern that was successfully pro-
        cessed by pcre2_jit_compile(), the way in which matching is executed is
-       entirely different. However, there is still the possibility of  runaway
-       matching  that  goes  on  for  a very long time, and so the match_limit
-       value is also used in this case (but in a different way) to  limit  how
+       entirely  different. However, there is still the possibility of runaway
+       matching that goes on for a very long  time,  and  so  the  match_limit
+       value  is  also used in this case (but in a different way) to limit how
        long the matching can continue.
 
        The default value for the limit can be set when PCRE2 is built; the de-
-       fault default is 10 million, which handles all  but  the  most  extreme
-       cases.  A  value for the match limit may also be supplied by an item at
+       fault  default  is  10  million, which handles all but the most extreme
+       cases. A value for the match limit may also be supplied by an  item  at
        the start of a pattern of the form
 
          (*LIMIT_MATCH=ddd)
 
-       where ddd is a decimal number. However, such a setting is  ignored  un-
-       less  ddd  is less than the limit set by the caller of pcre2_match() or
+       where  ddd  is a decimal number. However, such a setting is ignored un-
+       less ddd is less than the limit set by the caller of  pcre2_match()  or
        pcre2_dfa_match() or, if no such limit is set, less than the default.
 
        int pcre2_set_depth_limit(pcre2_match_context *mcontext,
          uint32_t value);
 
-       This  parameter  limits   the   depth   of   nested   backtracking   in
-       pcre2_match().   Each time a nested backtracking point is passed, a new
+       This   parameter   limits   the   depth   of   nested  backtracking  in
+       pcre2_match().  Each time a nested backtracking point is passed, a  new
        memory "frame" is used to remember the state of matching at that point.
-       Thus,  this  parameter  indirectly  limits the amount of memory that is
-       used in a match. However, because the size of each memory  "frame"  de-
-       pends  on  the number of capturing parentheses, the actual memory limit
-       varies from pattern to pattern. This limit was more useful in  versions
+       Thus, this parameter indirectly limits the amount  of  memory  that  is
+       used  in  a match. However, because the size of each memory "frame" de-
+       pends on the number of capturing parentheses, the actual  memory  limit
+       varies  from pattern to pattern. This limit was more useful in versions
        before 10.30, where function recursion was used for backtracking.
 
-       The  depth limit is not relevant, and is ignored, when matching is done
+       The depth limit is not relevant, and is ignored, when matching is  done
        using JIT compiled code. However, it is supported by pcre2_dfa_match(),
-       which  uses it to limit the depth of nested internal recursive function
-       calls that implement atomic groups, lookaround assertions, and  pattern
+       which uses it to limit the depth of nested internal recursive  function
+       calls  that implement atomic groups, lookaround assertions, and pattern
        recursions. This limits, indirectly, the amount of system stack that is
-       used. It was more useful in versions before 10.32,  when  stack  memory
+       used.  It  was  more useful in versions before 10.32, when stack memory
        was used for local workspace vectors for recursive function calls. From
-       version 10.32, only local variables are allocated on the stack  and  as
+       version  10.32,  only local variables are allocated on the stack and as
        each call uses only a few hundred bytes, even a small stack can support
        quite a lot of recursion.
 
-       If the depth of internal recursive function calls is great enough,  lo-
-       cal  workspace vectors are allocated on the heap from version 10.32 on-
-       wards, so the depth limit also indirectly limits  the  amount  of  heap
+       If  the depth of internal recursive function calls is great enough, lo-
+       cal workspace vectors are allocated on the heap from version 10.32  on-
+       wards,  so  the  depth  limit also indirectly limits the amount of heap
        memory that is used. A recursive pattern such as /(.(?2))((?1)|)/, when
-       matched to a very long string using pcre2_dfa_match(), can use a  great
-       deal  of memory. However, it is probably better to limit heap usage di-
+       matched  to a very long string using pcre2_dfa_match(), can use a great
+       deal of memory. However, it is probably better to limit heap usage  di-
        rectly by calling pcre2_set_heap_limit().
 
-       The default value for the depth limit can be set when PCRE2  is  built;
-       if  it  is not, the default is set to the same value as the default for
-       the  match  limit.   If  the  limit  is  exceeded,   pcre2_match()   or
+       The  default  value for the depth limit can be set when PCRE2 is built;
+       if it is not, the default is set to the same value as the  default  for
+       the   match   limit.   If  the  limit  is  exceeded,  pcre2_match()  or
        pcre2_dfa_match() returns PCRE2_ERROR_DEPTHLIMIT. A value for the depth
-       limit may also be supplied by an item at the start of a pattern of  the
+       limit  may also be supplied by an item at the start of a pattern of the
        form
 
          (*LIMIT_DEPTH=ddd)
 
-       where  ddd  is a decimal number. However, such a setting is ignored un-
-       less ddd is less than the limit set by the caller of  pcre2_match()  or
+       where ddd is a decimal number. However, such a setting is  ignored  un-
+       less  ddd  is less than the limit set by the caller of pcre2_match() or
        pcre2_dfa_match() or, if no such limit is set, less than the default.
 
 
@@ -1102,96 +1132,96 @@ CHECKING BUILD-TIME OPTIONS
 
        int pcre2_config(uint32_t what, void *where);
 
-       The  function  pcre2_config()  makes  it possible for a PCRE2 client to
-       find the value of certain  configuration  parameters  and  to  discover
-       which  optional features have been compiled into the PCRE2 library. The
+       The function pcre2_config() makes it possible for  a  PCRE2  client  to
+       find  the  value  of  certain  configuration parameters and to discover
+       which optional features have been compiled into the PCRE2 library.  The
        pcre2build documentation has more details about these features.
 
-       The first argument for pcre2_config() specifies  which  information  is
+       The  first  argument  for pcre2_config() specifies which information is
        required. The second argument is a pointer to memory into which the in-
        formation is placed. If NULL is passed, the function returns the amount
-       of  memory that is needed for the requested information. For calls that
-       return numerical values, the value is in bytes; when  requesting  these
-       values,  where  should point to appropriately aligned memory. For calls
-       that return strings, the required length is given in  code  units,  not
+       of memory that is needed for the requested information. For calls  that
+       return  numerical  values, the value is in bytes; when requesting these
+       values, where should point to appropriately aligned memory.  For  calls
+       that  return  strings,  the required length is given in code units, not
        counting the terminating zero.
 
-       When  requesting information, the returned value from pcre2_config() is
-       non-negative on success, or the negative error code  PCRE2_ERROR_BADOP-
-       TION  if the value in the first argument is not recognized. The follow-
+       When requesting information, the returned value from pcre2_config()  is
+       non-negative  on success, or the negative error code PCRE2_ERROR_BADOP-
+       TION if the value in the first argument is not recognized. The  follow-
        ing information is available:
 
          PCRE2_CONFIG_BSR
 
-       The output is a uint32_t integer whose value indicates  what  character
-       sequences  the  \R  escape  sequence  matches  by  default.  A value of
-       PCRE2_BSR_UNICODE means that \R matches any  Unicode  line  ending  se-
+       The  output  is a uint32_t integer whose value indicates what character
+       sequences the \R  escape  sequence  matches  by  default.  A  value  of
+       PCRE2_BSR_UNICODE  means  that  \R  matches any Unicode line ending se-
        quence; a value of PCRE2_BSR_ANYCRLF means that \R matches only CR, LF,
        or CRLF. The default can be overridden when a pattern is compiled.
 
          PCRE2_CONFIG_COMPILED_WIDTHS
 
-       The output is a uint32_t integer whose lower bits indicate  which  code
-       unit  widths  were  selected  when PCRE2 was built. The 1-bit indicates
-       8-bit support, and the 2-bit and 4-bit indicate 16-bit and 32-bit  sup-
+       The  output  is a uint32_t integer whose lower bits indicate which code
+       unit widths were selected when PCRE2 was  built.  The  1-bit  indicates
+       8-bit  support, and the 2-bit and 4-bit indicate 16-bit and 32-bit sup-
        port, respectively.
 
          PCRE2_CONFIG_DEPTHLIMIT
 
-       The  output  is a uint32_t integer that gives the default limit for the
-       depth of nested backtracking in pcre2_match() or the  depth  of  nested
-       recursions,  lookarounds,  and atomic groups in pcre2_dfa_match(). Fur-
+       The output is a uint32_t integer that gives the default limit  for  the
+       depth  of  nested  backtracking in pcre2_match() or the depth of nested
+       recursions, lookarounds, and atomic groups in  pcre2_dfa_match().  Fur-
        ther details are given with pcre2_set_depth_limit() above.
 
          PCRE2_CONFIG_HEAPLIMIT
 
-       The output is a uint32_t integer that gives, in kibibytes, the  default
-       limit   for  the  amount  of  heap  memory  used  by  pcre2_match()  or
-       pcre2_dfa_match().     Further     details     are      given      with
+       The  output is a uint32_t integer that gives, in kibibytes, the default
+       limit  for  the  amount  of  heap  memory  used  by  pcre2_match()   or
+       pcre2_dfa_match().      Further      details     are     given     with
        pcre2_set_heap_limit() above.
 
          PCRE2_CONFIG_JIT
 
-       The  output  is  a  uint32_t  integer that is set to one if support for
+       The output is a uint32_t integer that is set  to  one  if  support  for
        just-in-time compiling is available; otherwise it is set to zero.
 
          PCRE2_CONFIG_JITTARGET
 
-       The where argument should point to a buffer that is at  least  48  code
-       units  long.  (The  exact  length  required  can  be  found  by calling
-       pcre2_config() with where set to NULL.) The buffer  is  filled  with  a
-       string  that  contains  the  name of the architecture for which the JIT
-       compiler is configured, for example "x86 32bit  (little  endian  +  un-
-       aligned)".  If  JIT  support is not available, PCRE2_ERROR_BADOPTION is
-       returned, otherwise the number of code units used is returned. This  is
+       The  where  argument  should point to a buffer that is at least 48 code
+       units long.  (The  exact  length  required  can  be  found  by  calling
+       pcre2_config()  with  where  set  to NULL.) The buffer is filled with a
+       string that contains the name of the architecture  for  which  the  JIT
+       compiler  is  configured,  for  example "x86 32bit (little endian + un-
+       aligned)". If JIT support is not  available,  PCRE2_ERROR_BADOPTION  is
+       returned,  otherwise the number of code units used is returned. This is
        the length of the string, plus one unit for the terminating zero.
 
          PCRE2_CONFIG_LINKSIZE
 
        The output is a uint32_t integer that contains the number of bytes used
-       for internal linkage in compiled regular  expressions.  When  PCRE2  is
-       configured,  the value can be set to 2, 3, or 4, with the default being
-       2. This is the value that is returned by pcre2_config(). However,  when
-       the  16-bit  library  is compiled, a value of 3 is rounded up to 4, and
-       when the 32-bit library is compiled, internal  linkages  always  use  4
+       for  internal  linkage  in  compiled regular expressions. When PCRE2 is
+       configured, the value can be set to 2, 3, or 4, with the default  being
+       2.  This is the value that is returned by pcre2_config(). However, when
+       the 16-bit library is compiled, a value of 3 is rounded up  to  4,  and
+       when  the  32-bit  library  is compiled, internal linkages always use 4
        bytes, so the configured value is not relevant.
 
        The default value of 2 for the 8-bit and 16-bit libraries is sufficient
-       for all but the most massive patterns, since it allows the size of  the
-       compiled  pattern  to  be  up  to 65535 code units. Larger values allow
-       larger regular expressions to be compiled by those two  libraries,  but
+       for  all but the most massive patterns, since it allows the size of the
+       compiled pattern to be up to 65535  code  units.  Larger  values  allow
+       larger  regular  expressions to be compiled by those two libraries, but
        at the expense of slower matching.
 
          PCRE2_CONFIG_MATCHLIMIT
 
        The output is a uint32_t integer that gives the default match limit for
-       pcre2_match(). Further details are given  with  pcre2_set_match_limit()
+       pcre2_match().  Further  details are given with pcre2_set_match_limit()
        above.
 
          PCRE2_CONFIG_NEWLINE
 
-       The  output  is  a  uint32_t  integer whose value specifies the default
-       character sequence that is recognized as meaning "newline". The  values
+       The output is a uint32_t integer  whose  value  specifies  the  default
+       character  sequence that is recognized as meaning "newline". The values
        are:
 
          PCRE2_NEWLINE_CR       Carriage return (CR)
@@ -1201,23 +1231,23 @@ CHECKING BUILD-TIME OPTIONS
          PCRE2_NEWLINE_ANYCRLF  Any of CR, LF, or CRLF
          PCRE2_NEWLINE_NUL      The NUL character (binary zero)
 
-       The  default  should  normally  correspond to the standard sequence for
+       The default should normally correspond to  the  standard  sequence  for
        your operating system.
 
          PCRE2_CONFIG_NEVER_BACKSLASH_C
 
-       The output is a uint32_t integer that is set to one if the  use  of  \C
-       was  permanently  disabled when PCRE2 was built; otherwise it is set to
+       The  output  is  a uint32_t integer that is set to one if the use of \C
+       was permanently disabled when PCRE2 was built; otherwise it is  set  to
        zero.
 
          PCRE2_CONFIG_PARENSLIMIT
 
-       The output is a uint32_t integer that gives the maximum depth of  nest-
+       The  output is a uint32_t integer that gives the maximum depth of nest-
        ing of parentheses (of any kind) in a pattern. This limit is imposed to
-       cap the amount of system stack used when a pattern is compiled.  It  is
-       specified  when PCRE2 is built; the default is 250. This limit does not
+       cap  the  amount of system stack used when a pattern is compiled. It is
+       specified when PCRE2 is built; the default is 250. This limit does  not
        take into account the stack that may already be used by the calling ap-
-       plication.   For  finer  control  over  compilation  stack  usage,  see
+       plication.  For  finer  control  over  compilation  stack  usage,   see
        pcre2_set_compile_recursion_guard().
 
          PCRE2_CONFIG_STACKRECURSE
@@ -1228,30 +1258,30 @@ CHECKING BUILD-TIME OPTIONS
          PCRE2_CONFIG_TABLES_LENGTH
 
        The output is a uint32_t integer that gives the length of PCRE2's char-
-       acter processing tables in bytes. For details of these tables  see  the
+       acter  processing  tables in bytes. For details of these tables see the
        section on locale support below.
 
          PCRE2_CONFIG_UNICODE_VERSION
 
-       The  where  argument  should point to a buffer that is at least 24 code
-       units long.  (The  exact  length  required  can  be  found  by  calling
-       pcre2_config()  with  where  set  to  NULL.) If PCRE2 has been compiled
-       without Unicode support, the buffer is filled with  the  text  "Unicode
-       not  supported".  Otherwise,  the  Unicode version string (for example,
-       "8.0.0") is inserted. The number of code units used is  returned.  This
+       The where argument should point to a buffer that is at  least  24  code
+       units  long.  (The  exact  length  required  can  be  found  by calling
+       pcre2_config() with where set to NULL.)  If  PCRE2  has  been  compiled
+       without  Unicode  support,  the buffer is filled with the text "Unicode
+       not supported". Otherwise, the Unicode  version  string  (for  example,
+       "8.0.0")  is  inserted. The number of code units used is returned. This
        is the length of the string plus one unit for the terminating zero.
 
          PCRE2_CONFIG_UNICODE
 
-       The  output is a uint32_t integer that is set to one if Unicode support
-       is available; otherwise it is set to zero. Unicode support implies  UTF
+       The output is a uint32_t integer that is set to one if Unicode  support
+       is  available; otherwise it is set to zero. Unicode support implies UTF
        support.
 
          PCRE2_CONFIG_VERSION
 
-       The  where  argument  should point to a buffer that is at least 24 code
-       units long.  (The  exact  length  required  can  be  found  by  calling
-       pcre2_config()  with  where set to NULL.) The buffer is filled with the
+       The where argument should point to a buffer that is at  least  24  code
+       units  long.  (The  exact  length  required  can  be  found  by calling
+       pcre2_config() with where set to NULL.) The buffer is filled  with  the
        PCRE2 version string, zero-terminated. The number of code units used is
        returned. This is the length of the string plus one unit for the termi-
        nating zero.
@@ -1269,103 +1299,103 @@ COMPILING A PATTERN
 
        pcre2_code *pcre2_code_copy_with_tables(const pcre2_code *code);
 
-       The pcre2_compile() function compiles a pattern into an internal  form.
-       The  pattern  is  defined  by a pointer to a string of code units and a
-       length (in code units). If the pattern is zero-terminated,  the  length
-       can  be  specified  as  PCRE2_ZERO_TERMINATED.  The  function returns a
+       The  pcre2_compile() function compiles a pattern into an internal form.
+       The pattern is defined by a pointer to a string of  code  units  and  a
+       length  (in  code units). If the pattern is zero-terminated, the length
+       can be specified  as  PCRE2_ZERO_TERMINATED.  The  function  returns  a
        pointer to a block of memory that contains the compiled pattern and re-
        lated data, or NULL if an error occurred.
 
-       If  the  compile context argument ccontext is NULL, memory for the com-
-       piled pattern is obtained by calling malloc().  Otherwise,  it  is  ob-
+       If the compile context argument ccontext is NULL, memory for  the  com-
+       piled  pattern  is  obtained  by calling malloc(). Otherwise, it is ob-
        tained from the same memory function that was used for the compile con-
        text. The caller must free the memory by calling pcre2_code_free() when
        it is no longer needed.  If pcre2_code_free() is called with a NULL ar-
        gument, it returns immediately, without doing anything.
 
        The function pcre2_code_copy() makes a copy of the compiled code in new
-       memory,  using  the same memory allocator as was used for the original.
-       However, if the code has been processed by the JIT  compiler  (see  be-
-       low),  the JIT information cannot be copied (because it is position-de-
-       pendent).  The new copy can initially be used only for  non-JIT  match-
-       ing,  though  it  can  be passed to pcre2_jit_compile() if required. If
+       memory, using the same memory allocator as was used for  the  original.
+       However,  if  the  code has been processed by the JIT compiler (see be-
+       low), the JIT information cannot be copied (because it is  position-de-
+       pendent).   The  new copy can initially be used only for non-JIT match-
+       ing, though it can be passed to  pcre2_jit_compile()  if  required.  If
        pcre2_code_copy() is called with a NULL argument, it returns NULL.
 
        The pcre2_code_copy() function provides a way for individual threads in
-       a  multithreaded  application  to acquire a private copy of shared com-
-       piled code.  However, it does not make a copy of the  character  tables
-       used  by  the compiled pattern; the new pattern code points to the same
-       tables as the original code.  (See "Locale Support" below  for  details
-       of  these  character  tables.) In many applications the same tables are
-       used throughout, so this behaviour is appropriate. Nevertheless,  there
+       a multithreaded application to acquire a private copy  of  shared  com-
+       piled  code.   However, it does not make a copy of the character tables
+       used by the compiled pattern; the new pattern code points to  the  same
+       tables  as  the original code.  (See "Locale Support" below for details
+       of these character tables.) In many applications the  same  tables  are
+       used  throughout, so this behaviour is appropriate. Nevertheless, there
        are occasions when a copy of a compiled pattern and the relevant tables
-       are needed. The pcre2_code_copy_with_tables() provides  this  facility.
-       Copies  of  both  the  code  and the tables are made, with the new code
-       pointing to the new tables. The memory for the new tables is  automati-
-       cally  freed  when  pcre2_code_free() is called for the new copy of the
-       compiled code. If pcre2_code_copy_with_tables() is called with  a  NULL
+       are  needed.  The pcre2_code_copy_with_tables() provides this facility.
+       Copies of both the code and the tables are  made,  with  the  new  code
+       pointing  to the new tables. The memory for the new tables is automati-
+       cally freed when pcre2_code_free() is called for the new  copy  of  the
+       compiled  code.  If pcre2_code_copy_with_tables() is called with a NULL
        argument, it returns NULL.
 
-       NOTE:  When  one  of  the matching functions is called, pointers to the
+       NOTE: When one of the matching functions is  called,  pointers  to  the
        compiled pattern and the subject string are set in the match data block
-       so  that  they  can be referenced by the substring extraction functions
-       after a successful match.  After running a match, you must not  free  a
-       compiled  pattern or a subject string until after all operations on the
-       match data block have taken place, unless, in the case of  the  subject
-       string,  you  have used the PCRE2_COPY_MATCHED_SUBJECT option, which is
-       described in the section entitled "Option bits for  pcre2_match()"  be-
+       so that they can be referenced by the  substring  extraction  functions
+       after  a  successful match.  After running a match, you must not free a
+       compiled pattern or a subject string until after all operations on  the
+       match  data  block have taken place, unless, in the case of the subject
+       string, you have used the PCRE2_COPY_MATCHED_SUBJECT option,  which  is
+       described  in  the section entitled "Option bits for pcre2_match()" be-
        low.
 
-       The  options argument for pcre2_compile() contains various bit settings
-       that affect the compilation. It should be zero if none of them are  re-
-       quired.  The  available  options  are described below. Some of them (in
-       particular, those that are compatible with Perl,  but  some  others  as
-       well)  can  also  be set and unset from within the pattern (see the de-
+       The options argument for pcre2_compile() contains various bit  settings
+       that  affect the compilation. It should be zero if none of them are re-
+       quired. The available options are described below.  Some  of  them  (in
+       particular,  those  that  are  compatible with Perl, but some others as
+       well) can also be set and unset from within the pattern  (see  the  de-
        tailed description in the pcre2pattern documentation).
 
-       For those options that can be different in different parts of the  pat-
-       tern,  the contents of the options argument specifies their settings at
-       the start of compilation. The  PCRE2_ANCHORED,  PCRE2_ENDANCHORED,  and
-       PCRE2_NO_UTF_CHECK  options  can be set at the time of matching as well
+       For  those options that can be different in different parts of the pat-
+       tern, the contents of the options argument specifies their settings  at
+       the  start  of  compilation. The PCRE2_ANCHORED, PCRE2_ENDANCHORED, and
+       PCRE2_NO_UTF_CHECK options can be set at the time of matching  as  well
        as at compile time.
 
-       Some additional options and less frequently required  compile-time  pa-
-       rameters  (for  example, the newline setting) can be provided in a com-
+       Some  additional  options and less frequently required compile-time pa-
+       rameters (for example, the newline setting) can be provided in  a  com-
        pile context (as described above).
 
        If errorcode or erroroffset is NULL, pcre2_compile() returns NULL imme-
-       diately.  Otherwise,  the  variables to which these point are set to an
+       diately. Otherwise, the variables to which these point are  set  to  an
        error code and an offset (number of code units) within the pattern, re-
        spectively, when pcre2_compile() returns NULL because a compilation er-
-       ror has occurred. The values are not defined when compilation  is  suc-
+       ror  has  occurred. The values are not defined when compilation is suc-
        cessful and pcre2_compile() returns a non-NULL value.
 
-       There  are nearly 100 positive error codes that pcre2_compile() may re-
-       turn if it finds an error in the pattern. There are also some  negative
-       error  codes that are used for invalid UTF strings when validity check-
-       ing is in force. These are the  same  as  given  by  pcre2_match()  and
+       There are nearly 100 positive error codes that pcre2_compile() may  re-
+       turn  if it finds an error in the pattern. There are also some negative
+       error codes that are used for invalid UTF strings when validity  check-
+       ing  is  in  force.  These  are  the same as given by pcre2_match() and
        pcre2_dfa_match(), and are described in the pcre2unicode documentation.
-       There is no separate documentation for the positive  error  codes,  be-
-       cause  the  textual  error  messages  that  are obtained by calling the
+       There  is  no  separate documentation for the positive error codes, be-
+       cause the textual error messages  that  are  obtained  by  calling  the
        pcre2_get_error_message() function (see "Obtaining a textual error mes-
-       sage"  below)  should  be  self-explanatory.  Macro names starting with
-       PCRE2_ERROR_ are defined for both positive and negative error codes  in
+       sage" below) should be  self-explanatory.  Macro  names  starting  with
+       PCRE2_ERROR_  are defined for both positive and negative error codes in
        pcre2.h.
 
        The value returned in erroroffset is an indication of where in the pat-
-       tern the error occurred. It is not necessarily the  furthest  point  in
+       tern  the  error  occurred. It is not necessarily the furthest point in
        the pattern that was read. For example, after the error "lookbehind as-
-       sertion is not fixed length", the error offset points to the  start  of
-       the  failing assertion. For an invalid UTF-8 or UTF-16 string, the off-
+       sertion  is  not fixed length", the error offset points to the start of
+       the failing assertion. For an invalid UTF-8 or UTF-16 string, the  off-
        set is that of the first code unit of the failing character.
 
-       Some errors are not detected until the whole pattern has been  scanned;
-       in  these  cases,  the offset passed back is the length of the pattern.
-       Note that the offset is in code units, not characters, even  in  a  UTF
+       Some  errors are not detected until the whole pattern has been scanned;
+       in these cases, the offset passed back is the length  of  the  pattern.
+       Note  that  the  offset is in code units, not characters, even in a UTF
        mode. It may sometimes point into the middle of a UTF-8 or UTF-16 char-
        acter.
 
-       This code fragment shows a typical straightforward call  to  pcre2_com-
+       This  code  fragment shows a typical straightforward call to pcre2_com-
        pile():
 
          pcre2_code *re;
@@ -1382,546 +1412,546 @@ COMPILING A PATTERN
 
    Main compile options
 
-       The  following  names for option bits are defined in the pcre2.h header
+       The following names for option bits are defined in the  pcre2.h  header
        file:
 
          PCRE2_ANCHORED
 
        If this bit is set, the pattern is forced to be "anchored", that is, it
-       is  constrained to match only at the first matching point in the string
-       that is being searched (the "subject string"). This effect can also  be
-       achieved  by appropriate constructs in the pattern itself, which is the
+       is constrained to match only at the first matching point in the  string
+       that  is being searched (the "subject string"). This effect can also be
+       achieved by appropriate constructs in the pattern itself, which is  the
        only way to do it in Perl.
 
          PCRE2_ALLOW_EMPTY_CLASS
 
-       By default, for compatibility with Perl, a closing square bracket  that
-       immediately  follows  an opening one is treated as a data character for
-       the class. When  PCRE2_ALLOW_EMPTY_CLASS  is  set,  it  terminates  the
+       By  default, for compatibility with Perl, a closing square bracket that
+       immediately follows an opening one is treated as a data  character  for
+       the  class.  When  PCRE2_ALLOW_EMPTY_CLASS  is  set,  it terminates the
        class, which therefore contains no characters and so can never match.
 
          PCRE2_ALT_BSUX
 
-       This  option  request  alternative  handling of three escape sequences,
-       which makes PCRE2's behaviour more like  ECMAscript  (aka  JavaScript).
+       This option request alternative handling  of  three  escape  sequences,
+       which  makes  PCRE2's  behaviour more like ECMAscript (aka JavaScript).
        When it is set:
 
        (1) \U matches an upper case "U" character; by default \U causes a com-
        pile time error (Perl uses \U to upper case subsequent characters).
 
        (2) \u matches a lower case "u" character unless it is followed by four
-       hexadecimal  digits,  in  which case the hexadecimal number defines the
-       code point to match. By default, \u causes a compile time  error  (Perl
+       hexadecimal digits, in which case the hexadecimal  number  defines  the
+       code  point  to match. By default, \u causes a compile time error (Perl
        uses it to upper case the following character).
 
-       (3)  \x matches a lower case "x" character unless it is followed by two
-       hexadecimal digits, in which case the hexadecimal  number  defines  the
-       code  point  to  match. By default, as in Perl, a hexadecimal number is
+       (3) \x matches a lower case "x" character unless it is followed by  two
+       hexadecimal  digits,  in  which case the hexadecimal number defines the
+       code point to match. By default, as in Perl, a  hexadecimal  number  is
        always expected after \x, but it may have zero, one, or two digits (so,
        for example, \xz matches a binary zero character followed by z).
 
        ECMAscript 6 added additional functionality to \u. This can be accessed
-       using the PCRE2_EXTRA_ALT_BSUX extra option  (see  "Extra  compile  op-
+       using  the  PCRE2_EXTRA_ALT_BSUX  extra  option (see "Extra compile op-
        tions" below).  Note that this alternative escape handling applies only
-       to patterns. Neither of these options affects  the  processing  of  re-
+       to  patterns.  Neither  of  these options affects the processing of re-
        placement strings passed to pcre2_substitute().
 
          PCRE2_ALT_CIRCUMFLEX
 
        In  multiline  mode  (when  PCRE2_MULTILINE  is  set),  the  circumflex
-       metacharacter matches at the start of the subject (unless  PCRE2_NOTBOL
-       is  set),  and  also  after  any internal newline. However, it does not
+       metacharacter  matches at the start of the subject (unless PCRE2_NOTBOL
+       is set), and also after any internal  newline.  However,  it  does  not
        match after a newline at the end of the subject, for compatibility with
-       Perl.  If  you want a multiline circumflex also to match after a termi-
+       Perl. If you want a multiline circumflex also to match after  a  termi-
        nating newline, you must set PCRE2_ALT_CIRCUMFLEX.
 
          PCRE2_ALT_VERBNAMES
 
-       By default, for compatibility with Perl, the name in any verb  sequence
-       such  as  (*MARK:NAME)  is any sequence of characters that does not in-
-       clude a closing parenthesis. The name is not processed in any way,  and
-       it  is  not possible to include a closing parenthesis in the name. How-
-       ever, if the PCRE2_ALT_VERBNAMES option is set, normal  backslash  pro-
-       cessing  is  applied to verb names and only an unescaped closing paren-
-       thesis terminates the name. A closing parenthesis can be included in  a
-       name  either  as  \)  or  between  \Q  and \E. If the PCRE2_EXTENDED or
-       PCRE2_EXTENDED_MORE option is set with  PCRE2_ALT_VERBNAMES,  unescaped
-       whitespace  in verb names is skipped and #-comments are recognized, ex-
+       By  default, for compatibility with Perl, the name in any verb sequence
+       such as (*MARK:NAME) is any sequence of characters that  does  not  in-
+       clude  a closing parenthesis. The name is not processed in any way, and
+       it is not possible to include a closing parenthesis in the  name.  How-
+       ever,  if  the PCRE2_ALT_VERBNAMES option is set, normal backslash pro-
+       cessing is applied to verb names and only an unescaped  closing  paren-
+       thesis  terminates the name. A closing parenthesis can be included in a
+       name either as \) or between  \Q  and  \E.  If  the  PCRE2_EXTENDED  or
+       PCRE2_EXTENDED_MORE  option  is set with PCRE2_ALT_VERBNAMES, unescaped
+       whitespace in verb names is skipped and #-comments are recognized,  ex-
        actly as in the rest of the pattern.
 
          PCRE2_AUTO_CALLOUT
 
-       If this bit  is  set,  pcre2_compile()  automatically  inserts  callout
-       items,  all  with  number 255, before each pattern item, except immedi-
-       ately before or after an explicit callout in the pattern.  For  discus-
+       If  this  bit  is  set,  pcre2_compile()  automatically inserts callout
+       items, all with number 255, before each pattern  item,  except  immedi-
+       ately  before  or after an explicit callout in the pattern. For discus-
        sion of the callout facility, see the pcre2callout documentation.
 
          PCRE2_CASELESS
 
-       If  this  bit is set, letters in the pattern match both upper and lower
-       case letters in the subject. It is equivalent to Perl's /i option,  and
-       it  can be changed within a pattern by a (?i) option setting. If either
-       PCRE2_UTF or PCRE2_UCP is set, Unicode  properties  are  used  for  all
-       characters  with more than one other case, and for all characters whose
-       code points are greater than U+007F. Note  that  there  are  two  ASCII
+       If this bit is set, letters in the pattern match both upper  and  lower
+       case  letters in the subject. It is equivalent to Perl's /i option, and
+       it can be changed within a pattern by a (?i) option setting. If  either
+       PCRE2_UTF  or  PCRE2_UCP  is  set,  Unicode properties are used for all
+       characters with more than one other case, and for all characters  whose
+       code  points  are  greater  than  U+007F. Note that there are two ASCII
        characters, K and S, that, in addition to their lower case ASCII equiv-
-       alents, are case-equivalent with U+212A (Kelvin sign) and U+017F  (long
-       S)  respectively. For lower valued characters with only one other case,
-       a lookup table is used for speed. When neither PCRE2_UTF nor  PCRE2_UCP
-       is  set,  a lookup table is used for all code points less than 256, and
-       higher code points (available  only  in  16-bit  or  32-bit  mode)  are
+       alents,  are case-equivalent with U+212A (Kelvin sign) and U+017F (long
+       S) respectively. For lower valued characters with only one other  case,
+       a  lookup table is used for speed. When neither PCRE2_UTF nor PCRE2_UCP
+       is set, a lookup table is used for all code points less than  256,  and
+       higher  code  points  (available  only  in  16-bit  or 32-bit mode) are
        treated as not having another case.
 
          PCRE2_DOLLAR_ENDONLY
 
-       If  this bit is set, a dollar metacharacter in the pattern matches only
-       at the end of the subject string. Without this option,  a  dollar  also
-       matches  immediately before a newline at the end of the string (but not
-       before any other newlines). The PCRE2_DOLLAR_ENDONLY option is  ignored
-       if  PCRE2_MULTILINE  is  set.  There is no equivalent to this option in
+       If this bit is set, a dollar metacharacter in the pattern matches  only
+       at  the  end  of the subject string. Without this option, a dollar also
+       matches immediately before a newline at the end of the string (but  not
+       before  any other newlines). The PCRE2_DOLLAR_ENDONLY option is ignored
+       if PCRE2_MULTILINE is set. There is no equivalent  to  this  option  in
        Perl, and no way to set it within a pattern.
 
          PCRE2_DOTALL
 
-       If this bit is set, a dot metacharacter  in  the  pattern  matches  any
-       character,  including  one  that  indicates a newline. However, it only
+       If  this  bit  is  set,  a dot metacharacter in the pattern matches any
+       character, including one that indicates a  newline.  However,  it  only
        ever matches one character, even if newlines are coded as CRLF. Without
        this option, a dot does not match when the current position in the sub-
-       ject is at a newline. This option is equivalent to  Perl's  /s  option,
+       ject  is  at  a newline. This option is equivalent to Perl's /s option,
        and it can be changed within a pattern by a (?s) option setting. A neg-
-       ative class such as [^a] always matches newline characters, and the  \N
-       escape  sequence always matches a non-newline character, independent of
+       ative  class such as [^a] always matches newline characters, and the \N
+       escape sequence always matches a non-newline character, independent  of
        the setting of PCRE2_DOTALL.
 
          PCRE2_DUPNAMES
 
-       If this bit is set, names used to identify capture groups need  not  be
-       unique.   This  can  be helpful for certain types of pattern when it is
-       known that only one instance of the named group can  ever  be  matched.
-       There  are  more  details  of  named capture groups below; see also the
+       If  this  bit is set, names used to identify capture groups need not be
+       unique.  This can be helpful for certain types of pattern  when  it  is
+       known  that  only  one instance of the named group can ever be matched.
+       There are more details of named capture  groups  below;  see  also  the
        pcre2pattern documentation.
 
          PCRE2_ENDANCHORED
 
-       If this bit is set, the end of any pattern match must be right  at  the
+       If  this  bit is set, the end of any pattern match must be right at the
        end of the string being searched (the "subject string"). If the pattern
        match succeeds by reaching (*ACCEPT), but does not reach the end of the
-       subject,  the match fails at the current starting point. For unanchored
-       patterns, a new match is then tried at the next  starting  point.  How-
+       subject, the match fails at the current starting point. For  unanchored
+       patterns,  a  new  match is then tried at the next starting point. How-
        ever, if the match succeeds by reaching the end of the pattern, but not
-       the end of the subject, backtracking occurs and  an  alternative  match
+       the  end  of  the subject, backtracking occurs and an alternative match
        may be found. Consider these two patterns:
 
          .(*ACCEPT)|..
          .|..
 
-       If  matched against "abc" with PCRE2_ENDANCHORED set, the first matches
-       "c" whereas the second matches "bc". The  effect  of  PCRE2_ENDANCHORED
-       can  also  be achieved by appropriate constructs in the pattern itself,
+       If matched against "abc" with PCRE2_ENDANCHORED set, the first  matches
+       "c"  whereas  the  second matches "bc". The effect of PCRE2_ENDANCHORED
+       can also be achieved by appropriate constructs in the  pattern  itself,
        which is the only way to do it in Perl.
 
        For DFA matching with pcre2_dfa_match(), PCRE2_ENDANCHORED applies only
-       to  the  first  (that  is,  the longest) matched string. Other parallel
-       matches, which are necessarily substrings of the first one, must  obvi-
+       to the first (that is, the  longest)  matched  string.  Other  parallel
+       matches,  which are necessarily substrings of the first one, must obvi-
        ously end before the end of the subject.
 
          PCRE2_EXTENDED
 
-       If  this bit is set, most white space characters in the pattern are to-
+       If this bit is set, most white space characters in the pattern are  to-
        tally ignored except when escaped or inside a character class. However,
-       white  space is not allowed within sequences such as (?> that introduce
-       various parenthesized groups, nor within numerical quantifiers such  as
+       white space is not allowed within sequences such as (?> that  introduce
+       various  parenthesized groups, nor within numerical quantifiers such as
        {1,3}. Ignorable white space is permitted between an item and a follow-
-       ing quantifier and between a quantifier and a following  +  that  indi-
+       ing  quantifier  and  between a quantifier and a following + that indi-
        cates possessiveness. PCRE2_EXTENDED is equivalent to Perl's /x option,
        and it can be changed within a pattern by a (?x) option setting.
 
-       When PCRE2 is compiled without Unicode support,  PCRE2_EXTENDED  recog-
-       nizes  as  white space only those characters with code points less than
+       When  PCRE2  is compiled without Unicode support, PCRE2_EXTENDED recog-
+       nizes as white space only those characters with code points  less  than
        256 that are flagged as white space in its low-character table. The ta-
        ble is normally created by pcre2_maketables(), which uses the isspace()
-       function to identify space characters. In most ASCII environments,  the
-       relevant  characters  are  those  with code points 0x0009 (tab), 0x000A
-       (linefeed), 0x000B (vertical tab), 0x000C (formfeed), 0x000D  (carriage
+       function  to identify space characters. In most ASCII environments, the
+       relevant characters are those with code  points  0x0009  (tab),  0x000A
+       (linefeed),  0x000B (vertical tab), 0x000C (formfeed), 0x000D (carriage
        return), and 0x0020 (space).
 
        When PCRE2 is compiled with Unicode support, in addition to these char-
-       acters, five more Unicode "Pattern White Space" characters  are  recog-
+       acters,  five  more Unicode "Pattern White Space" characters are recog-
        nized by PCRE2_EXTENDED. These are U+0085 (next line), U+200E (left-to-
-       right mark), U+200F (right-to-left mark), U+2028 (line separator),  and
-       U+2029  (paragraph  separator).  This  set of characters is the same as
-       recognized by Perl's /x option. Note that the horizontal  and  vertical
-       space  characters that are matched by the \h and \v escapes in patterns
+       right  mark), U+200F (right-to-left mark), U+2028 (line separator), and
+       U+2029 (paragraph separator). This set of characters  is  the  same  as
+       recognized  by  Perl's /x option. Note that the horizontal and vertical
+       space characters that are matched by the \h and \v escapes in  patterns
        are a much bigger set.
 
-       As well as ignoring most white space, PCRE2_EXTENDED also causes  char-
-       acters  between  an  unescaped # outside a character class and the next
-       newline, inclusive, to be ignored, which makes it possible  to  include
+       As  well as ignoring most white space, PCRE2_EXTENDED also causes char-
+       acters between an unescaped # outside a character class  and  the  next
+       newline,  inclusive,  to be ignored, which makes it possible to include
        comments inside complicated patterns. Note that the end of this type of
-       comment is a literal newline sequence in the pattern; escape  sequences
+       comment  is a literal newline sequence in the pattern; escape sequences
        that happen to represent a newline do not count.
 
        Which characters are interpreted as newlines can be specified by a set-
-       ting in the compile context that is passed to pcre2_compile() or  by  a
-       special  sequence at the start of the pattern, as described in the sec-
-       tion entitled "Newline conventions" in the pcre2pattern  documentation.
+       ting  in  the compile context that is passed to pcre2_compile() or by a
+       special sequence at the start of the pattern, as described in the  sec-
+       tion  entitled "Newline conventions" in the pcre2pattern documentation.
        A default is defined when PCRE2 is built.
 
          PCRE2_EXTENDED_MORE
 
-       This  option  has  the  effect of PCRE2_EXTENDED, but, in addition, un-
-       escaped space and horizontal tab characters are ignored inside a  char-
-       acter  class. Note: only these two characters are ignored, not the full
-       set of pattern white space characters that are ignored outside a  char-
-       acter  class.  PCRE2_EXTENDED_MORE  is equivalent to Perl's /xx option,
+       This option has the effect of PCRE2_EXTENDED,  but,  in  addition,  un-
+       escaped  space and horizontal tab characters are ignored inside a char-
+       acter class. Note: only these two characters are ignored, not the  full
+       set  of pattern white space characters that are ignored outside a char-
+       acter class. PCRE2_EXTENDED_MORE is equivalent to  Perl's  /xx  option,
        and it can be changed within a pattern by a (?xx) option setting.
 
          PCRE2_FIRSTLINE
 
        If this option is set, the start of an unanchored pattern match must be
-       before  or  at  the  first  newline in the subject string following the
-       start of matching, though the matched text may continue over  the  new-
+       before or at the first newline in  the  subject  string  following  the
+       start  of  matching, though the matched text may continue over the new-
        line. If startoffset is non-zero, the limiting newline is not necessar-
-       ily the first newline in the  subject.  For  example,  if  the  subject
+       ily  the  first  newline  in  the  subject. For example, if the subject
        string is "abc\nxyz" (where \n represents a single-character newline) a
-       pattern match for "yz" succeeds with PCRE2_FIRSTLINE if startoffset  is
-       greater  than 3. See also PCRE2_USE_OFFSET_LIMIT, which provides a more
-       general limiting facility. If PCRE2_FIRSTLINE is  set  with  an  offset
-       limit,  a match must occur in the first line and also within the offset
+       pattern  match for "yz" succeeds with PCRE2_FIRSTLINE if startoffset is
+       greater than 3. See also PCRE2_USE_OFFSET_LIMIT, which provides a  more
+       general  limiting  facility.  If  PCRE2_FIRSTLINE is set with an offset
+       limit, a match must occur in the first line and also within the  offset
        limit. In other words, whichever limit comes first is used.
 
          PCRE2_LITERAL
 
        If this option is set, all meta-characters in the pattern are disabled,
-       and  it is treated as a literal string. Matching literal strings with a
+       and it is treated as a literal string. Matching literal strings with  a
        regular expression engine is not the most efficient way of doing it. If
-       you  are  doing  a  lot of literal matching and are worried about effi-
+       you are doing a lot of literal matching and  are  worried  about  effi-
        ciency, you should consider using other approaches. The only other main
        options  that  are  allowed  with  PCRE2_LITERAL  are:  PCRE2_ANCHORED,
        PCRE2_ENDANCHORED, PCRE2_AUTO_CALLOUT, PCRE2_CASELESS, PCRE2_FIRSTLINE,
        PCRE2_MATCH_INVALID_UTF,  PCRE2_NO_START_OPTIMIZE,  PCRE2_NO_UTF_CHECK,
-       PCRE2_UTF, and  PCRE2_USE_OFFSET_LIMIT.  The  extra  options  PCRE2_EX-
+       PCRE2_UTF,  and  PCRE2_USE_OFFSET_LIMIT.  The  extra  options PCRE2_EX-
        TRA_MATCH_LINE and PCRE2_EXTRA_MATCH_WORD are also supported. Any other
        options cause an error.
 
          PCRE2_MATCH_INVALID_UTF
 
-       This option forces PCRE2_UTF (see below) and also enables  support  for
-       matching  by  pcre2_match() in subject strings that contain invalid UTF
-       sequences.  This facility is not supported for DFA  matching.  For  de-
+       This  option  forces PCRE2_UTF (see below) and also enables support for
+       matching by pcre2_match() in subject strings that contain  invalid  UTF
+       sequences.   This  facility  is not supported for DFA matching. For de-
        tails, see the pcre2unicode documentation.
 
          PCRE2_MATCH_UNSET_BACKREF
 
-       If  this  option  is  set,  a  backreference  to an unset capture group
-       matches an empty string (by default this causes  the  current  matching
+       If this option is set,  a  backreference  to  an  unset  capture  group
+       matches  an  empty  string (by default this causes the current matching
        alternative to fail).  A pattern such as (\1)(a) succeeds when this op-
-       tion is set (assuming it can find an "a" in the  subject),  whereas  it
-       fails  by  default,  for  Perl compatibility. Setting this option makes
+       tion  is  set  (assuming it can find an "a" in the subject), whereas it
+       fails by default, for Perl compatibility.  Setting  this  option  makes
        PCRE2 behave more like ECMAscript (aka JavaScript).
 
          PCRE2_MULTILINE
 
-       By default, for the purposes of matching "start of line"  and  "end  of
-       line",  PCRE2  treats the subject string as consisting of a single line
-       of characters, even if it actually contains  newlines.  The  "start  of
-       line"  metacharacter  (^)  matches only at the start of the string, and
-       the "end of line" metacharacter ($) matches only  at  the  end  of  the
-       string,  or  before a terminating newline (except when PCRE2_DOLLAR_EN-
+       By  default,  for  the purposes of matching "start of line" and "end of
+       line", PCRE2 treats the subject string as consisting of a  single  line
+       of  characters,  even  if  it actually contains newlines. The "start of
+       line" metacharacter (^) matches only at the start of  the  string,  and
+       the  "end  of  line"  metacharacter  ($) matches only at the end of the
+       string, or before a terminating newline (except  when  PCRE2_DOLLAR_EN-
        DONLY is set). Note, however, that unless PCRE2_DOTALL is set, the "any
-       character"  metacharacter  (.) does not match at a newline. This behav-
+       character" metacharacter (.) does not match at a newline.  This  behav-
        iour (for ^, $, and dot) is the same as Perl.
 
-       When PCRE2_MULTILINE it is set, the "start of line" and "end  of  line"
-       constructs  match  immediately following or immediately before internal
-       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
+       When  PCRE2_MULTILINE  it is set, the "start of line" and "end of line"
+       constructs match immediately following or immediately  before  internal
+       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
        changed within a pattern by a (?m) option setting. Note that the "start
        of line" metacharacter does not match after a newline at the end of the
-       subject, for compatibility with Perl.  However, you can change this  by
-       setting  the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a
-       subject string, or no occurrences of ^  or  $  in  a  pattern,  setting
+       subject,  for compatibility with Perl.  However, you can change this by
+       setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in  a
+       subject  string,  or  no  occurrences  of  ^ or $ in a pattern, setting
        PCRE2_MULTILINE has no effect.
 
          PCRE2_NEVER_BACKSLASH_C
 
-       This  option  locks out the use of \C in the pattern that is being com-
-       piled.  This escape can  cause  unpredictable  behaviour  in  UTF-8  or
-       UTF-16  modes,  because  it may leave the current matching point in the
+       This option locks out the use of \C in the pattern that is  being  com-
+       piled.   This  escape  can  cause  unpredictable  behaviour in UTF-8 or
+       UTF-16 modes, because it may leave the current matching  point  in  the
        middle of a multi-code-unit character. This option may be useful in ap-
        plications that process patterns from external sources. Note that there
        is also a build-time option that permanently locks out the use of \C.
 
          PCRE2_NEVER_UCP
 
-       This option locks out the use of Unicode properties  for  handling  \B,
+       This  option  locks  out the use of Unicode properties for handling \B,
        \b, \D, \d, \S, \s, \W, \w, and some of the POSIX character classes, as
-       described for the PCRE2_UCP option below. In  particular,  it  prevents
-       the  creator of the pattern from enabling this facility by starting the
-       pattern with (*UCP). This option may be  useful  in  applications  that
+       described  for  the  PCRE2_UCP option below. In particular, it prevents
+       the creator of the pattern from enabling this facility by starting  the
+       pattern  with  (*UCP).  This  option may be useful in applications that
        process patterns from external sources. The option combination PCRE_UCP
        and PCRE_NEVER_UCP causes an error.
 
          PCRE2_NEVER_UTF
 
-       This option locks out interpretation of the pattern as  UTF-8,  UTF-16,
+       This  option  locks out interpretation of the pattern as UTF-8, UTF-16,
        or UTF-32, depending on which library is in use. In particular, it pre-
-       vents the creator of the pattern from switching to  UTF  interpretation
-       by  starting  the pattern with (*UTF). This option may be useful in ap-
+       vents  the  creator of the pattern from switching to UTF interpretation
+       by starting the pattern with (*UTF). This option may be useful  in  ap-
        plications that process patterns from external sources. The combination
        of PCRE2_UTF and PCRE2_NEVER_UTF causes an error.
 
          PCRE2_NO_AUTO_CAPTURE
 
        If this option is set, it disables the use of numbered capturing paren-
-       theses in the pattern. Any opening parenthesis that is not followed  by
-       ?  behaves as if it were followed by ?: but named parentheses can still
+       theses  in the pattern. Any opening parenthesis that is not followed by
+       ? behaves as if it were followed by ?: but named parentheses can  still
        be used for capturing (and they acquire numbers in the usual way). This
-       is  the  same as Perl's /n option.  Note that, when this option is set,
-       references to capture groups  (backreferences  or  recursion/subroutine
-       calls)  may  only refer to named groups, though the reference can be by
+       is the same as Perl's /n option.  Note that, when this option  is  set,
+       references  to  capture  groups (backreferences or recursion/subroutine
+       calls) may only refer to named groups, though the reference can  be  by
        name or by number.
 
          PCRE2_NO_AUTO_POSSESS
 
        If this option is set, it disables "auto-possessification", which is an
-       optimization  that,  for example, turns a+b into a++b in order to avoid
-       backtracks into a+ that can never be successful. However,  if  callouts
-       are  in  use,  auto-possessification means that some callouts are never
+       optimization that, for example, turns a+b into a++b in order  to  avoid
+       backtracks  into  a+ that can never be successful. However, if callouts
+       are in use, auto-possessification means that some  callouts  are  never
        taken. You can set this option if you want the matching functions to do
-       a  full  unoptimized  search and run all the callouts, but it is mainly
+       a full unoptimized search and run all the callouts, but  it  is  mainly
        provided for testing purposes.
 
          PCRE2_NO_DOTSTAR_ANCHOR
 
        If this option is set, it disables an optimization that is applied when
-       .*  is  the  first significant item in a top-level branch of a pattern,
-       and all the other branches also start with .* or with \A or  \G  or  ^.
-       The  optimization  is  automatically disabled for .* if it is inside an
+       .* is the first significant item in a top-level branch  of  a  pattern,
+       and  all  the  other branches also start with .* or with \A or \G or ^.
+       The optimization is automatically disabled for .* if it  is  inside  an
        atomic group or a capture group that is the subject of a backreference,
-       or  if  the pattern contains (*PRUNE) or (*SKIP). When the optimization
-       is  not  disabled,  such  a  pattern  is  automatically   anchored   if
+       or if the pattern contains (*PRUNE) or (*SKIP). When  the  optimization
+       is   not   disabled,  such  a  pattern  is  automatically  anchored  if
        PCRE2_DOTALL is set for all the .* items and PCRE2_MULTILINE is not set
-       for any ^ items. Otherwise, the fact that any match must  start  either
-       at  the start of the subject or following a newline is remembered. Like
+       for  any  ^ items. Otherwise, the fact that any match must start either
+       at the start of the subject or following a newline is remembered.  Like
        other optimizations, this can cause callouts to be skipped.
 
          PCRE2_NO_START_OPTIMIZE
 
-       This is an option whose main effect is at matching time.  It  does  not
+       This  is  an  option whose main effect is at matching time. It does not
        change what pcre2_compile() generates, but it does affect the output of
        the JIT compiler.
 
-       There are a number of optimizations that may occur at the  start  of  a
-       match,  in  order  to speed up the process. For example, if it is known
-       that an unanchored match must start with a specific  code  unit  value,
-       the  matching code searches the subject for that value, and fails imme-
-       diately if it cannot find it, without actually running the main  match-
-       ing  function.  This means that a special item such as (*COMMIT) at the
-       start of a pattern is not considered until after  a  suitable  starting
-       point  for  the  match  has  been found. Also, when callouts or (*MARK)
-       items are in use, these "start-up" optimizations can cause them  to  be
-       skipped  if  the pattern is never actually used. The start-up optimiza-
-       tions are in effect a pre-scan of the subject that takes  place  before
+       There  are  a  number of optimizations that may occur at the start of a
+       match, in order to speed up the process. For example, if  it  is  known
+       that  an  unanchored  match must start with a specific code unit value,
+       the matching code searches the subject for that value, and fails  imme-
+       diately  if it cannot find it, without actually running the main match-
+       ing function. This means that a special item such as (*COMMIT)  at  the
+       start  of  a  pattern is not considered until after a suitable starting
+       point for the match has been found.  Also,  when  callouts  or  (*MARK)
+       items  are  in use, these "start-up" optimizations can cause them to be
+       skipped if the pattern is never actually used. The  start-up  optimiza-
+       tions  are  in effect a pre-scan of the subject that takes place before
        the pattern is run.
 
        The PCRE2_NO_START_OPTIMIZE option disables the start-up optimizations,
-       possibly causing performance to suffer,  but  ensuring  that  in  cases
-       where  the  result is "no match", the callouts do occur, and that items
+       possibly  causing  performance  to  suffer,  but ensuring that in cases
+       where the result is "no match", the callouts do occur, and  that  items
        such as (*COMMIT) and (*MARK) are considered at every possible starting
        position in the subject string.
 
-       Setting  PCRE2_NO_START_OPTIMIZE  may  change the outcome of a matching
+       Setting PCRE2_NO_START_OPTIMIZE may change the outcome  of  a  matching
        operation.  Consider the pattern
 
          (*COMMIT)ABC
 
-       When this is compiled, PCRE2 records the fact that a match  must  start
-       with  the  character  "A".  Suppose the subject string is "DEFABC". The
-       start-up optimization scans along the subject, finds "A" and  runs  the
-       first  match attempt from there. The (*COMMIT) item means that the pat-
-       tern must match the current starting position, which in this  case,  it
-       does.  However,  if  the same match is run with PCRE2_NO_START_OPTIMIZE
-       set, the initial scan along the subject string  does  not  happen.  The
-       first  match  attempt  is  run  starting  from "D" and when this fails,
-       (*COMMIT) prevents any further matches being tried, so the overall  re-
+       When  this  is compiled, PCRE2 records the fact that a match must start
+       with the character "A". Suppose the subject  string  is  "DEFABC".  The
+       start-up  optimization  scans along the subject, finds "A" and runs the
+       first match attempt from there. The (*COMMIT) item means that the  pat-
+       tern  must  match the current starting position, which in this case, it
+       does. However, if the same match is  run  with  PCRE2_NO_START_OPTIMIZE
+       set,  the  initial  scan  along the subject string does not happen. The
+       first match attempt is run starting  from  "D"  and  when  this  fails,
+       (*COMMIT)  prevents any further matches being tried, so the overall re-
        sult is "no match".
 
-       As  another  start-up  optimization makes use of a minimum length for a
+       As another start-up optimization makes use of a minimum  length  for  a
        matching subject, which is recorded when possible. Consider the pattern
 
          (*MARK:1)B(*MARK:2)(X|Y)
 
-       The minimum length for a match is two characters.  If  the  subject  is
+       The  minimum  length  for  a match is two characters. If the subject is
        "XXBB", the "starting character" optimization skips "XX", then tries to
-       match "BB", which is long enough. In the process, (*MARK:2) is  encoun-
-       tered  and  remembered.  When  the match attempt fails, the next "B" is
-       found, but there is only one character left, so there are no  more  at-
-       tempts,  and  "no  match"  is returned with the "last mark seen" set to
-       "2". If NO_START_OPTIMIZE is set, however, matches are tried  at  every
-       possible  starting position, including at the end of the subject, where
-       (*MARK:1) is encountered, but there is no "B", so the "last mark  seen"
-       that  is returned is "1". In this case, the optimizations do not affect
+       match  "BB", which is long enough. In the process, (*MARK:2) is encoun-
+       tered and remembered. When the match attempt fails,  the  next  "B"  is
+       found,  but  there is only one character left, so there are no more at-
+       tempts, and "no match" is returned with the "last  mark  seen"  set  to
+       "2".  If  NO_START_OPTIMIZE is set, however, matches are tried at every
+       possible starting position, including at the end of the subject,  where
+       (*MARK:1)  is encountered, but there is no "B", so the "last mark seen"
+       that is returned is "1". In this case, the optimizations do not  affect
        the overall match result, which is still "no match", but they do affect
        the auxiliary information that is returned.
 
          PCRE2_NO_UTF_CHECK
 
-       When  PCRE2_UTF  is set, the validity of the pattern as a UTF string is
-       automatically checked. There are  discussions  about  the  validity  of
-       UTF-8  strings,  UTF-16 strings, and UTF-32 strings in the pcre2unicode
-       document. If an invalid UTF sequence is found, pcre2_compile()  returns
+       When PCRE2_UTF is set, the validity of the pattern as a UTF  string  is
+       automatically  checked.  There  are  discussions  about the validity of
+       UTF-8 strings, UTF-16 strings, and UTF-32 strings in  the  pcre2unicode
+       document.  If an invalid UTF sequence is found, pcre2_compile() returns
        a negative error code.
 
-       If  you  know  that your pattern is a valid UTF string, and you want to
-       skip  this  check  for   performance   reasons,   you   can   set   the
+       If you know that your pattern is a valid UTF string, and  you  want  to
+       skip   this   check   for   performance   reasons,   you  can  set  the
        PCRE2_NO_UTF_CHECK option. When it is set, the effect of passing an in-
-       valid UTF string as a pattern is undefined. It may cause  your  program
+       valid  UTF  string as a pattern is undefined. It may cause your program
        to crash or loop.
 
        Note  that  this  option  can  also  be  passed  to  pcre2_match()  and
-       pcre_dfa_match(), to suppress UTF  validity  checking  of  the  subject
+       pcre_dfa_match(),  to  suppress  UTF  validity  checking of the subject
        string.
 
        Note also that setting PCRE2_NO_UTF_CHECK at compile time does not dis-
-       able the error that is given if an escape sequence for an invalid  Uni-
-       code  code  point is encountered in the pattern. In particular, the so-
-       called "surrogate" code points (0xd800 to 0xdfff) are invalid.  If  you
-       want  to  allow  escape  sequences  such  as  \x{d800}  you can set the
-       PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES extra option, as described  in  the
-       section  entitled "Extra compile options" below.  However, this is pos-
+       able  the error that is given if an escape sequence for an invalid Uni-
+       code code point is encountered in the pattern. In particular,  the  so-
+       called  "surrogate"  code points (0xd800 to 0xdfff) are invalid. If you
+       want to allow escape  sequences  such  as  \x{d800}  you  can  set  the
+       PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES  extra  option, as described in the
+       section entitled "Extra compile options" below.  However, this is  pos-
        sible only in UTF-8 and UTF-32 modes, because these values are not rep-
        resentable in UTF-16.
 
          PCRE2_UCP
 
        This option has two effects. Firstly, it change the way PCRE2 processes
-       \B, \b, \D, \d, \S, \s,  \W,  \w,  and  some  of  the  POSIX  character
-       classes.  By  default,  only  ASCII  characters  are recognized, but if
+       \B,  \b,  \D,  \d,  \S,  \s,  \W,  \w,  and some of the POSIX character
+       classes. By default, only  ASCII  characters  are  recognized,  but  if
        PCRE2_UCP is set, Unicode properties are used instead to classify char-
-       acters.  More  details  are  given  in the section on generic character
-       types in the pcre2pattern page. If you set PCRE2_UCP, matching  one  of
+       acters. More details are given in  the  section  on  generic  character
+       types  in  the pcre2pattern page. If you set PCRE2_UCP, matching one of
        the items it affects takes much longer.
 
-       The  second  effect of PCRE2_UCP is to force the use of Unicode proper-
-       ties for upper/lower casing operations on characters with  code  points
-       greater  than 127, even when PCRE2_UTF is not set. This makes it possi-
+       The second effect of PCRE2_UCP is to force the use of  Unicode  proper-
+       ties  for  upper/lower casing operations on characters with code points
+       greater than 127, even when PCRE2_UTF is not set. This makes it  possi-
        ble, for example, to process strings in the 16-bit UCS-2 code. This op-
-       tion  is available only if PCRE2 has been compiled with Unicode support
+       tion is available only if PCRE2 has been compiled with Unicode  support
        (which is the default).
 
          PCRE2_UNGREEDY
 
-       This option inverts the "greediness" of the quantifiers  so  that  they
-       are  not greedy by default, but become greedy if followed by "?". It is
-       not compatible with Perl. It can also be set by a (?U)  option  setting
+       This  option  inverts  the "greediness" of the quantifiers so that they
+       are not greedy by default, but become greedy if followed by "?". It  is
+       not  compatible  with Perl. It can also be set by a (?U) option setting
        within the pattern.
 
          PCRE2_USE_OFFSET_LIMIT
 
        This option must be set for pcre2_compile() if pcre2_set_offset_limit()
-       is going to be used to set a non-default offset limit in a  match  con-
-       text  for  matches  that  use this pattern. An error is generated if an
-       offset limit is set without this option. For more details, see the  de-
-       scription  of  pcre2_set_offset_limit()  in  the section that describes
+       is  going  to be used to set a non-default offset limit in a match con-
+       text for matches that use this pattern. An error  is  generated  if  an
+       offset  limit is set without this option. For more details, see the de-
+       scription of pcre2_set_offset_limit() in  the  section  that  describes
        match contexts. See also the PCRE2_FIRSTLINE option above.
 
          PCRE2_UTF
 
-       This option causes PCRE2 to regard both the  pattern  and  the  subject
-       strings  that  are  subsequently processed as strings of UTF characters
-       instead of single-code-unit strings. It  is  available  when  PCRE2  is
-       built  to  include  Unicode  support (which is the default). If Unicode
+       This  option  causes  PCRE2  to regard both the pattern and the subject
+       strings that are subsequently processed as strings  of  UTF  characters
+       instead  of  single-code-unit  strings.  It  is available when PCRE2 is
+       built to include Unicode support (which is  the  default).  If  Unicode
        support is not available, the use of this option provokes an error. De-
-       tails  of how PCRE2_UTF changes the behaviour of PCRE2 are given in the
+       tails of how PCRE2_UTF changes the behaviour of PCRE2 are given in  the
        pcre2unicode  page.  In  particular,  note  that  it  changes  the  way
        PCRE2_CASELESS handles characters with code points greater than 127.
 
    Extra compile options
 
-       The  option  bits  that  can be set in a compile context by calling the
+       The option bits that can be set in a compile  context  by  calling  the
        pcre2_set_compile_extra_options() function are as follows:
 
          PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES
 
-       This option applies when compiling a pattern in UTF-8 or  UTF-32  mode.
-       It  is  forbidden in UTF-16 mode, and ignored in non-UTF modes. Unicode
+       This  option  applies when compiling a pattern in UTF-8 or UTF-32 mode.
+       It is forbidden in UTF-16 mode, and ignored in non-UTF  modes.  Unicode
        "surrogate" code points in the range 0xd800 to 0xdfff are used in pairs
-       in  UTF-16  to  encode  code points with values in the range 0x10000 to
-       0x10ffff. The surrogates cannot therefore  be  represented  in  UTF-16.
+       in UTF-16 to encode code points with values in  the  range  0x10000  to
+       0x10ffff.  The  surrogates  cannot  therefore be represented in UTF-16.
        They can be represented in UTF-8 and UTF-32, but are defined as invalid
-       code points, and cause errors if  encountered  in  a  UTF-8  or  UTF-32
+       code  points,  and  cause  errors  if  encountered in a UTF-8 or UTF-32
        string that is being checked for validity by PCRE2.
 
-       These  values also cause errors if encountered in escape sequences such
+       These values also cause errors if encountered in escape sequences  such
        as \x{d912} within a pattern. However, it seems that some applications,
        when using PCRE2 to check for unwanted characters in UTF-8 strings, ex-
-       plicitly  test  for  the  surrogates  using   escape   sequences.   The
-       PCRE2_NO_UTF_CHECK  option  does not disable the error that occurs, be-
+       plicitly   test   for   the  surrogates  using  escape  sequences.  The
+       PCRE2_NO_UTF_CHECK option does not disable the error that  occurs,  be-
        cause it applies only to the testing of input strings for UTF validity.
 
-       If the extra option PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is set,  surro-
-       gate  code  point values in UTF-8 and UTF-32 patterns no longer provoke
-       errors and are incorporated in the compiled pattern. However, they  can
-       only  match  subject characters if the matching function is called with
+       If  the extra option PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is set, surro-
+       gate code point values in UTF-8 and UTF-32 patterns no  longer  provoke
+       errors  and are incorporated in the compiled pattern. However, they can
+       only match subject characters if the matching function is  called  with
        PCRE2_NO_UTF_CHECK set.
 
          PCRE2_EXTRA_ALT_BSUX
 
-       The original option PCRE2_ALT_BSUX causes PCRE2 to process \U, \u,  and
-       \x  in  the way that ECMAscript (aka JavaScript) does. Additional func-
+       The  original option PCRE2_ALT_BSUX causes PCRE2 to process \U, \u, and
+       \x in the way that ECMAscript (aka JavaScript) does.  Additional  func-
        tionality was defined by ECMAscript 6; setting PCRE2_EXTRA_ALT_BSUX has
-       the  effect  of PCRE2_ALT_BSUX, but in addition it recognizes \u{hhh..}
+       the effect of PCRE2_ALT_BSUX, but in addition it  recognizes  \u{hhh..}
        as a hexadecimal character code, where hhh.. is any number of hexadeci-
        mal digits.
 
          PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL
 
-       This  is a dangerous option. Use with care. By default, an unrecognized
-       escape such as \j or a malformed one such as \x{2z} causes  a  compile-
+       This is a dangerous option. Use with care. By default, an  unrecognized
+       escape  such  as \j or a malformed one such as \x{2z} causes a compile-
        time error when detected by pcre2_compile(). Perl is somewhat inconsis-
-       tent in handling such items: for example, \j is treated  as  a  literal
-       "j",  and non-hexadecimal digits in \x{} are just ignored, though warn-
-       ings are given in both cases if Perl's warning switch is enabled.  How-
-       ever,  a  malformed  octal  number  after \o{ always causes an error in
+       tent  in  handling  such items: for example, \j is treated as a literal
+       "j", and non-hexadecimal digits in \x{} are just ignored, though  warn-
+       ings  are given in both cases if Perl's warning switch is enabled. How-
+       ever, a malformed octal number after \o{  always  causes  an  error  in
        Perl.
 
-       If the PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL  extra  option  is  passed  to
-       pcre2_compile(),  all  unrecognized  or  malformed escape sequences are
-       treated as single-character escapes. For example, \j is a  literal  "j"
-       and  \x{2z}  is treated as the literal string "x{2z}". Setting this op-
+       If  the  PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL  extra  option  is passed to
+       pcre2_compile(), all unrecognized or  malformed  escape  sequences  are
+       treated  as  single-character escapes. For example, \j is a literal "j"
+       and \x{2z} is treated as the literal string "x{2z}". Setting  this  op-
        tion means that typos in patterns may go undetected and have unexpected
-       results.  Also  note  that a sequence such as [\N{] is interpreted as a
-       malformed attempt at [\N{...}] and so is treated as [N{]  whereas  [\N]
+       results. Also note that a sequence such as [\N{] is  interpreted  as  a
+       malformed  attempt  at [\N{...}] and so is treated as [N{] whereas [\N]
        gives an error because an unqualified \N is a valid escape sequence but
-       is not supported in a character class. To reiterate: this is a  danger-
+       is  not supported in a character class. To reiterate: this is a danger-
        ous option. Use with great care.
 
          PCRE2_EXTRA_ESCAPED_CR_IS_LF
 
-       There  are  some  legacy applications where the escape sequence \r in a
-       pattern is expected to match a newline. If this option is set, \r in  a
-       pattern  is  converted to \n so that it matches a LF (linefeed) instead
-       of a CR (carriage return) character. The option does not affect a  lit-
-       eral  CR in the pattern, nor does it affect CR specified as an explicit
+       There are some legacy applications where the escape sequence  \r  in  a
+       pattern  is expected to match a newline. If this option is set, \r in a
+       pattern is converted to \n so that it matches a LF  (linefeed)  instead
+       of  a CR (carriage return) character. The option does not affect a lit-
+       eral CR in the pattern, nor does it affect CR specified as an  explicit
        code point such as \x{0D}.
 
          PCRE2_EXTRA_MATCH_LINE
 
-       This option is provided for use by  the  -x  option  of  pcre2grep.  It
-       causes  the  pattern  only to match complete lines. This is achieved by
-       automatically inserting the code for "^(?:" at the start  of  the  com-
-       piled  pattern  and ")$" at the end. Thus, when PCRE2_MULTILINE is set,
-       the matched line may be in the middle of the subject string.  This  op-
+       This  option  is  provided  for  use  by the -x option of pcre2grep. It
+       causes the pattern only to match complete lines. This  is  achieved  by
+       automatically  inserting  the  code for "^(?:" at the start of the com-
+       piled pattern and ")$" at the end. Thus, when PCRE2_MULTILINE  is  set,
+       the  matched  line may be in the middle of the subject string. This op-
        tion can be used with PCRE2_LITERAL.
 
          PCRE2_EXTRA_MATCH_WORD
 
-       This  option  is  provided  for  use  by the -w option of pcre2grep. It
-       causes the pattern only to match strings that have a word  boundary  at
-       the  start and the end. This is achieved by automatically inserting the
-       code for "\b(?:" at the start of the compiled pattern and ")\b" at  the
-       end.  The option may be used with PCRE2_LITERAL. However, it is ignored
+       This option is provided for use by  the  -w  option  of  pcre2grep.  It
+       causes  the  pattern only to match strings that have a word boundary at
+       the start and the end. This is achieved by automatically inserting  the
+       code  for "\b(?:" at the start of the compiled pattern and ")\b" at the
+       end. The option may be used with PCRE2_LITERAL. However, it is  ignored
        if PCRE2_EXTRA_MATCH_LINE is also set.
 
 
@@ -1944,16 +1974,16 @@ JUST-IN-TIME (JIT) COMPILATION
 
        void pcre2_jit_stack_free(pcre2_jit_stack *jit_stack);
 
-       These functions provide support for  JIT  compilation,  which,  if  the
-       just-in-time  compiler  is available, further processes a compiled pat-
+       These  functions  provide  support  for  JIT compilation, which, if the
+       just-in-time compiler is available, further processes a  compiled  pat-
        tern into machine code that executes much faster than the pcre2_match()
-       interpretive  matching function. Full details are given in the pcre2jit
+       interpretive matching function. Full details are given in the  pcre2jit
        documentation.
 
-       JIT compilation is a heavyweight optimization. It can  take  some  time
-       for  patterns  to  be analyzed, and for one-off matches and simple pat-
-       terns the benefit of faster execution might be offset by a much  slower
-       compilation  time.  Most (but not all) patterns can be optimized by the
+       JIT  compilation  is  a heavyweight optimization. It can take some time
+       for patterns to be analyzed, and for one-off matches  and  simple  pat-
+       terns  the benefit of faster execution might be offset by a much slower
+       compilation time.  Most (but not all) patterns can be optimized by  the
        JIT compiler.
 
 
@@ -1964,46 +1994,46 @@ LOCALE SUPPORT
        void pcre2_maketables_free(pcre2_general_context *gcontext,
          const uint8_t *tables);
 
-       PCRE2 handles caseless matching, and determines whether characters  are
-       letters,  digits, or whatever, by reference to a set of tables, indexed
+       PCRE2  handles caseless matching, and determines whether characters are
+       letters, digits, or whatever, by reference to a set of tables,  indexed
        by character code point. However, this applies only to characters whose
-       code  points  are  less than 256. By default, higher-valued code points
+       code points are less than 256. By default,  higher-valued  code  points
        never match escapes such as \w or \d.
 
-       When PCRE2 is built with Unicode support  (the  default),  the  Unicode
+       When  PCRE2  is  built  with Unicode support (the default), the Unicode
        properties of all characters can be tested with \p and \P, or, alterna-
-       tively, the PCRE2_UCP option can be set when  a  pattern  is  compiled;
-       this  causes  \w and friends to use Unicode property support instead of
-       the built-in tables.  PCRE2_UCP also causes upper/lower  casing  opera-
-       tions  on  characters  with code points greater than 127 to use Unicode
+       tively,  the  PCRE2_UCP  option  can be set when a pattern is compiled;
+       this causes \w and friends to use Unicode property support  instead  of
+       the  built-in  tables.  PCRE2_UCP also causes upper/lower casing opera-
+       tions on characters with code points greater than 127  to  use  Unicode
        properties. These effects apply even when PCRE2_UTF is not set.
 
-       The use of locales with Unicode is discouraged.  If  you  are  handling
-       characters  with  code  points  greater than 127, you should either use
+       The  use  of  locales  with Unicode is discouraged. If you are handling
+       characters with code points greater than 127,  you  should  either  use
        Unicode support, or use locales, but not try to mix the two.
 
-       PCRE2 contains a built-in set of character tables that are used by  de-
-       fault.   These  are sufficient for many applications. Normally, the in-
-       ternal tables recognize only ASCII characters. However, when  PCRE2  is
+       PCRE2  contains a built-in set of character tables that are used by de-
+       fault.  These are sufficient for many applications. Normally,  the  in-
+       ternal  tables  recognize only ASCII characters. However, when PCRE2 is
        built, it is possible to cause the internal tables to be rebuilt in the
        default "C" locale of the local system, which may cause them to be dif-
        ferent.
 
-       The  built-in tables can be overridden by tables supplied by the appli-
-       cation that calls PCRE2. These may be created  in  a  different  locale
-       from  the  default.  As more and more applications change to using Uni-
+       The built-in tables can be overridden by tables supplied by the  appli-
+       cation  that  calls  PCRE2.  These may be created in a different locale
+       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  pcre2_maketables()  function,
+       External  tables  are built by calling the pcre2_maketables() function,
        in the relevant locale. The only argument to this function is a general
-       context, which can be used to pass a custom memory  allocator.  If  the
+       context,  which  can  be used to pass a custom memory allocator. If the
        argument is NULL, the system malloc() is used. The result can be passed
        to pcre2_compile() as often as necessary, by creating a compile context
-       and  calling  pcre2_set_character_tables()  to  set  the tables pointer
+       and calling pcre2_set_character_tables()  to  set  the  tables  pointer
        therein.
 
-       For example, to build and use  tables  that  are  appropriate  for  the
-       French  locale  (where accented characters with values greater than 127
+       For  example,  to  build  and  use  tables that are appropriate for the
+       French locale (where accented characters with values greater  than  127
        are treated as letters), the following code could be used:
 
          setlocale(LC_CTYPE, "fr_FR");
@@ -2012,31 +2042,31 @@ LOCALE SUPPORT
          pcre2_set_character_tables(ccontext, tables);
          re = pcre2_compile(..., ccontext);
 
-       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".
 
        The pointer that is passed (via the compile context) to pcre2_compile()
        is saved with the compiled pattern, and the same tables are used by the
-       matching  functions.  Thus,  for  any  single  pattern, compilation and
-       matching both happen in the same locale, but different patterns can  be
+       matching functions. Thus,  for  any  single  pattern,  compilation  and
+       matching  both happen in the same locale, but different patterns can be
        processed in different locales.
 
-       It  is the caller's responsibility to ensure that the memory containing
+       It is the caller's responsibility to ensure that the memory  containing
        the tables remains available while they are still in use. When they are
-       no  longer  needed, you can discard them using pcre2_maketables_free(),
-       which should pass as its first parameter the same global  context  that
+       no longer needed, you can discard them  using  pcre2_maketables_free(),
+       which  should  pass as its first parameter the same global context that
        was used to create the tables.
 
    Saving locale tables
 
-       The  tables  described above are just a sequence of binary bytes, which
-       makes them independent of hardware characteristics such  as  endianness
-       or  whether  the processor is 32-bit or 64-bit. A copy of the result of
-       pcre2_maketables() can therefore be saved in a file  or  elsewhere  and
-       re-used  later, even in a different program or on another computer. The
-       size of the tables (number  of  bytes)  must  be  obtained  by  calling
-       pcre2_config()   with  the  PCRE2_CONFIG_TABLES_LENGTH  option  because
-       pcre2_maketables()  does  not  return  this  value.   Note   that   the
+       The tables described above are just a sequence of binary  bytes,  which
+       makes  them  independent of hardware characteristics such as endianness
+       or whether the processor is 32-bit or 64-bit. A copy of the  result  of
+       pcre2_maketables()  can  therefore  be saved in a file or elsewhere and
+       re-used later, even in a different program or on another computer.  The
+       size  of  the  tables  (number  of  bytes)  must be obtained by calling
+       pcre2_config()  with  the  PCRE2_CONFIG_TABLES_LENGTH  option   because
+       pcre2_maketables()   does   not   return  this  value.  Note  that  the
        pcre2_dftables program, which is part of the PCRE2 build system, can be
        used stand-alone to create a file that contains a set of binary tables.
        See the pcre2build documentation for details.
@@ -2046,13 +2076,13 @@ INFORMATION ABOUT A COMPILED PATTERN
 
        int pcre2_pattern_info(const pcre2 *code, uint32_t what, void *where);
 
-       The  pcre2_pattern_info()  function returns general information about a
+       The pcre2_pattern_info() function returns general information  about  a
        compiled pattern. For information about callouts, see the next section.
-       The  first  argument  for pcre2_pattern_info() is a pointer to the com-
+       The first argument for pcre2_pattern_info() is a pointer  to  the  com-
        piled pattern. The second argument specifies which piece of information
-       is  required,  and the third argument is a pointer to a variable to re-
-       ceive the data. If the third argument is NULL, the  first  argument  is
-       ignored,  and  the  function  returns the size in bytes of the variable
+       is required, and the third argument is a pointer to a variable  to  re-
+       ceive  the  data.  If the third argument is NULL, the first argument is
+       ignored, and the function returns the size in  bytes  of  the  variable
        that is required for the information requested. Otherwise, the yield of
        the function is zero for success, or one of the following negative num-
        bers:
@@ -2063,8 +2093,8 @@ INFORMATION ABOUT A COMPILED PATTERN
          PCRE2_ERROR_UNSET          the requested field is not set
 
        The "magic number" is placed at the start of each compiled pattern as a
-       simple  check  against  passing  an arbitrary memory pointer. Here is a
-       typical call of pcre2_pattern_info(), to obtain the length of the  com-
+       simple check against passing an arbitrary memory  pointer.  Here  is  a
+       typical  call of pcre2_pattern_info(), to obtain the length of the com-
        piled pattern:
 
          int rc;
@@ -2082,22 +2112,22 @@ INFORMATION ABOUT A COMPILED PATTERN
          PCRE2_INFO_EXTRAOPTIONS
 
        Return copies of the pattern's options. The third argument should point
-       to  a  uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the op-
-       tions that were passed to  pcre2_compile(),  whereas  PCRE2_INFO_ALLOP-
-       TIONS  returns  the compile options as modified by any top-level (*XXX)
-       option settings such as (*UTF) at the  start  of  the  pattern  itself.
-       PCRE2_INFO_EXTRAOPTIONS  returns the extra options that were set in the
-       compile context by calling the pcre2_set_compile_extra_options()  func-
+       to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly  the  op-
+       tions  that  were  passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP-
+       TIONS returns the compile options as modified by any  top-level  (*XXX)
+       option  settings  such  as  (*UTF)  at the start of the pattern itself.
+       PCRE2_INFO_EXTRAOPTIONS returns the extra options that were set in  the
+       compile  context by calling the pcre2_set_compile_extra_options() func-
        tion.
 
-       For  example, if the pattern /(*UTF)abc/ is compiled with the PCRE2_EX-
-       TENDED option, the result for PCRE2_INFO_ALLOPTIONS  is  PCRE2_EXTENDED
-       and  PCRE2_UTF.   Option settings such as (?i) that can change within a
+       For example, if the pattern /(*UTF)abc/ is compiled with the  PCRE2_EX-
+       TENDED  option,  the result for PCRE2_INFO_ALLOPTIONS is PCRE2_EXTENDED
+       and PCRE2_UTF.  Option settings such as (?i) that can change  within  a
        pattern do not affect the result of PCRE2_INFO_ALLOPTIONS, even if they
-       appear  right  at the start of the pattern. (This was different in some
+       appear right at the start of the pattern. (This was different  in  some
        earlier releases.)
 
-       A pattern compiled without PCRE2_ANCHORED is automatically anchored  by
+       A  pattern compiled without PCRE2_ANCHORED is automatically anchored by
        PCRE2 if the first significant item in every top-level branch is one of
        the following:
 
@@ -2106,7 +2136,7 @@ INFORMATION ABOUT A COMPILED PATTERN
          \G    always
          .*    sometimes - see below
 
-       When .* is the first significant item, anchoring is possible only  when
+       When  .* is the first significant item, anchoring is possible only when
        all the following are true:
 
          .* is not in an atomic group
@@ -2116,94 +2146,94 @@ INFORMATION ABOUT A COMPILED PATTERN
          Neither (*PRUNE) nor (*SKIP) appears in the pattern
          PCRE2_NO_DOTSTAR_ANCHOR is not set
 
-       For  patterns  that are auto-anchored, the PCRE2_ANCHORED bit is set in
+       For patterns that are auto-anchored, the PCRE2_ANCHORED bit is  set  in
        the options returned for PCRE2_INFO_ALLOPTIONS.
 
          PCRE2_INFO_BACKREFMAX
 
-       Return the number of the highest  backreference  in  the  pattern.  The
-       third  argument  should  point  to  a  uint32_t variable. Named capture
-       groups acquire numbers as well as names, and these  count  towards  the
-       highest  backreference.  Backreferences  such as \4 or \g{12} match the
+       Return  the  number  of  the  highest backreference in the pattern. The
+       third argument should point  to  a  uint32_t  variable.  Named  capture
+       groups  acquire  numbers  as well as names, and these count towards the
+       highest backreference. Backreferences such as \4 or  \g{12}  match  the
        captured characters of the given group, but in addition, the check that
        a capture group is set in a conditional group such as (?(3)a|b) is also
        a backreference.  Zero is returned if there are no backreferences.
 
          PCRE2_INFO_BSR
 
-       The output is a uint32_t integer whose value indicates  what  character
-       sequences  the \R escape sequence matches. A value of PCRE2_BSR_UNICODE
-       means that \R matches any Unicode line  ending  sequence;  a  value  of
+       The  output  is a uint32_t integer whose value indicates what character
+       sequences the \R escape sequence matches. A value of  PCRE2_BSR_UNICODE
+       means  that  \R  matches  any  Unicode line ending sequence; a value of
        PCRE2_BSR_ANYCRLF means that \R matches only CR, LF, or CRLF.
 
          PCRE2_INFO_CAPTURECOUNT
 
-       Return  the  highest  capture  group number in the pattern. In patterns
+       Return the highest capture group number in  the  pattern.  In  patterns
        where (?| is not used, this is also the total number of capture groups.
        The third argument should point to a uint32_t variable.
 
          PCRE2_INFO_DEPTHLIMIT
 
-       If  the  pattern set a backtracking depth limit by including an item of
-       the form (*LIMIT_DEPTH=nnnn) at the start, the value is  returned.  The
+       If the pattern set a backtracking depth limit by including an  item  of
+       the  form  (*LIMIT_DEPTH=nnnn) at the start, the value is returned. The
        third argument should point to a uint32_t integer. If no such value has
-       been set, the call to pcre2_pattern_info() returns the error  PCRE2_ER-
+       been  set, the call to pcre2_pattern_info() returns the error PCRE2_ER-
        ROR_UNSET. Note that this limit will only be used during matching if it
-       is less than the limit set or defaulted by  the  caller  of  the  match
+       is  less  than  the  limit  set or defaulted by the caller of the match
        function.
 
          PCRE2_INFO_FIRSTBITMAP
 
-       In  the absence of a single first code unit for a non-anchored pattern,
-       pcre2_compile() may construct a 256-bit table that defines a fixed  set
-       of  values for the first code unit in any match. For example, a pattern
-       that starts with [abc] results in a table with  three  bits  set.  When
-       code  unit  values greater than 255 are supported, the flag bit for 255
-       means "any code unit of value 255 or above". If such a table  was  con-
-       structed,  a pointer to it is returned. Otherwise NULL is returned. The
+       In the absence of a single first code unit for a non-anchored  pattern,
+       pcre2_compile()  may construct a 256-bit table that defines a fixed set
+       of values for the first code unit in any match. For example, a  pattern
+       that  starts  with  [abc]  results in a table with three bits set. When
+       code unit values greater than 255 are supported, the flag bit  for  255
+       means  "any  code unit of value 255 or above". If such a table was con-
+       structed, a pointer to it is returned. Otherwise NULL is returned.  The
        third argument should point to a const uint8_t * variable.
 
          PCRE2_INFO_FIRSTCODETYPE
 
        Return information about the first code unit of any matched string, for
-       a  non-anchored  pattern. The third argument should point to a uint32_t
-       variable. If there is a fixed first value, for example, the letter  "c"
-       from  a  pattern such as (cat|cow|coyote), 1 is returned, and the value
-       can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is  no  fixed
-       first  value,  but it is known that a match can occur only at the start
-       of the subject or following a newline in the subject,  2  is  returned.
+       a non-anchored pattern. The third argument should point to  a  uint32_t
+       variable.  If there is a fixed first value, for example, the letter "c"
+       from a pattern such as (cat|cow|coyote), 1 is returned, and  the  value
+       can  be  retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed
+       first value, but it is known that a match can occur only at  the  start
+       of  the  subject  or following a newline in the subject, 2 is returned.
        Otherwise, and for anchored patterns, 0 is returned.
 
          PCRE2_INFO_FIRSTCODEUNIT
 
-       Return  the  value  of  the first code unit of any matched string for a
-       pattern where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise  return  0.
-       The  third  argument  should point to a uint32_t variable. In the 8-bit
-       library, the value is always less than 256. In the 16-bit  library  the
-       value  can  be  up  to 0xffff. In the 32-bit library in UTF-32 mode the
+       Return the value of the first code unit of any  matched  string  for  a
+       pattern  where  PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0.
+       The third argument should point to a uint32_t variable.  In  the  8-bit
+       library,  the  value is always less than 256. In the 16-bit library the
+       value can be up to 0xffff. In the 32-bit library  in  UTF-32  mode  the
        value can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32
        mode.
 
          PCRE2_INFO_FRAMESIZE
 
        Return the size (in bytes) of the data frames that are used to remember
-       backtracking positions when the pattern is processed  by  pcre2_match()
-       without  the  use  of  JIT. The third argument should point to a size_t
+       backtracking  positions  when the pattern is processed by pcre2_match()
+       without the use of JIT. The third argument should  point  to  a  size_t
        variable. The frame size depends on the number of capturing parentheses
        in the pattern. Each additional capture group adds two PCRE2_SIZE vari-
        ables.
 
          PCRE2_INFO_HASBACKSLASHC
 
-       Return 1 if the pattern contains any instances of \C, otherwise 0.  The
+       Return  1 if the pattern contains any instances of \C, otherwise 0. The
        third argument should point to a uint32_t variable.
 
          PCRE2_INFO_HASCRORLF
 
-       Return  1  if  the  pattern  contains any explicit matches for CR or LF
-       characters, otherwise 0. The third argument should point to a  uint32_t
-       variable.  An explicit match is either a literal CR or LF character, or
-       \r or \n or one of the  equivalent  hexadecimal  or  octal  escape  se-
+       Return 1 if the pattern contains any explicit  matches  for  CR  or  LF
+       characters,  otherwise 0. The third argument should point to a uint32_t
+       variable. An explicit match is either a literal CR or LF character,  or
+       \r  or  \n  or  one  of  the equivalent hexadecimal or octal escape se-
        quences.
 
          PCRE2_INFO_HEAPLIMIT
@@ -2211,45 +2241,45 @@ INFORMATION ABOUT A COMPILED PATTERN
        If the pattern set a heap memory limit by including an item of the form
        (*LIMIT_HEAP=nnnn) at the start, the value is returned. The third argu-
        ment should point to a uint32_t integer. If no such value has been set,
-       the call to pcre2_pattern_info() returns the  error  PCRE2_ERROR_UNSET.
-       Note  that  this  limit will only be used during matching if it is less
+       the  call  to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET.
+       Note that this limit will only be used during matching if  it  is  less
        than the limit set or defaulted by the caller of the match function.
 
          PCRE2_INFO_JCHANGED
 
-       Return 1 if the (?J) or (?-J) option setting is used  in  the  pattern,
-       otherwise  0.  The  third argument should point to a uint32_t variable.
-       (?J) and (?-J) set and unset the local PCRE2_DUPNAMES  option,  respec-
+       Return  1  if  the (?J) or (?-J) option setting is used in the pattern,
+       otherwise 0. The third argument should point to  a  uint32_t  variable.
+       (?J)  and  (?-J) set and unset the local PCRE2_DUPNAMES option, respec-
        tively.
 
          PCRE2_INFO_JITSIZE
 
-       If  the  compiled  pattern was successfully processed by pcre2_jit_com-
-       pile(), return the size of the  JIT  compiled  code,  otherwise  return
+       If the compiled pattern was successfully  processed  by  pcre2_jit_com-
+       pile(),  return  the  size  of  the JIT compiled code, otherwise return
        zero. The third argument should point to a size_t variable.
 
          PCRE2_INFO_LASTCODETYPE
 
-       Returns  1 if there is a rightmost literal code unit that must exist in
-       any matched string, other than at its start. The third argument  should
+       Returns 1 if there is a rightmost literal code unit that must exist  in
+       any  matched string, other than at its start. The third argument should
        point to a uint32_t variable. If there is no such value, 0 is returned.
-       When 1 is returned, the code unit value itself can be  retrieved  using
+       When  1  is returned, the code unit value itself can be retrieved using
        PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last literal value is
-       recorded only if it follows something of variable length. For  example,
-       for  the pattern /^a\d+z\d+/ the returned value is 1 (with "z" returned
-       from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/ the returned value  is
+       recorded  only if it follows something of variable length. For example,
+       for the pattern /^a\d+z\d+/ the returned value is 1 (with "z"  returned
+       from  PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/ the returned value is
        0.
 
          PCRE2_INFO_LASTCODEUNIT
 
-       Return  the value of the rightmost literal code unit that must exist in
-       any matched string, other than  at  its  start,  for  a  pattern  where
+       Return the value of the rightmost literal code unit that must exist  in
+       any  matched  string,  other  than  at  its  start, for a pattern where
        PCRE2_INFO_LASTCODETYPE returns 1. Otherwise, return 0. The third argu-
        ment should point to a uint32_t variable.
 
          PCRE2_INFO_MATCHEMPTY
 
-       Return 1 if the pattern might match an empty string, otherwise  0.  The
+       Return  1  if the pattern might match an empty string, otherwise 0. The
        third argument should point to a uint32_t variable. When a pattern con-
        tains recursive subroutine calls it is not always possible to determine
        whether or not it can match an empty string. PCRE2 takes a cautious ap-
@@ -2257,44 +2287,44 @@ INFORMATION ABOUT A COMPILED PATTERN
 
          PCRE2_INFO_MATCHLIMIT
 
-       If the pattern set a match limit by  including  an  item  of  the  form
-       (*LIMIT_MATCH=nnnn)  at the start, the value is returned. The third ar-
-       gument should point to a uint32_t integer. If no such  value  has  been
+       If  the  pattern  set  a  match  limit by including an item of the form
+       (*LIMIT_MATCH=nnnn) at the start, the value is returned. The third  ar-
+       gument  should  point  to a uint32_t integer. If no such value has been
        set, the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UN-
-       SET. Note that this limit will only be used during matching  if  it  is
-       less  than  the limit set or defaulted by the caller of the match func-
+       SET.  Note  that  this limit will only be used during matching if it is
+       less than the limit set or defaulted by the caller of the  match  func-
        tion.
 
          PCRE2_INFO_MAXLOOKBEHIND
 
-       A lookbehind assertion moves back a certain number of  characters  (not
-       code  units)  when  it starts to process each of its branches. This re-
-       quest returns the largest of these backward moves. The  third  argument
+       A  lookbehind  assertion moves back a certain number of characters (not
+       code units) when it starts to process each of its  branches.  This  re-
+       quest  returns  the largest of these backward moves. The third argument
        should point to a uint32_t integer. The simple assertions \b and \B re-
-       quire a one-character lookbehind and cause PCRE2_INFO_MAXLOOKBEHIND  to
-       return  1  in  the absence of anything longer. \A also registers a one-
-       character lookbehind, though it does not actually inspect the  previous
+       quire  a one-character lookbehind and cause PCRE2_INFO_MAXLOOKBEHIND to
+       return 1 in the absence of anything longer. \A also  registers  a  one-
+       character  lookbehind, though it does not actually inspect the previous
        character.
 
        Note that this information is useful for multi-segment matching only if
-       the pattern contains no nested lookbehinds. For  example,  the  pattern
-       (?<=a(?<=ba)c)  returns  a maximum lookbehind of 2, but when it is pro-
-       cessed, the first lookbehind moves back by two characters, matches  one
-       character,  then  the  nested lookbehind also moves back by two charac-
+       the  pattern  contains  no nested lookbehinds. For example, the pattern
+       (?<=a(?<=ba)c) returns a maximum lookbehind of 2, but when it  is  pro-
+       cessed,  the first lookbehind moves back by two characters, matches one
+       character, then the nested lookbehind also moves back  by  two  charac-
        ters. This puts the matching point three characters earlier than it was
-       at  the start.  PCRE2_INFO_MAXLOOKBEHIND is really only useful as a de-
-       bugging tool. See the pcre2partial documentation for  a  discussion  of
+       at the start.  PCRE2_INFO_MAXLOOKBEHIND is really only useful as a  de-
+       bugging  tool.  See  the pcre2partial documentation for a discussion of
        multi-segment matching.
 
          PCRE2_INFO_MINLENGTH
 
-       If  a  minimum  length  for  matching subject strings was computed, its
+       If a minimum length for matching  subject  strings  was  computed,  its
        value is returned. Otherwise the returned value is 0. This value is not
-       computed  when PCRE2_NO_START_OPTIMIZE is set. The value is a number of
-       characters, which in UTF mode may be different from the number of  code
-       units.  The  third  argument  should  point to a uint32_t variable. The
-       value is a lower bound to the length of any matching string. There  may
-       not  be  any  strings  of that length that do actually match, but every
+       computed when PCRE2_NO_START_OPTIMIZE is set. The value is a number  of
+       characters,  which in UTF mode may be different from the number of code
+       units. The third argument should point  to  a  uint32_t  variable.  The
+       value  is a lower bound to the length of any matching string. There may
+       not be any strings of that length that do  actually  match,  but  every
        string that does match is at least that long.
 
          PCRE2_INFO_NAMECOUNT
@@ -2302,51 +2332,51 @@ INFORMATION ABOUT A COMPILED PATTERN
          PCRE2_INFO_NAMETABLE
 
        PCRE2 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
-       pcre2_substring_get_byname()  are provided for extracting captured sub-
-       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
-       pointers in the output vector (described with pcre2_match() below).  To
+       pcre2_substring_get_byname() are provided for extracting captured  sub-
+       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
+       pointers  in the output vector (described with pcre2_match() below). To
        do the conversion, you need to use the name-to-number map, which is de-
        scribed by these three values.
 
-       The map consists of a number of  fixed-size  entries.  PCRE2_INFO_NAME-
-       COUNT  gives  the number of entries, and PCRE2_INFO_NAMEENTRYSIZE gives
-       the size of each entry in code units; both of these return  a  uint32_t
+       The  map  consists  of a number of fixed-size entries. PCRE2_INFO_NAME-
+       COUNT gives the number of entries, and  PCRE2_INFO_NAMEENTRYSIZE  gives
+       the  size  of each entry in code units; both of these return a uint32_t
        value. The entry size depends on the length of the longest name.
 
        PCRE2_INFO_NAMETABLE returns a pointer to the first entry of the table.
        This is a PCRE2_SPTR pointer to a block of code units. In the 8-bit li-
-       brary,  the first two bytes of each entry are the number of the captur-
-       ing parenthesis, most significant byte first. In  the  16-bit  library,
-       the  pointer  points  to 16-bit code units, the first of which contains
-       the parenthesis number. In the 32-bit library, the  pointer  points  to
-       32-bit  code units, the first of which contains the parenthesis number.
+       brary, the first two bytes of each entry are the number of the  captur-
+       ing  parenthesis,  most  significant byte first. In the 16-bit library,
+       the pointer points to 16-bit code units, the first  of  which  contains
+       the  parenthesis  number.  In the 32-bit library, the pointer points to
+       32-bit code units, the first of which contains the parenthesis  number.
        The rest of the entry is the corresponding name, zero terminated.
 
-       The names are in alphabetical order. If (?| is used to create  multiple
+       The  names are in alphabetical order. If (?| is used to create multiple
        capture groups with the same number, as described in the section on du-
        plicate group numbers in the pcre2pattern page, the groups may be given
-       the  same  name,  but  there  is only one entry in the table. Different
+       the same name, but there is only one  entry  in  the  table.  Different
        names for groups of the same number are not permitted.
 
-       Duplicate names for capture groups with different numbers  are  permit-
+       Duplicate  names  for capture groups with different numbers are permit-
        ted, but only if PCRE2_DUPNAMES is set. They appear in the table in the
-       order in which they were found in the pattern. In the  absence  of  (?|
-       this  is  the  order of increasing number; when (?| is used this is not
-       necessarily the case because later capture groups may have  lower  num-
+       order  in  which  they were found in the pattern. In the absence of (?|
+       this is the order of increasing number; when (?| is used  this  is  not
+       necessarily  the  case because later capture groups may have lower num-
        bers.
 
-       As  a  simple  example of the name/number table, consider the following
-       pattern after compilation by the 8-bit library  (assume  PCRE2_EXTENDED
+       As a simple example of the name/number table,  consider  the  following
+       pattern  after  compilation by the 8-bit library (assume PCRE2_EXTENDED
        is set, so white space - including newlines - is ignored):
 
          (? (?(\d\d)?\d\d) -
          (?\d\d) - (?\d\d) )
 
        There are four named capture groups, 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 ??:
 
@@ -2355,8 +2385,8 @@ INFORMATION ABOUT A COMPILED PATTERN
          00 04 m  o  n  t  h  00
          00 02 y  e  a  r  00 ??
 
-       When writing code to extract data from named capture groups  using  the
-       name-to-number  map,  remember that the length of the entries is likely
+       When  writing  code to extract data from named capture groups using the
+       name-to-number map, remember that the length of the entries  is  likely
        to be different for each compiled pattern.
 
          PCRE2_INFO_NEWLINE
@@ -2375,14 +2405,14 @@ INFORMATION ABOUT A COMPILED PATTERN
 
          PCRE2_INFO_SIZE
 
-       Return  the  size  of  the compiled pattern in bytes (for all three li-
-       braries). The third argument should point to a  size_t  variable.  This
-       value  includes  the  size  of the general data block that precedes the
-       code units of the compiled pattern itself. The value that is used  when
-       pcre2_compile()  is  getting memory in which to place the compiled pat-
+       Return the size of the compiled pattern in bytes  (for  all  three  li-
+       braries).  The  third  argument should point to a size_t variable. This
+       value includes the size of the general data  block  that  precedes  the
+       code  units of the compiled pattern itself. The value that is used when
+       pcre2_compile() is getting memory in which to place the  compiled  pat-
        tern may be slightly larger than the value returned by this option, be-
-       cause  there  are  cases where the code that calculates the size has to
-       over-estimate. Processing a pattern with the JIT compiler does not  al-
+       cause there are cases where the code that calculates the  size  has  to
+       over-estimate.  Processing a pattern with the JIT compiler does not al-
        ter the value returned by this option.
 
 
@@ -2393,30 +2423,30 @@ INFORMATION ABOUT A PATTERN'S CALLOUTS
          void *user_data);
 
        A script language that supports the use of string arguments in callouts
-       might like to scan all the callouts in a  pattern  before  running  the
+       might  like  to  scan  all the callouts in a pattern before running the
        match. This can be done by calling pcre2_callout_enumerate(). The first
-       argument is a pointer to a compiled pattern, the  second  points  to  a
-       callback  function,  and the third is arbitrary user data. The callback
-       function is called for every callout in the pattern  in  the  order  in
+       argument  is  a  pointer  to a compiled pattern, the second points to a
+       callback function, and the third is arbitrary user data.  The  callback
+       function  is  called  for  every callout in the pattern in the order in
        which they appear. Its first argument is a pointer to a callout enumer-
-       ation block, and its second argument is the user_data  value  that  was
-       passed  to  pcre2_callout_enumerate(). The contents of the callout enu-
-       meration block are described in the pcre2callout  documentation,  which
+       ation  block,  and  its second argument is the user_data value that was
+       passed to pcre2_callout_enumerate(). The contents of the  callout  enu-
+       meration  block  are described in the pcre2callout documentation, which
        also gives further details about callouts.
 
 
 SERIALIZATION AND PRECOMPILING
 
-       It  is  possible  to  save  compiled patterns on disc or elsewhere, and
-       reload them later, subject to a number of  restrictions.  The  host  on
-       which  the  patterns  are  reloaded must be running the same version of
+       It is possible to save compiled patterns  on  disc  or  elsewhere,  and
+       reload  them  later,  subject  to a number of restrictions. The host on
+       which the patterns are reloaded must be running  the  same  version  of
        PCRE2, with the same code unit width, and must also have the same endi-
-       anness,  pointer  width,  and PCRE2_SIZE type. Before compiled patterns
-       can be saved, they must be converted to a "serialized" form,  which  in
-       the  case of PCRE2 is really just a bytecode dump.  The functions whose
-       names begin with pcre2_serialize_ are used for converting to  and  from
-       the  serialized form. They are described in the pcre2serialize documen-
-       tation. Note that PCRE2 serialization does not  convert  compiled  pat-
+       anness, pointer width, and PCRE2_SIZE type.  Before  compiled  patterns
+       can  be  saved, they must be converted to a "serialized" form, which in
+       the case of PCRE2 is really just a bytecode dump.  The functions  whose
+       names  begin  with pcre2_serialize_ are used for converting to and from
+       the serialized form. They are described in the pcre2serialize  documen-
+       tation.  Note  that  PCRE2 serialization does not convert compiled pat-
        terns to an abstract format like Java or .NET serialization.
 
 
@@ -2430,58 +2460,58 @@ THE MATCH DATA BLOCK
 
        void pcre2_match_data_free(pcre2_match_data *match_data);
 
-       Information  about  a  successful  or unsuccessful match is placed in a
-       match data block, which is an opaque  structure  that  is  accessed  by
-       function  calls.  In particular, the match data block contains a vector
-       of offsets into the subject string that define the matched part of  the
-       subject  and  any  substrings  that were captured. This is known as the
+       Information about a successful or unsuccessful match  is  placed  in  a
+       match  data  block,  which  is  an opaque structure that is accessed by
+       function calls. In particular, the match data block contains  a  vector
+       of  offsets into the subject string that define the matched part of the
+       subject and any substrings that were captured. This  is  known  as  the
        ovector.
 
-       Before calling pcre2_match(), pcre2_dfa_match(),  or  pcre2_jit_match()
+       Before  calling  pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match()
        you must create a match data block by calling one of the creation func-
-       tions above. For pcre2_match_data_create(), the first argument  is  the
-       number  of  pairs of offsets in the ovector. One pair of offsets is re-
-       quired to identify the string that matched the whole pattern,  with  an
-       additional  pair for each captured substring. For example, a value of 4
-       creates enough space to record the matched portion of the subject  plus
-       three  captured  substrings. A minimum of at least 1 pair is imposed by
+       tions  above.  For pcre2_match_data_create(), the first argument is the
+       number of pairs of offsets in the ovector. One pair of offsets  is  re-
+       quired  to  identify the string that matched the whole pattern, with an
+       additional pair for each captured substring. For example, a value of  4
+       creates  enough space to record the matched portion of the subject plus
+       three captured substrings. A minimum of at least 1 pair is  imposed  by
        pcre2_match_data_create(), so it is always possible to return the over-
        all matched string.
 
        The second argument of pcre2_match_data_create() is a pointer to a gen-
-       eral context, which can specify custom memory management for  obtaining
+       eral  context, which can specify custom memory management for obtaining
        the memory for the match data block. If you are not using custom memory
        management, pass NULL, which causes malloc() to be used.
 
-       For pcre2_match_data_create_from_pattern(), the  first  argument  is  a
+       For  pcre2_match_data_create_from_pattern(),  the  first  argument is a
        pointer to a compiled pattern. The ovector is created to be exactly the
        right size to hold all the substrings a pattern might capture. The sec-
-       ond  argument is again a pointer to a general context, but in this case
+       ond argument is again a pointer to a general context, but in this  case
        if NULL is passed, the memory is obtained using the same allocator that
        was used for the compiled pattern (custom or default).
 
-       A  match  data block can be used many times, with the same or different
-       compiled patterns. You can extract information from a match data  block
-       after  a  match  operation  has  finished, using functions that are de-
+       A match data block can be used many times, with the same  or  different
+       compiled  patterns. You can extract information from a match data block
+       after a match operation has finished,  using  functions  that  are  de-
        scribed in the sections on matched strings and other match data below.
 
-       When a call of pcre2_match() fails, valid  data  is  available  in  the
-       match  block  only  when  the  error  is PCRE2_ERROR_NOMATCH, PCRE2_ER-
-       ROR_PARTIAL, or one of the error codes for an invalid UTF  string.  Ex-
+       When  a  call  of  pcre2_match()  fails, valid data is available in the
+       match block only  when  the  error  is  PCRE2_ERROR_NOMATCH,  PCRE2_ER-
+       ROR_PARTIAL,  or  one of the error codes for an invalid UTF string. Ex-
        actly what is available depends on the error, and is detailed below.
 
-       When  one of the matching functions is called, pointers to the compiled
-       pattern and the subject string are set in the match data block so  that
-       they  can  be referenced by the extraction functions after a successful
+       When one of the matching functions is called, pointers to the  compiled
+       pattern  and the subject string are set in the match data block so that
+       they can be referenced by the extraction functions after  a  successful
        match. After running a match, you must not free a compiled pattern or a
-       subject  string until after all operations on the match data block (for
-       that match) have taken place,  unless,  in  the  case  of  the  subject
-       string,  you  have used the PCRE2_COPY_MATCHED_SUBJECT option, which is
-       described in the section entitled "Option bits for  pcre2_match()"  be-
+       subject string until after all operations on the match data block  (for
+       that  match)  have  taken  place,  unless,  in  the case of the subject
+       string, you have used the PCRE2_COPY_MATCHED_SUBJECT option,  which  is
+       described  in  the section entitled "Option bits for pcre2_match()" be-
        low.
 
-       When  a match data block itself is no longer needed, it should be freed
-       by calling pcre2_match_data_free(). If this function is called  with  a
+       When a match data block itself is no longer needed, it should be  freed
+       by  calling  pcre2_match_data_free(). If this function is called with a
        NULL argument, it returns immediately, without doing anything.
 
 
@@ -2492,15 +2522,15 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION
          uint32_t options, pcre2_match_data *match_data,
          pcre2_match_context *mcontext);
 
-       The  function pcre2_match() is called to match a subject string against
-       a compiled pattern, which is passed in the code argument. You can  call
+       The function pcre2_match() is called to match a subject string  against
+       a  compiled pattern, which is passed in the code argument. You can call
        pcre2_match() with the same code argument as many times as you like, in
-       order to find multiple matches in the subject string or to  match  dif-
+       order  to  find multiple matches in the subject string or to match dif-
        ferent subject strings with the same pattern.
 
-       This  function is the main matching facility of the library, and it op-
-       erates in a Perl-like manner. For specialist use there is also  an  al-
-       ternative  matching  function,  which is described below in the section
+       This function is the main matching facility of the library, and it  op-
+       erates  in  a Perl-like manner. For specialist use there is also an al-
+       ternative matching function, which is described below  in  the  section
        about the pcre2_dfa_match() function.
 
        Here is an example of a simple call to pcre2_match():
@@ -2515,215 +2545,215 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION
            md,             /* the match data block */
            NULL);          /* a match context; NULL means use defaults */
 
-       If the subject string is zero-terminated, the length can  be  given  as
+       If  the  subject  string is zero-terminated, the length can be given as
        PCRE2_ZERO_TERMINATED. A match context must be provided if certain less
        common matching parameters are to be changed. For details, see the sec-
        tion on the match context above.
 
    The string to be matched by pcre2_match()
 
-       The  subject string is passed to pcre2_match() as a pointer in subject,
-       a length in length, and a starting offset in  startoffset.  The  length
-       and  offset  are  in  code units, not characters.  That is, they are in
-       bytes for the 8-bit library, 16-bit code units for the 16-bit  library,
-       and  32-bit  code units for the 32-bit library, whether or not UTF pro-
+       The subject string is passed to pcre2_match() as a pointer in  subject,
+       a  length  in  length, and a starting offset in startoffset. The length
+       and offset are in code units, not characters.  That  is,  they  are  in
+       bytes  for the 8-bit library, 16-bit code units for the 16-bit library,
+       and 32-bit code units for the 32-bit library, whether or not  UTF  pro-
        cessing is enabled.
 
        If startoffset is greater than the length of the subject, pcre2_match()
-       returns  PCRE2_ERROR_BADOFFSET.  When  the starting offset is zero, the
-       search for a match starts at the beginning of the subject, and this  is
+       returns PCRE2_ERROR_BADOFFSET. When the starting offset  is  zero,  the
+       search  for a match starts at the beginning of the subject, and this is
        by far the most common case. In UTF-8 or UTF-16 mode, the starting off-
-       set must point to the start of a character, or to the end of  the  sub-
-       ject  (in  UTF-32 mode, one code unit equals one character, so all off-
-       sets are valid). Like the pattern string, the subject may  contain  bi-
+       set  must  point to the start of a character, or to the end of the sub-
+       ject (in UTF-32 mode, one code unit equals one character, so  all  off-
+       sets  are  valid). Like the pattern string, the subject may contain bi-
        nary zeros.
 
-       A  non-zero  starting offset is useful when searching for another match
-       in the same subject by calling pcre2_match()  again  after  a  previous
-       success.   Setting  startoffset  differs  from passing over a shortened
-       string and setting PCRE2_NOTBOL in the case of a  pattern  that  begins
+       A non-zero starting offset is useful when searching for  another  match
+       in  the  same  subject  by calling pcre2_match() again after a previous
+       success.  Setting startoffset differs from  passing  over  a  shortened
+       string  and  setting  PCRE2_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
-       only if the current position in the subject is not  a  word  boundary.)
+       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.)
        When applied to the string "Mississipi" the first call to pcre2_match()
-       finds the first occurrence. If pcre2_match() is called again with  just
-       the  remainder  of the subject, namely "issipi", it does not match, be-
-       cause \B is always false at the start of the subject, which  is  deemed
-       to  be  a word boundary. However, if pcre2_match() is passed the entire
+       finds  the first occurrence. If pcre2_match() is called again with just
+       the remainder of the subject, namely "issipi", it does not  match,  be-
+       cause  \B  is always false at the start of the subject, which is deemed
+       to be a word boundary. However, if pcre2_match() 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.
 
-       Finding all the matches in a subject is tricky  when  the  pattern  can
+       Finding  all  the  matches  in a subject is tricky when the pattern can
        match an empty string. It is possible to emulate Perl's /g behaviour by
-       first  trying  the  match  again  at  the   same   offset,   with   the
-       PCRE2_NOTEMPTY_ATSTART  and  PCRE2_ANCHORED  options,  and then if that
-       fails, advancing the starting  offset  and  trying  an  ordinary  match
-       again.  There  is  some  code  that  demonstrates how to do this in the
-       pcre2demo sample program. In the most general case, you have  to  check
-       to  see  if the newline convention recognizes CRLF as a newline, and if
-       so, and the current character is CR followed by LF, advance the  start-
+       first   trying   the   match   again  at  the  same  offset,  with  the
+       PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED options,  and  then  if  that
+       fails,  advancing  the  starting  offset  and  trying an ordinary match
+       again. There is some code that demonstrates  how  to  do  this  in  the
+       pcre2demo  sample  program. In the most general case, you have to check
+       to see if the newline convention recognizes CRLF as a newline,  and  if
+       so,  and the current character is CR followed by LF, advance the start-
        ing offset by two characters instead of one.
 
        If a non-zero starting offset is passed when the pattern is anchored, a
        single attempt to match at the given offset is made. This can only suc-
-       ceed  if  the  pattern does not require the match to be at the start of
-       the subject. In other words, the anchoring must be the result  of  set-
-       ting  the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL, not
+       ceed if the pattern does not require the match to be at  the  start  of
+       the  subject.  In other words, the anchoring must be the result of set-
+       ting the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL,  not
        by starting the pattern with ^ or \A.
 
    Option bits for pcre2_match()
 
        The unused bits of the options argument for pcre2_match() must be zero.
-       The    only    bits    that    may    be    set   are   PCRE2_ANCHORED,
-       PCRE2_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL,  PCRE2_NO-
+       The   only   bits    that    may    be    set    are    PCRE2_ANCHORED,
+       PCRE2_COPY_MATCHED_SUBJECT,  PCRE2_ENDANCHORED, PCRE2_NOTBOL, PCRE2_NO-
        TEOL,     PCRE2_NOTEMPTY,     PCRE2_NOTEMPTY_ATSTART,     PCRE2_NO_JIT,
-       PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and  PCRE2_PARTIAL_SOFT.  Their
+       PCRE2_NO_UTF_CHECK,  PCRE2_PARTIAL_HARD,  and PCRE2_PARTIAL_SOFT. Their
        action is described below.
 
-       Setting  PCRE2_ANCHORED  or PCRE2_ENDANCHORED at match time is not sup-
-       ported by the just-in-time (JIT) compiler. If it is set,  JIT  matching
-       is  disabled  and  the interpretive code in pcre2_match() is run. Apart
-       from PCRE2_NO_JIT (obviously), the remaining options are supported  for
+       Setting PCRE2_ANCHORED or PCRE2_ENDANCHORED at match time is  not  sup-
+       ported  by  the just-in-time (JIT) compiler. If it is set, JIT matching
+       is disabled and the interpretive code in pcre2_match()  is  run.  Apart
+       from  PCRE2_NO_JIT (obviously), the remaining options are supported for
        JIT matching.
 
          PCRE2_ANCHORED
 
        The PCRE2_ANCHORED option limits pcre2_match() to matching at the first
-       matching position. If a pattern was compiled  with  PCRE2_ANCHORED,  or
-       turned  out to be anchored by virtue of its contents, it cannot be made
-       unachored at matching time. Note that setting the option at match  time
+       matching  position.  If  a pattern was compiled with PCRE2_ANCHORED, or
+       turned out to be anchored by virtue of its contents, it cannot be  made
+       unachored  at matching time. Note that setting the option at match time
        disables JIT matching.
 
          PCRE2_COPY_MATCHED_SUBJECT
 
-       By  default,  a  pointer to the subject is remembered in the match data
-       block so that, after a successful match, it can be  referenced  by  the
-       substring  extraction  functions.  This means that the subject's memory
-       must not be freed until all such operations are complete. For some  ap-
-       plications  where the lifetime of the subject string is not guaranteed,
-       it may be necessary to make a copy of the subject  string,  but  it  is
-       wasteful  to do this unless the match is successful. After a successful
-       match, if PCRE2_COPY_MATCHED_SUBJECT is set, the subject is copied  and
-       the  new  pointer  is remembered in the match data block instead of the
-       original subject pointer. The memory allocator that was  used  for  the
-       match  block  itself  is  used.  The  copy  is automatically freed when
-       pcre2_match_data_free() is called to free the match data block.  It  is
+       By default, a pointer to the subject is remembered in  the  match  data
+       block  so  that,  after a successful match, it can be referenced by the
+       substring extraction functions. This means that  the  subject's  memory
+       must  not be freed until all such operations are complete. For some ap-
+       plications where the lifetime of the subject string is not  guaranteed,
+       it  may  be  necessary  to make a copy of the subject string, but it is
+       wasteful to do this unless the match is successful. After a  successful
+       match,  if PCRE2_COPY_MATCHED_SUBJECT is set, the subject is copied and
+       the new pointer is remembered in the match data block  instead  of  the
+       original  subject  pointer.  The memory allocator that was used for the
+       match block itself is  used.  The  copy  is  automatically  freed  when
+       pcre2_match_data_free()  is  called to free the match data block. It is
        also automatically freed if the match data block is re-used for another
        match operation.
 
          PCRE2_ENDANCHORED
 
-       If the PCRE2_ENDANCHORED option is set, any string  that  pcre2_match()
-       matches  must be right at the end of the subject string. Note that set-
+       If  the  PCRE2_ENDANCHORED option is set, any string that pcre2_match()
+       matches must be right at the end of the subject string. Note that  set-
        ting the option at match time disables JIT matching.
 
          PCRE2_NOTBOL
 
        This option specifies that first character of the subject string is not
-       the  beginning  of  a  line, so the circumflex metacharacter should not
-       match before it. Setting this without  having  set  PCRE2_MULTILINE  at
+       the beginning of a line, so the  circumflex  metacharacter  should  not
+       match  before  it.  Setting  this without having set PCRE2_MULTILINE at
        compile time causes circumflex never to match. This option affects only
        the behaviour of the circumflex metacharacter. It does not affect \A.
 
          PCRE2_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
-       in multiline mode) a newline immediately before it. Setting this  with-
-       out  having  set PCRE2_MULTILINE at compile time causes dollar never to
+       of a line, so the dollar metacharacter should not match it nor  (except
+       in  multiline mode) a newline immediately before it. Setting this with-
+       out having set PCRE2_MULTILINE at compile time causes dollar  never  to
        match. This option affects only the behaviour of the dollar metacharac-
        ter. It does not affect \Z or \z.
 
          PCRE2_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
-       the  alternatives  match  the empty string, the entire match fails. For
+       set.  If  there are alternatives in the pattern, they are tried. If all
+       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  an
+       is  applied  to  a  string not beginning with "a" or "b", it matches an
        empty string at the start of the subject. With PCRE2_NOTEMPTY set, this
-       match is not valid, so pcre2_match() searches further into  the  string
+       match  is  not valid, so pcre2_match() searches further into the string
        for occurrences of "a" or "b".
 
          PCRE2_NOTEMPTY_ATSTART
 
-       This  is  like PCRE2_NOTEMPTY, except that it locks out an empty string
+       This is like PCRE2_NOTEMPTY, except that it locks out an  empty  string
        match only at the first matching position, that is, at the start of the
-       subject  plus  the  starting offset. An empty string match later in the
+       subject plus the starting offset. An empty string match  later  in  the
        subject is permitted.  If the pattern is anchored, such a match can oc-
        cur only if the pattern contains \K.
 
          PCRE2_NO_JIT
 
-       By   default,   if   a  pattern  has  been  successfully  processed  by
-       pcre2_jit_compile(), JIT is automatically used  when  pcre2_match()  is
-       called  with  options  that JIT supports. Setting PCRE2_NO_JIT disables
+       By  default,  if  a  pattern  has  been   successfully   processed   by
+       pcre2_jit_compile(),  JIT  is  automatically used when pcre2_match() is
+       called with options that JIT supports.  Setting  PCRE2_NO_JIT  disables
        the use of JIT; it forces matching to be done by the interpreter.
 
          PCRE2_NO_UTF_CHECK
 
        When PCRE2_UTF is set at compile time, the validity of the subject as a
-       UTF   string   is   checked  unless  PCRE2_NO_UTF_CHECK  is  passed  to
+       UTF  string  is  checked  unless  PCRE2_NO_UTF_CHECK   is   passed   to
        pcre2_match() or PCRE2_MATCH_INVALID_UTF was passed to pcre2_compile().
        The latter special case is discussed in detail in the pcre2unicode doc-
        umentation.
 
-       In the default case, if a non-zero starting offset is given, the  check
-       is  applied  only  to  that part of the subject that could be inspected
-       during matching, and there is a check that the starting  offset  points
-       to  the first code unit of a character or to the end of the subject. If
-       there are no lookbehind assertions in the pattern, the check starts  at
+       In  the default case, if a non-zero starting offset is given, the check
+       is applied only to that part of the subject  that  could  be  inspected
+       during  matching,  and there is a check that the starting offset points
+       to the first code unit of a character or to the end of the subject.  If
+       there  are no lookbehind assertions in the pattern, the check starts at
        the starting offset.  Otherwise, it starts at the length of the longest
-       lookbehind before the starting offset, or at the start of  the  subject
-       if  there are not that many characters before the starting offset. Note
+       lookbehind  before  the starting offset, or at the start of the subject
+       if there are not that many characters before the starting offset.  Note
        that the sequences \b and \B are one-character lookbehinds.
 
        The check is carried out before any other processing takes place, and a
-       negative  error  code is returned if the check fails. There are several
-       UTF error codes for each code unit width,  corresponding  to  different
-       problems  with  the code unit sequence. There are discussions about the
-       validity of UTF-8 strings, UTF-16 strings, and UTF-32  strings  in  the
+       negative error code is returned if the check fails. There  are  several
+       UTF  error  codes  for each code unit width, corresponding to different
+       problems with the code unit sequence. There are discussions  about  the
+       validity  of  UTF-8  strings, UTF-16 strings, and UTF-32 strings in the
        pcre2unicode documentation.
 
        If you know that your subject is valid, and you want to skip this check
        for performance reasons, you can set the PCRE2_NO_UTF_CHECK option when
-       calling  pcre2_match().  You  might  want to do this for the second and
-       subsequent calls to pcre2_match() if you are making repeated  calls  to
+       calling pcre2_match(). You might want to do this  for  the  second  and
+       subsequent  calls  to pcre2_match() if you are making repeated calls to
        find multiple matches in the same subject string.
 
-       Warning:  Unless  PCRE2_MATCH_INVALID_UTF was set at compile time, when
-       PCRE2_NO_UTF_CHECK is set at match time the effect of  passing  an  in-
+       Warning: Unless PCRE2_MATCH_INVALID_UTF was set at compile  time,  when
+       PCRE2_NO_UTF_CHECK  is  set  at match time the effect of passing an in-
        valid string as a subject, or an invalid value of startoffset, is unde-
-       fined.  Your program may crash or loop indefinitely or give  wrong  re-
+       fined.   Your  program may crash or loop indefinitely or give wrong re-
        sults.
 
          PCRE2_PARTIAL_HARD
          PCRE2_PARTIAL_SOFT
 
        These options turn on the partial matching feature. A partial match oc-
-       curs if the end of the subject  string  is  reached  successfully,  but
+       curs  if  the  end  of  the subject string is reached successfully, but
        there are not enough subject characters to complete the match. In addi-
-       tion, either at least one character must have  been  inspected  or  the
-       pattern  must  contain  a  lookbehind,  or the pattern must be one that
+       tion,  either  at  least  one character must have been inspected or the
+       pattern must contain a lookbehind, or the  pattern  must  be  one  that
        could match an empty string.
 
-       If this situation arises when PCRE2_PARTIAL_SOFT  (but  not  PCRE2_PAR-
+       If  this  situation  arises when PCRE2_PARTIAL_SOFT (but not PCRE2_PAR-
        TIAL_HARD) is set, matching continues by testing any remaining alterna-
-       tives. Only if no complete match can be  found  is  PCRE2_ERROR_PARTIAL
-       returned  instead  of  PCRE2_ERROR_NOMATCH.  In other words, PCRE2_PAR-
-       TIAL_SOFT specifies that the caller is prepared  to  handle  a  partial
+       tives.  Only  if  no complete match can be found is PCRE2_ERROR_PARTIAL
+       returned instead of PCRE2_ERROR_NOMATCH.  In  other  words,  PCRE2_PAR-
+       TIAL_SOFT  specifies  that  the  caller is prepared to handle a partial
        match, but only if no complete match can be found.
 
-       If  PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
-       case, if a partial match is found,  pcre2_match()  immediately  returns
-       PCRE2_ERROR_PARTIAL,  without  considering  any  other alternatives. In
+       If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In  this
+       case,  if  a  partial match is found, pcre2_match() immediately returns
+       PCRE2_ERROR_PARTIAL, without considering  any  other  alternatives.  In
        other words, when PCRE2_PARTIAL_HARD is set, a partial match is consid-
        ered to be more important that an alternative complete match.
 
@@ -2733,38 +2763,38 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION
 
 NEWLINE HANDLING WHEN MATCHING
 
-       When PCRE2 is built, a default newline convention is set; this is  usu-
-       ally  the standard convention for the operating system. The default can
-       be overridden in a compile context by calling  pcre2_set_newline().  It
-       can  also be overridden by starting a pattern string with, for example,
-       (*CRLF), as described in the section  on  newline  conventions  in  the
-       pcre2pattern  page. During matching, the newline choice affects the be-
-       haviour of the dot, circumflex, and dollar metacharacters. It may  also
-       alter  the  way  the  match starting position is advanced after a match
+       When  PCRE2 is built, a default newline convention is set; this is usu-
+       ally the standard convention for the operating system. The default  can
+       be  overridden  in a compile context by calling pcre2_set_newline(). It
+       can also be overridden by starting a pattern string with, for  example,
+       (*CRLF),  as  described  in  the  section on newline conventions in the
+       pcre2pattern page. During matching, the newline choice affects the  be-
+       haviour  of the dot, circumflex, and dollar metacharacters. It may also
+       alter the way the match starting position is  advanced  after  a  match
        failure for an unanchored pattern.
 
        When PCRE2_NEWLINE_CRLF, PCRE2_NEWLINE_ANYCRLF, or PCRE2_NEWLINE_ANY is
-       set  as  the  newline convention, and a match attempt for an unanchored
+       set as the newline convention, and a match attempt  for  an  unanchored
        pattern fails when the current starting position is at a CRLF sequence,
-       and  the  pattern contains no explicit matches for CR or LF characters,
-       the match position is advanced by two characters  instead  of  one,  in
+       and the pattern contains no 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 PCRE2_DOTALL  op-
-       tion  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.
-       However,  the  pattern  [\r\n]A does match that string, because it con-
+       expected.  For example, if the pattern is .+A (and the PCRE2_DOTALL op-
+       tion 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.
+       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 in the pattern, or one of the \r or \n  or  equivalent
+       those  characters  in the pattern, or one of the \r or \n or equivalent
        octal or hexadecimal escape sequences. Implicit matches such as [^X] do
-       not count, nor does \s, even though it includes CR and LF in the  char-
+       not  count, nor does \s, even though it includes CR and LF in the char-
        acters 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.
 
@@ -2775,82 +2805,82 @@ HOW PCRE2_MATCH() RETURNS A STRING AND CAPTURED SUBSTRINGS
 
        PCRE2_SIZE *pcre2_get_ovector_pointer(pcre2_match_data *match_data);
 
-       In  general, a pattern matches a certain portion of the subject, and in
-       addition, further substrings from the subject  may  be  picked  out  by
-       parenthesized  parts  of  the  pattern.  Following the usage in Jeffrey
-       Friedl's book, this is called "capturing"  in  what  follows,  and  the
-       phrase  "capture  group" (Perl terminology) is used for a fragment of a
-       pattern that picks out a substring. PCRE2 supports several other  kinds
+       In general, a pattern matches a certain portion of the subject, and  in
+       addition,  further  substrings  from  the  subject may be picked out by
+       parenthesized parts of the pattern.  Following  the  usage  in  Jeffrey
+       Friedl's  book,  this  is  called  "capturing" in what follows, and the
+       phrase "capture group" (Perl terminology) is used for a fragment  of  a
+       pattern  that picks out a substring. PCRE2 supports several other kinds
        of parenthesized group that do not cause substrings to be captured. The
-       pcre2_pattern_info() function can be used to find out how many  capture
+       pcre2_pattern_info()  function can be used to find out how many capture
        groups there are in a compiled pattern.
 
-       You  can  use  auxiliary functions for accessing captured substrings by
+       You can use auxiliary functions for accessing  captured  substrings  by
        number or by name, as described in sections below.
 
        Alternatively, you can make direct use of the vector of PCRE2_SIZE val-
-       ues,  called  the  ovector,  which  contains  the  offsets  of captured
-       strings.  It  is  part  of  the  match  data   block.    The   function
-       pcre2_get_ovector_pointer()  returns  the  address  of the ovector, and
+       ues, called  the  ovector,  which  contains  the  offsets  of  captured
+       strings.   It   is   part  of  the  match  data  block.   The  function
+       pcre2_get_ovector_pointer() returns the address  of  the  ovector,  and
        pcre2_get_ovector_count() returns the number of pairs of values it con-
        tains.
 
        Within the ovector, the first in each pair of values is set to the off-
        set of the first code unit of a substring, and the second is set to the
-       offset  of the first code unit after the end of a substring. These val-
-       ues are always code unit offsets, not character offsets. That is,  they
+       offset of the first code unit after the end of a substring. These  val-
+       ues  are always code unit offsets, not character offsets. That is, they
        are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit li-
        brary, and 32-bit offsets in the 32-bit library.
 
-       After a partial match  (error  return  PCRE2_ERROR_PARTIAL),  only  the
-       first  pair  of  offsets  (that is, ovector[0] and ovector[1]) are set.
-       They identify the part of the subject that was partially  matched.  See
+       After  a  partial  match  (error  return PCRE2_ERROR_PARTIAL), only the
+       first pair of offsets (that is, ovector[0]  and  ovector[1])  are  set.
+       They  identify  the part of the subject that was partially matched. See
        the pcre2partial documentation for details of partial matching.
 
-       After  a  fully  successful match, the first pair of offsets identifies
-       the portion of the subject string that was matched by the  entire  pat-
-       tern.  The  next  pair is used for the first captured substring, and so
-       on. The value returned by pcre2_match() is one more  than  the  highest
-       numbered  pair  that  has been set. For example, if two substrings have
-       been captured, the returned value is 3. If there are no  captured  sub-
+       After a fully successful match, the first pair  of  offsets  identifies
+       the  portion  of the subject string that was matched by the entire pat-
+       tern. The next pair is used for the first captured  substring,  and  so
+       on.  The  value  returned by pcre2_match() is one more than the highest
+       numbered pair that has been set. For example, if  two  substrings  have
+       been  captured,  the returned value is 3. If there are no captured sub-
        strings, the return value from a successful match is 1, indicating that
        just the first pair of offsets has been set.
 
-       If a pattern uses the \K escape sequence within a  positive  assertion,
+       If  a  pattern uses the \K escape sequence within a positive assertion,
        the reported start of a successful match can be greater than the end of
-       the match.  For example, if the pattern  (?=ab\K)  is  matched  against
+       the  match.   For  example,  if the pattern (?=ab\K) is matched against
        "ab", the start and end offset values for the match are 2 and 0.
 
-       If  a  capture group is matched repeatedly within a single match opera-
+       If a capture group is matched repeatedly within a single  match  opera-
        tion, it is the last portion of the subject that it matched that is re-
        turned.
 
        If the ovector is too small to hold all the captured substring offsets,
-       as much as possible is filled in, and the function returns a  value  of
-       zero.  If captured substrings are not of interest, pcre2_match() may be
+       as  much  as possible is filled in, and the function returns a value of
+       zero. If captured substrings are not of interest, pcre2_match() may  be
        called with a match data block whose ovector is of minimum length (that
        is, one pair).
 
-       It  is  possible for capture group number n+1 to match some part of the
-       subject when group n has not been used at  all.  For  example,  if  the
+       It is possible for capture group number n+1 to match some part  of  the
+       subject  when  group  n  has  not been used at all. For example, if the
        string "abc" is matched against the pattern (a|(z))(bc) the return from
-       the function is 4, and groups 1 and 3 are matched, but 2 is  not.  When
-       this  happens,  both values in the offset pairs corresponding to unused
+       the  function  is 4, and groups 1 and 3 are matched, but 2 is not. When
+       this happens, both values in the offset pairs corresponding  to  unused
        groups are set to PCRE2_UNSET.
 
-       Offset values that correspond to unused groups at the end  of  the  ex-
-       pression  are also set to PCRE2_UNSET. For example, if the string "abc"
-       is matched against the pattern (abc)(x(yz)?)? groups 2 and  3  are  not
-       matched.  The  return  from the function is 2, because the highest used
-       capture group number is 1. The offsets for for  the  second  and  third
-       capture  groupss  (assuming  the vector is large enough, of course) are
+       Offset  values  that  correspond to unused groups at the end of the ex-
+       pression are also set to PCRE2_UNSET. For example, if the string  "abc"
+       is  matched  against  the pattern (abc)(x(yz)?)? groups 2 and 3 are not
+       matched. The return from the function is 2, because  the  highest  used
+       capture  group  number  is  1. The offsets for for the second and third
+       capture groupss (assuming the vector is large enough,  of  course)  are
        set to PCRE2_UNSET.
 
        Elements in the ovector that do not correspond to capturing parentheses
        in the pattern are never changed. That is, if a pattern contains n cap-
        turing parentheses, no more than ovector[0] to ovector[2n+1] are set by
-       pcre2_match().  The  other  elements retain whatever values they previ-
-       ously had. After a failed match attempt, the contents  of  the  ovector
+       pcre2_match(). The other elements retain whatever  values  they  previ-
+       ously  had.  After  a failed match attempt, the contents of the ovector
        are unchanged.
 
 
@@ -2860,69 +2890,69 @@ OTHER INFORMATION ABOUT A MATCH
 
        PCRE2_SIZE pcre2_get_startchar(pcre2_match_data *match_data);
 
-       As  well as the offsets in the ovector, other information about a match
-       is retained in the match data block and can be retrieved by  the  above
-       functions  in  appropriate  circumstances.  If they are called at other
+       As well as the offsets in the ovector, other information about a  match
+       is  retained  in the match data block and can be retrieved by the above
+       functions in appropriate circumstances. If they  are  called  at  other
        times, the result is undefined.
 
-       After a successful match, a partial match (PCRE2_ERROR_PARTIAL),  or  a
-       failure  to  match (PCRE2_ERROR_NOMATCH), a mark name may be available.
-       The function pcre2_get_mark() can be called to access this name,  which
-       can  be  specified  in  the  pattern by any of the backtracking control
+       After  a  successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
+       failure to match (PCRE2_ERROR_NOMATCH), a mark name may  be  available.
+       The  function pcre2_get_mark() can be called to access this name, which
+       can be specified in the pattern by  any  of  the  backtracking  control
        verbs, not just (*MARK). The same function applies to all the verbs. It
        returns a pointer to the zero-terminated name, which is within the com-
        piled pattern. If no name is available, NULL is returned. The length of
-       the  name  (excluding  the terminating zero) is stored in the code unit
-       that precedes the name. You should use this length instead  of  relying
+       the name (excluding the terminating zero) is stored in  the  code  unit
+       that  precedes  the name. You should use this length instead of relying
        on the terminating zero if the name might contain a binary zero.
 
-       After  a  successful  match, the name that is returned is the last mark
+       After a successful match, the name that is returned is  the  last  mark
        name encountered on the matching path through the pattern. Instances of
-       backtracking  verbs  without  names do not count. Thus, for example, if
+       backtracking verbs without names do not count. Thus,  for  example,  if
        the matching path contains (*MARK:A)(*PRUNE), the name "A" is returned.
        After a "no match" or a partial match, the last encountered name is re-
        turned. For example, consider this pattern:
 
          ^(*MARK:A)((*MARK:B)a|b)c
 
-       When it matches "bc", the returned name is A. The B mark is  "seen"  in
-       the  first  branch of the group, but it is not on the matching path. On
-       the other hand, when this pattern fails to  match  "bx",  the  returned
+       When  it  matches "bc", the returned name is A. The B mark is "seen" in
+       the first branch of the group, but it is not on the matching  path.  On
+       the  other  hand,  when  this pattern fails to match "bx", the returned
        name is B.
 
-       Warning:  By  default, certain start-of-match optimizations are used to
-       give a fast "no match" result in some situations. For example,  if  the
-       anchoring  is removed from the pattern above, there is an initial check
-       for the presence of "c" in the subject before running the matching  en-
+       Warning: By default, certain start-of-match optimizations are  used  to
+       give  a  fast "no match" result in some situations. For example, if the
+       anchoring is removed from the pattern above, there is an initial  check
+       for  the presence of "c" in the subject before running the matching en-
        gine. This check fails for "bx", causing a match failure without seeing
-       any marks. You can disable the start-of-match optimizations by  setting
-       the  PCRE2_NO_START_OPTIMIZE  option for pcre2_compile() or by starting
+       any  marks. You can disable the start-of-match optimizations by setting
+       the PCRE2_NO_START_OPTIMIZE option for pcre2_compile() or  by  starting
        the pattern with (*NO_START_OPT).
 
-       After a successful match, a partial match, or one of  the  invalid  UTF
-       errors  (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
+       After  a  successful  match, a partial match, or one of the invalid UTF
+       errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar()  can
        be called. After a successful or partial match it returns the code unit
-       offset  of  the character at which the match started. For a non-partial
-       match, this can be different to the value of ovector[0] if the  pattern
-       contains  the  \K escape sequence. After a partial match, however, this
-       value is always the same as ovector[0] because \K does not  affect  the
+       offset of the character at which the match started. For  a  non-partial
+       match,  this can be different to the value of ovector[0] if the pattern
+       contains the \K escape sequence. After a partial match,  however,  this
+       value  is  always the same as ovector[0] because \K does not affect the
        result of a partial match.
 
-       After  a UTF check failure, pcre2_get_startchar() can be used to obtain
+       After a UTF check failure, pcre2_get_startchar() can be used to  obtain
        the code unit offset of the invalid UTF character. Details are given in
        the pcre2unicode page.
 
 
 ERROR RETURNS FROM pcre2_match()
 
-       If  pcre2_match() fails, it returns a negative number. This can be con-
-       verted to a text string by calling the pcre2_get_error_message()  func-
-       tion  (see  "Obtaining a textual error message" below).  Negative error
-       codes are also returned by other functions,  and  are  documented  with
-       them.  The codes are given names in the header file. If UTF checking is
+       If pcre2_match() fails, it returns a negative number. This can be  con-
+       verted  to a text string by calling the pcre2_get_error_message() func-
+       tion (see "Obtaining a textual error message" below).   Negative  error
+       codes  are  also  returned  by other functions, and are documented with
+       them. The codes are given names in the header file. If UTF checking  is
        in force and an invalid UTF subject string is detected, one of a number
-       of  UTF-specific negative error codes is returned. Details are given in
-       the pcre2unicode page. The following are the other errors that  may  be
+       of UTF-specific negative error codes is returned. Details are given  in
+       the  pcre2unicode  page. The following are the other errors that may be
        returned by pcre2_match():
 
          PCRE2_ERROR_NOMATCH
@@ -2931,20 +2961,20 @@ ERROR RETURNS FROM pcre2_match()
 
          PCRE2_ERROR_PARTIAL
 
-       The  subject  string did not match, but it did match partially. See the
+       The subject string did not match, but it did match partially.  See  the
        pcre2partial documentation for details of partial matching.
 
          PCRE2_ERROR_BADMAGIC
 
        PCRE2 stores a 4-byte "magic number" at the start of the compiled code,
-       to  catch  the case when it is passed a junk pointer. This is the error
+       to catch the case when it is passed a junk pointer. This is  the  error
        that is returned when the magic number is not present.
 
          PCRE2_ERROR_BADMODE
 
-       This error is given when a compiled pattern is passed to a function  in
-       a  library  of a different code unit width, for example, a pattern com-
-       piled by the 8-bit library is passed to  a  16-bit  or  32-bit  library
+       This  error is given when a compiled pattern is passed to a function in
+       a library of a different code unit width, for example, a  pattern  com-
+       piled  by  the  8-bit  library  is passed to a 16-bit or 32-bit library
        function.
 
          PCRE2_ERROR_BADOFFSET
@@ -2958,15 +2988,15 @@ ERROR RETURNS FROM pcre2_match()
          PCRE2_ERROR_BADUTFOFFSET
 
        The UTF code unit sequence that was passed as a subject was checked and
-       found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but  the
-       value  of startoffset did not point to the beginning of a UTF character
+       found  to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
+       value of startoffset did not point to the beginning of a UTF  character
        or the end of the subject.
 
          PCRE2_ERROR_CALLOUT
 
-       This error is never generated by pcre2_match() itself. It  is  provided
-       for  use  by  callout  functions  that  want  to cause pcre2_match() or
-       pcre2_callout_enumerate() to return a distinctive error code.  See  the
+       This  error  is never generated by pcre2_match() itself. It is provided
+       for use by callout  functions  that  want  to  cause  pcre2_match()  or
+       pcre2_callout_enumerate()  to  return a distinctive error code. See the
        pcre2callout documentation for details.
 
          PCRE2_ERROR_DEPTHLIMIT
@@ -2979,14 +3009,14 @@ ERROR RETURNS FROM pcre2_match()
 
          PCRE2_ERROR_INTERNAL
 
-       An  unexpected  internal error has occurred. This error could be caused
+       An unexpected internal error has occurred. This error could  be  caused
        by a bug in PCRE2 or by overwriting of the compiled pattern.
 
          PCRE2_ERROR_JIT_STACKLIMIT
 
        This error is returned when a pattern that was successfully studied us-
        ing JIT is being matched, but the memory available for the just-in-time
-       processing stack is not large enough. See  the  pcre2jit  documentation
+       processing  stack  is  not large enough. See the pcre2jit documentation
        for more details.
 
          PCRE2_ERROR_MATCHLIMIT
@@ -2995,11 +3025,11 @@ ERROR RETURNS FROM pcre2_match()
 
          PCRE2_ERROR_NOMEMORY
 
-       If  a  pattern contains many nested backtracking points, heap memory is
-       used to remember them. This error is given when the  memory  allocation
-       function  (default  or  custom)  fails.  Note  that  a different error,
-       PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed  exceeds
-       the    heap   limit.   PCRE2_ERROR_NOMEMORY   is   also   returned   if
+       If a pattern contains many nested backtracking points, heap  memory  is
+       used  to  remember them. This error is given when the memory allocation
+       function (default or  custom)  fails.  Note  that  a  different  error,
+       PCRE2_ERROR_HEAPLIMIT,  is given if the amount of memory needed exceeds
+       the   heap   limit.   PCRE2_ERROR_NOMEMORY   is   also   returned    if
        PCRE2_COPY_MATCHED_SUBJECT is set and memory allocation fails.
 
          PCRE2_ERROR_NULL
@@ -3008,12 +3038,12 @@ ERROR RETURNS FROM pcre2_match()
 
          PCRE2_ERROR_RECURSELOOP
 
-       This error is returned when  pcre2_match()  detects  a  recursion  loop
-       within  the  pattern. Specifically, it means that either the whole pat-
+       This  error  is  returned  when  pcre2_match() detects a recursion loop
+       within the pattern. Specifically, it means that either the  whole  pat-
        tern or a capture group has been called recursively for the second time
-       at  the  same position in the subject string. Some simple patterns that
-       might do this are detected and faulted at compile time, but  more  com-
-       plicated  cases,  in particular mutual recursions between two different
+       at the same position in the subject string. Some simple  patterns  that
+       might  do  this are detected and faulted at compile time, but more com-
+       plicated cases, in particular mutual recursions between  two  different
        groups, cannot be detected until matching is attempted.
 
 
@@ -3022,20 +3052,20 @@ OBTAINING A TEXTUAL ERROR MESSAGE
        int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer,
          PCRE2_SIZE bufflen);
 
-       A text message for an error code  from  any  PCRE2  function  (compile,
-       match,  or  auxiliary)  can be obtained by calling pcre2_get_error_mes-
-       sage(). The code is passed as the first argument,  with  the  remaining
-       two  arguments  specifying  a  code  unit buffer and its length in code
-       units, into which the text message is placed. The message  is  returned
-       in  code  units  of the appropriate width for the library that is being
+       A  text  message  for  an  error code from any PCRE2 function (compile,
+       match, or auxiliary) can be obtained  by  calling  pcre2_get_error_mes-
+       sage().  The  code  is passed as the first argument, with the remaining
+       two arguments specifying a code unit buffer  and  its  length  in  code
+       units,  into  which the text message is placed. The message is returned
+       in code units of the appropriate width for the library  that  is  being
        used.
 
-       The returned message is terminated with a trailing zero, and the  func-
-       tion  returns  the  number  of  code units used, excluding the trailing
+       The  returned message is terminated with a trailing zero, and the func-
+       tion returns the number of code  units  used,  excluding  the  trailing
        zero. If the error number is unknown, the negative error code PCRE2_ER-
-       ROR_BADDATA  is  returned.  If  the buffer is too small, the message is
+       ROR_BADDATA is returned. If the buffer is too  small,  the  message  is
        truncated (but still with a trailing zero), and the negative error code
-       PCRE2_ERROR_NOMEMORY  is returned.  None of the messages are very long;
+       PCRE2_ERROR_NOMEMORY is returned.  None of the messages are very  long;
        a buffer size of 120 code units is ample.
 
 
@@ -3054,39 +3084,39 @@ EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
 
        void pcre2_substring_free(PCRE2_UCHAR *buffer);
 
-       Captured substrings can be accessed directly by using  the  ovector  as
+       Captured  substrings  can  be accessed directly by using the ovector as
        described above.  For convenience, auxiliary functions are provided for
-       extracting  captured  substrings  as  new,  separate,   zero-terminated
+       extracting   captured  substrings  as  new,  separate,  zero-terminated
        strings. 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
+       and  has  a  further  zero  added on the end, but the result is not, of
        course, a C string.
 
        The functions in this section identify substrings by number. The number
        zero refers to the entire matched substring, with higher numbers refer-
-       ring  to  substrings  captured by parenthesized groups. After a partial
-       match, only substring zero is available.  An  attempt  to  extract  any
-       other  substring  gives the error PCRE2_ERROR_PARTIAL. The next section
+       ring to substrings captured by parenthesized groups.  After  a  partial
+       match,  only  substring  zero  is  available. An attempt to extract any
+       other substring gives the error PCRE2_ERROR_PARTIAL. The  next  section
        describes similar functions for extracting captured substrings by name.
 
-       If a pattern uses the \K escape sequence within a  positive  assertion,
+       If  a  pattern uses the \K escape sequence within a positive assertion,
        the reported start of a successful match can be greater than the end of
-       the match.  For example, if the pattern  (?=ab\K)  is  matched  against
-       "ab",  the  start  and  end offset values for the match are 2 and 0. In
-       this situation, calling these functions with a  zero  substring  number
+       the  match.   For  example,  if the pattern (?=ab\K) is matched against
+       "ab", the start and end offset values for the match are  2  and  0.  In
+       this  situation,  calling  these functions with a zero substring number
        extracts a zero-length empty string.
 
-       You  can  find the length in code units of a captured substring without
-       extracting it by calling pcre2_substring_length_bynumber().  The  first
-       argument  is a pointer to the match data block, the second is the group
-       number, and the third is a pointer to a variable into which the  length
-       is  placed.  If  you just want to know whether or not the substring has
+       You can find the length in code units of a captured  substring  without
+       extracting  it  by calling pcre2_substring_length_bynumber(). The first
+       argument is a pointer to the match data block, the second is the  group
+       number,  and the third is a pointer to a variable into which the length
+       is placed. If you just want to know whether or not  the  substring  has
        been captured, you can pass the third argument as NULL.
 
-       The pcre2_substring_copy_bynumber() function  copies  a  captured  sub-
-       string  into  a supplied buffer, whereas pcre2_substring_get_bynumber()
-       copies it into new memory, obtained using the  same  memory  allocation
-       function  that  was  used for the match data block. The first two argu-
-       ments of these functions are a pointer to the match data  block  and  a
+       The  pcre2_substring_copy_bynumber()  function  copies  a captured sub-
+       string into a supplied buffer,  whereas  pcre2_substring_get_bynumber()
+       copies  it  into  new memory, obtained using the same memory allocation
+       function that was used for the match data block. The  first  two  argu-
+       ments  of  these  functions are a pointer to the match data block and a
        capture group number.
 
        The final arguments of pcre2_substring_copy_bynumber() are a pointer to
@@ -3095,25 +3125,25 @@ EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
        for the extracted substring, excluding the terminating zero.
 
        For pcre2_substring_get_bynumber() the third and fourth arguments point
-       to  variables that are updated with a pointer to the new memory and the
-       number of code units that comprise the substring, again  excluding  the
-       terminating  zero.  When  the substring is no longer needed, the memory
+       to variables that are updated with a pointer to the new memory and  the
+       number  of  code units that comprise the substring, again excluding the
+       terminating zero. When the substring is no longer  needed,  the  memory
        should be freed by calling pcre2_substring_free().
 
-       The return value from all these functions is zero  for  success,  or  a
-       negative  error  code.  If  the pattern match failed, the match failure
-       code is returned.  If a substring number greater than zero is used  af-
-       ter  a  partial  match, PCRE2_ERROR_PARTIAL is returned. Other possible
+       The  return  value  from  all these functions is zero for success, or a
+       negative error code. If the pattern match  failed,  the  match  failure
+       code  is returned.  If a substring number greater than zero is used af-
+       ter a partial match, PCRE2_ERROR_PARTIAL is  returned.  Other  possible
        error codes are:
 
          PCRE2_ERROR_NOMEMORY
 
-       The buffer was too small for  pcre2_substring_copy_bynumber(),  or  the
+       The  buffer  was  too small for pcre2_substring_copy_bynumber(), or the
        attempt to get memory failed for pcre2_substring_get_bynumber().
 
          PCRE2_ERROR_NOSUBSTRING
 
-       There  is  no  substring  with that number in the pattern, that is, the
+       There is no substring with that number in the  pattern,  that  is,  the
        number is greater than the number of capturing parentheses.
 
          PCRE2_ERROR_UNAVAILABLE
@@ -3124,8 +3154,8 @@ EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
 
          PCRE2_ERROR_UNSET
 
-       The substring did not participate in the match.  For  example,  if  the
-       pattern  is  (abc)|(def) and the subject is "def", and the ovector con-
+       The  substring  did  not  participate in the match. For example, if the
+       pattern is (abc)|(def) and the subject is "def", and the  ovector  con-
        tains at least two capturing slots, substring number 1 is unset.
 
 
@@ -3136,31 +3166,31 @@ EXTRACTING A LIST OF ALL CAPTURED SUBSTRINGS
 
        void pcre2_substring_list_free(PCRE2_SPTR *list);
 
-       The pcre2_substring_list_get() function  extracts  all  available  sub-
-       strings  and  builds  a  list of pointers to them. It also (optionally)
-       builds a second list that contains their lengths (in code  units),  ex-
-       cluding  a  terminating zero that is added to each of them. All this is
+       The  pcre2_substring_list_get()  function  extracts  all available sub-
+       strings and builds a list of pointers to  them.  It  also  (optionally)
+       builds  a  second list that contains their lengths (in code units), ex-
+       cluding a terminating zero that is added to each of them. All  this  is
        done in a single block of memory that is obtained using the same memory
        allocation function that was used to get the match data block.
 
-       This  function  must be called only after a successful match. If called
+       This function must be called only after a successful match.  If  called
        after a partial match, the error code PCRE2_ERROR_PARTIAL is returned.
 
-       The address of the memory block is returned via listptr, which is  also
+       The  address 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 pointer. The address of the list of lengths is  returned  via
-       lengthsptr.  If your strings do not contain binary zeros and you do not
+       by  a  NULL pointer. The address of the list of lengths is returned via
+       lengthsptr. If your strings do not contain binary zeros and you do  not
        therefore need the lengths, you may supply NULL as the lengthsptr argu-
-       ment  to  disable  the  creation of a list of lengths. The yield of the
-       function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the  mem-
-       ory  block could not be obtained. When the list is no longer needed, it
+       ment to disable the creation of a list of lengths.  The  yield  of  the
+       function  is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
+       ory block could not be obtained. When the list is no longer needed,  it
        should be freed by calling pcre2_substring_list_free().
 
        If this function encounters a substring that is unset, which can happen
-       when  capture  group  number  n+1 matches some part of the subject, but
-       group n has not been used at all, it returns an empty string. This  can
+       when capture group number n+1 matches some part  of  the  subject,  but
+       group  n has not been used at all, it returns an empty string. This can
        be distinguished from a genuine zero-length substring by inspecting the
-       appropriate offset in the ovector, which contain PCRE2_UNSET for  unset
+       appropriate  offset in the ovector, which contain PCRE2_UNSET for unset
        substrings, or by calling pcre2_substring_length_bynumber().
 
 
@@ -3180,7 +3210,7 @@ EXTRACTING CAPTURED SUBSTRINGS BY NAME
 
        void pcre2_substring_free(PCRE2_UCHAR *buffer);
 
-       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(?\d+)...
@@ -3188,32 +3218,32 @@ EXTRACTING CAPTURED SUBSTRINGS BY NAME
        the number of the capture group called "xxx" is 2. If the name is known
        to be unique (PCRE2_DUPNAMES was not set), you can find the number from
        the name by calling pcre2_substring_number_from_name(). The first argu-
-       ment  is the compiled pattern, and the second is the name. The yield of
-       the function is the group number, PCRE2_ERROR_NOSUBSTRING if  there  is
-       no  group  with that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if there is
-       more than one group with that name.  Given the number, you can  extract
-       the  substring  directly from the ovector, or use one of the "bynumber"
+       ment is the compiled pattern, and the second is the name. The yield  of
+       the  function  is the group number, PCRE2_ERROR_NOSUBSTRING if there is
+       no group with that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if  there  is
+       more  than one group with that name.  Given the number, you can extract
+       the substring directly from the ovector, or use one of  the  "bynumber"
        functions described above.
 
-       For convenience, there are also "byname" functions that  correspond  to
+       For  convenience,  there are also "byname" functions that correspond to
        the "bynumber" functions, the only difference being that the second ar-
-       gument is a name instead of a number.  If  PCRE2_DUPNAMES  is  set  and
+       gument  is  a  name  instead  of a number. If PCRE2_DUPNAMES is set and
        there are duplicate names, these functions scan all the groups with the
-       given name, and return the captured  substring  from  the  first  named
+       given  name,  and  return  the  captured substring from the first named
        group that is set.
 
-       If  there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
-       returned. If all groups with the name have  numbers  that  are  greater
+       If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING  is
+       returned.  If  all  groups  with the name have numbers that are greater
        than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is re-
-       turned. If there is at least one group with a slot in the ovector,  but
+       turned.  If there is at least one group with a slot in the ovector, but
        no group is found to be set, PCRE2_ERROR_UNSET is returned.
 
        Warning: If the pattern uses the (?| feature to set up multiple capture
-       groups with the same number, as described in the section  on  duplicate
+       groups  with  the same number, as described in the section on duplicate
        group numbers in the pcre2pattern page, you cannot use names to distin-
-       guish the different capture groups, because names are not  included  in
-       the  compiled  code.  The  matching process uses only numbers. For this
-       reason, the use of different names for  groups  with  the  same  number
+       guish  the  different capture groups, because names are not included in
+       the compiled code. The matching process uses  only  numbers.  For  this
+       reason,  the  use  of  different  names for groups with the same number
        causes an error at compile time.
 
 
@@ -3226,126 +3256,126 @@ CREATING A NEW STRING WITH SUBSTITUTIONS
          PCRE2_SIZE rlength, PCRE2_UCHAR *outputbuffer,
          PCRE2_SIZE *outlengthptr);
 
-       This  function  optionally calls pcre2_match() and then makes a copy of
-       the subject string in outputbuffer, replacing parts that  were  matched
-       with  the replacement string, whose length is supplied in rlength. This
-       can be given as PCRE2_ZERO_TERMINATED  for  a  zero-terminated  string.
+       This function optionally calls pcre2_match() and then makes a  copy  of
+       the  subject  string in outputbuffer, replacing parts that were matched
+       with the replacement string, whose length is supplied in rlength.  This
+       can  be  given  as  PCRE2_ZERO_TERMINATED for a zero-terminated string.
        There is an option (see PCRE2_SUBSTITUTE_REPLACEMENT_ONLY below) to re-
-       turn just the replacement string(s). The default action is  to  perform
-       just  one  replacement  if  the pattern matches, but there is an option
-       that requests multiple replacements  (see  PCRE2_SUBSTITUTE_GLOBAL  be-
+       turn  just  the replacement string(s). The default action is to perform
+       just one replacement if the pattern matches, but  there  is  an  option
+       that  requests  multiple  replacements (see PCRE2_SUBSTITUTE_GLOBAL be-
        low).
 
-       If  successful,  pcre2_substitute() returns the number of substitutions
-       that were carried out. This may be zero if no match was found,  and  is
-       never  greater  than one unless PCRE2_SUBSTITUTE_GLOBAL is set. A nega-
+       If successful, pcre2_substitute() returns the number  of  substitutions
+       that  were  carried out. This may be zero if no match was found, and is
+       never greater than one unless PCRE2_SUBSTITUTE_GLOBAL is set.  A  nega-
        tive value is returned if an error is detected.
 
-       Matches in which a \K item in a lookahead in  the  pattern  causes  the
-       match  to  end  before it starts are not supported, and give rise to an
+       Matches  in  which  a  \K item in a lookahead in the pattern causes the
+       match to end before it starts are not supported, and give  rise  to  an
        error return. For global replacements, matches in which \K in a lookbe-
-       hind  causes the match to start earlier than the point that was reached
+       hind causes the match to start earlier than the point that was  reached
        in the previous iteration are also not supported.
 
-       The first seven arguments of pcre2_substitute() are  the  same  as  for
+       The  first  seven  arguments  of pcre2_substitute() are the same as for
        pcre2_match(), except that the partial matching options are not permit-
-       ted, and match_data may be passed as NULL, in which case a  match  data
-       block  is obtained and freed within this function, using memory manage-
-       ment functions from the match context, if provided, or else those  that
+       ted,  and  match_data may be passed as NULL, in which case a match data
+       block is obtained and freed within this function, using memory  manage-
+       ment  functions from the match context, if provided, or else those that
        were used to allocate memory for the compiled code.
 
-       If  match_data is not NULL and PCRE2_SUBSTITUTE_MATCHED is not set, the
+       If match_data is not NULL and PCRE2_SUBSTITUTE_MATCHED is not set,  the
        provided block is used for all calls to pcre2_match(), and its contents
-       afterwards  are  the result of the final call. For global changes, this
+       afterwards are the result of the final call. For global  changes,  this
        will always be a no-match error. The contents of the ovector within the
        match data block may or may not have been changed.
 
-       As  well as the usual options for pcre2_match(), a number of additional
-       options can be set in the options argument of pcre2_substitute().   One
-       such  option is PCRE2_SUBSTITUTE_MATCHED. When this is set, an external
-       match_data block must be provided, and it must have been  used  for  an
-       external  call  to pcre2_match(). The data in the match_data block (re-
+       As well as the usual options for pcre2_match(), a number of  additional
+       options  can be set in the options argument of pcre2_substitute().  One
+       such option is PCRE2_SUBSTITUTE_MATCHED. When this is set, an  external
+       match_data  block  must  be provided, and it must have been used for an
+       external call to pcre2_match(). The data in the match_data  block  (re-
        turn code, offset vector) is used for the first substitution instead of
-       calling  pcre2_match()  from  within pcre2_substitute(). This allows an
+       calling pcre2_match() from within pcre2_substitute().  This  allows  an
        application to check for a match before choosing to substitute, without
        having to repeat the match.
 
-       The  contents  of  the  externally  supplied  match  data block are not
-       changed  when  PCRE2_SUBSTITUTE_MATCHED  is   set.   If   PCRE2_SUBSTI-
-       TUTE_GLOBAL  is  also set, pcre2_match() is called after the first sub-
-       stitution to check for further matches, but this is done using  an  in-
-       ternally  obtained  match  data block, thus always leaving the external
+       The contents of the  externally  supplied  match  data  block  are  not
+       changed   when   PCRE2_SUBSTITUTE_MATCHED   is  set.  If  PCRE2_SUBSTI-
+       TUTE_GLOBAL is also set, pcre2_match() is called after the  first  sub-
+       stitution  to  check for further matches, but this is done using an in-
+       ternally obtained match data block, thus always  leaving  the  external
        block unchanged.
 
-       The code argument is not used for matching before the  first  substitu-
-       tion  when  PCRE2_SUBSTITUTE_MATCHED  is  set, but it must be provided,
-       even when PCRE2_SUBSTITUTE_GLOBAL is not set, because it  contains  in-
+       The  code  argument is not used for matching before the first substitu-
+       tion when PCRE2_SUBSTITUTE_MATCHED is set, but  it  must  be  provided,
+       even  when  PCRE2_SUBSTITUTE_GLOBAL is not set, because it contains in-
        formation such as the UTF setting and the number of capturing parenthe-
        ses in the pattern.
 
-       The default action of pcre2_substitute() is to return  a  copy  of  the
+       The  default  action  of  pcre2_substitute() is to return a copy of the
        subject string with matched substrings replaced. However, if PCRE2_SUB-
-       STITUTE_REPLACEMENT_ONLY is set, only the  replacement  substrings  are
+       STITUTE_REPLACEMENT_ONLY  is  set,  only the replacement substrings are
        returned. In the global case, multiple replacements are concatenated in
-       the output buffer. Substitution callouts (see below)  can  be  used  to
+       the  output  buffer.  Substitution  callouts (see below) can be used to
        separate them if necessary.
 
-       The  outlengthptr  argument of pcre2_substitute() must point to a vari-
-       able that contains the length, in code units, of the output buffer.  If
-       the  function is successful, the value is updated to contain the length
-       in code units of the new string, excluding the trailing  zero  that  is
+       The outlengthptr argument of pcre2_substitute() must point to  a  vari-
+       able  that contains the length, in code units, of the output buffer. If
+       the function is successful, the value is updated to contain the  length
+       in  code  units  of the new string, excluding the trailing zero that is
        automatically added.
 
-       If  the  function is not successful, the value set via outlengthptr de-
-       pends on the type of  error.  For  syntax  errors  in  the  replacement
+       If the function is not successful, the value set via  outlengthptr  de-
+       pends  on  the  type  of  error.  For  syntax errors in the replacement
        string, the value is the offset in the replacement string where the er-
-       ror was detected. For other errors, the value  is  PCRE2_UNSET  by  de-
+       ror  was  detected.  For  other errors, the value is PCRE2_UNSET by de-
        fault. This includes the case of the output buffer being too small, un-
        less PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set.
 
-       PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when  the  output
+       PCRE2_SUBSTITUTE_OVERFLOW_LENGTH  changes  what happens when the output
        buffer is too small. The default action is to return PCRE2_ERROR_NOMEM-
-       ORY immediately. If this option  is  set,  however,  pcre2_substitute()
+       ORY  immediately.  If  this  option is set, however, pcre2_substitute()
        continues to go through the motions of matching and substituting (with-
-       out, of course, writing anything) in order to compute the size of  buf-
-       fer  that  is  needed.  This  value is passed back via the outlengthptr
-       variable, with  the  result  of  the  function  still  being  PCRE2_ER-
+       out,  of course, writing anything) in order to compute the size of buf-
+       fer that is needed. This value is  passed  back  via  the  outlengthptr
+       variable,  with  the  result  of  the  function  still  being PCRE2_ER-
        ROR_NOMEMORY.
 
-       Passing  a  buffer  size  of zero is a permitted way of finding out how
-       much memory is needed for given substitution. However, this  does  mean
+       Passing a buffer size of zero is a permitted way  of  finding  out  how
+       much  memory  is needed for given substitution. However, this does mean
        that the entire operation is carried out twice. Depending on the appli-
-       cation, it may be more efficient to allocate a large  buffer  and  free
-       the   excess   afterwards,   instead  of  using  PCRE2_SUBSTITUTE_OVER-
+       cation,  it  may  be more efficient to allocate a large buffer and free
+       the  excess  afterwards,  instead   of   using   PCRE2_SUBSTITUTE_OVER-
        FLOW_LENGTH.
 
-       The replacement string, which is interpreted as a  UTF  string  in  UTF
-       mode,  is checked for UTF validity unless PCRE2_NO_UTF_CHECK is set. An
+       The  replacement  string,  which  is interpreted as a UTF string in UTF
+       mode, is checked for UTF validity unless PCRE2_NO_UTF_CHECK is set.  An
        invalid UTF replacement string causes an immediate return with the rel-
        evant UTF error code.
 
-       If  PCRE2_SUBSTITUTE_LITERAL  is set, the replacement string is not in-
+       If PCRE2_SUBSTITUTE_LITERAL is set, the replacement string is  not  in-
        terpreted in any way. By default, however, a dollar character is an es-
-       cape  character  that can specify the insertion of characters from cap-
-       ture groups and names from (*MARK) or other control verbs in  the  pat-
+       cape character that can specify the insertion of characters  from  cap-
+       ture  groups  and names from (*MARK) or other control verbs in the pat-
        tern. The following forms are always recognized:
 
          $$                  insert a dollar character
          $ or ${}      insert the contents of group 
          $*MARK or ${*MARK}  insert a control verb name
 
-       Either  a  group  number  or  a  group name can be given for . Curly
-       brackets are required only if the following character would  be  inter-
+       Either a group number or a group name  can  be  given  for  .  Curly
+       brackets  are  required only if the following character would be inter-
        preted as part of the number or name. The number may be zero to include
-       the entire matched string.   For  example,  if  the  pattern  a(b)c  is
-       matched  with "=abc=" and the replacement string "+$1$0$1+", the result
+       the  entire  matched  string.   For  example,  if  the pattern a(b)c is
+       matched with "=abc=" and the replacement string "+$1$0$1+", the  result
        is "=+babcb+=".
 
-       $*MARK inserts the name from the last encountered backtracking  control
-       verb  on the matching path that has a name. (*MARK) must always include
-       a name, but the other verbs need not.  For  example,  in  the  case  of
+       $*MARK  inserts the name from the last encountered backtracking control
+       verb on the matching path that has a name. (*MARK) must always  include
+       a  name,  but  the  other  verbs  need not. For example, in the case of
        (*MARK:A)(*PRUNE) the name inserted is "A", but for (*MARK:A)(*PRUNE:B)
-       the relevant name is "B". This facility can be used to  perform  simple
+       the  relevant  name is "B". This facility can be used to perform simple
        simultaneous substitutions, as this pcre2test example shows:
 
          /(*MARK:pear)apple|(*MARK:orange)lemon/g,replace=${*MARK}
@@ -3353,15 +3383,15 @@ CREATING A NEW STRING WITH SUBSTITUTIONS
           2: pear orange
 
        PCRE2_SUBSTITUTE_GLOBAL causes the function to iterate over the subject
-       string, replacing every matching substring. If this option is not  set,
-       only  the  first matching substring is replaced. The search for matches
-       takes place in the original subject string (that is, previous  replace-
-       ments  do  not  affect  it).  Iteration is implemented by advancing the
-       startoffset value for each search, which is always  passed  the  entire
+       string,  replacing every matching substring. If this option is not set,
+       only the first matching substring is replaced. The search  for  matches
+       takes  place in the original subject string (that is, previous replace-
+       ments do not affect it).  Iteration is  implemented  by  advancing  the
+       startoffset  value  for  each search, which is always passed the entire
        subject string. If an offset limit is set in the match context, search-
        ing stops when that limit is reached.
 
-       You can restrict the effect of a global substitution to  a  portion  of
+       You  can  restrict  the effect of a global substitution to a portion of
        the subject string by setting either or both of startoffset and an off-
        set limit. Here is a pcre2test example:
 
@@ -3369,73 +3399,73 @@ CREATING A NEW STRING WITH SUBSTITUTIONS
          ABC ABC ABC ABC\=offset=3,offset_limit=12
           2: ABC A!C A!C ABC
 
-       When continuing with global substitutions after  matching  a  substring
+       When  continuing  with  global substitutions after matching a substring
        with zero length, an attempt to find a non-empty match at the same off-
        set is performed.  If this is not successful, the offset is advanced by
        one character except when CRLF is a valid newline sequence and the next
-       two characters are CR, LF. In this case, the offset is advanced by  two
+       two  characters are CR, LF. In this case, the offset is advanced by two
        characters.
 
        PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capture groups that
        do not appear in the pattern to be treated as unset groups. This option
-       should  be used with care, because it means that a typo in a group name
+       should be used with care, because it means that a typo in a group  name
        or number no longer causes the PCRE2_ERROR_NOSUBSTRING error.
 
        PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capture groups (including un-
-       known  groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be treated
-       as empty strings when inserted as described above. If  this  option  is
+       known groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be  treated
+       as  empty  strings  when inserted as described above. If this option is
        not set, an attempt to insert an unset group causes the PCRE2_ERROR_UN-
-       SET error. This option does not  influence  the  extended  substitution
+       SET  error.  This  option  does not influence the extended substitution
        syntax described below.
 
-       PCRE2_SUBSTITUTE_EXTENDED  causes extra processing to be applied to the
-       replacement string. Without this option, only the dollar  character  is
-       special,  and  only  the  group insertion forms listed above are valid.
+       PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to  the
+       replacement  string.  Without this option, only the dollar character is
+       special, and only the group insertion forms  listed  above  are  valid.
        When PCRE2_SUBSTITUTE_EXTENDED is set, two things change:
 
-       Firstly, backslash in a replacement string is interpreted as an  escape
+       Firstly,  backslash in a replacement string is interpreted as an escape
        character. The usual forms such as \n or \x{ddd} can be used to specify
-       particular character codes, and backslash followed by any  non-alphanu-
-       meric  character  quotes  that character. Extended quoting can be coded
+       particular  character codes, and backslash followed by any non-alphanu-
+       meric character quotes that character. Extended quoting  can  be  coded
        using \Q...\E, exactly as in pattern strings.
 
-       There are also four escape sequences for forcing the case  of  inserted
-       letters.   The  insertion  mechanism has three states: no case forcing,
+       There  are  also four escape sequences for forcing the case of inserted
+       letters.  The insertion mechanism has three states:  no  case  forcing,
        force upper case, and force lower case. The escape sequences change the
        current state: \U and \L change to upper or lower case forcing, respec-
-       tively, and \E (when not terminating a \Q quoted sequence)  reverts  to
-       no  case  forcing. The sequences \u and \l force the next character (if
-       it is a letter) to upper or lower  case,  respectively,  and  then  the
+       tively,  and  \E (when not terminating a \Q quoted sequence) reverts to
+       no case forcing. The sequences \u and \l force the next  character  (if
+       it  is  a  letter)  to  upper or lower case, respectively, and then the
        state automatically reverts to no case forcing. Case forcing applies to
-       all inserted  characters, including those from capture groups and  let-
-       ters  within \Q...\E quoted sequences. If either PCRE2_UTF or PCRE2_UCP
-       was set when the pattern was compiled, Unicode properties are used  for
+       all  inserted  characters, including those from capture groups and let-
+       ters within \Q...\E quoted sequences. If either PCRE2_UTF or  PCRE2_UCP
+       was  set when the pattern was compiled, Unicode properties are used for
        case forcing characters whose code points are greater than 127.
 
        Note that case forcing sequences such as \U...\E do not nest. For exam-
-       ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc";  the  final
-       \E  has  no  effect.  Note  also  that the PCRE2_ALT_BSUX and PCRE2_EX-
+       ple,  the  result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
+       \E has no effect. Note  also  that  the  PCRE2_ALT_BSUX  and  PCRE2_EX-
        TRA_ALT_BSUX options do not apply to replacement strings.
 
-       The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to  add  more
-       flexibility  to  capture  group  substitution. The syntax is similar to
+       The  second  effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
+       flexibility to capture group substitution. The  syntax  is  similar  to
        that used by Bash:
 
          ${:-}
          ${:+:}
 
-       As before,  may be a group number or a name. The first  form  speci-
-       fies  a  default  value. If group  is set, its value is inserted; if
-       not,  is expanded and the  result  inserted.  The  second  form
-       specifies  strings that are expanded and inserted when group  is set
-       or unset, respectively. The first form is just a  convenient  shorthand
+       As  before,   may be a group number or a name. The first form speci-
+       fies a default value. If group  is set, its value  is  inserted;  if
+       not,    is  expanded  and  the result inserted. The second form
+       specifies strings that are expanded and inserted when group  is  set
+       or  unset,  respectively. The first form is just a convenient shorthand
        for
 
          ${:+${}:}
 
-       Backslash  can  be  used to escape colons and closing curly brackets in
-       the replacement strings. A change of the case forcing  state  within  a
-       replacement  string  remains  in  force  afterwards,  as  shown in this
+       Backslash can be used to escape colons and closing  curly  brackets  in
+       the  replacement  strings.  A change of the case forcing state within a
+       replacement string remains  in  force  afterwards,  as  shown  in  this
        pcre2test example:
 
          /(some)?(body)/substitute_extended,replace=${1:+\U:\L}HeLLo
@@ -3444,8 +3474,8 @@ CREATING A NEW STRING WITH SUBSTITUTIONS
              somebody
           1: HELLO
 
-       The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these  extended
-       substitutions.  However,  PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause un-
+       The  PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
+       substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does  cause  un-
        known groups in the extended syntax forms to be treated as unset.
 
        If  PCRE2_SUBSTITUTE_LITERAL  is  set,  PCRE2_SUBSTITUTE_UNKNOWN_UNSET,
@@ -3454,37 +3484,37 @@ CREATING A NEW STRING WITH SUBSTITUTIONS
 
    Substitution errors
 
-       In the event of an error, pcre2_substitute() returns a  negative  error
-       code.  Except for PCRE2_ERROR_NOMATCH (which is never returned), errors
+       In  the  event of an error, pcre2_substitute() returns a negative error
+       code. Except for PCRE2_ERROR_NOMATCH (which is never returned),  errors
        from pcre2_match() are passed straight back.
 
        PCRE2_ERROR_NOSUBSTRING is returned for a non-existent substring inser-
        tion, unless PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set.
 
        PCRE2_ERROR_UNSET is returned for an unset substring insertion (includ-
-       ing an unknown substring when  PCRE2_SUBSTITUTE_UNKNOWN_UNSET  is  set)
-       when  the simple (non-extended) syntax is used and PCRE2_SUBSTITUTE_UN-
+       ing  an  unknown  substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
+       when the simple (non-extended) syntax is used and  PCRE2_SUBSTITUTE_UN-
        SET_EMPTY is not set.
 
-       PCRE2_ERROR_NOMEMORY is returned  if  the  output  buffer  is  not  big
+       PCRE2_ERROR_NOMEMORY  is  returned  if  the  output  buffer  is not big
        enough. If the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set, the size
-       of buffer that is needed is returned via outlengthptr. Note  that  this
+       of  buffer  that is needed is returned via outlengthptr. Note that this
        does not happen by default.
 
        PCRE2_ERROR_NULL is returned if PCRE2_SUBSTITUTE_MATCHED is set but the
        match_data argument is NULL.
 
-       PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax  errors  in
-       the  replacement  string,  with  more particular errors being PCRE2_ER-
+       PCRE2_ERROR_BADREPLACEMENT  is  used for miscellaneous syntax errors in
+       the replacement string, with more  particular  errors  being  PCRE2_ER-
        ROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REPMISSINGBRACE
-       (closing  curly bracket not found), PCRE2_ERROR_BADSUBSTITUTION (syntax
-       error in extended group substitution),  and  PCRE2_ERROR_BADSUBSPATTERN
+       (closing curly bracket not found), PCRE2_ERROR_BADSUBSTITUTION  (syntax
+       error  in  extended group substitution), and PCRE2_ERROR_BADSUBSPATTERN
        (the pattern match ended before it started or the match started earlier
-       than the current position in the subject, which can  happen  if  \K  is
+       than  the  current  position  in the subject, which can happen if \K is
        used in an assertion).
 
        As for all PCRE2 errors, a text message that describes the error can be
-       obtained by calling the pcre2_get_error_message()  function  (see  "Ob-
+       obtained  by  calling  the pcre2_get_error_message() function (see "Ob-
        taining a textual error message" above).
 
    Substitution callouts
@@ -3493,15 +3523,15 @@ CREATING A NEW STRING WITH SUBSTITUTIONS
          int (*callout_function)(pcre2_substitute_callout_block *, void *),
          void *callout_data);
 
-       The  pcre2_set_substitution_callout() function can be used to specify a
-       callout function for pcre2_substitute(). This information is passed  in
+       The pcre2_set_substitution_callout() function can be used to specify  a
+       callout  function for pcre2_substitute(). This information is passed in
        a match context. The callout function is called after each substitution
        has been processed, but it can cause the replacement not to happen. The
-       callout  function is not called for simulated substitutions that happen
+       callout function is not called for simulated substitutions that  happen
        as a result of the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option.
 
        The first argument of the callout function is a pointer to a substitute
-       callout  block structure, which contains the following fields, not nec-
+       callout block structure, which contains the following fields, not  nec-
        essarily in this order:
 
          uint32_t    version;
@@ -3512,34 +3542,34 @@ CREATING A NEW STRING WITH SUBSTITUTIONS
          uint32_t    oveccount;
          PCRE2_SIZE  output_offsets[2];
 
-       The version field contains the version number of the block format.  The
-       current  version  is  0.  The version number will increase in future if
-       more fields are added, but the intention is never to remove any of  the
+       The  version field contains the version number of the block format. The
+       current version is 0. The version number will  increase  in  future  if
+       more  fields are added, but the intention is never to remove any of the
        existing fields.
 
        The subscount field is the number of the current match. It is 1 for the
        first callout, 2 for the second, and so on. The input and output point-
        ers are copies of the values passed to pcre2_substitute().
 
-       The  ovector  field points to the ovector, which contains the result of
+       The ovector field points to the ovector, which contains the  result  of
        the most recent match. The oveccount field contains the number of pairs
        that are set in the ovector, and is always greater than zero.
 
-       The  output_offsets  vector  contains the offsets of the replacement in
-       the output string. This has already been processed for dollar  and  (if
+       The output_offsets vector contains the offsets of  the  replacement  in
+       the  output  string. This has already been processed for dollar and (if
        requested) backslash substitutions as described above.
 
-       The  second  argument  of  the  callout function is the value passed as
-       callout_data when the function was registered. The  value  returned  by
+       The second argument of the callout function  is  the  value  passed  as
+       callout_data  when  the  function was registered. The value returned by
        the callout function is interpreted as follows:
 
-       If  the  value is zero, the replacement is accepted, and, if PCRE2_SUB-
-       STITUTE_GLOBAL is set, processing continues with a search for the  next
-       match.  If  the  value  is not zero, the current replacement is not ac-
-       cepted. If the value is greater than zero,  processing  continues  when
-       PCRE2_SUBSTITUTE_GLOBAL  is set. Otherwise (the value is less than zero
-       or PCRE2_SUBSTITUTE_GLOBAL is not set), the the rest of  the  input  is
-       copied  to the output and the call to pcre2_substitute() exits, return-
+       If the value is zero, the replacement is accepted, and,  if  PCRE2_SUB-
+       STITUTE_GLOBAL  is set, processing continues with a search for the next
+       match. If the value is not zero, the current  replacement  is  not  ac-
+       cepted.  If  the  value is greater than zero, processing continues when
+       PCRE2_SUBSTITUTE_GLOBAL is set. Otherwise (the value is less than  zero
+       or  PCRE2_SUBSTITUTE_GLOBAL  is  not set), the the rest of the input is
+       copied to the output and the call to pcre2_substitute() exits,  return-
        ing the number of matches so far.
 
 
@@ -3548,56 +3578,56 @@ DUPLICATE CAPTURE GROUP NAMES
        int pcre2_substring_nametable_scan(const pcre2_code *code,
          PCRE2_SPTR name, PCRE2_SPTR *first, PCRE2_SPTR *last);
 
-       When a pattern is compiled with the PCRE2_DUPNAMES  option,  names  for
-       capture  groups  are not required to be unique. Duplicate names are al-
-       ways allowed for groups with the same number, created by using the  (?|
+       When  a  pattern  is compiled with the PCRE2_DUPNAMES option, names for
+       capture groups are not required to be unique. Duplicate names  are  al-
+       ways  allowed for groups with the same number, created by using the (?|
        feature. Indeed, if such groups are named, they are required to use the
        same names.
 
-       Normally, patterns that use duplicate names are such that  in  any  one
-       match,  only  one of each set of identically-named groups participates.
+       Normally,  patterns  that  use duplicate names are such that in any one
+       match, only one of each set of identically-named  groups  participates.
        An example is shown in the pcre2pattern documentation.
 
-       When  duplicates   are   present,   pcre2_substring_copy_byname()   and
-       pcre2_substring_get_byname()  return  the first substring corresponding
-       to the given name that is set. Only if none are set is  PCRE2_ERROR_UN-
-       SET  is  returned.  The pcre2_substring_number_from_name() function re-
-       turns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are  duplicate
+       When   duplicates   are   present,   pcre2_substring_copy_byname()  and
+       pcre2_substring_get_byname() return the first  substring  corresponding
+       to  the given name that is set. Only if none are set is PCRE2_ERROR_UN-
+       SET is returned. The  pcre2_substring_number_from_name()  function  re-
+       turns  the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are duplicate
        names.
 
-       If  you want to get full details of all captured substrings for a given
-       name, you must use the pcre2_substring_nametable_scan()  function.  The
-       first  argument is the compiled pattern, and the second is the name. If
-       the third and fourth arguments are NULL, the function returns  a  group
+       If you want to get full details of all captured substrings for a  given
+       name,  you  must use the pcre2_substring_nametable_scan() function. The
+       first argument is the compiled pattern, and the second is the name.  If
+       the  third  and fourth arguments are NULL, the function returns a group
        number for a unique name, or PCRE2_ERROR_NOUNIQUESUBSTRING otherwise.
 
        When the third and fourth arguments are not NULL, they must be pointers
-       to variables that are updated by the function. After it has  run,  they
+       to  variables  that are updated by the function. After it has run, they
        point to the first and last entries in the name-to-number table for the
-       given name, and the function returns the length of each entry  in  code
-       units.  In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are
+       given  name,  and the function returns the length of each entry in code
+       units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there  are
        no entries for the given name.
 
        The format of the name table is described above in the section entitled
-       Information  about  a  pattern.  Given all the relevant entries for the
-       name, you can extract each of their numbers,  and  hence  the  captured
+       Information about a pattern. Given all the  relevant  entries  for  the
+       name,  you  can  extract  each of their numbers, and hence the captured
        data.
 
 
 FINDING ALL POSSIBLE MATCHES AT ONE POSITION
 
-       The  traditional  matching  function  uses a similar algorithm to Perl,
-       which stops when it finds the first match at a given point in the  sub-
+       The traditional matching function uses a  similar  algorithm  to  Perl,
+       which  stops when it finds the first match at a given point in the sub-
        ject. If you want to find all possible matches, or the longest possible
-       match at a given position,  consider  using  the  alternative  matching
-       function  (see  below) instead. If you cannot use the alternative func-
+       match  at  a  given  position,  consider using the alternative matching
+       function (see below) instead. If you cannot use the  alternative  func-
        tion, you can kludge it up by making use of the callout facility, which
        is described in the pcre2callout documentation.
 
        What you have to do is to insert a callout right at the end of the pat-
-       tern.  When your callout function is called, extract and save the  cur-
-       rent  matched  substring.  Then return 1, which forces pcre2_match() to
-       backtrack and try other alternatives. Ultimately, when it runs  out  of
+       tern.   When your callout function is called, extract and save the cur-
+       rent matched substring. Then return 1, which  forces  pcre2_match()  to
+       backtrack  and  try other alternatives. Ultimately, when it runs out of
        matches, pcre2_match() will yield PCRE2_ERROR_NOMATCH.
 
 
@@ -3609,26 +3639,26 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION
          pcre2_match_context *mcontext,
          int *workspace, PCRE2_SIZE wscount);
 
-       The  function  pcre2_dfa_match()  is  called  to match a subject string
-       against a compiled pattern, using a matching algorithm that  scans  the
+       The function pcre2_dfa_match() is called  to  match  a  subject  string
+       against  a  compiled pattern, using a matching algorithm that scans the
        subject string just once (not counting lookaround assertions), and does
-       not backtrack.  This has different characteristics to the normal  algo-
-       rithm,  and  is not compatible with Perl. Some of the features of PCRE2
-       patterns are not supported.  Nevertheless, there are  times  when  this
-       kind  of  matching  can be useful. For a discussion of the two matching
+       not  backtrack.  This has different characteristics to the normal algo-
+       rithm, and is not compatible with Perl. Some of the features  of  PCRE2
+       patterns  are  not  supported.  Nevertheless, there are times when this
+       kind of matching can be useful. For a discussion of  the  two  matching
        algorithms, and a list of features that pcre2_dfa_match() does not sup-
        port, see the pcre2matching documentation.
 
-       The  arguments  for  the pcre2_dfa_match() function are the same as for
+       The arguments for the pcre2_dfa_match() function are the  same  as  for
        pcre2_match(), plus two extras. The ovector within the match data block
        is used in a different way, and this is described below. The other com-
-       mon arguments are used in the same way as for pcre2_match(),  so  their
+       mon  arguments  are used in the same way as for pcre2_match(), so their
        description is not repeated here.
 
-       The  two  additional  arguments provide workspace for the function. The
-       workspace vector should contain at least 20 elements. It  is  used  for
+       The two additional arguments provide workspace for  the  function.  The
+       workspace  vector  should  contain at least 20 elements. It is used for
        keeping  track  of  multiple  paths  through  the  pattern  tree.  More
-       workspace is needed for patterns and subjects where there are a lot  of
+       workspace  is needed for patterns and subjects where there are a lot of
        potential matches.
 
        Here is an example of a simple call to pcre2_dfa_match():
@@ -3648,45 +3678,45 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION
 
    Option bits for pcre_dfa_match()
 
-       The  unused  bits of the options argument for pcre2_dfa_match() must be
-       zero.  The  only   bits   that   may   be   set   are   PCRE2_ANCHORED,
-       PCRE2_COPY_MATCHED_SUBJECT,  PCRE2_ENDANCHORED, PCRE2_NOTBOL, PCRE2_NO-
+       The unused bits of the options argument for pcre2_dfa_match()  must  be
+       zero.   The   only   bits   that   may   be   set  are  PCRE2_ANCHORED,
+       PCRE2_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL,  PCRE2_NO-
        TEOL,   PCRE2_NOTEMPTY,   PCRE2_NOTEMPTY_ATSTART,   PCRE2_NO_UTF_CHECK,
-       PCRE2_PARTIAL_HARD,    PCRE2_PARTIAL_SOFT,    PCRE2_DFA_SHORTEST,   and
-       PCRE2_DFA_RESTART. All but the last four of these are exactly the  same
+       PCRE2_PARTIAL_HARD,   PCRE2_PARTIAL_SOFT,    PCRE2_DFA_SHORTEST,    and
+       PCRE2_DFA_RESTART.  All but the last four of these are exactly the same
        as for pcre2_match(), so their description is not repeated here.
 
          PCRE2_PARTIAL_HARD
          PCRE2_PARTIAL_SOFT
 
-       These  have  the  same general effect as they do for pcre2_match(), but
-       the details are slightly different. When PCRE2_PARTIAL_HARD is set  for
-       pcre2_dfa_match(),  it  returns  PCRE2_ERROR_PARTIAL  if the end of the
+       These have the same general effect as they do  for  pcre2_match(),  but
+       the  details are slightly different. When PCRE2_PARTIAL_HARD is set for
+       pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if  the  end  of  the
        subject is reached and there is still at least one matching possibility
        that requires additional characters. This happens even if some complete
-       matches have already been found. When PCRE2_PARTIAL_SOFT  is  set,  the
-       return  code  PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
-       if the end of the subject is  reached,  there  have  been  no  complete
+       matches  have  already  been found. When PCRE2_PARTIAL_SOFT is set, the
+       return code PCRE2_ERROR_NOMATCH is converted  into  PCRE2_ERROR_PARTIAL
+       if  the  end  of  the  subject  is reached, there have been no complete
        matches, but there is still at least one matching possibility. The por-
-       tion of the string that was inspected when the  longest  partial  match
+       tion  of  the  string that was inspected when the longest partial match
        was found is set as the first matching string in both cases. There is a
-       more detailed discussion of partial and  multi-segment  matching,  with
+       more  detailed  discussion  of partial and multi-segment matching, with
        examples, in the pcre2partial documentation.
 
          PCRE2_DFA_SHORTEST
 
-       Setting  the PCRE2_DFA_SHORTEST option causes the matching algorithm to
+       Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm  to
        stop as soon as it has found one match. Because of the way the alterna-
-       tive  algorithm  works, this is necessarily the shortest possible match
+       tive algorithm works, this is necessarily the shortest  possible  match
        at the first possible matching point in the subject string.
 
          PCRE2_DFA_RESTART
 
-       When pcre2_dfa_match() returns a partial match, it is possible to  call
+       When  pcre2_dfa_match() returns a partial match, it is possible to call
        it again, with additional subject characters, and have it continue with
        the same match. The PCRE2_DFA_RESTART option requests this action; when
-       it  is  set,  the workspace and wscount options must reference the same
-       vector as before because data about the match so far is  left  in  them
+       it is set, the workspace and wscount options must  reference  the  same
+       vector  as  before  because data about the match so far is left in them
        after a partial match. There is more discussion of this facility in the
        pcre2partial documentation.
 
@@ -3694,8 +3724,8 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION
 
        When pcre2_dfa_match() succeeds, it may have matched more than one sub-
        string in the subject. Note, however, that all the matches from one run
-       of the function start at the same point in  the  subject.  The  shorter
-       matches  are all initial substrings of the longer matches. For example,
+       of  the  function  start  at the same point in the subject. The shorter
+       matches are all initial substrings of the longer matches. For  example,
        if the pattern
 
          <.*>
@@ -3710,80 +3740,80 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION
           
          
 
-       On success, the yield of the function is a number  greater  than  zero,
-       which  is  the  number  of  matched substrings. The offsets of the sub-
-       strings are returned in the ovector, and can be extracted by number  in
-       the  same way as for pcre2_match(), but the numbers bear no relation to
-       any capture groups that may exist in the pattern, because DFA  matching
+       On  success,  the  yield of the function is a number greater than zero,
+       which is the number of matched substrings.  The  offsets  of  the  sub-
+       strings  are returned in the ovector, and can be extracted by number in
+       the same way as for pcre2_match(), but the numbers bear no relation  to
+       any  capture groups that may exist in the pattern, because DFA matching
        does not support capturing.
 
-       Calls  to the convenience functions that extract substrings by name re-
+       Calls to the convenience functions that extract substrings by name  re-
        turn the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used af-
-       ter  a  DFA match. The convenience functions that extract substrings by
+       ter a DFA match. The convenience functions that extract  substrings  by
        number never return PCRE2_ERROR_NOSUBSTRING.
 
-       The matched strings are stored in  the  ovector  in  reverse  order  of
-       length;  that  is,  the longest matching string is first. If there were
-       too many matches to fit into the ovector, the yield of the function  is
+       The  matched  strings  are  stored  in  the ovector in reverse order of
+       length; that is, the longest matching string is first.  If  there  were
+       too  many matches to fit into the ovector, the yield of the function is
        zero, and the vector is filled with the longest matches.
 
-       NOTE:  PCRE2's  "auto-possessification" optimization usually applies to
-       character repeats at the end of a pattern (as well as internally).  For
-       example,  the pattern "a\d+" is compiled as if it were "a\d++". For DFA
-       matching, this means that only one possible match is found. If you  re-
+       NOTE: PCRE2's "auto-possessification" optimization usually  applies  to
+       character  repeats at the end of a pattern (as well as internally). For
+       example, the pattern "a\d+" is compiled as if it were "a\d++". For  DFA
+       matching,  this means that only one possible match is found. If you re-
        ally do want multiple matches in such cases, either use an ungreedy re-
-       peat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when  com-
+       peat  such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when com-
        piling.
 
    Error returns from pcre2_dfa_match()
 
        The pcre2_dfa_match() function returns a negative number when it fails.
-       Many of the errors are the same  as  for  pcre2_match(),  as  described
+       Many  of  the  errors  are  the same as for pcre2_match(), as described
        above.  There are in addition the following errors that are specific to
        pcre2_dfa_match():
 
          PCRE2_ERROR_DFA_UITEM
 
-       This return is given if pcre2_dfa_match() encounters  an  item  in  the
-       pattern  that it does not support, for instance, the use of \C in a UTF
+       This  return  is  given  if pcre2_dfa_match() encounters an item in the
+       pattern that it does not support, for instance, the use of \C in a  UTF
        mode or a backreference.
 
          PCRE2_ERROR_DFA_UCOND
 
-       This return is given if pcre2_dfa_match() encounters a  condition  item
+       This  return  is given if pcre2_dfa_match() encounters a condition item
        that uses a backreference for the condition, or a test for recursion in
        a specific capture group. These are not supported.
 
          PCRE2_ERROR_DFA_UINVALID_UTF
 
-       This return is given if pcre2_dfa_match() is called for a pattern  that
-       was  compiled  with  PCRE2_MATCH_INVALID_UTF. This is not supported for
+       This  return is given if pcre2_dfa_match() is called for a pattern that
+       was compiled with PCRE2_MATCH_INVALID_UTF. This is  not  supported  for
        DFA matching.
 
          PCRE2_ERROR_DFA_WSSIZE
 
-       This return is given if pcre2_dfa_match() runs  out  of  space  in  the
+       This  return  is  given  if  pcre2_dfa_match() runs out of space in the
        workspace vector.
 
          PCRE2_ERROR_DFA_RECURSE
 
        When a recursion or subroutine call is processed, the matching function
-       calls itself recursively, using private  memory  for  the  ovector  and
-       workspace.   This  error  is given if the internal ovector is not large
-       enough. This should be extremely rare, as a  vector  of  size  1000  is
+       calls  itself  recursively,  using  private  memory for the ovector and
+       workspace.  This error is given if the internal ovector  is  not  large
+       enough.  This  should  be  extremely  rare, as a vector of size 1000 is
        used.
 
          PCRE2_ERROR_DFA_BADRESTART
 
-       When  pcre2_dfa_match()  is  called  with the PCRE2_DFA_RESTART option,
-       some plausibility checks are made on the  contents  of  the  workspace,
-       which  should  contain data about the previous partial match. If any of
+       When pcre2_dfa_match() is called  with  the  PCRE2_DFA_RESTART  option,
+       some  plausibility  checks  are  made on the contents of the workspace,
+       which should contain data about the previous partial match. If  any  of
        these checks fail, this error is given.
 
 
 SEE ALSO
 
-       pcre2build(3),   pcre2callout(3),    pcre2demo(3),    pcre2matching(3),
+       pcre2build(3),    pcre2callout(3),    pcre2demo(3),   pcre2matching(3),
        pcre2partial(3), pcre2posix(3), pcre2sample(3), pcre2unicode(3).
 
 
@@ -3796,7 +3826,7 @@ AUTHOR
 
 REVISION
 
-       Last updated: 05 October 2020
+       Last updated: 04 November 2020
        Copyright (c) 1997-2020 University of Cambridge.
 ------------------------------------------------------------------------------
  
diff --git a/doc/pcre2api.3 b/doc/pcre2api.3
index d04a7ff..1fee114 100644
--- a/doc/pcre2api.3
+++ b/doc/pcre2api.3
@@ -1,4 +1,4 @@
-.TH PCRE2API 3 "05 October 2020" "PCRE2 10.36"
+.TH PCRE2API 3 "04 November 2020" "PCRE2 10.36"
 .SH NAME
 PCRE2 - Perl-compatible regular expressions (revised API)
 .sp
@@ -564,24 +564,53 @@ documentation for more details.
 .P
 In a more complicated situation, where patterns are compiled only when they are
 first needed, but are still shared between threads, pointers to compiled
-patterns must be protected from simultaneous writing by multiple threads, at
-least until a pattern has been compiled. The logic can be something like this:
+patterns must be protected from simultaneous writing by multiple threads. This
+is somewhat tricky to do correctly. If you know that writing to a pointer is
+atomic in your environment, you can use logic like this:
 .sp
   Get a read-only (shared) lock (mutex) for pointer
   if (pointer == NULL)
     {
     Get a write (unique) lock for pointer
-    pointer = pcre2_compile(...
+    if (pointer == NULL) pointer = pcre2_compile(...
     }
   Release the lock
   Use pointer in pcre2_match()
 .sp
 Of course, testing for compilation errors should also be included in the code.
 .P
-If JIT is being used, but the JIT compilation is not being done immediately,
-(perhaps waiting to see if the pattern is used often enough) similar logic is
-required. JIT compilation updates a pointer within the compiled code block, so
-a thread must gain unique write access to the pointer before calling
+The reason for checking the pointer a second time is as follows: Several
+threads may have acquired the shared lock and tested the pointer for being
+NULL, but only one of them will be given the write lock, with the rest kept
+waiting. The winning thread will compile the pattern and store the result.
+After this thread releases the write lock, another thread will get it, and if
+it does not retest pointer for being NULL, will recompile the pattern and
+overwrite the pointer, creating a memory leak and possibly causing other
+issues.
+.P
+In an environment where writing to a pointer may not be atomic, the above logic
+is not sufficient. The thread that is doing the compiling may be descheduled
+after writing only part of the pointer, which could cause other threads to use
+an invalid value. Instead of checking the pointer itself, a separate "pointer
+is valid" flag (that can be updated atomically) must be used:
+.sp
+  Get a read-only (shared) lock (mutex) for pointer
+  if (!pointer_is_valid)
+    {
+    Get a write (unique) lock for pointer
+    if (!pointer_is_valid) 
+      {
+      pointer = pcre2_compile(...
+      pointer_is_valid = TRUE
+      }  
+    }
+  Release the lock
+  Use pointer in pcre2_match()
+.sp
+If JIT is being used, but the JIT compilation is not being done immediately
+(perhaps waiting to see if the pattern is used often enough), similar logic is
+required. JIT compilation updates a value within the compiled code block, so a
+thread must gain unique write access to the pointer before calling
 \fBpcre2_jit_compile()\fP. Alternatively, \fBpcre2_code_copy()\fP or
 \fBpcre2_code_copy_with_tables()\fP can be used to obtain a private copy of the
 compiled code before calling the JIT compiler.
@@ -3971,6 +4000,6 @@ Cambridge, England.
 .rs
 .sp
 .nf
-Last updated: 05 October 2020
+Last updated: 04 November 2020
 Copyright (c) 1997-2020 University of Cambridge.
 .fi