From 0fc5cda13b38b0a81036a3887c4ed50397002fba Mon Sep 17 00:00:00 2001 From: "Philip.Hazel" Date: Fri, 12 Oct 2018 17:02:34 +0000 Subject: [PATCH] Documentation and tests update for script runs. --- ChangeLog | 3 +- doc/html/pcre2matching.html | 26 +- doc/html/pcre2pattern.html | 121 +- doc/html/pcre2syntax.html | 45 +- doc/html/pcre2unicode.html | 112 +- doc/pcre2.txt | 2274 +++++++++++++++++++---------------- doc/pcre2matching.3 | 27 +- doc/pcre2pattern.3 | 85 +- doc/pcre2syntax.3 | 14 +- doc/pcre2unicode.3 | 106 +- testdata/testinput4 | 1 + testdata/testinput5 | 3 + testdata/testoutput4 | 2 + testdata/testoutput5 | 4 + 14 files changed, 1697 insertions(+), 1126 deletions(-) diff --git a/ChangeLog b/ChangeLog index 66cadf5..dda5ab4 100644 --- a/ChangeLog +++ b/ChangeLog @@ -31,8 +31,7 @@ hexadecimal digit" bit was removed. The default tables in src/pcre2_chartables.c.dist are updated. 8. Implement the new Perl "script run" features (*script_run:...) and -(*atomic_script_run:...) aka (*sr:...) and (*asr:...). At present, this is -not yet documented. +(*atomic_script_run:...) aka (*sr:...) and (*asr:...). Version 10.32 10-September-2018 diff --git a/doc/html/pcre2matching.html b/doc/html/pcre2matching.html index 602f3b2..3e32cb5 100644 --- a/doc/html/pcre2matching.html +++ b/doc/html/pcre2matching.html @@ -134,7 +134,8 @@ do want multiple matches in such cases, either use an ungreedy repeat

There are a number of features of PCRE2 regular expressions that are not -supported by the alternative matching algorithm. They are as follows: +supported or behave differently in the alternative matching function. Those +that are not supported cause an error if encountered.

1. Because the algorithm finds all possible matches, the greedy or ungreedy @@ -159,29 +160,32 @@ do this. This means that no captured substrings are available.

3. Because no substrings are captured, backreferences within the pattern are -not supported, and cause errors if encountered. +not supported.

4. For the same reason, conditional expressions that use a backreference as the condition or test for a specific group recursion are not supported.

-5. Because many paths through the tree may be active, the \K escape sequence, -which resets the start of the match when encountered (but may be on some paths -and not on others), is not supported. It causes an error if encountered. +5. Again for the same reason, script runs are not supported.

-6. Callouts are supported, but the value of the capture_top field is +6. Because many paths through the tree may be active, the \K escape sequence, +which resets the start of the match when encountered (but may be on some paths +and not on others), is not supported. +

+

+7. Callouts are supported, but the value of the capture_top field is always 1, and the value of the capture_last field is always 0.

-7. The \C escape sequence, which (in the standard algorithm) always matches a +8. The \C escape sequence, which (in the standard algorithm) always matches a single code unit, even in a UTF mode, is not supported in these modes, because the alternative algorithm moves through the subject string one character (not code unit) at a time, for all active paths through the tree.

-8. Except for (*FAIL), the backtracking control verbs such as (*PRUNE) are not +9. Except for (*FAIL), the backtracking control verbs such as (*PRUNE) are not supported. (*FAIL) is supported, and behaves like a failing negative assertion.


ADVANTAGES OF THE ALTERNATIVE ALGORITHM
@@ -215,7 +219,7 @@ because it has to search for all possible matches, but is also because it is less susceptible to optimization.

-2. Capturing parentheses and backreferences are not supported. +2. Capturing parentheses, backreferences, and script runs are not supported.

3. Although atomic groups are supported, their use does not provide the @@ -232,9 +236,9 @@ Cambridge, England.


REVISION

-Last updated: 29 September 2014 +Last updated: 10 October 2018
-Copyright © 1997-2014 University of Cambridge. +Copyright © 1997-2018 University of Cambridge.

Return to the PCRE2 index page. diff --git a/doc/html/pcre2pattern.html b/doc/html/pcre2pattern.html index 824d59b..e76035e 100644 --- a/doc/html/pcre2pattern.html +++ b/doc/html/pcre2pattern.html @@ -33,16 +33,17 @@ please consult the man page, in case the conversion went wrong.

  • ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS
  • BACKREFERENCES
  • ASSERTIONS -
  • CONDITIONAL SUBPATTERNS -
  • COMMENTS -
  • RECURSIVE PATTERNS -
  • SUBPATTERNS AS SUBROUTINES -
  • ONIGURUMA SUBROUTINE SYNTAX -
  • CALLOUTS -
  • BACKTRACKING CONTROL -
  • SEE ALSO -
  • AUTHOR -
  • REVISION +
  • SCRIPT RUNS +
  • CONDITIONAL SUBPATTERNS +
  • COMMENTS +
  • RECURSIVE PATTERNS +
  • SUBPATTERNS AS SUBROUTINES +
  • ONIGURUMA SUBROUTINE SYNTAX +
  • CALLOUTS +
  • BACKTRACKING CONTROL +
  • SEE ALSO +
  • AUTHOR +
  • REVISION
    PCRE2 REGULAR EXPRESSION DETAILS

    @@ -756,7 +757,7 @@ sequences that match characters with specific properties are available. In 8-bit non-UTF-8 mode, these sequences are of course limited to testing characters whose code points are less than 256, but they do work in this mode. In 32-bit non-UTF mode, code points greater than 0x10ffff (the Unicode limit) -may be encountered. These are all treated as being in the Common script and +may be encountered. These are all treated as being in the Unknown script and with an unassigned type. The extra escape sequences are: 

       \p{xx}   a character with the xx property
@@ -780,8 +781,10 @@ example:
   \p{Greek}
   \P{Han}
    -Those that are not part of an identified script are lumped together as -"Common". The current list of scripts is: +Unassigned characters (and in non-UTF 32-bit mode, characters with code points +greater than 0x10FFFF) are assigned the "Unknown" script. Others that are not +part of an identified script are lumped together as "Common". The current list +of scripts is:

    Adlam, @@ -928,6 +931,7 @@ Tibetan, Tifinagh, Tirhuta, Ugaritic, +Unknown, Vai, Warang_Citi, Yi, @@ -2589,8 +2593,70 @@ preceded by "foo", while is another pattern that matches "foo" preceded by three digits and any three characters that are not "999". +

    +
    SCRIPT RUNS
    +

    +In concept, a script run is a sequence of characters that are all from the same +Unicode script such as Latin or Greek. However, because some scripts are +commonly used together, and because some diacritical and other marks are used +with multiple scripts, it is not that simple. There is a full description of +the rules that PCRE2 uses in the section entitled +"Script Runs" +in the +pcre2unicode +documentation. +

    +

    +If part of a pattern is enclosed between (*script_run: or (*sr: and a closing +parenthesis, it fails if the sequence of characters that it matches are not a +script run. After a failure, normal backtracking occurs. Script runs can be +used to detect spoofing attacks using characters that look the same, but are +from different scripts. The string "paypal.com" is an infamous example, where +the letters could be a mixture of Latin and Cyrillic. This pattern ensures that +the matched characters in a sequence of non-spaces that follow white space are +a script run: +

    +  \s+(*sr:\S+)
+
    +To be sure that they are all from the Latin script (for example), a lookahead +can be used: +
    +  \s+(?=\p{Latin})(*sr:\S+)
+
    +This works as long as the first character is expected to be a character in that +script, and not (for example) punctuation, which is allowed with any script. If +this is not the case, a more creative lookahead is needed. For example, if +digits, underscore, and dots are permitted at the start: +
    +  \s+(?=[0-9_.]*\p{Latin})(*sr:\S+)
+
+
    +

    +

    +In many cases, backtracking into a script run pattern fragment is not +desirable. The script run can employ an atomic group to prevent this. Because +this is a common requirement, a shorthand notation is provided by +(*atomic_script_run: or (*asr: +

    +  (*asr:...) is the same as (*sr:(?>...))
+
    +Note that the atomic group is inside the script run. Putting it outside would +not prevent backtracking into the script run pattern. +

    +

    +Support for script runs is not available if PCRE2 is compiled without Unicode +support. A compile-time error is given if any of the above constructs is +encountered. Script runs are not supported by the alternate matching function, +pcre2_dfa_match() because they use the same mechanism as capturing +parentheses. +

    +

    +Warning: The (*ACCEPT) control verb +(see below) +should not be used within a script run subpattern, because it causes an +immediate exit from the subpattern, bypassing the script run checking.

    -
    CONDITIONAL SUBPATTERNS
    +
    CONDITIONAL SUBPATTERNS

    It is possible to cause the matching process to obey a subpattern conditionally or to choose between two alternative subpatterns, depending on @@ -2790,7 +2856,7 @@ positive and negative assertions, because matching always continues after the assertion, whether it succeeds or fails. (Compare non-conditional assertions, when captures are retained only for positive assertions that succeed.)

    -
    COMMENTS
    +
    COMMENTS

    There are two ways of including comments in patterns that are processed by PCRE2. In both cases, the start of the comment must not be in a character @@ -2820,7 +2886,7 @@ a newline in the pattern. The sequence \n is still literal at this stage, so it does not terminate the comment. Only an actual character with the code value 0x0a (the default newline) does so.

    -
    RECURSIVE PATTERNS
    +
    RECURSIVE PATTERNS

    Consider the problem of matching a string in parentheses, allowing for unlimited nested parentheses. Without the use of recursion, the best that can @@ -3008,7 +3074,7 @@ alternative matches "a" and then recurses. In the recursion, \1 does now match "b" and so the whole match succeeds. This match used to fail in Perl, but in later versions (I tried 5.024) it now works.

    -
    SUBPATTERNS AS SUBROUTINES
    +
    SUBPATTERNS AS SUBROUTINES

    If the syntax for a recursive subpattern call (either by number or by name) is used outside the parentheses to which it refers, it operates a bit @@ -3057,7 +3123,7 @@ in subpatterns when called as subroutines is described in the section entitled "Backtracking verbs in subroutines" below.

    -
    ONIGURUMA SUBROUTINE SYNTAX
    +
    ONIGURUMA SUBROUTINE SYNTAX

    For compatibility with Oniguruma, the non-Perl syntax \g followed by a name or a number enclosed either in angle brackets or single quotes, is an alternative @@ -3075,7 +3141,7 @@ plus or a minus sign it is taken as a relative reference. For example: Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are not synonymous. The former is a backreference; the latter is a subroutine call.

    -
    CALLOUTS
    +
    CALLOUTS

    Perl has a feature whereby using the sequence (?{...}) causes arbitrary Perl code to be obeyed in the middle of matching a regular expression. This makes it @@ -3151,7 +3217,7 @@ example: The doubling is removed before the string is passed to the callout function.

    -
    BACKTRACKING CONTROL
    +
    BACKTRACKING CONTROL

    There are a number of special "Backtracking Control Verbs" (to use Perl's terminology) that modify the behaviour of backtracking during matching. They @@ -3222,7 +3288,7 @@ documentation.

    Experiments with Perl suggest that it too has similar optimizations, and like PCRE2, turning them off can change the result of a match. -

    +


    Verbs that act immediately
    @@ -3245,6 +3311,11 @@ example: This matches "AB", "AAD", or "ACD"; when it matches "AB", "B" is captured by the outer parentheses. +

    +

    +Warning: (*ACCEPT) should not be used within a script run subpattern, +because it causes an immediate exit from the subpattern, bypassing the script +run checking. 

       (*FAIL) or (*FAIL:NAME)
    @@ -3644,12 +3715,12 @@ behaviour). However, if there is no such group within the subroutine subpattern, the subroutine match fails and there is a backtrack at the outer level.

    -
    SEE ALSO
    +
    SEE ALSO

    pcre2api(3), pcre2callout(3), pcre2matching(3), pcre2syntax(3), pcre2(3).

    -
    AUTHOR
    +
    AUTHOR

    Philip Hazel
    @@ -3658,9 +3729,9 @@ University Computing Service Cambridge, England.

    -
    REVISION
    +
    REVISION

    -Last updated: 24 September 2018 +Last updated: 12 October 2018
    Copyright © 1997-2018 University of Cambridge.
    diff --git a/doc/html/pcre2syntax.html b/doc/html/pcre2syntax.html index d6e1e30..e7a5df3 100644 --- a/doc/html/pcre2syntax.html +++ b/doc/html/pcre2syntax.html @@ -32,14 +32,15 @@ please consult the man page, in case the conversion went wrong.

  • NEWLINE CONVENTION
  • WHAT \R MATCHES
  • LOOKAHEAD AND LOOKBEHIND ASSERTIONS -
  • BACKREFERENCES -
  • SUBROUTINE REFERENCES (POSSIBLY RECURSIVE) -
  • CONDITIONAL PATTERNS -
  • BACKTRACKING CONTROL -
  • CALLOUTS -
  • SEE ALSO -
  • AUTHOR -
  • REVISION +
  • SCRIPT RUNS +
  • BACKREFERENCES +
  • SUBROUTINE REFERENCES (POSSIBLY RECURSIVE) +
  • CONDITIONAL PATTERNS +
  • BACKTRACKING CONTROL +
  • CALLOUTS +
  • SEE ALSO +
  • AUTHOR +
  • REVISION
    PCRE2 REGULAR EXPRESSION SYNTAX SUMMARY

    @@ -533,7 +534,17 @@ setting with a similar syntax. Each top-level branch of a lookbehind must be of a fixed length.

    -
    BACKREFERENCES
    +
    SCRIPT RUNS
    +

    +

    +  (*script_run:...)           ) script run, can be backtracked into
+  (*sr:...)                   )
+
+  (*atomic_script_run:...)    ) atomic script run
+  (*asr:...)                  )
+
    +

    +
    BACKREFERENCES

       \n              reference by number (can be ambiguous)
@@ -550,7 +561,7 @@ Each top-level branch of a lookbehind must be of a fixed length.
   (?P=name)       reference by name (Python)

    -
    SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)
    +
    SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)

       (?R)            recurse whole pattern
@@ -569,7 +580,7 @@ Each top-level branch of a lookbehind must be of a fixed length.
   \g'-n'          call subpattern by relative number (PCRE2 extension)

    -
    CONDITIONAL PATTERNS
    +
    CONDITIONAL PATTERNS

       (?(condition)yes-pattern)
@@ -592,7 +603,7 @@ Note the ambiguity of (?(R) and (?(Rn) which might be named reference
 conditions or recursion tests. Such a condition is interpreted as a reference
 condition if the relevant named group exists.
 
    
-
    BACKTRACKING CONTROL
    
+
    BACKTRACKING CONTROL
    
 
    
 All backtracking control verbs may be in the form (*VERB:NAME). For (*MARK) the
 name is mandatory, for the others it is optional. (*SKIP) changes its behaviour
@@ -619,7 +630,7 @@ pattern is not anchored.
 The effect of one of these verbs in a group called as a subroutine is confined
 to the subroutine call.
 
    
-
    CALLOUTS
    
+
    CALLOUTS
    
 
    
 
       (?C)            callout (assumed number 0)
@@ -630,12 +641,12 @@ The allowed string delimiters are ` ' " ^ % # $ (which are the same for the
 start and the end), and the starting delimiter { matched with the ending
 delimiter }. To encode the ending delimiter within the string, double it.
 
    
-
    SEE ALSO
    
+
    SEE ALSO
    
 
    
 pcre2pattern(3), pcre2api(3), pcre2callout(3),
 pcre2matching(3), pcre2(3).
 
    
-
    AUTHOR
    
+
    AUTHOR
    
 
    
 Philip Hazel
 
    
@@ -644,9 +655,9 @@ University Computing Service
 Cambridge, England.
 
    
 
    
-
    REVISION
    
+
    REVISION
    
 
    
-Last updated: 24 September 2018
+Last updated: 10 October 2018
 
    
 Copyright © 1997-2018 University of Cambridge.
 
    
diff --git a/doc/html/pcre2unicode.html b/doc/html/pcre2unicode.html
index 24f6d93..e446182 100644
--- a/doc/html/pcre2unicode.html
+++ b/doc/html/pcre2unicode.html
@@ -124,6 +124,116 @@ for characters whose code points are less than 128 and that have at most two
 case-equivalent values. For these, a direct table lookup is used for speed. A
 few Unicode characters such as Greek sigma have more than two code points that
 are case-equivalent, and these are treated as such.
+
    
+
    
+SCRIPT RUNS
+
    
+
    
+The pattern constructs (*script_run:...) and (*atomic_script_run:...), with
+synonyms (*sr:...) and (*asr:...), verify that the string matched within the
+parentheses is a script run. In concept, a script run is a sequence of
+characters that are all from the same Unicode script. However, because some
+scripts are commonly used together, and because some diacritical and other
+marks are used with multiple scripts, it is not that simple.
+
    
+
    
+Every Unicode character has a Script property, mostly with a value 
+corresponding to the name of a script, such as Latin, Greek, or Cyrillic. There
+are also three special values:
+
    
+
    
+"Unknown" is used for code points that have not been assigned, and also for the
+surrogate code points. In the PCRE2 32-bit library, characters whose code
+points are greater than the Unicode maximum (U+10FFFF), which are accessible 
+only in non-UTF mode, are assigned the Unknown script.
+
    
+
    
+"Common" is used for characters that are used with many scripts. These include
+punctuation, emoji, mathematical, musical, and currency symbols, and the ASCII
+digits 0 to 9.
+
    
+
    
+"Inherited" is used for characters such as diacritical marks that modify a
+previous character. These are considered to take on the script of the character
+that they modify.
+
    
+
    
+Some Inherited characters are used with many scripts, but many of them are only 
+normally used with a small number of scripts. For example, U+102E0 (Coptic 
+Epact thousands mark) is used only with Arabic and Coptic. In order to make it 
+possible to check this, a Unicode property called Script Extension exists. Its 
+value is a list of scripts that apply to the character. For the majority of 
+characters, the list contains just one script, the same one as the Script
+property. However, for characters such as U+102E0 more than one Script is
+listed. There are also some Common characters that have a single, non-Common
+script in their Script Extension list.
+
    
+
    
+The next section describes the basic rules for deciding whether a given string 
+of characters is a script run. Note, however, that there are some special cases 
+involving the Chinese Han script, and an additional constraint for decimal 
+digits. These are covered in subsequent sections.
+
    
+
    
+Basic script run rules
+
    
+
    
+A string that is less than two characters long is a script run. This is the
+only case in which an Unknown character can be part of a script run. Longer
+strings are checked using only the Script Extensions property, not the basic
+Script property.
+
    
+
    
+If a character's Script Extension property is the single value "Inherited", it
+is always accepted as part of a script run. This is also true for the property
+"Common", subject to the checking of decimal digits described below. All the
+remaining characters in a script run must have at least one script in common in
+their Script Extension lists. In set-theoretic terminology, the intersection of
+all the sets of scripts must not be empty.
+
    
+
    
+A simple example is an Internet name such as "google.com". The letters are all
+in the Latin script, and the dot is Common, so this string is a script run.
+However, the Cyrillic letter "o" looks exactly the same as the Latin "o"; a 
+string that looks the same, but with Cyrillic "o"s is not a script run.
+
    
+
    
+More interesting examples involve characters with more than one script in their 
+Script Extension. Consider the following characters:
+
    +  U+060C  Arabic comma
+  U+06D4  Arabic full stop
+
    
+The first has the Script Extension list Arabic, Hanifi Rohingya, Syriac, and 
+Thaana; the second has just Arabic and Hanifi Rohingya. Both of them could
+appear in script runs of either Arabic or Hanifi Rohingya. The first could also
+appear in Syriac or Thaana script runs, but the second could not.
+
    
+
    
+The Chinese Han script
+
    
+
    
+The Chinese Han script is commonly used in conjunction with other scripts for 
+writing certain languages. Japanese uses the Hiragana and Katakana scripts 
+together with Han; Korean uses Hangul and Han; Taiwanese Mandarin uses Bopomofo
+and Han. These three combinations are treated as special cases when checking
+script runs and are, in effect, "virtual scripts". Thus, a script run may
+contain a mixture of Hiragana, Katakana, and Han, or a mixture of Hangul and
+Han, or a mixture of Bopomofo and Han, but not, for example, a mixture of
+Hangul and Bopomofo and Han. PCRE2 (like Perl) follows Unicode's Technical
+Standard 39 ("Unicode Security Mechanisms", http://unicode.org/reports/tr39/)
+in allowing such mixtures.
+
    
+
    
+Decimal digits
+
    
+
    
+Unicode contains many sets of 10 decimal digits in different scripts, and some
+scripts (including the Common script) contain more than one set. Some of these
+decimal digits them are visually indistinguishable from the common ASCII
+digits. In addition to the script checking described above, if a script run
+contains any decimal digits, they must all come from the same set of 10
+adjacent characters.
 
    
 
    
 VALIDITY OF UTF STRINGS
@@ -300,7 +410,7 @@ Cambridge, England.
 REVISION
 
    
 
    
-Last updated: 02 September 2018
+Last updated: 12 October 2018
 
    
 Copyright © 1997-2018 University of Cambridge.
 
    
diff --git a/doc/pcre2.txt b/doc/pcre2.txt
index 2abc377..6ad6922 100644
--- a/doc/pcre2.txt
+++ b/doc/pcre2.txt
@@ -5391,8 +5391,8 @@ THE ALTERNATIVE MATCHING ALGORITHM
        SESS option when compiling.
 
        There are a number of features of PCRE2 regular  expressions  that  are
-       not  supported  by the alternative matching algorithm. They are as fol-
-       lows:
+       not  supported  or behave differently in the alternative matching func-
+       tion. Those that are not supported cause an error if encountered.
 
        1. Because the algorithm finds all  possible  matches,  the  greedy  or
        ungreedy  nature  of  repetition quantifiers is not relevant (though it
@@ -5417,47 +5417,48 @@ THE ALTERNATIVE MATCHING ALGORITHM
        strings are available.
 
        3. Because no substrings are captured, backreferences within  the  pat-
-       tern are not supported, and cause errors if encountered.
+       tern are not supported.
 
        4.  For  the same reason, conditional expressions that use a backrefer-
        ence as the condition or test for a specific group  recursion  are  not
        supported.
 
-       5.  Because  many  paths  through the tree may be active, the \K escape
-       sequence, which resets the start of the match when encountered (but may
-       be  on  some  paths  and not on others), is not supported. It causes an
-       error if encountered.
+       5. Again for the same reason, script runs are not supported.
 
-       6. Callouts are supported, but the value of the  capture_top  field  is
+       6.  Because  many  paths  through the tree may be active, the \K escape
+       sequence, which resets the start of the match when encountered (but may
+       be on some paths and not on others), is not supported.
+
+       7.  Callouts  are  supported, but the value of the capture_top field is
        always 1, and the value of the capture_last field is always 0.
 
-       7.  The  \C  escape  sequence, which (in the standard algorithm) always
-       matches a single code unit, even in a UTF mode,  is  not  supported  in
-       these  modes,  because the alternative algorithm moves through the sub-
-       ject string one character (not code unit) at a  time,  for  all  active
+       8. The \C escape sequence, which (in  the  standard  algorithm)  always
+       matches  a  single  code  unit, even in a UTF mode, is not supported in
+       these modes, because the alternative algorithm moves through  the  sub-
+       ject  string  one  character  (not code unit) at a time, for all active
        paths through the tree.
 
-       8.  Except for (*FAIL), the backtracking control verbs such as (*PRUNE)
-       are not supported. (*FAIL) is supported, and  behaves  like  a  failing
+       9. Except for (*FAIL), the backtracking control verbs such as  (*PRUNE)
+       are  not  supported.  (*FAIL)  is supported, and behaves like a failing
        negative assertion.
 
 
 ADVANTAGES OF THE ALTERNATIVE ALGORITHM
 
-       Using  the alternative matching algorithm provides the following advan-
+       Using the alternative matching algorithm provides the following  advan-
        tages:
 
        1. All possible matches (at a single point in the subject) are automat-
-       ically  found,  and  in particular, the longest match is found. To find
+       ically found, and in particular, the longest match is  found.  To  find
        more than one match using the standard algorithm, you have to do kludgy
        things with callouts.
 
-       2.  Because  the  alternative  algorithm  scans the subject string just
+       2. Because the alternative algorithm  scans  the  subject  string  just
        once, and never needs to backtrack (except for lookbehinds), it is pos-
-       sible  to  pass  very  long subject strings to the matching function in
+       sible to pass very long subject strings to  the  matching  function  in
        several pieces, checking for partial matching each time. Although it is
-       also  possible  to  do  multi-segment matching using the standard algo-
-       rithm, by retaining partially matched substrings, it  is  more  compli-
+       also possible to do multi-segment matching  using  the  standard  algo-
+       rithm,  by  retaining  partially matched substrings, it is more compli-
        cated. The pcre2partial documentation gives details of partial matching
        and discusses multi-segment matching.
 
@@ -5466,11 +5467,12 @@ DISADVANTAGES OF THE ALTERNATIVE ALGORITHM
 
        The alternative algorithm suffers from a number of disadvantages:
 
-       1. It is substantially slower than  the  standard  algorithm.  This  is
-       partly  because  it has to search for all possible matches, but is also
+       1.  It  is  substantially  slower  than the standard algorithm. This is
+       partly because it has to search for all possible matches, but  is  also
        because it is less susceptible to optimization.
 
-       2. Capturing parentheses and backreferences are not supported.
+       2.  Capturing parentheses, backreferences, and script runs are not sup-
+       ported.
 
        3. Although atomic groups are supported, their use does not provide the
        performance advantage that it does for the standard algorithm.
@@ -5485,8 +5487,8 @@ AUTHOR
 
 REVISION
 
-       Last updated: 29 September 2014
-       Copyright (c) 1997-2014 University of Cambridge.
+       Last updated: 10 October 2018
+       Copyright (c) 1997-2018 University of Cambridge.
 ------------------------------------------------------------------------------
  
  
@@ -6586,7 +6588,7 @@ BACKSLASH
        limited  to testing characters whose code points are less than 256, but
        they do work in this mode.  In 32-bit non-UTF mode, code points greater
        than  0x10ffff  (the  Unicode  limit) may be encountered. These are all
-       treated as being in the Common script and with an unassigned type.  The
+       treated as being in the Unknown script and with an unassigned type. The
        extra escape sequences are:
 
          \p{xx}   a character with the xx property
@@ -6607,8 +6609,10 @@ BACKSLASH
          \p{Greek}
          \P{Han}
 
-       Those that are not part of an identified script are lumped together  as
-       "Common". The current list of scripts is:
+       Unassigned characters (and in non-UTF 32-bit mode, characters with code
+       points greater than 0x10FFFF) are assigned the "Unknown" script. Others
+       that are not part of an identified script are lumped together as  "Com-
+       mon". The current list of scripts is:
 
        Adlam,  Ahom,  Anatolian_Hieroglyphs,  Arabic, Armenian, Avestan, Bali-
        nese, Bamum, Bassa_Vah, Batak, Bengali,  Bhaiksuki,  Bopomofo,  Brahmi,
@@ -6632,17 +6636,18 @@ BACKSLASH
        vian, Siddham, SignWriting, Sinhala,  Sogdian,  Sora_Sompeng,  Soyombo,
        Sundanese,  Syloti_Nagri,  Syriac, Tagalog, Tagbanwa, Tai_Le, Tai_Tham,
        Tai_Viet, Takri, Tamil, Tangut, Telugu, Thaana,  Thai,  Tibetan,  Tifi-
-       nagh, Tirhuta, Ugaritic, Vai, Warang_Citi, Yi, Zanabazar_Square.
+       nagh,   Tirhuta,   Ugaritic,   Unknown,   Vai,  Warang_Citi,  Yi,  Zan-
+       abazar_Square.
 
        Each character has exactly one Unicode general category property, spec-
-       ified by a two-letter abbreviation. For compatibility with Perl,  nega-
-       tion  can  be  specified  by including a circumflex between the opening
-       brace and the property name.  For  example,  \p{^Lu}  is  the  same  as
+       ified  by a two-letter abbreviation. For compatibility with Perl, nega-
+       tion can be specified by including a  circumflex  between  the  opening
+       brace  and  the  property  name.  For  example,  \p{^Lu} is the same as
        \P{Lu}.
 
        If only one letter is specified with \p or \P, it includes all the gen-
-       eral category properties that start with that letter. In this case,  in
-       the  absence of negation, the curly brackets in the escape sequence are
+       eral  category properties that start with that letter. In this case, in
+       the absence of negation, the curly brackets in the escape sequence  are
        optional; these two examples have the same effect:
 
          \p{L}
@@ -6694,86 +6699,86 @@ BACKSLASH
          Zp    Paragraph separator
          Zs    Space separator
 
-       The special property L& is also supported: it matches a character  that
-       has  the  Lu,  Ll, or Lt property, in other words, a letter that is not
+       The  special property L& is also supported: it matches a character that
+       has the Lu, Ll, or Lt property, in other words, a letter  that  is  not
        classified as a modifier or "other".
 
-       The Cs (Surrogate) property applies only to  characters  in  the  range
-       U+D800  to U+DFFF. Such characters are not valid in Unicode strings and
-       so cannot be tested by PCRE2, unless UTF  validity  checking  has  been
-       turned  off  (see  the discussion of PCRE2_NO_UTF_CHECK in the pcre2api
+       The  Cs  (Surrogate)  property  applies only to characters in the range
+       U+D800 to U+DFFF. Such characters are not valid in Unicode strings  and
+       so  cannot  be  tested  by PCRE2, unless UTF validity checking has been
+       turned off (see the discussion of PCRE2_NO_UTF_CHECK  in  the  pcre2api
        page). Perl does not support the Cs property.
 
-       The long synonyms for  property  names  that  Perl  supports  (such  as
-       \p{Letter})  are  not supported by PCRE2, nor is it permitted to prefix
+       The  long  synonyms  for  property  names  that  Perl supports (such as
+       \p{Letter}) are not supported by PCRE2, nor is it permitted  to  prefix
        any of these properties with "Is".
 
        No character that is in the Unicode table has the Cn (unassigned) prop-
        erty.  Instead, this property is assumed for any code point that is not
        in the Unicode table.
 
-       Specifying caseless matching does not affect  these  escape  sequences.
-       For  example,  \p{Lu}  always  matches only upper case letters. This is
+       Specifying  caseless  matching  does not affect these escape sequences.
+       For example, \p{Lu} always matches only upper  case  letters.  This  is
        different from the behaviour of current versions of Perl.
 
-       Matching characters by Unicode property is not fast, because PCRE2  has
-       to  do  a  multistage table lookup in order to find a character's prop-
+       Matching  characters by Unicode property is not fast, because PCRE2 has
+       to do a multistage table lookup in order to find  a  character's  prop-
        erty. That is why the traditional escape sequences such as \d and \w do
-       not  use  Unicode  properties  in PCRE2 by default, though you can make
-       them do so by setting the PCRE2_UCP option or by starting  the  pattern
+       not use Unicode properties in PCRE2 by default,  though  you  can  make
+       them  do  so by setting the PCRE2_UCP option or by starting the pattern
        with (*UCP).
 
    Extended grapheme clusters
 
-       The  \X  escape  matches  any number of Unicode characters that form an
+       The \X escape matches any number of Unicode  characters  that  form  an
        "extended grapheme cluster", and treats the sequence as an atomic group
-       (see  below).  Unicode supports various kinds of composite character by
-       giving each character a grapheme breaking property,  and  having  rules
+       (see below).  Unicode supports various kinds of composite character  by
+       giving  each  character  a grapheme breaking property, and having rules
        that use these properties to define the boundaries of extended grapheme
-       clusters. The rules are defined in Unicode Standard Annex 29,  "Unicode
-       Text  Segmentation".  Unicode 11.0.0 abandoned the use of some previous
-       properties that had been used for emojis.  Instead it introduced  vari-
-       ous  emoji-specific  properties.  PCRE2  uses  only the Extended Picto-
+       clusters.  The rules are defined in Unicode Standard Annex 29, "Unicode
+       Text Segmentation". Unicode 11.0.0 abandoned the use of  some  previous
+       properties  that had been used for emojis.  Instead it introduced vari-
+       ous emoji-specific properties. PCRE2  uses  only  the  Extended  Picto-
        graphic property.
 
-       \X always matches at least one character. Then it  decides  whether  to
+       \X  always  matches  at least one character. Then it decides whether to
        add additional characters according to the following rules for ending a
        cluster:
 
        1. End at the end of the subject string.
 
-       2. Do not end between CR and LF; otherwise end after any control  char-
+       2.  Do not end between CR and LF; otherwise end after any control char-
        acter.
 
-       3.  Do  not  break  Hangul (a Korean script) syllable sequences. Hangul
-       characters are of five types: L, V, T, LV, and LVT. An L character  may
-       be  followed by an L, V, LV, or LVT character; an LV or V character may
+       3. Do not break Hangul (a Korean  script)  syllable  sequences.  Hangul
+       characters  are of five types: L, V, T, LV, and LVT. An L character may
+       be followed by an L, V, LV, or LVT character; an LV or V character  may
        be followed by a V or T character; an LVT or T character may be follwed
        only by a T character.
 
-       4.  Do  not  end  before  extending  characters or spacing marks or the
-       "zero-width joiner" character.  Characters  with  the  "mark"  property
+       4. Do not end before extending  characters  or  spacing  marks  or  the
+       "zero-width  joiner"  character.  Characters  with  the "mark" property
        always have the "extend" grapheme breaking property.
 
        5. Do not end after prepend characters.
 
        6. Do not break within emoji modifier sequences or emoji zwj sequences.
        That is, do not break between characters with the Extended_Pictographic
-       property.   Extend  and  ZWJ characters are allowed between the charac-
+       property.  Extend and ZWJ characters are allowed  between  the  charac-
        ters.
 
-       7. Do not break within emoji flag sequences.  That  is,  do  not  break
-       between  regional  indicator (RI) characters if there are an odd number
+       7.  Do  not  break  within  emoji flag sequences. That is, do not break
+       between regional indicator (RI) characters if there are an  odd  number
        of RI characters before the break point.
 
        8. Otherwise, end the cluster.
 
    PCRE2's additional properties
 
-       As well as the standard Unicode properties described above, PCRE2  sup-
-       ports  four  more  that  make it possible to convert traditional escape
+       As  well as the standard Unicode properties described above, PCRE2 sup-
+       ports four more that make it possible  to  convert  traditional  escape
        sequences such as \w and \s to use Unicode properties. PCRE2 uses these
-       non-standard,  non-Perl  properties  internally  when PCRE2_UCP is set.
+       non-standard, non-Perl properties internally  when  PCRE2_UCP  is  set.
        However, they may also be used explicitly. These properties are:
 
          Xan   Any alphanumeric character
@@ -6781,69 +6786,69 @@ BACKSLASH
          Xsp   Any Perl space character
          Xwd   Any Perl "word" character
 
-       Xan matches characters that have either the L (letter) or the  N  (num-
-       ber)  property. Xps matches the characters tab, linefeed, vertical tab,
-       form feed, or carriage return, and any other character that has  the  Z
-       (separator)  property.   Xsp  is  the  same as Xps; in PCRE1 it used to
-       exclude vertical tab, for Perl compatibility,  but  Perl  changed.  Xwd
+       Xan  matches  characters that have either the L (letter) or the N (num-
+       ber) property. Xps matches the characters tab, linefeed, vertical  tab,
+       form  feed,  or carriage return, and any other character that has the Z
+       (separator) property.  Xsp is the same as Xps;  in  PCRE1  it  used  to
+       exclude  vertical  tab,  for  Perl compatibility, but Perl changed. Xwd
        matches the same characters as Xan, plus underscore.
 
-       There  is another non-standard property, Xuc, which matches any charac-
-       ter that can be represented by a Universal Character Name  in  C++  and
-       other  programming  languages.  These are the characters $, @, ` (grave
-       accent), and all characters with Unicode code points  greater  than  or
-       equal  to U+00A0, except for the surrogates U+D800 to U+DFFF. Note that
-       most base (ASCII) characters are excluded. (Universal  Character  Names
-       are  of  the  form \uHHHH or \UHHHHHHHH where H is a hexadecimal digit.
+       There is another non-standard property, Xuc, which matches any  charac-
+       ter  that  can  be represented by a Universal Character Name in C++ and
+       other programming languages. These are the characters $,  @,  `  (grave
+       accent),  and  all  characters with Unicode code points greater than or
+       equal to U+00A0, except for the surrogates U+D800 to U+DFFF. Note  that
+       most  base  (ASCII) characters are excluded. (Universal Character Names
+       are of the form \uHHHH or \UHHHHHHHH where H is  a  hexadecimal  digit.
        Note that the Xuc property does not match these sequences but the char-
        acters that they represent.)
 
    Resetting the match start
 
-       In  normal  use,  the  escape sequence \K causes any previously matched
-       characters not to be included in the final  matched  sequence  that  is
+       In normal use, the escape sequence \K  causes  any  previously  matched
+       characters  not  to  be  included in the final matched sequence that is
        returned. For example, the pattern:
 
          foo\Kbar
 
-       matches  "foobar",  but  reports that it has matched "bar". \K does not
+       matches "foobar", but reports that it has matched "bar".  \K  does  not
        interact with anchoring in any way. The pattern:
 
          ^foo\Kbar
 
-       matches only when the subject begins  with  "foobar"  (in  single  line
-       mode),  though  it again reports the matched string as "bar". This fea-
-       ture is similar to a lookbehind assertion (described below).   However,
-       in  this  case,  the part of the subject before the real match does not
-       have to be of fixed length, as lookbehind assertions do. The use of  \K
-       does  not interfere with the setting of captured substrings.  For exam-
+       matches  only  when  the  subject  begins with "foobar" (in single line
+       mode), though it again reports the matched string as "bar".  This  fea-
+       ture  is similar to a lookbehind assertion (described below).  However,
+       in this case, the part of the subject before the real  match  does  not
+       have  to be of fixed length, as lookbehind assertions do. The use of \K
+       does not interfere with the setting of captured substrings.  For  exam-
        ple, when the pattern
 
          (foo)\Kbar
 
        matches "foobar", the first substring is still set to "foo".
 
-       Perl documents that the use  of  \K  within  assertions  is  "not  well
-       defined".  In  PCRE2,  \K  is acted upon when it occurs inside positive
-       assertions, but is ignored in negative assertions.  Note  that  when  a
-       pattern  such  as (?=ab\K) matches, the reported start of the match can
-       be greater than the end of the match. Using \K in a  lookbehind  asser-
-       tion  at the start of a pattern can also lead to odd effects. For exam-
+       Perl  documents  that  the  use  of  \K  within assertions is "not well
+       defined". In PCRE2, \K is acted upon when  it  occurs  inside  positive
+       assertions,  but  is  ignored  in negative assertions. Note that when a
+       pattern such as (?=ab\K) matches, the reported start of the  match  can
+       be  greater  than the end of the match. Using \K in a lookbehind asser-
+       tion at the start of a pattern can also lead to odd effects. For  exam-
        ple, consider this pattern:
 
          (?<=\Kfoo)bar
 
-       If the subject is "foobar", a call to  pcre2_match()  with  a  starting
-       offset  of 3 succeeds and reports the matching string as "foobar", that
-       is, the start of the reported match is earlier  than  where  the  match
+       If  the  subject  is  "foobar", a call to pcre2_match() with a starting
+       offset of 3 succeeds and reports the matching string as "foobar",  that
+       is,  the  start  of  the reported match is earlier than where the match
        started.
 
    Simple assertions
 
-       The  final use of backslash is for certain simple assertions. An asser-
-       tion specifies a condition that has to be met at a particular point  in
-       a  match, without consuming any characters from the subject string. The
-       use of subpatterns for more complicated assertions is described  below.
+       The final use of backslash is for certain simple assertions. An  asser-
+       tion  specifies a condition that has to be met at a particular point in
+       a match, without consuming any characters from the subject string.  The
+       use  of subpatterns for more complicated assertions is described below.
        The backslashed assertions are:
 
          \b     matches at a word boundary
@@ -6854,190 +6859,190 @@ BACKSLASH
          \z     matches only at the end of the subject
          \G     matches at the first matching position in the subject
 
-       Inside  a  character  class, \b has a different meaning; it matches the
-       backspace character. If any other of  these  assertions  appears  in  a
+       Inside a character class, \b has a different meaning;  it  matches  the
+       backspace  character.  If  any  other  of these assertions appears in a
        character class, an "invalid escape sequence" error is generated.
 
-       A  word  boundary is a position in the subject string where the current
-       character and the previous character do not both match \w or  \W  (i.e.
-       one  matches  \w  and the other matches \W), or the start or end of the
-       string if the first or last character matches \w,  respectively.  In  a
-       UTF  mode,  the  meanings  of  \w  and \W can be changed by setting the
+       A word boundary is a position in the subject string where  the  current
+       character  and  the previous character do not both match \w or \W (i.e.
+       one matches \w and the other matches \W), or the start or  end  of  the
+       string  if  the  first or last character matches \w, respectively. In a
+       UTF mode, the meanings of \w and \W  can  be  changed  by  setting  the
        PCRE2_UCP option. When this is done, it also affects \b and \B. Neither
-       PCRE2  nor Perl has a separate "start of word" or "end of word" metase-
-       quence. However, whatever follows \b normally determines which  it  is.
+       PCRE2 nor Perl has a separate "start of word" or "end of word"  metase-
+       quence.  However,  whatever follows \b normally determines which it is.
        For example, the fragment \ba matches "a" at the start of a word.
 
-       The  \A,  \Z,  and \z assertions differ from the traditional circumflex
+       The \A, \Z, and \z assertions differ from  the  traditional  circumflex
        and dollar (described in the next section) in that they only ever match
-       at  the  very start and end of the subject string, whatever options are
-       set. Thus, they are independent of multiline mode. These  three  asser-
-       tions  are  not  affected  by the PCRE2_NOTBOL or PCRE2_NOTEOL options,
-       which affect only the behaviour of the circumflex and dollar  metachar-
-       acters.  However,  if the startoffset argument of pcre2_match() is non-
-       zero, indicating that matching is to start at a point  other  than  the
-       beginning  of  the subject, \A can never match.  The difference between
-       \Z and \z is that \Z matches before a newline at the end of the  string
+       at the very start and end of the subject string, whatever  options  are
+       set.  Thus,  they are independent of multiline mode. These three asser-
+       tions are not affected by the  PCRE2_NOTBOL  or  PCRE2_NOTEOL  options,
+       which  affect only the behaviour of the circumflex and dollar metachar-
+       acters. However, if the startoffset argument of pcre2_match()  is  non-
+       zero,  indicating  that  matching is to start at a point other than the
+       beginning of the subject, \A can never match.  The  difference  between
+       \Z  and \z is that \Z matches before a newline at the end of the string
        as well as at the very end, whereas \z matches only at the end.
 
-       The  \G assertion is true only when the current matching position is at
-       the start point of the matching process, as specified by the  startoff-
-       set  argument  of  pcre2_match().  It differs from \A when the value of
-       startoffset is non-zero. By calling pcre2_match() multiple  times  with
-       appropriate  arguments,  you  can  mimic Perl's /g option, and it is in
+       The \G assertion is true only when the current matching position is  at
+       the  start point of the matching process, as specified by the startoff-
+       set argument of pcre2_match(). It differs from \A  when  the  value  of
+       startoffset  is  non-zero. By calling pcre2_match() multiple times with
+       appropriate arguments, you can mimic Perl's /g option,  and  it  is  in
        this kind of implementation where \G can be useful.
 
-       Note, however, that PCRE2's implementation of \G,  being  true  at  the
-       starting  character  of  the matching process, is subtly different from
-       Perl's, which defines it as true at the end of the previous  match.  In
-       Perl,  these  can  be  different when the previously matched string was
+       Note,  however,  that  PCRE2's  implementation of \G, being true at the
+       starting character of the matching process, is  subtly  different  from
+       Perl's,  which  defines it as true at the end of the previous match. In
+       Perl, these can be different when the  previously  matched  string  was
        empty. Because PCRE2 does just one match at a time, it cannot reproduce
        this behaviour.
 
-       If  all  the alternatives of a pattern begin with \G, the expression is
+       If all the alternatives of a pattern begin with \G, the  expression  is
        anchored to the starting match position, and the "anchored" flag is set
        in the compiled regular expression.
 
 
 CIRCUMFLEX AND DOLLAR
 
-       The  circumflex  and  dollar  metacharacters are zero-width assertions.
-       That is, they test for a particular condition being true  without  con-
+       The circumflex and dollar  metacharacters  are  zero-width  assertions.
+       That  is,  they test for a particular condition being true without con-
        suming any characters from the subject string. These two metacharacters
-       are concerned with matching the starts and ends of lines. If  the  new-
-       line  convention is set so that only the two-character sequence CRLF is
-       recognized as a newline, isolated CR and LF characters are  treated  as
+       are  concerned  with matching the starts and ends of lines. If the new-
+       line convention is set so that only the two-character sequence CRLF  is
+       recognized  as  a newline, isolated CR and LF characters are treated as
        ordinary data characters, and are not recognized as newlines.
 
        Outside a character class, in the default matching mode, the circumflex
-       character is an assertion that is true only  if  the  current  matching
-       point  is  at the start of the subject string. If the startoffset argu-
-       ment of pcre2_match() is non-zero, or if PCRE2_NOTBOL is  set,  circum-
-       flex  can  never match if the PCRE2_MULTILINE option is unset. Inside a
-       character class, circumflex has  an  entirely  different  meaning  (see
+       character  is  an  assertion  that is true only if the current matching
+       point is at the start of the subject string. If the  startoffset  argu-
+       ment  of  pcre2_match() is non-zero, or if PCRE2_NOTBOL is set, circum-
+       flex can never match if the PCRE2_MULTILINE option is unset.  Inside  a
+       character  class,  circumflex  has  an  entirely different meaning (see
        below).
 
-       Circumflex  need  not be the first character of the pattern if a number
-       of alternatives are involved, but it should be the first thing in  each
-       alternative  in  which  it appears if the pattern is ever to match that
-       branch. If all possible alternatives start with a circumflex, that  is,
-       if  the  pattern  is constrained to match only at the start of the sub-
-       ject, it is said to be an "anchored" pattern.  (There  are  also  other
+       Circumflex need not be the first character of the pattern if  a  number
+       of  alternatives are involved, but it should be the first thing in each
+       alternative in which it appears if the pattern is ever  to  match  that
+       branch.  If all possible alternatives start with a circumflex, that is,
+       if the pattern is constrained to match only at the start  of  the  sub-
+       ject,  it  is  said  to be an "anchored" pattern. (There are also other
        constructs that can cause a pattern to be anchored.)
 
-       The  dollar  character is an assertion that is true only if the current
-       matching point is at the end of  the  subject  string,  or  immediately
-       before  a  newline  at  the  end  of  the  string  (by default), unless
+       The dollar character is an assertion that is true only if  the  current
+       matching  point  is  at  the  end of the subject string, or immediately
+       before a newline  at  the  end  of  the  string  (by  default),  unless
        PCRE2_NOTEOL is set. Note, however, that it does not actually match the
        newline. Dollar need not be the last character of the pattern if a num-
        ber of alternatives are involved, but it should be the last item in any
-       branch  in which it appears. Dollar has no special meaning in a charac-
+       branch in which it appears. Dollar has no special meaning in a  charac-
        ter class.
 
-       The meaning of dollar can be changed so that it  matches  only  at  the
-       very  end  of the string, by setting the PCRE2_DOLLAR_ENDONLY option at
+       The  meaning  of  dollar  can be changed so that it matches only at the
+       very end of the string, by setting the PCRE2_DOLLAR_ENDONLY  option  at
        compile time. This does not affect the \Z assertion.
 
        The meanings of the circumflex and dollar metacharacters are changed if
-       the  PCRE2_MULTILINE  option  is  set.  When this is the case, a dollar
-       character matches before any newlines in the string, as well as at  the
-       very  end, and a circumflex matches immediately after internal newlines
-       as well as at the start of the subject string. It does not match  after
-       a  newline  that ends the string, for compatibility with Perl. However,
+       the PCRE2_MULTILINE option is set. When this  is  the  case,  a  dollar
+       character  matches before any newlines in the string, as well as at the
+       very end, and a circumflex matches immediately after internal  newlines
+       as  well as at the start of the subject string. It does not match after
+       a newline that ends the string, for compatibility with  Perl.  However,
        this can be changed by setting the PCRE2_ALT_CIRCUMFLEX option.
 
-       For example, the pattern /^abc$/ matches the subject string  "def\nabc"
-       (where  \n  represents a newline) in multiline mode, but not otherwise.
-       Consequently, patterns that are anchored in single  line  mode  because
-       all  branches  start  with  ^ are not anchored in multiline mode, and a
-       match for circumflex is  possible  when  the  startoffset  argument  of
-       pcre2_match()  is  non-zero. The PCRE2_DOLLAR_ENDONLY option is ignored
+       For  example, the pattern /^abc$/ matches the subject string "def\nabc"
+       (where \n represents a newline) in multiline mode, but  not  otherwise.
+       Consequently,  patterns  that  are anchored in single line mode because
+       all branches start with ^ are not anchored in  multiline  mode,  and  a
+       match  for  circumflex  is  possible  when  the startoffset argument of
+       pcre2_match() is non-zero. The PCRE2_DOLLAR_ENDONLY option  is  ignored
        if PCRE2_MULTILINE is set.
 
-       When the newline convention (see "Newline  conventions"  below)  recog-
-       nizes  the two-character sequence CRLF as a newline, this is preferred,
-       even if the single characters CR and LF are  also  recognized  as  new-
-       lines.  For  example,  if  the newline convention is "any", a multiline
-       mode circumflex matches before "xyz" in the string "abc\r\nxyz"  rather
-       than  after  CR, even though CR on its own is a valid newline. (It also
+       When  the  newline  convention (see "Newline conventions" below) recog-
+       nizes the two-character sequence CRLF as a newline, this is  preferred,
+       even  if  the  single  characters CR and LF are also recognized as new-
+       lines. For example, if the newline convention  is  "any",  a  multiline
+       mode  circumflex matches before "xyz" in the string "abc\r\nxyz" rather
+       than after CR, even though CR on its own is a valid newline.  (It  also
        matches at the very start of the string, of course.)
 
-       Note that the sequences \A, \Z, and \z can be used to match  the  start
-       and  end of the subject in both modes, and if all branches of a pattern
-       start with \A it is always anchored, whether or not PCRE2_MULTILINE  is
+       Note  that  the sequences \A, \Z, and \z can be used to match the start
+       and end of the subject in both modes, and if all branches of a  pattern
+       start  with \A it is always anchored, whether or not PCRE2_MULTILINE is
        set.
 
 
 FULL STOP (PERIOD, DOT) AND \N
 
        Outside a character class, a dot in the pattern matches any one charac-
-       ter in the subject string except (by default) a character  that  signi-
+       ter  in  the subject string except (by default) a character that signi-
        fies the end of a line.
 
-       When  a line ending is defined as a single character, dot never matches
-       that character; when the two-character sequence CRLF is used, dot  does
-       not  match  CR  if  it  is immediately followed by LF, but otherwise it
-       matches all characters (including isolated CRs and LFs). When any  Uni-
-       code  line endings are being recognized, dot does not match CR or LF or
+       When a line ending is defined as a single character, dot never  matches
+       that  character; when the two-character sequence CRLF is used, dot does
+       not match CR if it is immediately followed  by  LF,  but  otherwise  it
+       matches  all characters (including isolated CRs and LFs). When any Uni-
+       code line endings are being recognized, dot does not match CR or LF  or
        any of the other line ending characters.
 
-       The behaviour of dot with regard to newlines can  be  changed.  If  the
-       PCRE2_DOTALL  option  is  set, a dot matches any one character, without
-       exception.  If the two-character sequence CRLF is present in  the  sub-
+       The  behaviour  of  dot  with regard to newlines can be changed. If the
+       PCRE2_DOTALL option is set, a dot matches any  one  character,  without
+       exception.   If  the two-character sequence CRLF is present in the sub-
        ject string, it takes two dots to match it.
 
-       The  handling of dot is entirely independent of the handling of circum-
-       flex and dollar, the only relationship being  that  they  both  involve
+       The handling of dot is entirely independent of the handling of  circum-
+       flex  and  dollar,  the  only relationship being that they both involve
        newlines. Dot has no special meaning in a character class.
 
-       The  escape  sequence  \N when not followed by an opening brace behaves
-       like a dot, except that it is not affected by the PCRE2_DOTALL  option.
-       In  other words, it matches any character except one that signifies the
+       The escape sequence \N when not followed by an  opening  brace  behaves
+       like  a dot, except that it is not affected by the PCRE2_DOTALL option.
+       In other words, it matches any character except one that signifies  the
        end of a line.
 
        When \N is followed by an opening brace it has a different meaning. See
-       the  section entitled "Non-printing characters" above for details. Perl
-       also uses \N{name} to specify characters by Unicode  name;  PCRE2  does
+       the section entitled "Non-printing characters" above for details.  Perl
+       also  uses  \N{name}  to specify characters by Unicode name; PCRE2 does
        not support this.
 
 
 MATCHING A SINGLE CODE UNIT
 
-       Outside  a character class, the escape sequence \C matches any one code
-       unit, whether or not a UTF mode is set. In the 8-bit library, one  code
-       unit  is  one  byte;  in the 16-bit library it is a 16-bit unit; in the
-       32-bit library it is a 32-bit unit. Unlike a  dot,  \C  always  matches
-       line-ending  characters.  The  feature  is provided in Perl in order to
+       Outside a character class, the escape sequence \C matches any one  code
+       unit,  whether or not a UTF mode is set. In the 8-bit library, one code
+       unit is one byte; in the 16-bit library it is a  16-bit  unit;  in  the
+       32-bit  library  it  is  a 32-bit unit. Unlike a dot, \C always matches
+       line-ending characters. The feature is provided in  Perl  in  order  to
        match individual bytes in UTF-8 mode, but it is unclear how it can use-
        fully be used.
 
-       Because  \C  breaks  up characters into individual code units, matching
-       one unit with \C in UTF-8 or UTF-16 mode means that  the  rest  of  the
-       string  may  start  with  a malformed UTF character. This has undefined
+       Because \C breaks up characters into individual  code  units,  matching
+       one  unit  with  \C  in UTF-8 or UTF-16 mode means that the rest of the
+       string may start with a malformed UTF  character.  This  has  undefined
        results, because PCRE2 assumes that it is matching character by charac-
-       ter  in  a  valid UTF string (by default it checks the subject string's
-       validity at the  start  of  processing  unless  the  PCRE2_NO_UTF_CHECK
+       ter in a valid UTF string (by default it checks  the  subject  string's
+       validity  at  the  start  of  processing  unless the PCRE2_NO_UTF_CHECK
        option is used).
 
-       An   application   can   lock   out  the  use  of  \C  by  setting  the
-       PCRE2_NEVER_BACKSLASH_C option when compiling a  pattern.  It  is  also
+       An  application  can  lock  out  the  use  of   \C   by   setting   the
+       PCRE2_NEVER_BACKSLASH_C  option  when  compiling  a pattern. It is also
        possible to build PCRE2 with the use of \C permanently disabled.
 
-       PCRE2  does  not allow \C to appear in lookbehind assertions (described
-       below) in UTF-8 or UTF-16 modes, because this would make it  impossible
-       to  calculate  the  length  of  the lookbehind. Neither the alternative
+       PCRE2 does not allow \C to appear in lookbehind  assertions  (described
+       below)  in UTF-8 or UTF-16 modes, because this would make it impossible
+       to calculate the length of  the  lookbehind.  Neither  the  alternative
        matching function pcre2_dfa_match() nor the JIT optimizer support \C in
        these UTF modes.  The former gives a match-time error; the latter fails
        to optimize and so the match is always run using the interpreter.
 
-       In the 32-bit library,  however,  \C  is  always  supported  (when  not
-       explicitly  locked  out)  because it always matches a single code unit,
+       In  the  32-bit  library,  however,  \C  is  always supported (when not
+       explicitly locked out) because it always matches a  single  code  unit,
        whether or not UTF-32 is specified.
 
        In general, the \C escape sequence is best avoided. However, one way of
-       using  it  that avoids the problem of malformed UTF-8 or UTF-16 charac-
-       ters is to use a lookahead to check the length of the  next  character,
-       as  in  this  pattern,  which could be used with a UTF-8 string (ignore
+       using it that avoids the problem of malformed UTF-8 or  UTF-16  charac-
+       ters  is  to use a lookahead to check the length of the next character,
+       as in this pattern, which could be used with  a  UTF-8  string  (ignore
        white space and line breaks):
 
          (?| (?=[\x00-\x7f])(\C) |
@@ -7045,10 +7050,10 @@ MATCHING A SINGLE CODE UNIT
              (?=[\x{800}-\x{ffff}])(\C)(\C)(\C) |
              (?=[\x{10000}-\x{1fffff}])(\C)(\C)(\C)(\C))
 
-       In this example, a group that starts  with  (?|  resets  the  capturing
+       In  this  example,  a  group  that starts with (?| resets the capturing
        parentheses numbers in each alternative (see "Duplicate Subpattern Num-
        bers" below). The assertions at the start of each branch check the next
-       UTF-8  character  for  values  whose encoding uses 1, 2, 3, or 4 bytes,
+       UTF-8 character for values whose encoding uses 1, 2,  3,  or  4  bytes,
        respectively. The character's individual bytes are then captured by the
        appropriate number of \C groups.
 
@@ -7057,115 +7062,115 @@ SQUARE BRACKETS AND CHARACTER CLASSES
 
        An opening square bracket introduces a character class, terminated by a
        closing square bracket. A closing square bracket on its own is not spe-
-       cial  by  default.  If a closing square bracket is required as a member
+       cial by default.  If a closing square bracket is required as  a  member
        of the class, it should be the first data character in the class (after
-       an  initial  circumflex,  if present) or escaped with a backslash. This
-       means that, by default, an empty class cannot be defined.  However,  if
-       the  PCRE2_ALLOW_EMPTY_CLASS option is set, a closing square bracket at
+       an initial circumflex, if present) or escaped with  a  backslash.  This
+       means  that,  by default, an empty class cannot be defined. However, if
+       the PCRE2_ALLOW_EMPTY_CLASS option is set, a closing square bracket  at
        the start does end the (empty) class.
 
-       A character class matches a single character in the subject. A  matched
+       A  character class matches a single character in the subject. A matched
        character must be in the set of characters defined by the class, unless
-       the first character in the class definition is a circumflex,  in  which
+       the  first  character in the class definition is a circumflex, in which
        case the subject character must not be in the set defined by the class.
-       If a circumflex is actually required as a member of the  class,  ensure
+       If  a  circumflex is actually required as a member of the class, ensure
        it is not the first character, or escape it with a backslash.
 
-       For  example, the character class [aeiou] matches any lower case vowel,
-       while [^aeiou] matches any character that is not a  lower  case  vowel.
+       For example, the character class [aeiou] matches any lower case  vowel,
+       while  [^aeiou]  matches  any character that is not a lower case vowel.
        Note that a circumflex is just a convenient notation for specifying the
-       characters that are in the class by enumerating those that are  not.  A
-       class  that starts with a circumflex is not an assertion; it still con-
-       sumes a character from the subject string, and therefore  it  fails  if
+       characters  that  are in the class by enumerating those that are not. A
+       class that starts with a circumflex is not an assertion; it still  con-
+       sumes  a  character  from the subject string, and therefore it fails if
        the current pointer is at the end of the string.
 
-       Characters  in  a class may be specified by their code points using \o,
-       \x, or \N{U+hh..} in the usual way. When caseless matching is set,  any
-       letters  in a class represent both their upper case and lower case ver-
-       sions, so for example, a caseless [aeiou] matches "A" as well  as  "a",
-       and  a  caseless [^aeiou] does not match "A", whereas a caseful version
+       Characters in a class may be specified by their code points  using  \o,
+       \x,  or \N{U+hh..} in the usual way. When caseless matching is set, any
+       letters in a class represent both their upper case and lower case  ver-
+       sions,  so  for example, a caseless [aeiou] matches "A" as well as "a",
+       and a caseless [^aeiou] does not match "A", whereas a  caseful  version
        would.
 
-       Characters that might indicate line breaks are  never  treated  in  any
-       special  way  when  matching  character  classes,  whatever line-ending
-       sequence is in use,  and  whatever  setting  of  the  PCRE2_DOTALL  and
-       PCRE2_MULTILINE  options  is  used. A class such as [^a] always matches
+       Characters  that  might  indicate  line breaks are never treated in any
+       special way  when  matching  character  classes,  whatever  line-ending
+       sequence  is  in  use,  and  whatever  setting  of the PCRE2_DOTALL and
+       PCRE2_MULTILINE options is used. A class such as  [^a]  always  matches
        one of these characters.
 
        The generic character type escape sequences \d, \D, \h, \H, \p, \P, \s,
-       \S,  \v,  \V,  \w,  and \W may appear in a character class, and add the
-       characters that they  match  to  the  class.  For  example,  [\dABCDEF]
-       matches  any  hexadecimal  digit.  In  UTF  modes, the PCRE2_UCP option
-       affects the meanings of \d, \s, \w and their upper case partners,  just
-       as  it does when they appear outside a character class, as described in
-       the section  entitled  "Generic  character  types"  above.  The  escape
-       sequence  \b  has  a  different  meaning  inside  a character class; it
-       matches the backspace character. The sequences \B, \R, and \X  are  not
-       special  inside  a  character class. Like any other unrecognized escape
-       sequences, they cause an error. The same is true for \N when  not  fol-
+       \S, \v, \V, \w, and \W may appear in a character  class,  and  add  the
+       characters  that  they  match  to  the  class.  For example, [\dABCDEF]
+       matches any hexadecimal digit.  In  UTF  modes,  the  PCRE2_UCP  option
+       affects  the meanings of \d, \s, \w and their upper case partners, just
+       as it does when they appear outside a character class, as described  in
+       the  section  entitled  "Generic  character  types"  above.  The escape
+       sequence \b has a  different  meaning  inside  a  character  class;  it
+       matches  the  backspace character. The sequences \B, \R, and \X are not
+       special inside a character class. Like any  other  unrecognized  escape
+       sequences,  they  cause an error. The same is true for \N when not fol-
        lowed by an opening brace.
 
-       The  minus (hyphen) character can be used to specify a range of charac-
-       ters in a character  class.  For  example,  [d-m]  matches  any  letter
-       between  d  and  m,  inclusive.  If  a minus character is required in a
-       class, it must be escaped with a backslash  or  appear  in  a  position
-       where  it cannot be interpreted as indicating a range, typically as the
+       The minus (hyphen) character can be used to specify a range of  charac-
+       ters  in  a  character  class.  For  example,  [d-m] matches any letter
+       between d and m, inclusive. If a  minus  character  is  required  in  a
+       class,  it  must  be  escaped  with a backslash or appear in a position
+       where it cannot be interpreted as indicating a range, typically as  the
        first or last character in the class, or immediately after a range. For
-       example,  [b-d-z] matches letters in the range b to d, a hyphen charac-
+       example, [b-d-z] matches letters in the range b to d, a hyphen  charac-
        ter, or z.
 
        Perl treats a hyphen as a literal if it appears before or after a POSIX
        class (see below) or before or after a character type escape such as as
-       \d or \H.  However, unless the hyphen is  the  last  character  in  the
-       class,  Perl  outputs  a  warning  in its warning mode, as this is most
-       likely a user error. As PCRE2 has no facility for warning, an error  is
+       \d  or  \H.   However,  unless  the hyphen is the last character in the
+       class, Perl outputs a warning in its warning  mode,  as  this  is  most
+       likely  a user error. As PCRE2 has no facility for warning, an error is
        given in these cases.
 
        It is not possible to have the literal character "]" as the end charac-
-       ter of a range. A pattern such as [W-]46] is interpreted as a class  of
-       two  characters ("W" and "-") followed by a literal string "46]", so it
-       would match "W46]" or "-46]". However, if the "]"  is  escaped  with  a
-       backslash  it is interpreted as the end of range, so [W-\]46] is inter-
-       preted as a class containing a range followed by two other  characters.
-       The  octal or hexadecimal representation of "]" can also be used to end
+       ter  of a range. A pattern such as [W-]46] is interpreted as a class of
+       two characters ("W" and "-") followed by a literal string "46]", so  it
+       would  match  "W46]"  or  "-46]". However, if the "]" is escaped with a
+       backslash it is interpreted as the end of range, so [W-\]46] is  inter-
+       preted  as a class containing a range followed by two other characters.
+       The octal or hexadecimal representation of "]" can also be used to  end
        a range.
 
        Ranges normally include all code points between the start and end char-
-       acters,  inclusive.  They  can  also  be used for code points specified
+       acters, inclusive. They can also be  used  for  code  points  specified
        numerically, for example [\000-\037]. Ranges can include any characters
-       that  are  valid  for  the current mode. In any UTF mode, the so-called
-       "surrogate" characters (those whose code points lie between 0xd800  and
-       0xdfff  inclusive)  may  not  be  specified  explicitly by default (the
-       PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES option disables this  check).  How-
+       that are valid for the current mode. In any  UTF  mode,  the  so-called
+       "surrogate"  characters (those whose code points lie between 0xd800 and
+       0xdfff inclusive) may not  be  specified  explicitly  by  default  (the
+       PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES  option  disables this check). How-
        ever, ranges such as [\x{d7ff}-\x{e000}], which include the surrogates,
        are always permitted.
 
-       There is a special case in EBCDIC environments  for  ranges  whose  end
+       There  is  a  special  case in EBCDIC environments for ranges whose end
        points are both specified as literal letters in the same case. For com-
-       patibility with Perl, EBCDIC code points within the range that are  not
-       letters  are  omitted. For example, [h-k] matches only four characters,
+       patibility  with Perl, EBCDIC code points within the range that are not
+       letters are omitted. For example, [h-k] matches only  four  characters,
        even though the codes for h and k are 0x88 and 0x92, a range of 11 code
-       points.  However,  if  the range is specified numerically, for example,
+       points. However, if the range is specified  numerically,  for  example,
        [\x88-\x92] or [h-\x92], all code points are included.
 
        If a range that includes letters is used when caseless matching is set,
        it matches the letters in either case. For example, [W-c] is equivalent
-       to [][\\^_`wxyzabc], matched caselessly, and  in  a  non-UTF  mode,  if
-       character  tables  for  a French locale are in use, [\xc8-\xcb] matches
+       to  [][\\^_`wxyzabc],  matched  caselessly,  and  in a non-UTF mode, if
+       character tables for a French locale are in  use,  [\xc8-\xcb]  matches
        accented E characters in both cases.
 
-       A circumflex can conveniently be used with  the  upper  case  character
-       types  to specify a more restricted set of characters than the matching
-       lower case type.  For example, the class [^\W_] matches any  letter  or
+       A  circumflex  can  conveniently  be used with the upper case character
+       types to specify a more restricted set of characters than the  matching
+       lower  case  type.  For example, the class [^\W_] matches any letter or
        digit, but not underscore, whereas [\w] includes underscore. A positive
        character class should be read as "something OR something OR ..." and a
        negative class as "NOT something AND NOT something AND NOT ...".
 
-       The  only  metacharacters  that are recognized in character classes are
-       backslash, hyphen (only where it can be  interpreted  as  specifying  a
-       range),  circumflex  (only  at the start), opening square bracket (only
-       when it can be interpreted as introducing a POSIX class name, or for  a
-       special  compatibility  feature  -  see the next two sections), and the
+       The only metacharacters that are recognized in  character  classes  are
+       backslash,  hyphen  (only  where  it can be interpreted as specifying a
+       range), circumflex (only at the start), opening  square  bracket  (only
+       when  it can be interpreted as introducing a POSIX class name, or for a
+       special compatibility feature - see the next  two  sections),  and  the
        terminating  closing  square  bracket.  However,  escaping  other  non-
        alphanumeric characters does no harm.
 
@@ -7173,7 +7178,7 @@ SQUARE BRACKETS AND CHARACTER CLASSES
 POSIX CHARACTER CLASSES
 
        Perl supports the POSIX notation for character classes. This uses names
-       enclosed by [: and :] within the enclosing square brackets. PCRE2  also
+       enclosed  by [: and :] within the enclosing square brackets. PCRE2 also
        supports this notation. For example,
 
          [01[:alpha:]%]
@@ -7196,13 +7201,13 @@ POSIX CHARACTER CLASSES
          word     "word" characters (same as \w)
          xdigit   hexadecimal digits
 
-       The default "space" characters are HT (9), LF (10), VT (11),  FF  (12),
-       CR  (13),  and space (32). If locale-specific matching is taking place,
-       the list of space characters may be different; there may  be  fewer  or
+       The  default  "space" characters are HT (9), LF (10), VT (11), FF (12),
+       CR (13), and space (32). If locale-specific matching is  taking  place,
+       the  list  of  space characters may be different; there may be fewer or
        more of them. "Space" and \s match the same set of characters.
 
-       The  name  "word"  is  a Perl extension, and "blank" is a GNU extension
-       from Perl 5.8. Another Perl extension is negation, which  is  indicated
+       The name "word" is a Perl extension, and "blank"  is  a  GNU  extension
+       from  Perl  5.8. Another Perl extension is negation, which is indicated
        by a ^ character after the colon. For example,
 
          [12[:^digit:]]
@@ -7213,9 +7218,9 @@ POSIX CHARACTER CLASSES
 
        By default, characters with values greater than 127 do not match any of
        the POSIX character classes, although this may be different for charac-
-       ters  in  the range 128-255 when locale-specific matching is happening.
-       However, if the PCRE2_UCP option is passed to pcre2_compile(), some  of
-       the  classes are changed so that Unicode character properties are used.
+       ters in the range 128-255 when locale-specific matching  is  happening.
+       However,  if the PCRE2_UCP option is passed to pcre2_compile(), some of
+       the classes are changed so that Unicode character properties are  used.
        This  is  achieved  by  replacing  certain  POSIX  classes  with  other
        sequences, as follows:
 
@@ -7229,10 +7234,10 @@ POSIX CHARACTER CLASSES
          [:upper:]  becomes  \p{Lu}
          [:word:]   becomes  \p{Xwd}
 
-       Negated  versions, such as [:^alpha:] use \P instead of \p. Three other
+       Negated versions, such as [:^alpha:] use \P instead of \p. Three  other
        POSIX classes are handled specially in UCP mode:
 
-       [:graph:] This matches characters that have glyphs that mark  the  page
+       [:graph:] This  matches  characters that have glyphs that mark the page
                  when printed. In Unicode property terms, it matches all char-
                  acters with the L, M, N, P, S, or Cf properties, except for:
 
@@ -7241,60 +7246,60 @@ POSIX CHARACTER CLASSES
                    U+2066 - U+2069  Various "isolate"s
 
 
-       [:print:] This matches the same  characters  as  [:graph:]  plus  space
-                 characters  that  are  not controls, that is, characters with
+       [:print:] This  matches  the  same  characters  as [:graph:] plus space
+                 characters that are not controls, that  is,  characters  with
                  the Zs property.
 
        [:punct:] This matches all characters that have the Unicode P (punctua-
-                 tion)  property,  plus those characters with code points less
+                 tion) property, plus those characters with code  points  less
                  than 256 that have the S (Symbol) property.
 
-       The other POSIX classes are unchanged, and match only  characters  with
+       The  other  POSIX classes are unchanged, and match only characters with
        code points less than 256.
 
 
 COMPATIBILITY FEATURE FOR WORD BOUNDARIES
 
-       In  the POSIX.2 compliant library that was included in 4.4BSD Unix, the
-       ugly syntax [[:<:]] and [[:>:]] is used for matching  "start  of  word"
+       In the POSIX.2 compliant library that was included in 4.4BSD Unix,  the
+       ugly  syntax  [[:<:]]  and [[:>:]] is used for matching "start of word"
        and "end of word". PCRE2 treats these items as follows:
 
          [[:<:]]  is converted to  \b(?=\w)
          [[:>:]]  is converted to  \b(?<=\w)
 
        Only these exact character sequences are recognized. A sequence such as
-       [a[:<:]b] provokes error for an unrecognized  POSIX  class  name.  This
-       support  is not compatible with Perl. It is provided to help migrations
+       [a[:<:]b]  provokes  error  for  an unrecognized POSIX class name. This
+       support is not compatible with Perl. It is provided to help  migrations
        from other environments, and is best not used in any new patterns. Note
-       that  \b matches at the start and the end of a word (see "Simple asser-
-       tions" above), and in a Perl-style pattern the preceding  or  following
-       character  normally  shows  which  is  wanted, without the need for the
-       assertions that are used above in order to give exactly the  POSIX  be-
+       that \b matches at the start and the end of a word (see "Simple  asser-
+       tions"  above),  and in a Perl-style pattern the preceding or following
+       character normally shows which is wanted,  without  the  need  for  the
+       assertions  that  are used above in order to give exactly the POSIX be-
        haviour.
 
 
 VERTICAL BAR
 
-       Vertical  bar characters are used to separate alternative patterns. For
+       Vertical bar characters are used to separate alternative patterns.  For
        example, the pattern
 
          gilbert|sullivan
 
-       matches either "gilbert" or "sullivan". Any number of alternatives  may
-       appear,  and  an  empty  alternative  is  permitted (matching the empty
+       matches  either "gilbert" or "sullivan". Any number of alternatives may
+       appear, and an empty  alternative  is  permitted  (matching  the  empty
        string). The matching process tries each alternative in turn, from left
-       to  right, and the first one that succeeds is used. If the alternatives
-       are within a subpattern (defined below), "succeeds" means matching  the
+       to right, and the first one that succeeds is used. If the  alternatives
+       are  within a subpattern (defined below), "succeeds" means matching the
        rest of the main pattern as well as the alternative in the subpattern.
 
 
 INTERNAL OPTION SETTING
 
-       The  settings  of  the  PCRE2_CASELESS,  PCRE2_MULTILINE, PCRE2_DOTALL,
-       PCRE2_EXTENDED, PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE  options
-       can  be  changed  from  within  the  pattern  by  a sequence of letters
-       enclosed between "(?"  and ")". These options are Perl-compatible,  and
-       are  described in detail in the pcre2api documentation. The option let-
+       The settings  of  the  PCRE2_CASELESS,  PCRE2_MULTILINE,  PCRE2_DOTALL,
+       PCRE2_EXTENDED,  PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE options
+       can be changed from  within  the  pattern  by  a  sequence  of  letters
+       enclosed  between "(?"  and ")". These options are Perl-compatible, and
+       are described in detail in the pcre2api documentation. The option  let-
        ters are:
 
          i  for PCRE2_CASELESS
@@ -7305,49 +7310,49 @@ INTERNAL OPTION SETTING
          xx for PCRE2_EXTENDED_MORE
 
        For example, (?im) sets caseless, multiline matching. It is also possi-
-       ble  to  unset  these  options by preceding the relevant letters with a
+       ble to unset these options by preceding the  relevant  letters  with  a
        hyphen, for example (?-im). The two "extended" options are not indepen-
        dent; unsetting either one cancels the effects of both of them.
 
-       A   combined  setting  and  unsetting  such  as  (?im-sx),  which  sets
-       PCRE2_CASELESS and PCRE2_MULTILINE  while  unsetting  PCRE2_DOTALL  and
-       PCRE2_EXTENDED,  is  also  permitted. Only one hyphen may appear in the
-       options string. If a letter appears both before and after  the  hyphen,
-       the  option  is unset. An empty options setting "(?)" is allowed. Need-
+       A  combined  setting  and  unsetting  such  as  (?im-sx),  which   sets
+       PCRE2_CASELESS  and  PCRE2_MULTILINE  while  unsetting PCRE2_DOTALL and
+       PCRE2_EXTENDED, is also permitted. Only one hyphen may  appear  in  the
+       options  string.  If a letter appears both before and after the hyphen,
+       the option is unset. An empty options setting "(?)" is  allowed.  Need-
        less to say, it has no effect.
 
-       If the first character following (? is a circumflex, it causes  all  of
-       the  above  options to be unset. Thus, (?^) is equivalent to (?-imnsx).
-       Letters may follow the circumflex to  cause  some  options  to  be  re-
+       If  the  first character following (? is a circumflex, it causes all of
+       the above options to be unset. Thus, (?^) is equivalent  to  (?-imnsx).
+       Letters  may  follow  the  circumflex  to  cause some options to be re-
        instated, but a hyphen may not appear.
 
-       The  PCRE2-specific  options  PCRE2_DUPNAMES  and PCRE2_UNGREEDY can be
-       changed in the same way as the Perl-compatible  options  by  using  the
+       The PCRE2-specific options PCRE2_DUPNAMES  and  PCRE2_UNGREEDY  can  be
+       changed  in  the  same  way as the Perl-compatible options by using the
        characters J and U respectively. However, these are not unset by (?^).
 
-       When  one  of  these  option  changes occurs at top level (that is, not
-       inside subpattern parentheses), the change applies to the remainder  of
-       the  pattern  that  follows.  An option change within a subpattern (see
-       below for a description of subpatterns) affects only that part  of  the
+       When one of these option changes occurs at  top  level  (that  is,  not
+       inside  subpattern parentheses), the change applies to the remainder of
+       the pattern that follows. An option change  within  a  subpattern  (see
+       below  for  a description of subpatterns) affects only that part of the
        subpattern that follows it, so
 
          (a(?i)b)c
 
-       matches  abc  and  aBc and no other strings (assuming PCRE2_CASELESS is
-       not used).  By this means, options can be made to have  different  set-
+       matches abc and aBc and no other strings  (assuming  PCRE2_CASELESS  is
+       not  used).   By this means, options can be made to have different set-
        tings in different parts of the pattern. Any changes made in one alter-
        native do carry on into subsequent branches within the same subpattern.
        For example,
 
          (a(?i)b|c)
 
-       matches  "ab",  "aB",  "c",  and "C", even though when matching "C" the
-       first branch is abandoned before the option setting.  This  is  because
-       the  effects  of option settings happen at compile time. There would be
+       matches "ab", "aB", "c", and "C", even though  when  matching  "C"  the
+       first  branch  is  abandoned before the option setting. This is because
+       the effects of option settings happen at compile time. There  would  be
        some very weird behaviour otherwise.
 
-       As a convenient shorthand, if any option settings are required  at  the
-       start  of a non-capturing subpattern (see the next section), the option
+       As  a  convenient shorthand, if any option settings are required at the
+       start of a non-capturing subpattern (see the next section), the  option
        letters may appear between the "?" and the ":". Thus the two patterns
 
          (?i:saturday|sunday)
@@ -7355,14 +7360,14 @@ INTERNAL OPTION SETTING
 
        match exactly the same set of strings.
 
-       Note: There are other PCRE2-specific options that can  be  set  by  the
+       Note:  There  are  other  PCRE2-specific options that can be set by the
        application when the compiling function is called. The pattern can con-
-       tain special leading sequences such as (*CRLF)  to  override  what  the
-       application  has  set  or what has been defaulted. Details are given in
-       the section entitled "Newline sequences"  above.  There  are  also  the
-       (*UTF)  and  (*UCP)  leading  sequences that can be used to set UTF and
-       Unicode property modes; they are equivalent to  setting  the  PCRE2_UTF
-       and  PCRE2_UCP  options, respectively. However, the application can set
+       tain  special  leading  sequences  such as (*CRLF) to override what the
+       application has set or what has been defaulted. Details  are  given  in
+       the  section  entitled  "Newline  sequences"  above. There are also the
+       (*UTF) and (*UCP) leading sequences that can be used  to  set  UTF  and
+       Unicode  property  modes;  they are equivalent to setting the PCRE2_UTF
+       and PCRE2_UCP options, respectively. However, the application  can  set
        the PCRE2_NEVER_UTF and PCRE2_NEVER_UCP options, which lock out the use
        of the (*UTF) and (*UCP) sequences.
 
@@ -7376,18 +7381,18 @@ SUBPATTERNS
 
          cat(aract|erpillar|)
 
-       matches "cataract", "caterpillar", or "cat". Without  the  parentheses,
+       matches  "cataract",  "caterpillar", or "cat". Without the parentheses,
        it would match "cataract", "erpillar" or an empty string.
 
-       2.  It  sets  up  the  subpattern as a capturing subpattern. This means
+       2. It sets up the subpattern as  a  capturing  subpattern.  This  means
        that, when the whole pattern matches, the portion of the subject string
-       that  matched  the  subpattern is passed back to the caller, separately
-       from the portion that matched the whole pattern. (This applies only  to
-       the  traditional  matching function; the DFA matching function does not
+       that matched the subpattern is passed back to  the  caller,  separately
+       from  the portion that matched the whole pattern. (This applies only to
+       the traditional matching function; the DFA matching function  does  not
        support capturing.)
 
        Opening parentheses are counted from left to right (starting from 1) to
-       obtain  numbers  for  the  capturing  subpatterns.  For example, if the
+       obtain numbers for the  capturing  subpatterns.  For  example,  if  the
        string "the red king" is matched against the pattern
 
          the ((red|white) (king|queen))
@@ -7395,12 +7400,12 @@ SUBPATTERNS
        the captured substrings are "red king", "red", and "king", and are num-
        bered 1, 2, and 3, respectively.
 
-       The  fact  that  plain  parentheses  fulfil two functions is not always
-       helpful.  There are often times when a grouping subpattern is  required
-       without  a capturing requirement. If an opening parenthesis is followed
-       by a question mark and a colon, the subpattern does not do any  captur-
-       ing,  and  is  not  counted when computing the number of any subsequent
-       capturing subpatterns. For example, if the string "the white queen"  is
+       The fact that plain parentheses fulfil  two  functions  is  not  always
+       helpful.   There are often times when a grouping subpattern is required
+       without a capturing requirement. If an opening parenthesis is  followed
+       by  a question mark and a colon, the subpattern does not do any captur-
+       ing, and is not counted when computing the  number  of  any  subsequent
+       capturing  subpatterns. For example, if the string "the white queen" is
        matched against the pattern
 
          the ((?:red|white) (king|queen))
@@ -7408,37 +7413,37 @@ SUBPATTERNS
        the captured substrings are "white queen" and "queen", and are numbered
        1 and 2. The maximum number of capturing subpatterns is 65535.
 
-       As a convenient shorthand, if any option settings are required  at  the
-       start  of  a  non-capturing  subpattern,  the option letters may appear
+       As  a  convenient shorthand, if any option settings are required at the
+       start of a non-capturing subpattern,  the  option  letters  may  appear
        between the "?" and the ":". Thus the two patterns
 
          (?i:saturday|sunday)
          (?:(?i)saturday|sunday)
 
        match exactly the same set of strings. Because alternative branches are
-       tried  from  left  to right, and options are not reset until the end of
-       the subpattern is reached, an option setting in one branch does  affect
-       subsequent  branches,  so  the above patterns match "SUNDAY" as well as
+       tried from left to right, and options are not reset until  the  end  of
+       the  subpattern is reached, an option setting in one branch does affect
+       subsequent branches, so the above patterns match "SUNDAY"  as  well  as
        "Saturday".
 
 
 DUPLICATE SUBPATTERN NUMBERS
 
        Perl 5.10 introduced a feature whereby each alternative in a subpattern
-       uses  the same numbers for its capturing parentheses. Such a subpattern
-       starts with (?| and is itself a non-capturing subpattern. For  example,
+       uses the same numbers for its capturing parentheses. Such a  subpattern
+       starts  with (?| and is itself a non-capturing subpattern. For example,
        consider this pattern:
 
          (?|(Sat)ur|(Sun))day
 
-       Because  the two alternatives are inside a (?| group, both sets of cap-
-       turing parentheses are numbered one. Thus, when  the  pattern  matches,
-       you  can  look  at captured substring number one, whichever alternative
-       matched. This construct is useful when you want to  capture  part,  but
+       Because the two alternatives are inside a (?| group, both sets of  cap-
+       turing  parentheses  are  numbered one. Thus, when the pattern matches,
+       you can look at captured substring number  one,  whichever  alternative
+       matched.  This  construct  is useful when you want to capture part, but
        not all, of one of a number of alternatives. Inside a (?| group, paren-
-       theses are numbered as usual, but the number is reset at the  start  of
-       each  branch.  The numbers of any capturing parentheses that follow the
-       subpattern start after the highest number used in any branch. The  fol-
+       theses  are  numbered as usual, but the number is reset at the start of
+       each branch. The numbers of any capturing parentheses that  follow  the
+       subpattern  start after the highest number used in any branch. The fol-
        lowing example is taken from the Perl documentation. The numbers under-
        neath show in which buffer the captured content will be stored.
 
@@ -7446,14 +7451,14 @@ DUPLICATE SUBPATTERN NUMBERS
          / ( a )  (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x
          # 1            2         2  3        2     3     4
 
-       A backreference to a numbered subpattern uses  the  most  recent  value
-       that  is  set  for that number by any subpattern. The following pattern
+       A  backreference  to  a  numbered subpattern uses the most recent value
+       that is set for that number by any subpattern.  The  following  pattern
        matches "abcabc" or "defdef":
 
          /(?|(abc)|(def))\1/
 
-       In contrast, a subroutine call to a numbered subpattern  always  refers
-       to  the  first  one in the pattern with the given number. The following
+       In  contrast,  a subroutine call to a numbered subpattern always refers
+       to the first one in the pattern with the given  number.  The  following
        pattern matches "abcabc" or "defabc":
 
          /(?|(abc)|(def))(?1)/
@@ -7461,75 +7466,75 @@ DUPLICATE SUBPATTERN NUMBERS
        A relative reference such as (?-1) is no different: it is just a conve-
        nient way of computing an absolute group number.
 
-       If  a condition test for a subpattern's having matched refers to a non-
-       unique number, the test is true if any of the subpatterns of that  num-
+       If a condition test for a subpattern's having matched refers to a  non-
+       unique  number, the test is true if any of the subpatterns of that num-
        ber have matched.
 
-       An  alternative approach to using this "branch reset" feature is to use
+       An alternative approach to using this "branch reset" feature is to  use
        duplicate named subpatterns, as described in the next section.
 
 
 NAMED SUBPATTERNS
 
-       Identifying capturing parentheses by number is simple, but  it  can  be
-       very  hard  to  keep track of the numbers in complicated patterns. Fur-
+       Identifying  capturing  parentheses  by number is simple, but it can be
+       very hard to keep track of the numbers in  complicated  patterns.  Fur-
        thermore, if an expression is modified, the numbers may change. To help
-       with  this  difficulty,  PCRE2 supports the naming of capturing subpat-
-       terns. This feature was not added to Perl until  release  5.10.  Python
-       had  the feature earlier, and PCRE1 introduced it at release 4.0, using
+       with this difficulty, PCRE2 supports the naming  of  capturing  subpat-
+       terns.  This  feature  was not added to Perl until release 5.10. Python
+       had the feature earlier, and PCRE1 introduced it at release 4.0,  using
        the Python syntax. PCRE2 supports both the Perl and the Python syntax.
 
-       In PCRE2, a capturing subpattern can be named in  one  of  three  ways:
+       In  PCRE2,  a  capturing  subpattern can be named in one of three ways:
        (?...) or (?'name'...) as in Perl, or (?P...) as in Python.
-       Names consist of up to 32 alphanumeric characters and underscores,  but
-       must  start  with a non-digit. References to capturing parentheses from
+       Names  consist of up to 32 alphanumeric characters and underscores, but
+       must start with a non-digit. References to capturing  parentheses  from
        other parts of the pattern, such as backreferences, recursion, and con-
        ditions, can all be made by name as well as by number.
 
-       Named  capturing  parentheses  are  allocated numbers as well as names,
-       exactly as if the names were not present. In both PCRE2 and Perl,  cap-
-       turing  subpatterns  are primarily identified by numbers; any names are
-       just aliases for these numbers. The PCRE2 API provides  function  calls
-       for  extracting  the  complete  name-to-number translation table from a
-       compiled pattern, as well as convenience functions for extracting  cap-
+       Named capturing parentheses are allocated numbers  as  well  as  names,
+       exactly  as if the names were not present. In both PCRE2 and Perl, cap-
+       turing subpatterns are primarily identified by numbers; any  names  are
+       just  aliases  for these numbers. The PCRE2 API provides function calls
+       for extracting the complete name-to-number  translation  table  from  a
+       compiled  pattern, as well as convenience functions for extracting cap-
        tured substrings by name.
 
-       Warning:  When  more  than  one  subpattern  has  the  same  number, as
-       described in the previous section, a name given to one of them  applies
-       to  all  of them.  Perl allows identically numbered subpatterns to have
-       different names. Consider this pattern, where there are  two  capturing
+       Warning: When  more  than  one  subpattern  has  the  same  number,  as
+       described  in the previous section, a name given to one of them applies
+       to all of them.  Perl allows identically numbered subpatterns  to  have
+       different  names.  Consider this pattern, where there are two capturing
        subpatterns, both numbered 1:
 
          (?|(?aa)|(?bb))
 
-       Perl  allows  this,  with  both  names AA and BB as aliases of group 1.
+       Perl allows this, with both names AA and BB  as  aliases  of  group  1.
        Thus, after a successful match, both names yield the same value (either
        "aa" or "bb").
 
-       In  an attempt to reduce confusion, PCRE2 does not allow the same group
+       In an attempt to reduce confusion, PCRE2 does not allow the same  group
        number to be associated with more than one name. The example above pro-
-       vokes  a  compile-time  error. However, there is still scope for confu-
+       vokes a compile-time error. However, there is still  scope  for  confu-
        sion. Consider this pattern:
 
          (?|(?aa)|(bb))
 
-       Although the second subpattern number 1 is not  explicitly  named,  the
+       Although  the  second  subpattern number 1 is not explicitly named, the
        name AA is still an alias for subpattern 1. Whether the pattern matches
-       "aa" or "bb", a reference by  name  to  group  AA  yields  the  matched
+       "aa"  or  "bb",  a  reference  by  name  to group AA yields the matched
        string.
 
-       By  default, a name must be unique within a pattern, except that dupli-
-       cate names are permitted for subpatterns  with  the  same  number,  for
+       By default, a name must be unique within a pattern, except that  dupli-
+       cate  names  are  permitted  for  subpatterns with the same number, for
        example:
 
          (?|(?aa)|(?bb))
 
        The duplicate name constraint can be disabled by setting the PCRE2_DUP-
        NAMES option at compile time, or by the use of (?J) within the pattern.
-       Duplicate  names  can be useful for patterns where only one instance of
-       the named parentheses can match. Suppose you want to match the name  of
-       a  weekday,  either as a 3-letter abbreviation or as the full name, and
-       in both cases you  want  to  extract  the  abbreviation.  This  pattern
+       Duplicate names can be useful for patterns where only one  instance  of
+       the  named parentheses can match. Suppose you want to match the name of
+       a weekday, either as a 3-letter abbreviation or as the full  name,  and
+       in  both  cases  you  want  to  extract  the abbreviation. This pattern
        (ignoring the line breaks) does the job:
 
          (?Mon|Fri|Sun)(?:day)?|
@@ -7538,17 +7543,17 @@ NAMED SUBPATTERNS
          (?Thu)(?:rsday)?|
          (?Sat)(?:urday)?
 
-       There  are  five capturing substrings, but only one is ever set after a
-       match.  The convenience functions  for  extracting  the  data  by  name
-       returns  the  substring  for  the first (and in this example, the only)
-       subpattern of that name that matched.  This  saves  searching  to  find
-       which  numbered  subpattern it was. (An alternative way of solving this
+       There are five capturing substrings, but only one is ever set  after  a
+       match.   The  convenience  functions  for  extracting  the data by name
+       returns the substring for the first (and in  this  example,  the  only)
+       subpattern  of  that  name  that  matched. This saves searching to find
+       which numbered subpattern it was. (An alternative way of  solving  this
        problem is to use a "branch reset" subpattern, as described in the pre-
        vious section.)
 
        If you make a backreference to a non-unique named subpattern from else-
-       where in the pattern, the subpatterns to  which  the  name  refers  are
-       checked  in  the order in which they appear in the overall pattern. The
+       where  in  the  pattern,  the  subpatterns to which the name refers are
+       checked in the order in which they appear in the overall  pattern.  The
        first one that is set is used for the reference. For example, this pat-
        tern matches both "foofoo" and "barbar" but not "foobar" or "barfoo":
 
@@ -7556,21 +7561,21 @@ NAMED SUBPATTERNS
 
 
        If you make a subroutine call to a non-unique named subpattern, the one
-       that corresponds to the first occurrence of the name is  used.  In  the
+       that  corresponds  to  the first occurrence of the name is used. In the
        absence of duplicate numbers this is the one with the lowest number.
 
        If you use a named reference in a condition test (see the section about
        conditions below), either to check whether a subpattern has matched, or
-       to  check for recursion, all subpatterns with the same name are tested.
-       If the condition is true for any one of them, the overall condition  is
-       true.  This  is  the  same  behaviour as testing by number. For further
-       details of the interfaces  for  handling  named  subpatterns,  see  the
+       to check for recursion, all subpatterns with the same name are  tested.
+       If  the condition is true for any one of them, the overall condition is
+       true. This is the same behaviour as  testing  by  number.  For  further
+       details  of  the  interfaces  for  handling  named subpatterns, see the
        pcre2api documentation.
 
 
 REPETITION
 
-       Repetition  is  specified  by  quantifiers, which can follow any of the
+       Repetition is specified by quantifiers, which can  follow  any  of  the
        following items:
 
          a literal data character
@@ -7584,17 +7589,17 @@ REPETITION
          a parenthesized subpattern (including most assertions)
          a subroutine call to a subpattern (recursive or otherwise)
 
-       The general repetition quantifier specifies a minimum and maximum  num-
-       ber  of  permitted matches, by giving the two numbers in curly brackets
-       (braces), separated by a comma. The numbers must be  less  than  65536,
+       The  general repetition quantifier specifies a minimum and maximum num-
+       ber of permitted matches, by giving the two numbers in  curly  brackets
+       (braces),  separated  by  a comma. The numbers must be less than 65536,
        and the first must be less than or equal to the second. For example:
 
          z{2,4}
 
-       matches  "zz",  "zzz",  or  "zzzz". A closing brace on its own is not a
-       special character. If the second number is omitted, but  the  comma  is
-       present,  there  is  no upper limit; if the second number and the comma
-       are both omitted, the quantifier specifies an exact number of  required
+       matches "zz", "zzz", or "zzzz". A closing brace on its  own  is  not  a
+       special  character.  If  the second number is omitted, but the comma is
+       present, there is no upper limit; if the second number  and  the  comma
+       are  both omitted, the quantifier specifies an exact number of required
        matches. Thus
 
          [aeiou]{3,}
@@ -7603,50 +7608,50 @@ REPETITION
 
          \d{8}
 
-       matches  exactly  8  digits. An opening curly bracket that appears in a
-       position where a quantifier is not allowed, or one that does not  match
-       the  syntax of a quantifier, is taken as a literal character. For exam-
+       matches exactly 8 digits. An opening curly bracket that  appears  in  a
+       position  where a quantifier is not allowed, or one that does not match
+       the syntax of a quantifier, is taken as a literal character. For  exam-
        ple, {,6} is not a quantifier, but a literal string of four characters.
 
        In UTF modes, quantifiers apply to characters rather than to individual
-       code  units. Thus, for example, \x{100}{2} matches two characters, each
+       code units. Thus, for example, \x{100}{2} matches two characters,  each
        of which is represented by a two-byte sequence in a UTF-8 string. Simi-
-       larly,  \X{3} matches three Unicode extended grapheme clusters, each of
-       which may be several code units long (and  they  may  be  of  different
+       larly, \X{3} matches three Unicode extended grapheme clusters, each  of
+       which  may  be  several  code  units long (and they may be of different
        lengths).
 
        The quantifier {0} is permitted, causing the expression to behave as if
        the previous item and the quantifier were not present. This may be use-
-       ful  for  subpatterns that are referenced as subroutines from elsewhere
+       ful for subpatterns that are referenced as subroutines  from  elsewhere
        in the pattern (but see also the section entitled "Defining subpatterns
-       for  use  by  reference only" below). Items other than subpatterns that
+       for use by reference only" below). Items other  than  subpatterns  that
        have a {0} quantifier are omitted from the compiled pattern.
 
-       For convenience, the three most common quantifiers have  single-charac-
+       For  convenience, the three most common quantifiers have single-charac-
        ter abbreviations:
 
          *    is equivalent to {0,}
          +    is equivalent to {1,}
          ?    is equivalent to {0,1}
 
-       It  is  possible  to construct infinite loops by following a subpattern
+       It is possible to construct infinite loops by  following  a  subpattern
        that can match no characters with a quantifier that has no upper limit,
        for example:
 
          (a?)*
 
-       Earlier  versions  of  Perl  and PCRE1 used to give an error at compile
+       Earlier versions of Perl and PCRE1 used to give  an  error  at  compile
        time for such patterns. However, because there are cases where this can
        be useful, such patterns are now accepted, but if any repetition of the
-       subpattern does in fact match no characters, the loop is forcibly  bro-
+       subpattern  does in fact match no characters, the loop is forcibly bro-
        ken.
 
-       By  default,  the quantifiers are "greedy", that is, they match as much
-       as possible (up to the maximum  number  of  permitted  times),  without
-       causing  the  rest of the pattern to fail. The classic example of where
+       By default, the quantifiers are "greedy", that is, they match  as  much
+       as  possible  (up  to  the  maximum number of permitted times), without
+       causing the rest of the pattern to fail. The classic example  of  where
        this gives problems is in trying to match comments in C programs. These
-       appear  between  /*  and  */ and within the comment, individual * and /
-       characters may appear. An attempt to match C comments by  applying  the
+       appear between /* and */ and within the comment,  individual  *  and  /
+       characters  may  appear. An attempt to match C comments by applying the
        pattern
 
          /\*.*\*/
@@ -7655,19 +7660,19 @@ REPETITION
 
          /* first comment */  not comment  /* second comment */
 
-       fails,  because it matches the entire string owing to the greediness of
+       fails, because it matches the entire string owing to the greediness  of
        the .*  item.
 
        If a quantifier is followed by a question mark, it ceases to be greedy,
-       and  instead  matches the minimum number of times possible, so the pat-
+       and instead matches the minimum number of times possible, so  the  pat-
        tern
 
          /\*.*?\*/
 
-       does the right thing with the C comments. The meaning  of  the  various
-       quantifiers  is  not  otherwise  changed,  just the preferred number of
-       matches.  Do not confuse this use of question mark with its  use  as  a
-       quantifier  in its own right. Because it has two uses, it can sometimes
+       does  the  right  thing with the C comments. The meaning of the various
+       quantifiers is not otherwise changed,  just  the  preferred  number  of
+       matches.   Do  not  confuse this use of question mark with its use as a
+       quantifier in its own right. Because it has two uses, it can  sometimes
        appear doubled, as in
 
          \d??\d
@@ -7676,45 +7681,45 @@ REPETITION
        only way the rest of the pattern matches.
 
        If the PCRE2_UNGREEDY option is set (an option that is not available in
-       Perl), the quantifiers are not greedy by default, but  individual  ones
-       can  be  made  greedy  by following them with a question mark. In other
+       Perl),  the  quantifiers are not greedy by default, but individual ones
+       can be made greedy by following them with a  question  mark.  In  other
        words, it inverts the default behaviour.
 
-       When a parenthesized subpattern is quantified  with  a  minimum  repeat
-       count  that is greater than 1 or with a limited maximum, more memory is
-       required for the compiled pattern, in proportion to  the  size  of  the
+       When  a  parenthesized  subpattern  is quantified with a minimum repeat
+       count that is greater than 1 or with a limited maximum, more memory  is
+       required  for  the  compiled  pattern, in proportion to the size of the
        minimum or maximum.
 
-       If  a  pattern  starts  with  .*  or  .{0,} and the PCRE2_DOTALL option
-       (equivalent to Perl's /s) is set, thus allowing the dot to  match  new-
-       lines,  the  pattern  is  implicitly anchored, because whatever follows
-       will be tried against every character position in the  subject  string,
-       so  there  is  no  point  in retrying the overall match at any position
+       If a pattern starts with  .*  or  .{0,}  and  the  PCRE2_DOTALL  option
+       (equivalent  to  Perl's /s) is set, thus allowing the dot to match new-
+       lines, the pattern is implicitly  anchored,  because  whatever  follows
+       will  be  tried against every character position in the subject string,
+       so there is no point in retrying the  overall  match  at  any  position
        after the first. PCRE2 normally treats such a pattern as though it were
        preceded by \A.
 
-       In  cases  where  it  is known that the subject string contains no new-
-       lines, it is worth setting PCRE2_DOTALL in order to obtain  this  opti-
+       In cases where it is known that the subject  string  contains  no  new-
+       lines,  it  is worth setting PCRE2_DOTALL in order to obtain this opti-
        mization, or alternatively, using ^ to indicate anchoring explicitly.
 
-       However,  there  are  some cases where the optimization cannot be used.
-       When .*  is inside capturing parentheses that  are  the  subject  of  a
-       backreference  elsewhere  in the pattern, a match at the start may fail
+       However, there are some cases where the optimization  cannot  be  used.
+       When  .*   is  inside  capturing  parentheses that are the subject of a
+       backreference elsewhere in the pattern, a match at the start  may  fail
        where a later one succeeds. Consider, for example:
 
          (.*)abc\1
 
-       If the subject is "xyz123abc123" the match point is the fourth  charac-
+       If  the subject is "xyz123abc123" the match point is the fourth charac-
        ter. For this reason, such a pattern is not implicitly anchored.
 
-       Another  case where implicit anchoring is not applied is when the lead-
-       ing .* is inside an atomic group. Once again, a match at the start  may
+       Another case where implicit anchoring is not applied is when the  lead-
+       ing  .* is inside an atomic group. Once again, a match at the start may
        fail where a later one succeeds. Consider this pattern:
 
          (?>.*?a)b
 
-       It  matches "ab" in the subject "aab". The use of the backtracking con-
-       trol verbs (*PRUNE) and (*SKIP) also  disable  this  optimization,  and
+       It matches "ab" in the subject "aab". The use of the backtracking  con-
+       trol  verbs  (*PRUNE)  and  (*SKIP) also disable this optimization, and
        there is an option, PCRE2_NO_DOTSTAR_ANCHOR, to do so explicitly.
 
        When a capturing subpattern is repeated, the value captured is the sub-
@@ -7723,8 +7728,8 @@ REPETITION
          (tweedle[dume]{3}\s*)+
 
        has matched "tweedledum tweedledee" the value of the captured substring
-       is  "tweedledee".  However,  if there are nested capturing subpatterns,
-       the corresponding captured values may have been set in previous  itera-
+       is "tweedledee". However, if there are  nested  capturing  subpatterns,
+       the  corresponding captured values may have been set in previous itera-
        tions. For example, after
 
          (a|(b))+
@@ -7734,58 +7739,58 @@ REPETITION
 
 ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS
 
-       With  both  maximizing ("greedy") and minimizing ("ungreedy" or "lazy")
-       repetition, failure of what follows normally causes the  repeated  item
-       to  be  re-evaluated to see if a different number of repeats allows the
-       rest of the pattern to match. Sometimes it is useful to  prevent  this,
-       either  to  change the nature of the match, or to cause it fail earlier
-       than it otherwise might, when the author of the pattern knows there  is
+       With both maximizing ("greedy") and minimizing ("ungreedy"  or  "lazy")
+       repetition,  failure  of what follows normally causes the repeated item
+       to be re-evaluated to see if a different number of repeats  allows  the
+       rest  of  the pattern to match. Sometimes it is useful to prevent this,
+       either to change the nature of the match, or to cause it  fail  earlier
+       than  it otherwise might, when the author of the pattern knows there is
        no point in carrying on.
 
-       Consider,  for  example, the pattern \d+foo when applied to the subject
+       Consider, for example, the pattern \d+foo when applied to  the  subject
        line
 
          123456bar
 
        After matching all 6 digits and then failing to match "foo", the normal
-       action  of  the matcher is to try again with only 5 digits matching the
-       \d+ item, and then with  4,  and  so  on,  before  ultimately  failing.
-       "Atomic  grouping"  (a  term taken from Jeffrey Friedl's book) provides
-       the means for specifying that once a subpattern has matched, it is  not
+       action of the matcher is to try again with only 5 digits  matching  the
+       \d+  item,  and  then  with  4,  and  so on, before ultimately failing.
+       "Atomic grouping" (a term taken from Jeffrey  Friedl's  book)  provides
+       the  means for specifying that once a subpattern has matched, it is not
        to be re-evaluated in this way.
 
-       If  we  use atomic grouping for the previous example, the matcher gives
-       up immediately on failing to match "foo" the first time.  The  notation
+       If we use atomic grouping for the previous example, the  matcher  gives
+       up  immediately  on failing to match "foo" the first time. The notation
        is a kind of special parenthesis, starting with (?> as in this example:
 
          (?>\d+)foo
 
-       Perl  5.28  introduced an experimental alphabetic form starting with (*
+       Perl 5.28 introduced an experimental alphabetic form starting  with  (*
        which may be easier to remember:
 
          (*atomic:\d+)foo
 
-       This kind of parenthesis "locks up" the  part of the  pattern  it  con-
-       tains  once  it  has matched, and a failure further into the pattern is
-       prevented from backtracking into it. Backtracking past it  to  previous
+       This  kind  of  parenthesis "locks up" the  part of the pattern it con-
+       tains once it has matched, and a failure further into  the  pattern  is
+       prevented  from  backtracking into it. Backtracking past it to previous
        items, however, works as normal.
 
-       An  alternative  description  is that a subpattern of this type matches
-       exactly the string of characters that an identical  standalone  pattern
+       An alternative description is that a subpattern of  this  type  matches
+       exactly  the  string of characters that an identical standalone pattern
        would match, if anchored at the current point in the subject string.
 
        Atomic grouping subpatterns are not capturing subpatterns. Simple cases
        such as the above example can be thought of as a maximizing repeat that
-       must  swallow  everything  it can. So, while both \d+ and \d+? are pre-
-       pared to adjust the number of digits they match in order  to  make  the
+       must swallow everything it can. So, while both \d+ and  \d+?  are  pre-
+       pared  to  adjust  the number of digits they match in order to make the
        rest of the pattern match, (?>\d+) can only match an entire sequence of
        digits.
 
-       Atomic groups in general can of course contain arbitrarily  complicated
-       subpatterns,  and  can  be  nested. However, when the subpattern for an
+       Atomic  groups in general can of course contain arbitrarily complicated
+       subpatterns, and can be nested. However, when  the  subpattern  for  an
        atomic group is just a single repeated item, as in the example above, a
-       simpler  notation,  called  a "possessive quantifier" can be used. This
-       consists of an additional + character  following  a  quantifier.  Using
+       simpler notation, called a "possessive quantifier" can  be  used.  This
+       consists  of  an  additional  + character following a quantifier. Using
        this notation, the previous example can be rewritten as
 
          \d++foo
@@ -7795,46 +7800,46 @@ ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS
 
          (abc|xyz){2,3}+
 
-       Possessive  quantifiers  are  always  greedy;  the   setting   of   the
-       PCRE2_UNGREEDY  option  is  ignored. They are a convenient notation for
-       the simpler forms of atomic group. However, there is no  difference  in
+       Possessive   quantifiers   are   always  greedy;  the  setting  of  the
+       PCRE2_UNGREEDY option is ignored. They are a  convenient  notation  for
+       the  simpler  forms of atomic group. However, there is no difference in
        the meaning of a possessive quantifier and the equivalent atomic group,
-       though there may be a performance  difference;  possessive  quantifiers
+       though  there  may  be a performance difference; possessive quantifiers
        should be slightly faster.
 
-       The  possessive  quantifier syntax is an extension to the Perl 5.8 syn-
-       tax.  Jeffrey Friedl originated the idea (and the name)  in  the  first
+       The possessive quantifier syntax is an extension to the Perl  5.8  syn-
+       tax.   Jeffrey  Friedl  originated the idea (and the name) in the first
        edition of his book. Mike McCloskey liked it, so implemented it when he
        built Sun's Java package, and PCRE1 copied it from there. It ultimately
        found its way into Perl at release 5.10.
 
-       PCRE2  has  an  optimization  that automatically "possessifies" certain
-       simple pattern constructs. For example, the sequence A+B is treated  as
-       A++B  because  there is no point in backtracking into a sequence of A's
+       PCRE2 has an optimization  that  automatically  "possessifies"  certain
+       simple  pattern constructs. For example, the sequence A+B is treated as
+       A++B because there is no point in backtracking into a sequence  of  A's
        when B must follow.  This feature can be disabled by the PCRE2_NO_AUTO-
        POSSESS option, or starting the pattern with (*NO_AUTO_POSSESS).
 
-       When  a  pattern  contains an unlimited repeat inside a subpattern that
-       can itself be repeated an unlimited number of  times,  the  use  of  an
-       atomic  group  is  the  only way to avoid some failing matches taking a
+       When a pattern contains an unlimited repeat inside  a  subpattern  that
+       can  itself  be  repeated  an  unlimited number of times, the use of an
+       atomic group is the only way to avoid some  failing  matches  taking  a
        very long time indeed. The pattern
 
          (\D+|<\d+>)*[!?]
 
-       matches an unlimited number of substrings that either consist  of  non-
-       digits,  or  digits  enclosed in <>, followed by either ! or ?. When it
+       matches  an  unlimited number of substrings that either consist of non-
+       digits, or digits enclosed in <>, followed by either ! or  ?.  When  it
        matches, it runs quickly. However, if it is applied to
 
          aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
 
-       it takes a long time before reporting  failure.  This  is  because  the
-       string  can be divided between the internal \D+ repeat and the external
-       * repeat in a large number of ways, and all  have  to  be  tried.  (The
-       example  uses  [!?]  rather than a single character at the end, because
-       both PCRE2 and Perl have an optimization that allows for  fast  failure
-       when  a single character is used. They remember the last single charac-
-       ter that is required for a match, and fail early if it is  not  present
-       in  the  string.)  If  the pattern is changed so that it uses an atomic
+       it  takes  a  long  time  before reporting failure. This is because the
+       string can be divided between the internal \D+ repeat and the  external
+       *  repeat  in  a  large  number of ways, and all have to be tried. (The
+       example uses [!?] rather than a single character at  the  end,  because
+       both  PCRE2  and Perl have an optimization that allows for fast failure
+       when a single character is used. They remember the last single  charac-
+       ter  that  is required for a match, and fail early if it is not present
+       in the string.) If the pattern is changed so that  it  uses  an  atomic
        group, like this:
 
          ((?>\D+)|<\d+>)*[!?]
@@ -7845,29 +7850,29 @@ ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS
 BACKREFERENCES
 
        Outside a character class, a backslash followed by a digit greater than
-       0  (and possibly further digits) is a backreference to a capturing sub-
-       pattern earlier (that is, to its left) in the pattern,  provided  there
+       0 (and possibly further digits) is a backreference to a capturing  sub-
+       pattern  earlier  (that is, to its left) in the pattern, provided there
        have been that many previous capturing left parentheses.
 
-       However,  if the decimal number following the backslash is less than 8,
-       it is always taken as a backreference, and  causes  an  error  only  if
-       there  are  not that many capturing left parentheses in the entire pat-
-       tern. In other words, the parentheses that are referenced need  not  be
-       to  the left of the reference for numbers less than 8. A "forward back-
-       reference" of this type can make sense when a  repetition  is  involved
-       and  the  subpattern to the right has participated in an earlier itera-
+       However, if the decimal number following the backslash is less than  8,
+       it  is  always  taken  as  a backreference, and causes an error only if
+       there are not that many capturing left parentheses in the  entire  pat-
+       tern.  In  other words, the parentheses that are referenced need not be
+       to the left of the reference for numbers less than 8. A "forward  back-
+       reference"  of  this  type can make sense when a repetition is involved
+       and the subpattern to the right has participated in an  earlier  itera-
        tion.
 
-       It is not possible to have a numerical  "forward  backreference"  to  a
-       subpattern  whose  number  is  8  or  more  using this syntax because a
-       sequence such as \50 is interpreted as a character  defined  in  octal.
+       It  is  not  possible  to have a numerical "forward backreference" to a
+       subpattern whose number is 8  or  more  using  this  syntax  because  a
+       sequence  such  as  \50 is interpreted as a character defined in octal.
        See the subsection entitled "Non-printing characters" above for further
-       details of the handling of digits following a backslash.  There  is  no
-       such  problem  when  named parentheses are used. A backreference to any
+       details  of  the  handling of digits following a backslash. There is no
+       such problem when named parentheses are used. A  backreference  to  any
        subpattern is possible using named parentheses (see below).
 
-       Another way of avoiding the ambiguity inherent in  the  use  of  digits
-       following  a  backslash  is  to use the \g escape sequence. This escape
+       Another  way  of  avoiding  the ambiguity inherent in the use of digits
+       following a backslash is to use the \g  escape  sequence.  This  escape
        must be followed by a signed or unsigned number, optionally enclosed in
        braces. These examples are all identical:
 
@@ -7875,46 +7880,46 @@ BACKREFERENCES
          (ring), \g1
          (ring), \g{1}
 
-       An  unsigned number specifies an absolute reference without the ambigu-
+       An unsigned number specifies an absolute reference without the  ambigu-
        ity that is present in the older syntax. It is also useful when literal
-       digits  follow  the reference. A signed number is a relative reference.
+       digits follow the reference. A signed number is a  relative  reference.
        Consider this example:
 
          (abc(def)ghi)\g{-1}
 
        The sequence \g{-1} is a reference to the most recently started captur-
        ing subpattern before \g, that is, is it equivalent to \2 in this exam-
-       ple.  Similarly, \g{-2} would be equivalent to \1. The use of  relative
-       references  can  be helpful in long patterns, and also in patterns that
-       are created by  joining  together  fragments  that  contain  references
+       ple.   Similarly, \g{-2} would be equivalent to \1. The use of relative
+       references can be helpful in long patterns, and also in  patterns  that
+       are  created  by  joining  together  fragments  that contain references
        within themselves.
 
-       The  sequence  \g{+1}  is a reference to the next capturing subpattern.
-       This kind of forward reference can be useful it patterns  that  repeat.
+       The sequence \g{+1} is a reference to the  next  capturing  subpattern.
+       This  kind  of forward reference can be useful it patterns that repeat.
        Perl does not support the use of + in this way.
 
        A backreference matches whatever actually matched the capturing subpat-
-       tern in the current subject string, rather than anything  matching  the
-       subpattern  itself (see "Subpatterns as subroutines" below for a way of
+       tern  in  the current subject string, rather than anything matching the
+       subpattern itself (see "Subpatterns as subroutines" below for a way  of
        doing that). So the pattern
 
          (sens|respons)e and \1ibility
 
-       matches "sense and sensibility" and "response and responsibility",  but
-       not  "sense and responsibility". If caseful matching is in force at the
-       time of the backreference, the case of letters is relevant.  For  exam-
+       matches  "sense and sensibility" and "response and responsibility", but
+       not "sense and responsibility". If caseful matching is in force at  the
+       time  of  the backreference, the case of letters is relevant. For exam-
        ple,
 
          ((?i)rah)\s+\1
 
-       matches  "rah  rah"  and  "RAH RAH", but not "RAH rah", even though the
+       matches "rah rah" and "RAH RAH", but not "RAH  rah",  even  though  the
        original capturing subpattern is matched caselessly.
 
-       There are several different ways of  writing  backreferences  to  named
-       subpatterns.  The  .NET syntax \k{name} and the Perl syntax \k or
-       \k'name' are supported, as is the Python syntax (?P=name). Perl  5.10's
-       unified  backreference syntax, in which \g can be used for both numeric
-       and named references, is also supported. We  could  rewrite  the  above
+       There  are  several  different  ways of writing backreferences to named
+       subpatterns. The .NET syntax \k{name} and the Perl syntax  \k  or
+       \k'name'  are supported, as is the Python syntax (?P=name). Perl 5.10's
+       unified backreference syntax, in which \g can be used for both  numeric
+       and  named  references,  is  also supported. We could rewrite the above
        example in any of the following ways:
 
          (?(?i)rah)\s+\k
@@ -7922,32 +7927,32 @@ BACKREFERENCES
          (?P(?i)rah)\s+(?P=p1)
          (?(?i)rah)\s+\g{p1}
 
-       A  subpattern  that  is  referenced  by  name may appear in the pattern
+       A subpattern that is referenced by  name  may  appear  in  the  pattern
        before or after the reference.
 
-       There may be more than one backreference to the same subpattern.  If  a
-       subpattern  has not actually been used in a particular match, any back-
+       There  may  be more than one backreference to the same subpattern. If a
+       subpattern has not actually been used in a particular match, any  back-
        references to it always fail by default. For example, the pattern
 
          (a|(bc))\2
 
-       always fails if it starts to match "a" rather than  "bc".  However,  if
+       always  fails  if  it starts to match "a" rather than "bc". However, if
        the PCRE2_MATCH_UNSET_BACKREF option is set at compile time, a backref-
        erence to an unset value matches an empty string.
 
-       Because there may be many capturing parentheses in a pattern, all  dig-
-       its  following  a backslash are taken as part of a potential backrefer-
-       ence number.  If the pattern continues with  a  digit  character,  some
-       delimiter   must  be  used  to  terminate  the  backreference.  If  the
-       PCRE2_EXTENDED or PCRE2_EXTENDED_MORE option is set, this can be  white
-       space.  Otherwise,  the  \g{ syntax or an empty comment (see "Comments"
+       Because  there may be many capturing parentheses in a pattern, all dig-
+       its following a backslash are taken as part of a  potential  backrefer-
+       ence  number.   If  the  pattern continues with a digit character, some
+       delimiter  must  be  used  to  terminate  the  backreference.  If   the
+       PCRE2_EXTENDED  or PCRE2_EXTENDED_MORE option is set, this can be white
+       space. Otherwise, the \g{ syntax or an empty  comment  (see  "Comments"
        below) can be used.
 
    Recursive backreferences
 
-       A backreference that occurs inside the parentheses to which  it  refers
-       fails  when  the subpattern is first used, so, for example, (a\1) never
-       matches.  However, such references can be useful inside  repeated  sub-
+       A  backreference  that occurs inside the parentheses to which it refers
+       fails when the subpattern is first used, so, for example,  (a\1)  never
+       matches.   However,  such references can be useful inside repeated sub-
        patterns. For example, the pattern
 
          (a|b\1)+
@@ -7955,86 +7960,86 @@ BACKREFERENCES
        matches any number of "a"s and also "aba", "ababbaa" etc. At each iter-
        ation of the subpattern, the backreference matches the character string
        corresponding to the previous iteration. In order for this to work, the
-       pattern must be such that the first iteration does not  need  to  match
-       the  backreference. This can be done using alternation, as in the exam-
+       pattern  must  be  such that the first iteration does not need to match
+       the backreference. This can be done using alternation, as in the  exam-
        ple above, or by a quantifier with a minimum of zero.
 
-       Backreferences of this type cause the group that they reference  to  be
-       treated  as  an atomic group.  Once the whole group has been matched, a
-       subsequent matching failure cannot cause backtracking into  the  middle
+       Backreferences  of  this type cause the group that they reference to be
+       treated as an atomic group.  Once the whole group has been  matched,  a
+       subsequent  matching  failure cannot cause backtracking into the middle
        of the group.
 
 
 ASSERTIONS
 
-       An  assertion  is  a  test on the characters following or preceding the
+       An assertion is a test on the characters  following  or  preceding  the
        current matching point that does not consume any characters. The simple
-       assertions  coded  as  \b,  \B,  \A,  \G, \Z, \z, ^ and $ are described
+       assertions coded as \b, \B, \A, \G, \Z,  \z,  ^  and  $  are  described
        above.
 
-       More complicated assertions are coded as  subpatterns.  There  are  two
-       kinds:  those  that  look  ahead of the current position in the subject
-       string, and those that look behind it, and in each  case  an  assertion
-       may  be  positive (must match for the assertion to be true) or negative
-       (must not match for the assertion to be true). An assertion  subpattern
-       is  matched  in  the  normal way, and if it is true, matching continues
-       after it, but with the matching position in the subject string  is  was
+       More  complicated  assertions  are  coded as subpatterns. There are two
+       kinds: those that look ahead of the current  position  in  the  subject
+       string,  and  those  that look behind it, and in each case an assertion
+       may be positive (must match for the assertion to be true)  or  negative
+       (must  not match for the assertion to be true). An assertion subpattern
+       is matched in the normal way, and if it  is  true,  matching  continues
+       after  it,  but with the matching position in the subject string is was
        it was before the assertion was processed.
 
-       A  lookaround  assertion  may  also appear as the condition in a condi-
+       A lookaround assertion may also appear as the  condition  in  a  condi-
        tional subpattern (see below). In this case, the result of matching the
        assertion determines which branch of the condition is followed.
 
-       Assertion  subpatterns  are  not capturing subpatterns. If an assertion
-       contains capturing subpatterns within it, these  are  counted  for  the
-       purposes  of  numbering the capturing subpatterns in the whole pattern.
-       Within each branch of an assertion, locally captured substrings may  be
+       Assertion subpatterns are not capturing subpatterns.  If  an  assertion
+       contains  capturing  subpatterns  within  it, these are counted for the
+       purposes of numbering the capturing subpatterns in the  whole  pattern.
+       Within  each branch of an assertion, locally captured substrings may be
        referenced in the usual way.  For example, a sequence such as (.)\g{-1}
        can be used to check that two adjacent characters are the same.
 
-       When a branch within an assertion fails to match, any  substrings  that
-       were  captured  are  discarded (as happens with any pattern branch that
-       fails to match). A  negative  assertion  is  true  only  when  all  its
+       When  a  branch within an assertion fails to match, any substrings that
+       were captured are discarded (as happens with any  pattern  branch  that
+       fails  to  match).  A  negative  assertion  is  true  only when all its
        branches fail to match; this means that no captured substrings are ever
-       retained after a successful negative assertion. When an assertion  con-
+       retained  after a successful negative assertion. When an assertion con-
        tains a matching branch, what happens depends on the type of assertion.
 
-       For  a  positive  assertion, internally captured substrings in the suc-
-       cessful branch are retained, and matching continues with the next  pat-
-       tern  item  after  the  assertion. For a negative assertion, a matching
-       branch means that the assertion is not true. If such  an  assertion  is
+       For a positive assertion, internally captured substrings  in  the  suc-
+       cessful  branch are retained, and matching continues with the next pat-
+       tern item after the assertion. For a  negative  assertion,  a  matching
+       branch  means  that  the assertion is not true. If such an assertion is
        being used as a condition in a conditional subpattern (see below), cap-
        tured substrings are retained, because matching continues with the "no"
        branch of the condition. For other failing negative assertions, control
        passes to the previous backtracking point, thus discarding any captured
        strings within the assertion.
 
-       For   compatibility  with  Perl,  most  assertion  subpatterns  may  be
-       repeated; though it makes no sense to assert  the  same  thing  several
-       times,  the  side  effect  of capturing parentheses may occasionally be
-       useful. However, an assertion that forms the  condition  for  a  condi-
-       tional  subpattern may not be quantified. In practice, for other asser-
+       For  compatibility  with  Perl,  most  assertion  subpatterns  may   be
+       repeated;  though  it  makes  no sense to assert the same thing several
+       times, the side effect of capturing  parentheses  may  occasionally  be
+       useful.  However,  an  assertion  that forms the condition for a condi-
+       tional subpattern may not be quantified. In practice, for other  asser-
        tions, there only three cases:
 
-       (1) If the quantifier is {0}, the  assertion  is  never  obeyed  during
-       matching.   However,  it  may  contain internal capturing parenthesized
+       (1)  If  the  quantifier  is  {0}, the assertion is never obeyed during
+       matching.  However, it may  contain  internal  capturing  parenthesized
        groups that are called from elsewhere via the subroutine mechanism.
 
-       (2) If quantifier is {0,n} where n is greater than zero, it is  treated
-       as  if  it  were  {0,1}.  At run time, the rest of the pattern match is
+       (2)  If quantifier is {0,n} where n is greater than zero, it is treated
+       as if it were {0,1}. At run time, the rest  of  the  pattern  match  is
        tried with and without the assertion, the order depending on the greed-
        iness of the quantifier.
 
-       (3)  If  the minimum repetition is greater than zero, the quantifier is
-       ignored.  The assertion is obeyed just  once  when  encountered  during
+       (3) If the minimum repetition is greater than zero, the  quantifier  is
+       ignored.   The  assertion  is  obeyed just once when encountered during
        matching.
 
    Alphabetic assertion names
 
-       Traditionally,  symbolic  sequences such as (?= and (?<= have been used
-       to specify lookaround assertions. Perl 5.28 introduced some  experimen-
+       Traditionally, symbolic sequences such as (?= and (?<= have  been  used
+       to  specify lookaround assertions. Perl 5.28 introduced some experimen-
        tal alphabetic alternatives which might be easier to remember. They all
-       start with (* instead of (? and must be written using lower  case  let-
+       start  with  (* instead of (? and must be written using lower case let-
        ters. PCRE2 supports the following synonyms:
 
          (*positive_lookahead:  or (*pla: is the same as (?=
@@ -8042,8 +8047,8 @@ ASSERTIONS
          (*positive_lookbehind: or (*plb: is the same as (?<=
          (*negative_lookbehind: or (*nlb: is the same as (?...))
+
+       Note that the atomic group is inside the script run. Putting it outside
+       would not prevent backtracking into the script run pattern.
+
+       Support for script runs is not available if PCRE2 is  compiled  without
+       Unicode support. A compile-time error is given if any of the above con-
+       structs is encountered. Script runs are not supported by the  alternate
+       matching  function,  pcre2_dfa_match() because they use the same mecha-
+       nism as capturing parentheses.
+
+       Warning: The (*ACCEPT) control verb (see  below)  should  not  be  used
+       within  a  script  run  subpattern, because it causes an immediate exit
+       from the subpattern, bypassing the script run checking.
+
+
 CONDITIONAL SUBPATTERNS
 
-       It  is possible to cause the matching process to obey a subpattern con-
-       ditionally or to choose between two alternative subpatterns,  depending
-       on  the result of an assertion, or whether a specific capturing subpat-
-       tern has already been matched. The two possible  forms  of  conditional
+       It is possible to cause the matching process to obey a subpattern  con-
+       ditionally  or to choose between two alternative subpatterns, depending
+       on the result of an assertion, or whether a specific capturing  subpat-
+       tern  has  already  been matched. The two possible forms of conditional
        subpattern are:
 
          (?(condition)yes-pattern)
          (?(condition)yes-pattern|no-pattern)
 
-       If  the  condition is satisfied, the yes-pattern is used; otherwise the
-       no-pattern (if present) is used. An absent no-pattern is equivalent  to
-       an  empty string (it always matches). If there are more than two alter-
+       If the condition is satisfied, the yes-pattern is used;  otherwise  the
+       no-pattern  (if present) is used. An absent no-pattern is equivalent to
+       an empty string (it always matches). If there are more than two  alter-
        natives in the subpattern, a compile-time error occurs. Each of the two
        alternatives may itself contain nested subpatterns of any form, includ-
        ing  conditional  subpatterns;  the  restriction  to  two  alternatives
@@ -8220,88 +8281,88 @@ CONDITIONAL SUBPATTERNS
          (?(1) (A|B|C) | (D | (?(2)E|F) | E) )
 
 
-       There are five kinds of condition: references  to  subpatterns,  refer-
-       ences  to  recursion,  two pseudo-conditions called DEFINE and VERSION,
+       There  are  five  kinds of condition: references to subpatterns, refer-
+       ences to recursion, two pseudo-conditions called  DEFINE  and  VERSION,
        and assertions.
 
    Checking for a used subpattern by number
 
-       If the text between the parentheses consists of a sequence  of  digits,
+       If  the  text between the parentheses consists of a sequence of digits,
        the condition is true if a capturing subpattern of that number has pre-
-       viously matched. If there is more than one  capturing  subpattern  with
-       the  same  number  (see  the earlier section about duplicate subpattern
-       numbers), the condition is true if any of them have matched. An  alter-
-       native  notation is to precede the digits with a plus or minus sign. In
-       this case, the subpattern number is relative rather than absolute.  The
-       most  recently opened parentheses can be referenced by (?(-1), the next
-       most recent by (?(-2), and so on. Inside loops it can also  make  sense
+       viously  matched.  If  there is more than one capturing subpattern with
+       the same number (see the earlier  section  about  duplicate  subpattern
+       numbers),  the condition is true if any of them have matched. An alter-
+       native notation is to precede the digits with a plus or minus sign.  In
+       this  case, the subpattern number is relative rather than absolute. The
+       most recently opened parentheses can be referenced by (?(-1), the  next
+       most  recent  by (?(-2), and so on. Inside loops it can also make sense
        to refer to subsequent groups. The next parentheses to be opened can be
-       referenced as (?(+1), and so on. (The value zero in any of these  forms
+       referenced  as (?(+1), and so on. (The value zero in any of these forms
        is not used; it provokes a compile-time error.)
 
-       Consider  the  following  pattern, which contains non-significant white
-       space to make it more readable (assume the PCRE2_EXTENDED  option)  and
+       Consider the following pattern, which  contains  non-significant  white
+       space  to  make it more readable (assume the PCRE2_EXTENDED option) and
        to divide it into three parts for ease of discussion:
 
          ( \( )?    [^()]+    (?(1) \) )
 
-       The  first  part  matches  an optional opening parenthesis, and if that
+       The first part matches an optional opening  parenthesis,  and  if  that
        character is present, sets it as the first captured substring. The sec-
-       ond  part  matches one or more characters that are not parentheses. The
-       third part is a conditional subpattern that tests whether  or  not  the
-       first  set  of  parentheses  matched.  If they did, that is, if subject
-       started with an opening parenthesis, the condition is true, and so  the
-       yes-pattern  is  executed and a closing parenthesis is required. Other-
-       wise, since no-pattern is not present, the subpattern matches  nothing.
-       In  other  words,  this  pattern matches a sequence of non-parentheses,
+       ond part matches one or more characters that are not  parentheses.  The
+       third  part  is  a conditional subpattern that tests whether or not the
+       first set of parentheses matched. If they  did,  that  is,  if  subject
+       started  with an opening parenthesis, the condition is true, and so the
+       yes-pattern is executed and a closing parenthesis is  required.  Other-
+       wise,  since no-pattern is not present, the subpattern matches nothing.
+       In other words, this pattern matches  a  sequence  of  non-parentheses,
        optionally enclosed in parentheses.
 
-       If you were embedding this pattern in a larger one,  you  could  use  a
+       If  you  were  embedding  this pattern in a larger one, you could use a
        relative reference:
 
          ...other stuff... ( \( )?    [^()]+    (?(-1) \) ) ...
 
-       This  makes  the  fragment independent of the parentheses in the larger
+       This makes the fragment independent of the parentheses  in  the  larger
        pattern.
 
    Checking for a used subpattern by name
 
-       Perl uses the syntax (?()...) or (?('name')...)  to  test  for  a
-       used  subpattern  by  name.  For compatibility with earlier versions of
-       PCRE1, which had this facility before Perl, the syntax (?(name)...)  is
-       also  recognized.  Note,  however, that undelimited names consisting of
-       the letter R followed by digits are ambiguous (see the  following  sec-
+       Perl  uses  the  syntax  (?()...) or (?('name')...) to test for a
+       used subpattern by name. For compatibility  with  earlier  versions  of
+       PCRE1,  which had this facility before Perl, the syntax (?(name)...) is
+       also recognized. Note, however, that undelimited  names  consisting  of
+       the  letter  R followed by digits are ambiguous (see the following sec-
        tion).
 
        Rewriting the above example to use a named subpattern gives this:
 
          (? \( )?    [^()]+    (?() \) )
 
-       If  the  name used in a condition of this kind is a duplicate, the test
-       is applied to all subpatterns of the same name, and is true if any  one
+       If the name used in a condition of this kind is a duplicate,  the  test
+       is  applied to all subpatterns of the same name, and is true if any one
        of them has matched.
 
    Checking for pattern recursion
 
-       "Recursion"  in  this sense refers to any subroutine-like call from one
-       part of the pattern to another, whether or not it  is  actually  recur-
-       sive.  See  the sections entitled "Recursive patterns" and "Subpatterns
+       "Recursion" in this sense refers to any subroutine-like call  from  one
+       part  of  the  pattern to another, whether or not it is actually recur-
+       sive. See the sections entitled "Recursive patterns"  and  "Subpatterns
        as subroutines" below for details of recursion and subpattern calls.
 
-       If a condition is the string (R), and there is no subpattern  with  the
-       name  R,  the condition is true if matching is currently in a recursion
-       or subroutine call to the whole pattern or any  subpattern.  If  digits
-       follow  the  letter  R,  and there is no subpattern with that name, the
+       If  a  condition is the string (R), and there is no subpattern with the
+       name R, the condition is true if matching is currently in  a  recursion
+       or  subroutine  call  to the whole pattern or any subpattern. If digits
+       follow the letter R, and there is no subpattern  with  that  name,  the
        condition is true if the most recent call is into a subpattern with the
-       given  number,  which must exist somewhere in the overall pattern. This
+       given number, which must exist somewhere in the overall  pattern.  This
        is a contrived example that is equivalent to a+b:
 
          ((?(R1)a+|(?1)b))
 
-       However, in both cases, if there is a subpattern with a matching  name,
-       the  condition  tests  for  its  being set, as described in the section
-       above, instead of testing for recursion. For example, creating a  group
-       with  the  name  R1  by  adding (?) to the above pattern completely
+       However,  in both cases, if there is a subpattern with a matching name,
+       the condition tests for its being set,  as  described  in  the  section
+       above,  instead of testing for recursion. For example, creating a group
+       with the name R1 by adding (?)  to  the  above  pattern  completely
        changes its meaning.
 
        If a name preceded by ampersand follows the letter R, for example:
@@ -8312,7 +8373,7 @@ CONDITIONAL SUBPATTERNS
        of that name (which must exist within the pattern).
 
        This condition does not check the entire recursion stack. It tests only
-       the current level. If the name used in a condition of this  kind  is  a
+       the  current  level.  If the name used in a condition of this kind is a
        duplicate, the test is applied to all subpatterns of the same name, and
        is true if any one of them is the most recent recursion.
 
@@ -8321,10 +8382,10 @@ CONDITIONAL SUBPATTERNS
    Defining subpatterns for use by reference only
 
        If the condition is the string (DEFINE), the condition is always false,
-       even  if there is a group with the name DEFINE. In this case, there may
+       even if there is a group with the name DEFINE. In this case, there  may
        be only one alternative in the subpattern. It is always skipped if con-
-       trol  reaches  this point in the pattern; the idea of DEFINE is that it
-       can be used to define subroutines that can  be  referenced  from  else-
+       trol reaches this point in the pattern; the idea of DEFINE is  that  it
+       can  be  used  to  define subroutines that can be referenced from else-
        where. (The use of subroutines is described below.) For example, a pat-
        tern to match an IPv4 address such as "192.168.23.245" could be written
        like this (ignore white space and line breaks):
@@ -8332,97 +8393,97 @@ CONDITIONAL SUBPATTERNS
          (?(DEFINE) (? 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d) )
          \b (?&byte) (\.(?&byte)){3} \b
 
-       The  first part of the pattern is a DEFINE group inside which a another
-       group named "byte" is defined. This matches an individual component  of
-       an  IPv4  address  (a number less than 256). When matching takes place,
-       this part of the pattern is skipped because DEFINE acts  like  a  false
-       condition.  The  rest of the pattern uses references to the named group
-       to match the four dot-separated components of an IPv4 address,  insist-
+       The first part of the pattern is a DEFINE group inside which a  another
+       group  named "byte" is defined. This matches an individual component of
+       an IPv4 address (a number less than 256). When  matching  takes  place,
+       this  part  of  the pattern is skipped because DEFINE acts like a false
+       condition. The rest of the pattern uses references to the  named  group
+       to  match the four dot-separated components of an IPv4 address, insist-
        ing on a word boundary at each end.
 
    Checking the PCRE2 version
 
-       Programs  that link with a PCRE2 library can check the version by call-
-       ing pcre2_config() with appropriate arguments.  Users  of  applications
-       that  do  not have access to the underlying code cannot do this. A spe-
-       cial "condition" called VERSION exists to allow such users to  discover
+       Programs that link with a PCRE2 library can check the version by  call-
+       ing  pcre2_config()  with  appropriate arguments. Users of applications
+       that do not have access to the underlying code cannot do this.  A  spe-
+       cial  "condition" called VERSION exists to allow such users to discover
        which version of PCRE2 they are dealing with by using this condition to
-       match a string such as "yesno". VERSION must be followed either by  "="
+       match  a string such as "yesno". VERSION must be followed either by "="
        or ">=" and a version number.  For example:
 
          (?(VERSION>=10.4)yes|no)
 
-       This  pattern matches "yes" if the PCRE2 version is greater or equal to
-       10.4, or "no" otherwise. The fractional part of the version number  may
+       This pattern matches "yes" if the PCRE2 version is greater or equal  to
+       10.4,  or "no" otherwise. The fractional part of the version number may
        not contain more than two digits.
 
    Assertion conditions
 
-       If  the  condition  is  not  in any of the above formats, it must be an
-       assertion.  This may be a positive or negative lookahead or  lookbehind
-       assertion.  Consider  this  pattern,  again  containing non-significant
+       If the condition is not in any of the above  formats,  it  must  be  an
+       assertion.   This may be a positive or negative lookahead or lookbehind
+       assertion. Consider  this  pattern,  again  containing  non-significant
        white space, and with the two alternatives on the second line:
 
          (?(?=[^a-z]*[a-z])
          \d{2}-[a-z]{3}-\d{2}  |  \d{2}-\d{2}-\d{2} )
 
-       The condition  is  a  positive  lookahead  assertion  that  matches  an
-       optional  sequence of non-letters followed by a letter. In other words,
-       it tests for the presence of at least one letter in the subject.  If  a
-       letter  is found, the subject is matched against the first alternative;
-       otherwise it is  matched  against  the  second.  This  pattern  matches
-       strings  in  one  of the two forms dd-aaa-dd or dd-dd-dd, where aaa are
+       The  condition  is  a  positive  lookahead  assertion  that  matches an
+       optional sequence of non-letters followed by a letter. In other  words,
+       it  tests  for the presence of at least one letter in the subject. If a
+       letter is found, the subject is matched against the first  alternative;
+       otherwise  it  is  matched  against  the  second.  This pattern matches
+       strings in one of the two forms dd-aaa-dd or dd-dd-dd,  where  aaa  are
        letters and dd are digits.
 
-       When an assertion that is a condition contains  capturing  subpatterns,
-       any  capturing that occurs in a matching branch is retained afterwards,
+       When  an  assertion that is a condition contains capturing subpatterns,
+       any capturing that occurs in a matching branch is retained  afterwards,
        for both positive and negative assertions, because matching always con-
        tinues after the assertion, whether it succeeds or fails. (Compare non-
-       conditional assertions, when captures are retained  only  for  positive
+       conditional  assertions,  when  captures are retained only for positive
        assertions that succeed.)
 
 
 COMMENTS
 
        There are two ways of including comments in patterns that are processed
-       by PCRE2. In both cases, the start of the comment  must  not  be  in  a
-       character  class,  nor  in  the middle of any other sequence of related
-       characters such as (?: or a subpattern name or number.  The  characters
+       by  PCRE2.  In  both  cases,  the start of the comment must not be in a
+       character class, nor in the middle of any  other  sequence  of  related
+       characters  such  as (?: or a subpattern name or number. The characters
        that make up a comment play no part in the pattern matching.
 
-       The  sequence (?# marks the start of a comment that continues up to the
-       next closing parenthesis. Nested parentheses are not permitted. If  the
-       PCRE2_EXTENDED  or  PCRE2_EXTENDED_MORE  option  is set, an unescaped #
-       character also introduces a comment, which in this  case  continues  to
-       immediately  after  the next newline character or character sequence in
+       The sequence (?# marks the start of a comment that continues up to  the
+       next  closing parenthesis. Nested parentheses are not permitted. If the
+       PCRE2_EXTENDED or PCRE2_EXTENDED_MORE option is  set,  an  unescaped  #
+       character  also  introduces  a comment, which in this case continues to
+       immediately after the next newline character or character  sequence  in
        the pattern. Which characters are interpreted as newlines is controlled
-       by  an option passed to the compiling function or by a special sequence
+       by an option passed to the compiling function or by a special  sequence
        at the start of the pattern, as described in the section entitled "New-
        line conventions" above. Note that the end of this type of comment is a
-       literal newline sequence in the pattern; escape sequences  that  happen
+       literal  newline  sequence in the pattern; escape sequences that happen
        to represent a newline do not count. For example, consider this pattern
-       when PCRE2_EXTENDED is set, and the default newline convention (a  sin-
+       when  PCRE2_EXTENDED is set, and the default newline convention (a sin-
        gle linefeed character) is in force:
 
          abc #comment \n still comment
 
-       On  encountering  the # character, pcre2_compile() skips along, looking
-       for a newline in the pattern. The sequence \n is still literal at  this
-       stage,  so  it does not terminate the comment. Only an actual character
+       On encountering the # character, pcre2_compile() skips  along,  looking
+       for  a newline in the pattern. The sequence \n is still literal at this
+       stage, so it does not terminate the comment. Only an  actual  character
        with the code value 0x0a (the default newline) does so.
 
 
 RECURSIVE PATTERNS
 
-       Consider the problem of matching a string in parentheses, allowing  for
-       unlimited  nested  parentheses.  Without the use of recursion, the best
-       that can be done is to use a pattern that  matches  up  to  some  fixed
-       depth  of  nesting.  It  is not possible to handle an arbitrary nesting
+       Consider  the problem of matching a string in parentheses, allowing for
+       unlimited nested parentheses. Without the use of  recursion,  the  best
+       that  can  be  done  is  to use a pattern that matches up to some fixed
+       depth of nesting. It is not possible to  handle  an  arbitrary  nesting
        depth.
 
        For some time, Perl has provided a facility that allows regular expres-
-       sions  to recurse (amongst other things). It does this by interpolating
-       Perl code in the expression at run time, and the code can refer to  the
+       sions to recurse (amongst other things). It does this by  interpolating
+       Perl  code in the expression at run time, and the code can refer to the
        expression itself. A Perl pattern using code interpolation to solve the
        parentheses problem can be created like this:
 
@@ -8432,175 +8493,175 @@ RECURSIVE PATTERNS
        refers recursively to the pattern in which it appears.
 
        Obviously,  PCRE2  cannot  support  the  interpolation  of  Perl  code.
-       Instead, it supports special syntax for recursion of  the  entire  pat-
+       Instead,  it  supports  special syntax for recursion of the entire pat-
        tern, and also for individual subpattern recursion. After its introduc-
-       tion in PCRE1 and Python,  this  kind  of  recursion  was  subsequently
+       tion  in  PCRE1  and  Python,  this  kind of recursion was subsequently
        introduced into Perl at release 5.10.
 
-       A  special  item  that consists of (? followed by a number greater than
-       zero and a closing parenthesis is a recursive subroutine  call  of  the
-       subpattern  of  the  given  number, provided that it occurs inside that
-       subpattern. (If not, it is a non-recursive subroutine  call,  which  is
-       described  in  the  next  section.)  The special item (?R) or (?0) is a
+       A special item that consists of (? followed by a  number  greater  than
+       zero  and  a  closing parenthesis is a recursive subroutine call of the
+       subpattern of the given number, provided that  it  occurs  inside  that
+       subpattern.  (If  not,  it is a non-recursive subroutine call, which is
+       described in the next section.) The special item  (?R)  or  (?0)  is  a
        recursive call of the entire regular expression.
 
-       This PCRE2 pattern solves the nested parentheses  problem  (assume  the
+       This  PCRE2  pattern  solves the nested parentheses problem (assume the
        PCRE2_EXTENDED option is set so that white space is ignored):
 
          \( ( [^()]++ | (?R) )* \)
 
-       First  it matches an opening parenthesis. Then it matches any number of
-       substrings which can either be a  sequence  of  non-parentheses,  or  a
-       recursive  match  of the pattern itself (that is, a correctly parenthe-
+       First it matches an opening parenthesis. Then it matches any number  of
+       substrings  which  can  either  be  a sequence of non-parentheses, or a
+       recursive match of the pattern itself (that is, a  correctly  parenthe-
        sized substring).  Finally there is a closing parenthesis. Note the use
        of a possessive quantifier to avoid backtracking into sequences of non-
        parentheses.
 
-       If this were part of a larger pattern, you would not  want  to  recurse
+       If  this  were  part of a larger pattern, you would not want to recurse
        the entire pattern, so instead you could use this:
 
          ( \( ( [^()]++ | (?1) )* \) )
 
-       We  have  put the pattern into parentheses, and caused the recursion to
+       We have put the pattern into parentheses, and caused the  recursion  to
        refer to them instead of the whole pattern.
 
-       In a larger pattern,  keeping  track  of  parenthesis  numbers  can  be
-       tricky.  This is made easier by the use of relative references. Instead
+       In  a  larger  pattern,  keeping  track  of  parenthesis numbers can be
+       tricky. This is made easier by the use of relative references.  Instead
        of (?1) in the pattern above you can write (?-2) to refer to the second
-       most  recently  opened  parentheses  preceding  the recursion. In other
-       words, a negative number counts capturing  parentheses  leftwards  from
+       most recently opened parentheses  preceding  the  recursion.  In  other
+       words,  a  negative  number counts capturing parentheses leftwards from
        the point at which it is encountered.
 
        Be aware however, that if duplicate subpattern numbers are in use, rel-
-       ative references refer to the earliest subpattern with the  appropriate
+       ative  references refer to the earliest subpattern with the appropriate
        number. Consider, for example:
 
          (?|(a)|(b)) (c) (?-2)
 
-       The  first  two  capturing  groups (a) and (b) are both numbered 1, and
-       group (c) is number 2. When the reference  (?-2)  is  encountered,  the
+       The first two capturing groups (a) and (b) are  both  numbered  1,  and
+       group  (c)  is  number  2. When the reference (?-2) is encountered, the
        second most recently opened parentheses has the number 1, but it is the
-       first such group (the (a) group) to which the  recursion  refers.  This
-       would  be  the  same  if  an absolute reference (?1) was used. In other
-       words, relative references are just a shorthand for computing  a  group
+       first  such  group  (the (a) group) to which the recursion refers. This
+       would be the same if an absolute reference  (?1)  was  used.  In  other
+       words,  relative  references are just a shorthand for computing a group
        number.
 
-       It  is  also  possible  to refer to subsequently opened parentheses, by
-       writing references such as (?+2). However, these  cannot  be  recursive
-       because  the  reference  is  not inside the parentheses that are refer-
-       enced. They are always non-recursive subroutine calls, as described  in
+       It is also possible to refer to  subsequently  opened  parentheses,  by
+       writing  references  such  as (?+2). However, these cannot be recursive
+       because the reference is not inside the  parentheses  that  are  refer-
+       enced.  They are always non-recursive subroutine calls, as described in
        the next section.
 
-       An  alternative  approach  is to use named parentheses. The Perl syntax
-       for this is (?&name); PCRE1's earlier syntax  (?P>name)  is  also  sup-
+       An alternative approach is to use named parentheses.  The  Perl  syntax
+       for  this  is  (?&name);  PCRE1's earlier syntax (?P>name) is also sup-
        ported. We could rewrite the above example as follows:
 
          (? \( ( [^()]++ | (?&pn) )* \) )
 
-       If  there  is more than one subpattern with the same name, the earliest
+       If there is more than one subpattern with the same name,  the  earliest
        one is used.
 
        The example pattern that we have been looking at contains nested unlim-
-       ited  repeats,  and  so the use of a possessive quantifier for matching
-       strings of non-parentheses is important when applying  the  pattern  to
+       ited repeats, and so the use of a possessive  quantifier  for  matching
+       strings  of  non-parentheses  is important when applying the pattern to
        strings that do not match. For example, when this pattern is applied to
 
          (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
 
-       it  yields  "no  match" quickly. However, if a possessive quantifier is
-       not used, the match runs for a very long time indeed because there  are
-       so  many  different  ways the + and * repeats can carve up the subject,
+       it yields "no match" quickly. However, if a  possessive  quantifier  is
+       not  used, the match runs for a very long time indeed because there are
+       so many different ways the + and * repeats can carve  up  the  subject,
        and all have to be tested before failure can be reported.
 
-       At the end of a match, the values of capturing  parentheses  are  those
-       from  the outermost level. If you want to obtain intermediate values, a
+       At  the  end  of a match, the values of capturing parentheses are those
+       from the outermost level. If you want to obtain intermediate values,  a
        callout function can be used (see below and the pcre2callout documenta-
        tion). If the pattern above is matched against
 
          (ab(cd)ef)
 
-       the  value  for  the  inner capturing parentheses (numbered 2) is "ef",
-       which is the last value taken on at the top level. If a capturing  sub-
-       pattern  is  not  matched at the top level, its final captured value is
-       unset, even if it was (temporarily) set at a deeper  level  during  the
+       the value for the inner capturing parentheses  (numbered  2)  is  "ef",
+       which  is the last value taken on at the top level. If a capturing sub-
+       pattern is not matched at the top level, its final  captured  value  is
+       unset,  even  if  it was (temporarily) set at a deeper level during the
        matching process.
 
-       Do  not  confuse  the (?R) item with the condition (R), which tests for
-       recursion.  Consider this pattern, which matches text in  angle  brack-
-       ets,  allowing for arbitrary nesting. Only digits are allowed in nested
-       brackets (that is, when recursing), whereas any characters are  permit-
+       Do not confuse the (?R) item with the condition (R),  which  tests  for
+       recursion.   Consider  this pattern, which matches text in angle brack-
+       ets, allowing for arbitrary nesting. Only digits are allowed in  nested
+       brackets  (that is, when recursing), whereas any characters are permit-
        ted at the outer level.
 
          < (?: (?(R) \d++  | [^<>]*+) | (?R)) * >
 
-       In  this  pattern, (?(R) is the start of a conditional subpattern, with
-       two different alternatives for the recursive and  non-recursive  cases.
+       In this pattern, (?(R) is the start of a conditional  subpattern,  with
+       two  different  alternatives for the recursive and non-recursive cases.
        The (?R) item is the actual recursive call.
 
    Differences in recursion processing between PCRE2 and Perl
 
        Some former differences between PCRE2 and Perl no longer exist.
 
-       Before  release 10.30, recursion processing in PCRE2 differed from Perl
-       in that a recursive subpattern call was always  treated  as  an  atomic
-       group.  That is, once it had matched some of the subject string, it was
-       never re-entered, even if it contained untried alternatives  and  there
-       was  a  subsequent matching failure. (Historical note: PCRE implemented
+       Before release 10.30, recursion processing in PCRE2 differed from  Perl
+       in  that  a  recursive  subpattern call was always treated as an atomic
+       group. That is, once it had matched some of the subject string, it  was
+       never  re-entered,  even if it contained untried alternatives and there
+       was a subsequent matching failure. (Historical note:  PCRE  implemented
        recursion before Perl did.)
 
-       Starting with release 10.30, recursive subroutine calls are  no  longer
+       Starting  with  release 10.30, recursive subroutine calls are no longer
        treated as atomic. That is, they can be re-entered to try unused alter-
-       natives if there is a matching failure later in the  pattern.  This  is
-       now  compatible  with the way Perl works. If you want a subroutine call
+       natives  if  there  is a matching failure later in the pattern. This is
+       now compatible with the way Perl works. If you want a  subroutine  call
        to be atomic, you must explicitly enclose it in an atomic group.
 
-       Supporting backtracking into recursions  simplifies  certain  types  of
+       Supporting  backtracking  into  recursions  simplifies certain types of
        recursive  pattern.  For  example,  this  pattern  matches  palindromic
        strings:
 
          ^((.)(?1)\2|.?)$
 
-       The second branch in the group matches a single  central  character  in
-       the  palindrome  when there are an odd number of characters, or nothing
-       when there are an even number of characters, but in order  to  work  it
-       has  to  be  able  to  try the second case when the rest of the pattern
+       The  second  branch  in the group matches a single central character in
+       the palindrome when there are an odd number of characters,  or  nothing
+       when  there  are  an even number of characters, but in order to work it
+       has to be able to try the second case when  the  rest  of  the  pattern
        match fails. If you want to match typical palindromic phrases, the pat-
-       tern  has  to  ignore  all  non-word characters, which can be done like
+       tern has to ignore all non-word characters,  which  can  be  done  like
        this:
 
          ^\W*+((.)\W*+(?1)\W*+\2|\W*+.?)\W*+$
 
-       If run with the PCRE2_CASELESS option,  this  pattern  matches  phrases
-       such  as "A man, a plan, a canal: Panama!". Note the use of the posses-
-       sive quantifier *+ to avoid backtracking  into  sequences  of  non-word
+       If  run  with  the  PCRE2_CASELESS option, this pattern matches phrases
+       such as "A man, a plan, a canal: Panama!". Note the use of the  posses-
+       sive  quantifier  *+  to  avoid backtracking into sequences of non-word
        characters. Without this, PCRE2 takes a great deal longer (ten times or
-       more) to match typical phrases, and Perl takes so long that  you  think
+       more)  to  match typical phrases, and Perl takes so long that you think
        it has gone into a loop.
 
-       Another  way  in which PCRE2 and Perl used to differ in their recursion
-       processing is in the handling of captured  values.  Formerly  in  Perl,
-       when  a  subpattern  was called recursively or as a subpattern (see the
-       next section), it had no access to any values that were  captured  out-
-       side  the  recursion,  whereas in PCRE2 these values can be referenced.
+       Another way in which PCRE2 and Perl used to differ in  their  recursion
+       processing  is  in  the  handling of captured values. Formerly in Perl,
+       when a subpattern was called recursively or as a  subpattern  (see  the
+       next  section),  it had no access to any values that were captured out-
+       side the recursion, whereas in PCRE2 these values  can  be  referenced.
        Consider this pattern:
 
          ^(.)(\1|a(?2))
 
-       This pattern matches "bab". The first capturing parentheses match  "b",
+       This  pattern matches "bab". The first capturing parentheses match "b",
        then in the second group, when the backreference \1 fails to match "b",
        the second alternative matches "a" and then recurses. In the recursion,
-       \1  does now match "b" and so the whole match succeeds. This match used
+       \1 does now match "b" and so the whole match succeeds. This match  used
        to fail in Perl, but in later versions (I tried 5.024) it now works.
 
 
 SUBPATTERNS AS SUBROUTINES
 
-       If the syntax for a recursive subpattern call (either by number  or  by
+       If  the  syntax for a recursive subpattern call (either by number or by
        name) is used outside the parentheses to which it refers, it operates a
        bit like a subroutine in a programming language. More accurately, PCRE2
-       treats  the referenced subpattern as an independent subpattern which it
-       tries to match at the current matching position. The called  subpattern
-       may  be defined before or after the reference. A numbered reference can
+       treats the referenced subpattern as an independent subpattern which  it
+       tries  to match at the current matching position. The called subpattern
+       may be defined before or after the reference. A numbered reference  can
        be absolute or relative, as in these examples:
 
          (...(absolute)...)...(?2)...
@@ -8611,106 +8672,106 @@ SUBPATTERNS AS SUBROUTINES
 
          (sens|respons)e and \1ibility
 
-       matches "sense and sensibility" and "response and responsibility",  but
+       matches  "sense and sensibility" and "response and responsibility", but
        not "sense and responsibility". If instead the pattern
 
          (sens|respons)e and (?1)ibility
 
-       is  used, it does match "sense and responsibility" as well as the other
-       two strings. Another example is  given  in  the  discussion  of  DEFINE
+       is used, it does match "sense and responsibility" as well as the  other
+       two  strings.  Another  example  is  given  in the discussion of DEFINE
        above.
 
-       Like  recursions,  subroutine  calls  used to be treated as atomic, but
-       this changed at PCRE2 release 10.30, so  backtracking  into  subroutine
-       calls  can  now  occur. However, any capturing parentheses that are set
+       Like recursions, subroutine calls used to be  treated  as  atomic,  but
+       this  changed  at  PCRE2 release 10.30, so backtracking into subroutine
+       calls can now occur. However, any capturing parentheses  that  are  set
        during the subroutine call revert to their previous values afterwards.
 
-       Processing options such as case-independence are fixed when  a  subpat-
-       tern  is defined, so if it is used as a subroutine, such options cannot
+       Processing  options  such as case-independence are fixed when a subpat-
+       tern is defined, so if it is used as a subroutine, such options  cannot
        be changed for different calls. For example, consider this pattern:
 
          (abc)(?i:(?-1))
 
-       It matches "abcabc". It does not match "abcABC" because the  change  of
+       It  matches  "abcabc". It does not match "abcABC" because the change of
        processing option does not affect the called subpattern.
 
-       The  behaviour of backtracking control verbs in subpatterns when called
+       The behaviour of backtracking control verbs in subpatterns when  called
        as subroutines is described in the section entitled "Backtracking verbs
        in subroutines" below.
 
 
 ONIGURUMA SUBROUTINE SYNTAX
 
-       For  compatibility with Oniguruma, the non-Perl syntax \g followed by a
+       For compatibility with Oniguruma, the non-Perl syntax \g followed by  a
        name or a number enclosed either in angle brackets or single quotes, is
-       an  alternative  syntax  for  referencing a subpattern as a subroutine,
-       possibly recursively. Here are two of the examples used above,  rewrit-
+       an alternative syntax for referencing a  subpattern  as  a  subroutine,
+       possibly  recursively. Here are two of the examples used above, rewrit-
        ten using this syntax:
 
          (? \( ( (?>[^()]+) | \g )* \) )
          (sens|respons)e and \g'1'ibility
 
-       PCRE2  supports an extension to Oniguruma: if a number is preceded by a
+       PCRE2 supports an extension to Oniguruma: if a number is preceded by  a
        plus or a minus sign it is taken as a relative reference. For example:
 
          (abc)(?i:\g<-1>)
 
-       Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are  not
-       synonymous.  The  former is a backreference; the latter is a subroutine
+       Note  that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are not
+       synonymous. The former is a backreference; the latter is  a  subroutine
        call.
 
 
 CALLOUTS
 
        Perl has a feature whereby using the sequence (?{...}) causes arbitrary
-       Perl  code to be obeyed in the middle of matching a regular expression.
+       Perl code to be obeyed in the middle of matching a regular  expression.
        This makes it possible, amongst other things, to extract different sub-
        strings that match the same pair of parentheses when there is a repeti-
        tion.
 
-       PCRE2 provides a similar feature, but of course it  cannot  obey  arbi-
-       trary  Perl  code. The feature is called "callout". The caller of PCRE2
-       provides an external function by putting its entry  point  in  a  match
-       context  using  the function pcre2_set_callout(), and then passing that
-       context to pcre2_match() or pcre2_dfa_match(). If no match  context  is
+       PCRE2  provides  a  similar feature, but of course it cannot obey arbi-
+       trary Perl code. The feature is called "callout". The caller  of  PCRE2
+       provides  an  external  function  by putting its entry point in a match
+       context using the function pcre2_set_callout(), and then  passing  that
+       context  to  pcre2_match() or pcre2_dfa_match(). If no match context is
        passed, or if the callout entry point is set to NULL, callouts are dis-
        abled.
 
-       Within a regular expression, (?C) indicates a point at  which  the
-       external  function  is  to  be  called. There are two kinds of callout:
-       those with a numerical argument and those with a string argument.  (?C)
-       on  its  own with no argument is treated as (?C0). A numerical argument
-       allows the  application  to  distinguish  between  different  callouts.
-       String  arguments  were added for release 10.20 to make it possible for
-       script languages that use PCRE2 to embed short scripts within  patterns
+       Within  a  regular expression, (?C) indicates a point at which the
+       external function is to be called. There  are  two  kinds  of  callout:
+       those  with a numerical argument and those with a string argument. (?C)
+       on its own with no argument is treated as (?C0). A  numerical  argument
+       allows  the  application  to  distinguish  between  different callouts.
+       String arguments were added for release 10.20 to make it  possible  for
+       script  languages that use PCRE2 to embed short scripts within patterns
        in a similar way to Perl.
 
        During matching, when PCRE2 reaches a callout point, the external func-
-       tion is called. It is provided with the number or  string  argument  of
-       the  callout, the position in the pattern, and one item of data that is
+       tion  is  called.  It is provided with the number or string argument of
+       the callout, the position in the pattern, and one item of data that  is
        also set in the match block. The callout function may cause matching to
        proceed, to backtrack, or to fail.
 
-       By  default,  PCRE2  implements  a  number of optimizations at matching
-       time, and one side-effect is that sometimes callouts  are  skipped.  If
-       you  need all possible callouts to happen, you need to set options that
-       disable the relevant optimizations. More details, including a  complete
-       description  of  the programming interface to the callout function, are
+       By default, PCRE2 implements a  number  of  optimizations  at  matching
+       time,  and  one  side-effect is that sometimes callouts are skipped. If
+       you need all possible callouts to happen, you need to set options  that
+       disable  the relevant optimizations. More details, including a complete
+       description of the programming interface to the callout  function,  are
        given in the pcre2callout documentation.
 
    Callouts with numerical arguments
 
-       If you just want to have  a  means  of  identifying  different  callout
-       points,  put  a  number  less than 256 after the letter C. For example,
+       If  you  just  want  to  have  a means of identifying different callout
+       points, put a number less than 256 after the  letter  C.  For  example,
        this pattern has two callout points:
 
          (?C1)abc(?C2)def
 
-       If the PCRE2_AUTO_CALLOUT flag is passed to pcre2_compile(),  numerical
-       callouts  are  automatically installed before each item in the pattern.
-       They are all numbered 255. If there is a conditional group in the  pat-
+       If  the PCRE2_AUTO_CALLOUT flag is passed to pcre2_compile(), numerical
+       callouts are automatically installed before each item in  the  pattern.
+       They  are all numbered 255. If there is a conditional group in the pat-
        tern whose condition is an assertion, an additional callout is inserted
-       just before the condition. An explicit callout may also be set at  this
+       just  before the condition. An explicit callout may also be set at this
        position, as in this example:
 
          (?(?C9)(?=a)abc|def)
@@ -8720,60 +8781,60 @@ CALLOUTS
 
    Callouts with string arguments
 
-       A delimited string may be used instead of a number as a  callout  argu-
-       ment.  The  starting  delimiter  must be one of ` ' " ^ % # $ { and the
+       A  delimited  string may be used instead of a number as a callout argu-
+       ment. The starting delimiter must be one of ` ' " ^ % #  $  {  and  the
        ending delimiter is the same as the start, except for {, where the end-
-       ing  delimiter  is  }.  If  the  ending  delimiter is needed within the
+       ing delimiter is }. If  the  ending  delimiter  is  needed  within  the
        string, it must be doubled. For example:
 
          (?C'ab ''c'' d')xyz(?C{any text})pqr
 
-       The doubling is removed before the string  is  passed  to  the  callout
+       The  doubling  is  removed  before  the string is passed to the callout
        function.
 
 
 BACKTRACKING CONTROL
 
-       There  are  a  number  of  special "Backtracking Control Verbs" (to use
-       Perl's terminology) that modify the behaviour  of  backtracking  during
-       matching.  They are generally of the form (*VERB) or (*VERB:NAME). Some
-       verbs take either form,  possibly  behaving  differently  depending  on
+       There are a number of special  "Backtracking  Control  Verbs"  (to  use
+       Perl's  terminology)  that  modify the behaviour of backtracking during
+       matching. They are generally of the form (*VERB) or (*VERB:NAME).  Some
+       verbs  take  either  form,  possibly  behaving differently depending on
        whether or not a name is present.
 
-       By  default,  for  compatibility  with  Perl, a name is any sequence of
+       By default, for compatibility with Perl, a  name  is  any  sequence  of
        characters that does not include a closing parenthesis. The name is not
-       processed  in  any  way,  and  it  is not possible to include a closing
-       parenthesis  in  the  name.   This  can  be  changed  by  setting   the
-       PCRE2_ALT_VERBNAMES  option,  but the result is no longer Perl-compati-
+       processed in any way, and it is  not  possible  to  include  a  closing
+       parenthesis   in  the  name.   This  can  be  changed  by  setting  the
+       PCRE2_ALT_VERBNAMES option, but the result is no  longer  Perl-compati-
        ble.
 
-       When PCRE2_ALT_VERBNAMES is set, backslash  processing  is  applied  to
-       verb  names  and  only  an unescaped closing parenthesis terminates the
-       name. However, the only backslash items that are permitted are \Q,  \E,
-       and  sequences such as \x{100} that define character code points. Char-
+       When  PCRE2_ALT_VERBNAMES  is  set,  backslash processing is applied to
+       verb names and only an unescaped  closing  parenthesis  terminates  the
+       name.  However, the only backslash items that are permitted are \Q, \E,
+       and sequences such as \x{100} that define character code points.  Char-
        acter type escapes such as \d are faulted.
 
        A closing parenthesis can be included in a name either as \) or between
-       \Q  and  \E. In addition to backslash processing, if the PCRE2_EXTENDED
+       \Q and \E. In addition to backslash processing, if  the  PCRE2_EXTENDED
        or PCRE2_EXTENDED_MORE option is also set, unescaped whitespace in verb
        names is skipped, and #-comments are recognized, exactly as in the rest
-       of the pattern.  PCRE2_EXTENDED and PCRE2_EXTENDED_MORE do  not  affect
+       of  the  pattern.  PCRE2_EXTENDED and PCRE2_EXTENDED_MORE do not affect
        verb names unless PCRE2_ALT_VERBNAMES is also set.
 
-       The  maximum  length of a name is 255 in the 8-bit library and 65535 in
-       the 16-bit and 32-bit libraries. If the name is empty, that is, if  the
-       closing  parenthesis immediately follows the colon, the effect is as if
+       The maximum length of a name is 255 in the 8-bit library and  65535  in
+       the  16-bit and 32-bit libraries. If the name is empty, that is, if the
+       closing parenthesis immediately follows the colon, the effect is as  if
        the colon were not there. Any number of these verbs may occur in a pat-
        tern.
 
-       Since  these  verbs  are  specifically related to backtracking, most of
-       them can be used only when the pattern is to be matched using the  tra-
+       Since these verbs are specifically related  to  backtracking,  most  of
+       them  can be used only when the pattern is to be matched using the tra-
        ditional matching function, because that uses a backtracking algorithm.
-       With the exception of (*FAIL), which behaves like  a  failing  negative
+       With  the  exception  of (*FAIL), which behaves like a failing negative
        assertion, the backtracking control verbs cause an error if encountered
        by the DFA matching function.
 
-       The behaviour of these verbs in repeated  groups,  assertions,  and  in
+       The  behaviour  of  these  verbs in repeated groups, assertions, and in
        subpatterns called as subroutines (whether or not recursively) is docu-
        mented below.
 
@@ -8781,16 +8842,16 @@ BACKTRACKING CONTROL
 
        PCRE2 contains some optimizations that are used to speed up matching by
        running some checks at the start of each match attempt. For example, it
-       may know the minimum length of matching subject, or that  a  particular
+       may  know  the minimum length of matching subject, or that a particular
        character must be present. When one of these optimizations bypasses the
-       running of a match,  any  included  backtracking  verbs  will  not,  of
+       running  of  a  match,  any  included  backtracking  verbs will not, of
        course, be processed. You can suppress the start-of-match optimizations
-       by setting the PCRE2_NO_START_OPTIMIZE option when  calling  pcre2_com-
-       pile(),  or by starting the pattern with (*NO_START_OPT). There is more
+       by  setting  the PCRE2_NO_START_OPTIMIZE option when calling pcre2_com-
+       pile(), or by starting the pattern with (*NO_START_OPT). There is  more
        discussion of this option in the section entitled "Compiling a pattern"
        in the pcre2api documentation.
 
-       Experiments  with  Perl  suggest that it too has similar optimizations,
+       Experiments with Perl suggest that it too  has  similar  optimizations,
        and like PCRE2, turning them off can change the result of a match.
 
    Verbs that act immediately
@@ -8799,63 +8860,67 @@ BACKTRACKING CONTROL
 
           (*ACCEPT) or (*ACCEPT:NAME)
 
-       This verb causes the match to end successfully, skipping the  remainder
-       of  the pattern. However, when it is inside a subpattern that is called
-       as a subroutine, only that subpattern is ended  successfully.  Matching
+       This  verb causes the match to end successfully, skipping the remainder
+       of the pattern. However, when it is inside a subpattern that is  called
+       as  a  subroutine, only that subpattern is ended successfully. Matching
        then continues at the outer level. If (*ACCEPT) in triggered in a posi-
-       tive assertion, the assertion succeeds; in a  negative  assertion,  the
+       tive  assertion,  the  assertion succeeds; in a negative assertion, the
        assertion fails.
 
-       If  (*ACCEPT)  is inside capturing parentheses, the data so far is cap-
+       If (*ACCEPT) is inside capturing parentheses, the data so far  is  cap-
        tured. For example:
 
          A((?:A|B(*ACCEPT)|C)D)
 
-       This matches "AB", "AAD", or "ACD"; when it matches "AB", "B"  is  cap-
+       This  matches  "AB", "AAD", or "ACD"; when it matches "AB", "B" is cap-
        tured by the outer parentheses.
 
+       Warning: (*ACCEPT) should not be used within a script  run  subpattern,
+       because  it causes an immediate exit from the subpattern, bypassing the
+       script run checking.
+
          (*FAIL) or (*FAIL:NAME)
 
-       This  verb causes a matching failure, forcing backtracking to occur. It
-       may be abbreviated to (*F). It is equivalent  to  (?!)  but  easier  to
+       This verb causes a matching failure, forcing backtracking to occur.  It
+       may  be  abbreviated  to  (*F).  It is equivalent to (?!) but easier to
        read. The Perl documentation notes that it is probably useful only when
        combined with (?{}) or (??{}). Those are, of course, Perl features that
-       are  not  present  in PCRE2. The nearest equivalent is the callout fea-
+       are not present in PCRE2. The nearest equivalent is  the  callout  fea-
        ture, as for example in this pattern:
 
          a+(?C)(*FAIL)
 
-       A match with the string "aaaa" always fails, but the callout  is  taken
+       A  match  with the string "aaaa" always fails, but the callout is taken
        before each backtrack happens (in this example, 10 times).
 
-       (*ACCEPT:NAME)   and   (*FAIL:NAME)   behave   exactly   the   same  as
+       (*ACCEPT:NAME)  and   (*FAIL:NAME)   behave   exactly   the   same   as
        (*MARK:NAME)(*ACCEPT) and (*MARK:NAME)(*FAIL), respectively.
 
    Recording which path was taken
 
-       There is one verb whose main purpose  is  to  track  how  a  match  was
-       arrived  at,  though  it  also  has a secondary use in conjunction with
+       There  is  one  verb  whose  main  purpose  is to track how a match was
+       arrived at, though it also has a  secondary  use  in  conjunction  with
        advancing the match starting point (see (*SKIP) below).
 
          (*MARK:NAME) or (*:NAME)
 
-       A name is always  required  with  this  verb.  There  may  be  as  many
-       instances  of  (*MARK) as you like in a pattern, and their names do not
+       A  name  is  always  required  with  this  verb.  There  may be as many
+       instances of (*MARK) as you like in a pattern, and their names  do  not
        have to be unique.
 
        When a match succeeds, the name of the last-encountered (*MARK:NAME) on
        the matching path is passed back to the caller as described in the sec-
        tion entitled "Other information about the match" in the pcre2api docu-
-       mentation.  This  applies  to all instances of (*MARK), including those
-       inside assertions and atomic groups. (There are  differences  in  those
-       cases  when  (*MARK)  is  used in conjunction with (*SKIP) as described
+       mentation. This applies to all instances of  (*MARK),  including  those
+       inside  assertions  and  atomic groups. (There are differences in those
+       cases when (*MARK) is used in conjunction  with  (*SKIP)  as  described
        below.)
 
-       As well as (*MARK), the (*COMMIT), (*PRUNE) and (*THEN) verbs may  have
-       associated  NAME  arguments.  Whichever is last on the matching path is
+       As  well as (*MARK), the (*COMMIT), (*PRUNE) and (*THEN) verbs may have
+       associated NAME arguments. Whichever is last on the  matching  path  is
        passed back. See below for more details of these other verbs.
 
-       Here is an example of  pcre2test  output,  where  the  "mark"  modifier
+       Here  is  an  example  of  pcre2test  output, where the "mark" modifier
        requests the retrieval and outputting of (*MARK) data:
 
            re> /X(*MARK:A)Y|X(*MARK:B)Z/mark
@@ -8867,76 +8932,76 @@ BACKTRACKING CONTROL
          MK: B
 
        The (*MARK) name is tagged with "MK:" in this output, and in this exam-
-       ple it indicates which of the two alternatives matched. This is a  more
-       efficient  way of obtaining this information than putting each alterna-
+       ple  it indicates which of the two alternatives matched. This is a more
+       efficient way of obtaining this information than putting each  alterna-
        tive in its own capturing parentheses.
 
-       If a verb with a name is encountered in a positive  assertion  that  is
-       true,  the  name  is recorded and passed back if it is the last-encoun-
+       If  a  verb  with a name is encountered in a positive assertion that is
+       true, the name is recorded and passed back if it  is  the  last-encoun-
        tered. This does not happen for negative assertions or failing positive
        assertions.
 
-       After  a  partial match or a failed match, the last encountered name in
+       After a partial match or a failed match, the last encountered  name  in
        the entire match process is returned. For example:
 
            re> /X(*MARK:A)Y|X(*MARK:B)Z/mark
          data> XP
          No match, mark = B
 
-       Note that in this unanchored example the  mark  is  retained  from  the
+       Note  that  in  this  unanchored  example the mark is retained from the
        match attempt that started at the letter "X" in the subject. Subsequent
        match attempts starting at "P" and then with an empty string do not get
        as far as the (*MARK) item, but nevertheless do not reset it.
 
-       If  you  are  interested  in  (*MARK)  values after failed matches, you
-       should probably set the PCRE2_NO_START_OPTIMIZE option (see  above)  to
+       If you are interested in  (*MARK)  values  after  failed  matches,  you
+       should  probably  set the PCRE2_NO_START_OPTIMIZE option (see above) to
        ensure that the match is always attempted.
 
    Verbs that act after backtracking
 
        The following verbs do nothing when they are encountered. Matching con-
-       tinues with what follows, but if there is a subsequent  match  failure,
-       causing  a  backtrack  to the verb, a failure is forced. That is, back-
-       tracking cannot pass to the left of the  verb.  However,  when  one  of
+       tinues  with  what follows, but if there is a subsequent match failure,
+       causing a backtrack to the verb, a failure is forced.  That  is,  back-
+       tracking  cannot  pass  to  the  left of the verb. However, when one of
        these verbs appears inside an atomic group or in a lookaround assertion
-       that is true, its effect is confined to that group,  because  once  the
-       group  has been matched, there is never any backtracking into it. Back-
+       that  is  true,  its effect is confined to that group, because once the
+       group has been matched, there is never any backtracking into it.  Back-
        tracking from beyond an assertion or an atomic group ignores the entire
        group, and seeks a preceeding backtracking point.
 
-       These  verbs  differ  in exactly what kind of failure occurs when back-
-       tracking reaches them. The behaviour described below  is  what  happens
-       when  the  verb is not in a subroutine or an assertion. Subsequent sec-
+       These verbs differ in exactly what kind of failure  occurs  when  back-
+       tracking  reaches  them.  The behaviour described below is what happens
+       when the verb is not in a subroutine or an assertion.  Subsequent  sec-
        tions cover these special cases.
 
          (*COMMIT) or (*COMMIT:NAME)
 
-       This verb causes the whole match to fail outright if there is  a  later
+       This  verb  causes the whole match to fail outright if there is a later
        matching failure that causes backtracking to reach it. Even if the pat-
-       tern is unanchored, no further attempts to find a  match  by  advancing
-       the  starting  point  take place. If (*COMMIT) is the only backtracking
+       tern  is  unanchored,  no further attempts to find a match by advancing
+       the starting point take place. If (*COMMIT) is  the  only  backtracking
        verb that is encountered, once it has been passed pcre2_match() is com-
        mitted to finding a match at the current starting point, or not at all.
        For example:
 
          a+(*COMMIT)b
 
-       This matches "xxaab" but not "aacaab". It can be thought of as  a  kind
+       This  matches  "xxaab" but not "aacaab". It can be thought of as a kind
        of dynamic anchor, or "I've started, so I must finish."
 
-       The  behaviour  of (*COMMIT:NAME) is not the same as (*MARK:NAME)(*COM-
-       MIT). It is like (*MARK:NAME) in that the name is remembered for  pass-
-       ing  back  to the caller. However, (*SKIP:NAME) searches only for names
-       set with  (*MARK),  ignoring  those  set  by  (*COMMIT),  (*PRUNE)  and
+       The behaviour of (*COMMIT:NAME) is not the same  as  (*MARK:NAME)(*COM-
+       MIT).  It is like (*MARK:NAME) in that the name is remembered for pass-
+       ing back to the caller. However, (*SKIP:NAME) searches only  for  names
+       set  with  (*MARK),  ignoring  those  set  by  (*COMMIT),  (*PRUNE) and
        (*THEN).
 
-       If  there  is more than one backtracking verb in a pattern, a different
-       one that follows (*COMMIT) may be triggered first,  so  merely  passing
+       If there is more than one backtracking verb in a pattern,  a  different
+       one  that  follows  (*COMMIT) may be triggered first, so merely passing
        (*COMMIT) during a match does not always guarantee that a match must be
        at this starting point.
 
-       Note that (*COMMIT) at the start of a pattern is not  the  same  as  an
-       anchor,  unless PCRE2's start-of-match optimizations are turned off, as
+       Note  that  (*COMMIT)  at  the start of a pattern is not the same as an
+       anchor, unless PCRE2's start-of-match optimizations are turned off,  as
        shown in this output from pcre2test:
 
            re> /(*COMMIT)abc/
@@ -8947,63 +9012,63 @@ BACKTRACKING CONTROL
          data> xyzabc
          No match
 
-       For the first pattern, PCRE2 knows that any match must start with  "a",
-       so  the optimization skips along the subject to "a" before applying the
-       pattern to the first set of data. The match attempt then succeeds.  The
-       second  pattern disables the optimization that skips along to the first
-       character. The pattern is now applied  starting  at  "x",  and  so  the
-       (*COMMIT)  causes  the  match to fail without trying any other starting
+       For  the first pattern, PCRE2 knows that any match must start with "a",
+       so the optimization skips along the subject to "a" before applying  the
+       pattern  to the first set of data. The match attempt then succeeds. The
+       second pattern disables the optimization that skips along to the  first
+       character.  The  pattern  is  now  applied  starting at "x", and so the
+       (*COMMIT) causes the match to fail without trying  any  other  starting
        points.
 
          (*PRUNE) or (*PRUNE:NAME)
 
-       This verb causes the match to fail at the current starting position  in
+       This  verb causes the match to fail at the current starting position in
        the subject if there is a later matching failure that causes backtrack-
-       ing to reach it. If the pattern is unanchored, the  normal  "bumpalong"
-       advance  to  the next starting character then happens. Backtracking can
-       occur as usual to the left of (*PRUNE), before it is reached,  or  when
-       matching  to  the  right  of  (*PRUNE), but if there is no match to the
-       right, backtracking cannot cross (*PRUNE). In simple cases, the use  of
-       (*PRUNE)  is just an alternative to an atomic group or possessive quan-
+       ing  to  reach it. If the pattern is unanchored, the normal "bumpalong"
+       advance to the next starting character then happens.  Backtracking  can
+       occur  as  usual to the left of (*PRUNE), before it is reached, or when
+       matching to the right of (*PRUNE), but if there  is  no  match  to  the
+       right,  backtracking cannot cross (*PRUNE). In simple cases, the use of
+       (*PRUNE) is just an alternative to an atomic group or possessive  quan-
        tifier, but there are some uses of (*PRUNE) that cannot be expressed in
-       any  other  way. In an anchored pattern (*PRUNE) has the same effect as
+       any other way. In an anchored pattern (*PRUNE) has the same  effect  as
        (*COMMIT).
 
        The behaviour of (*PRUNE:NAME) is not the same as (*MARK:NAME)(*PRUNE).
        It is like (*MARK:NAME) in that the name is remembered for passing back
-       to the caller. However, (*SKIP:NAME) searches only for names  set  with
+       to  the  caller. However, (*SKIP:NAME) searches only for names set with
        (*MARK), ignoring those set by (*COMMIT), (*PRUNE) or (*THEN).
 
          (*SKIP)
 
-       This  verb, when given without a name, is like (*PRUNE), except that if
-       the pattern is unanchored, the "bumpalong" advance is not to  the  next
+       This verb, when given without a name, is like (*PRUNE), except that  if
+       the  pattern  is unanchored, the "bumpalong" advance is not to the next
        character, but to the position in the subject where (*SKIP) was encoun-
-       tered. (*SKIP) signifies that whatever text was matched leading  up  to
-       it  cannot  be part of a successful match if there is a later mismatch.
+       tered.  (*SKIP)  signifies that whatever text was matched leading up to
+       it cannot be part of a successful match if there is a  later  mismatch.
        Consider:
 
          a+(*SKIP)b
 
-       If the subject is "aaaac...",  after  the  first  match  attempt  fails
-       (starting  at  the  first  character in the string), the starting point
+       If  the  subject  is  "aaaac...",  after  the first match attempt fails
+       (starting at the first character in the  string),  the  starting  point
        skips on to start the next attempt at "c". Note that a possessive quan-
-       tifer  does not have the same effect as this example; although it would
-       suppress backtracking  during  the  first  match  attempt,  the  second
-       attempt  would  start at the second character instead of skipping on to
+       tifer does not have the same effect as this example; although it  would
+       suppress  backtracking  during  the  first  match  attempt,  the second
+       attempt would start at the second character instead of skipping  on  to
        "c".
 
          (*SKIP:NAME)
 
-       When (*SKIP) has an associated name, its behaviour  is  modified.  When
-       such  a  (*SKIP) is triggered, the previous path through the pattern is
-       searched for the most recent (*MARK) that has the same name. If one  is
-       found,  the  "bumpalong" advance is to the subject position that corre-
-       sponds to that (*MARK) instead of to where (*SKIP) was encountered.  If
+       When  (*SKIP)  has  an associated name, its behaviour is modified. When
+       such a (*SKIP) is triggered, the previous path through the  pattern  is
+       searched  for the most recent (*MARK) that has the same name. If one is
+       found, the "bumpalong" advance is to the subject position  that  corre-
+       sponds  to that (*MARK) instead of to where (*SKIP) was encountered. If
        no (*MARK) with a matching name is found, the (*SKIP) is ignored.
 
-       The  search  for a (*MARK) name uses the normal backtracking mechanism,
-       which means that it does not  see  (*MARK)  settings  that  are  inside
+       The search for a (*MARK) name uses the normal  backtracking  mechanism,
+       which  means  that  it  does  not  see (*MARK) settings that are inside
        atomic groups or assertions, because they are never re-entered by back-
        tracking. Compare the following pcre2test examples:
 
@@ -9017,106 +9082,106 @@ BACKTRACKING CONTROL
           0: b
           1: b
 
-       In the first example, the (*MARK) setting is in an atomic group, so  it
+       In  the first example, the (*MARK) setting is in an atomic group, so it
        is not seen when (*SKIP:X) triggers, causing the (*SKIP) to be ignored.
-       This allows the second branch of the pattern to be tried at  the  first
-       character  position.  In the second example, the (*MARK) setting is not
-       in an atomic group. This allows (*SKIP:X) to find the (*MARK)  when  it
+       This  allows  the second branch of the pattern to be tried at the first
+       character position.  In the second example, the (*MARK) setting is  not
+       in  an  atomic group. This allows (*SKIP:X) to find the (*MARK) when it
        backtracks, and this causes a new matching attempt to start at the sec-
-       ond character. This time, the (*MARK) is never seen  because  "a"  does
+       ond  character.  This  time, the (*MARK) is never seen because "a" does
        not match "b", so the matcher immediately jumps to the second branch of
        the pattern.
 
-       Note that (*SKIP:NAME) searches only for names set by (*MARK:NAME).  It
-       ignores   names  that  are  set  by  (*COMMIT:NAME),  (*PRUNE:NAME)  or
+       Note  that (*SKIP:NAME) searches only for names set by (*MARK:NAME). It
+       ignores  names  that  are  set  by  (*COMMIT:NAME),  (*PRUNE:NAME)   or
        (*THEN:NAME).
 
          (*THEN) or (*THEN:NAME)
 
-       This verb causes a skip to the next innermost  alternative  when  back-
-       tracking  reaches  it.  That  is,  it  cancels any further backtracking
-       within the current alternative. Its name  comes  from  the  observation
+       This  verb  causes  a skip to the next innermost alternative when back-
+       tracking reaches it. That  is,  it  cancels  any  further  backtracking
+       within  the  current  alternative.  Its name comes from the observation
        that it can be used for a pattern-based if-then-else block:
 
          ( COND1 (*THEN) FOO | COND2 (*THEN) BAR | COND3 (*THEN) BAZ ) ...
 
-       If  the COND1 pattern matches, FOO is tried (and possibly further items
-       after the end of the group if FOO succeeds); on  failure,  the  matcher
-       skips  to  the second alternative and tries COND2, without backtracking
-       into COND1. If that succeeds and BAR fails, COND3 is tried.  If  subse-
-       quently  BAZ fails, there are no more alternatives, so there is a back-
-       track to whatever came before the  entire  group.  If  (*THEN)  is  not
+       If the COND1 pattern matches, FOO is tried (and possibly further  items
+       after  the  end  of the group if FOO succeeds); on failure, the matcher
+       skips to the second alternative and tries COND2,  without  backtracking
+       into  COND1.  If that succeeds and BAR fails, COND3 is tried. If subse-
+       quently BAZ fails, there are no more alternatives, so there is a  back-
+       track  to  whatever  came  before  the  entire group. If (*THEN) is not
        inside an alternation, it acts like (*PRUNE).
 
-       The  behaviour  of (*THEN:NAME) is not the same as (*MARK:NAME)(*THEN).
+       The behaviour of (*THEN:NAME) is not the same  as  (*MARK:NAME)(*THEN).
        It is like (*MARK:NAME) in that the name is remembered for passing back
-       to  the  caller. However, (*SKIP:NAME) searches only for names set with
+       to the caller. However, (*SKIP:NAME) searches only for names  set  with
        (*MARK), ignoring those set by (*COMMIT), (*PRUNE) and (*THEN).
 
-       A subpattern that does not contain a | character is just a part of  the
-       enclosing  alternative;  it  is  not a nested alternation with only one
-       alternative. The effect of (*THEN) extends beyond such a subpattern  to
-       the  enclosing alternative. Consider this pattern, where A, B, etc. are
-       complex pattern fragments that do not contain any | characters at  this
+       A  subpattern that does not contain a | character is just a part of the
+       enclosing alternative; it is not a nested  alternation  with  only  one
+       alternative.  The effect of (*THEN) extends beyond such a subpattern to
+       the enclosing alternative. Consider this pattern, where A, B, etc.  are
+       complex  pattern fragments that do not contain any | characters at this
        level:
 
          A (B(*THEN)C) | D
 
-       If  A and B are matched, but there is a failure in C, matching does not
+       If A and B are matched, but there is a failure in C, matching does  not
        backtrack into A; instead it moves to the next alternative, that is, D.
-       However,  if the subpattern containing (*THEN) is given an alternative,
+       However, if the subpattern containing (*THEN) is given an  alternative,
        it behaves differently:
 
          A (B(*THEN)C | (*FAIL)) | D
 
-       The effect of (*THEN) is now confined to the inner subpattern. After  a
+       The  effect of (*THEN) is now confined to the inner subpattern. After a
        failure in C, matching moves to (*FAIL), which causes the whole subpat-
-       tern to fail because there are no more alternatives  to  try.  In  this
+       tern  to  fail  because  there are no more alternatives to try. In this
        case, matching does now backtrack into A.
 
-       Note  that  a  conditional  subpattern  is not considered as having two
-       alternatives, because only one is ever used.  In  other  words,  the  |
+       Note that a conditional subpattern is  not  considered  as  having  two
+       alternatives,  because  only  one  is  ever used. In other words, the |
        character in a conditional subpattern has a different meaning. Ignoring
        white space, consider:
 
          ^.*? (?(?=a) a | b(*THEN)c )
 
-       If the subject is "ba", this pattern does not  match.  Because  .*?  is
-       ungreedy,  it  initially  matches  zero characters. The condition (?=a)
-       then fails, the character "b" is matched,  but  "c"  is  not.  At  this
-       point,  matching does not backtrack to .*? as might perhaps be expected
-       from the presence of the | character.  The  conditional  subpattern  is
+       If  the  subject  is  "ba", this pattern does not match. Because .*? is
+       ungreedy, it initially matches zero  characters.  The  condition  (?=a)
+       then  fails,  the  character  "b"  is  matched, but "c" is not. At this
+       point, matching does not backtrack to .*? as might perhaps be  expected
+       from  the  presence  of  the | character. The conditional subpattern is
        part of the single alternative that comprises the whole pattern, and so
-       the match fails. (If there was a backtrack into  .*?,  allowing  it  to
+       the  match  fails.  (If  there was a backtrack into .*?, allowing it to
        match "b", the match would succeed.)
 
-       The  verbs just described provide four different "strengths" of control
+       The verbs just described provide four different "strengths" of  control
        when subsequent matching fails. (*THEN) is the weakest, carrying on the
-       match  at  the next alternative. (*PRUNE) comes next, failing the match
-       at the current starting position, but allowing an advance to  the  next
-       character  (for an unanchored pattern). (*SKIP) is similar, except that
+       match at the next alternative. (*PRUNE) comes next, failing  the  match
+       at  the  current starting position, but allowing an advance to the next
+       character (for an unanchored pattern). (*SKIP) is similar, except  that
        the advance may be more than one character. (*COMMIT) is the strongest,
        causing the entire match to fail.
 
    More than one backtracking verb
 
-       If  more  than  one  backtracking verb is present in a pattern, the one
-       that is backtracked onto first acts. For example,  consider  this  pat-
+       If more than one backtracking verb is present in  a  pattern,  the  one
+       that  is  backtracked  onto first acts. For example, consider this pat-
        tern, where A, B, etc. are complex pattern fragments:
 
          (A(*COMMIT)B(*THEN)C|ABD)
 
-       If  A matches but B fails, the backtrack to (*COMMIT) causes the entire
+       If A matches but B fails, the backtrack to (*COMMIT) causes the  entire
        match to fail. However, if A and B match, but C fails, the backtrack to
-       (*THEN)  causes  the next alternative (ABD) to be tried. This behaviour
-       is consistent, but is not always the same as Perl's. It means  that  if
-       two  or  more backtracking verbs appear in succession, all the the last
+       (*THEN) causes the next alternative (ABD) to be tried.  This  behaviour
+       is  consistent,  but is not always the same as Perl's. It means that if
+       two or more backtracking verbs appear in succession, all the  the  last
        of them has no effect. Consider this example:
 
          ...(*COMMIT)(*PRUNE)...
 
        If there is a matching failure to the right, backtracking onto (*PRUNE)
-       causes  it to be triggered, and its action is taken. There can never be
+       causes it to be triggered, and its action is taken. There can never  be
        a backtrack onto (*COMMIT).
 
    Backtracking verbs in repeated groups
@@ -9126,73 +9191,73 @@ BACKTRACKING CONTROL
 
          /(a(*COMMIT)b)+ac/
 
-       If  the  subject  is  "abac", Perl matches unless its optimizations are
-       disabled, but PCRE2 always fails because the (*COMMIT)  in  the  second
+       If the subject is "abac", Perl matches  unless  its  optimizations  are
+       disabled,  but  PCRE2  always fails because the (*COMMIT) in the second
        repeat of the group acts.
 
    Backtracking verbs in assertions
 
-       (*FAIL)  in any assertion has its normal effect: it forces an immediate
-       backtrack. The behaviour of the other  backtracking  verbs  depends  on
-       whether  or  not the assertion is standalone or acting as the condition
+       (*FAIL) in any assertion has its normal effect: it forces an  immediate
+       backtrack.  The  behaviour  of  the other backtracking verbs depends on
+       whether or not the assertion is standalone or acting as  the  condition
        in a conditional subpattern.
 
-       (*ACCEPT) in a standalone positive assertion causes  the  assertion  to
-       succeed  without any further processing; captured strings and a (*MARK)
-       name (if  set)  are  retained.  In  a  standalone  negative  assertion,
-       (*ACCEPT)  causes the assertion to fail without any further processing;
+       (*ACCEPT)  in  a  standalone positive assertion causes the assertion to
+       succeed without any further processing; captured strings and a  (*MARK)
+       name  (if  set)  are  retained.  In  a  standalone  negative assertion,
+       (*ACCEPT) causes the assertion to fail without any further  processing;
        captured substrings and any (*MARK) name are discarded.
 
-       If the assertion is a condition, (*ACCEPT) causes the condition  to  be
-       true  for  a  positive assertion and false for a negative one; captured
+       If  the  assertion is a condition, (*ACCEPT) causes the condition to be
+       true for a positive assertion and false for a  negative  one;  captured
        substrings are retained in both cases.
 
        The remaining verbs act only when a later failure causes a backtrack to
-       reach  them. This means that their effect is confined to the assertion,
+       reach them. This means that their effect is confined to the  assertion,
        because lookaround assertions are atomic. A backtrack that occurs after
        an assertion is complete does not jump back into the assertion. Note in
-       particular that a (*MARK) name that is  set  in  an  assertion  is  not
+       particular  that  a  (*MARK)  name  that  is set in an assertion is not
        "seen" by an instance of (*SKIP:NAME) latter in the pattern.
 
-       The  effect of (*THEN) is not allowed to escape beyond an assertion. If
-       there are no more branches to try, (*THEN) causes a positive  assertion
+       The effect of (*THEN) is not allowed to escape beyond an assertion.  If
+       there  are no more branches to try, (*THEN) causes a positive assertion
        to be false, and a negative assertion to be true.
 
-       The  other  backtracking verbs are not treated specially if they appear
-       in a standalone positive assertion. In a  conditional  positive  asser-
+       The other backtracking verbs are not treated specially if  they  appear
+       in  a  standalone  positive assertion. In a conditional positive asser-
        tion, backtracking (from within the assertion) into (*COMMIT), (*SKIP),
-       or (*PRUNE) causes the condition to be false. However, for both  stand-
+       or  (*PRUNE) causes the condition to be false. However, for both stand-
        alone and conditional negative assertions, backtracking into (*COMMIT),
        (*SKIP), or (*PRUNE) causes the assertion to be true, without consider-
        ing any further alternative branches.
 
    Backtracking verbs in subroutines
 
-       These  behaviours  occur whether or not the subpattern is called recur-
+       These behaviours occur whether or not the subpattern is  called  recur-
        sively.
 
-       (*ACCEPT) in a subpattern called as a subroutine causes the  subroutine
-       match  to succeed without any further processing. Matching then contin-
-       ues after the subroutine call. Perl documents  this  behaviour.  Perl's
+       (*ACCEPT)  in a subpattern called as a subroutine causes the subroutine
+       match to succeed without any further processing. Matching then  contin-
+       ues  after  the  subroutine call. Perl documents this behaviour. Perl's
        treatment of the other verbs in subroutines is different in some cases.
 
-       (*FAIL)  in  a subpattern called as a subroutine has its normal effect:
+       (*FAIL) in a subpattern called as a subroutine has its  normal  effect:
        it forces an immediate backtrack.
 
-       (*COMMIT), (*SKIP), and (*PRUNE) cause the  subroutine  match  to  fail
+       (*COMMIT),  (*SKIP),  and  (*PRUNE)  cause the subroutine match to fail
        when triggered by being backtracked to in a subpattern called as a sub-
        routine. There is then a backtrack at the outer level.
 
        (*THEN), when triggered, skips to the next alternative in the innermost
        enclosing group within the subpattern that has alternatives (its normal
-       behaviour). However, if there is no such group  within  the  subroutine
-       subpattern,  the subroutine match fails and there is a backtrack at the
+       behaviour).  However,  if  there is no such group within the subroutine
+       subpattern, the subroutine match fails and there is a backtrack at  the
        outer level.
 
 
 SEE ALSO
 
-       pcre2api(3),   pcre2callout(3),    pcre2matching(3),    pcre2syntax(3),
+       pcre2api(3),    pcre2callout(3),    pcre2matching(3),   pcre2syntax(3),
        pcre2(3).
 
 
@@ -9205,7 +9270,7 @@ AUTHOR
 
 REVISION
 
-       Last updated: 24 September 2018
+       Last updated: 12 October 2018
        Copyright (c) 1997-2018 University of Cambridge.
 ------------------------------------------------------------------------------
  
@@ -10413,6 +10478,15 @@ LOOKAHEAD AND LOOKBEHIND ASSERTIONS
        Each top-level branch of a lookbehind must be of a fixed length.
 
 
+SCRIPT RUNS
+
+         (*script_run:...)           ) script run, can be backtracked into
+         (*sr:...)                   )
+
+         (*atomic_script_run:...)    ) atomic script run
+         (*asr:...)                  )
+
+
 BACKREFERENCES
 
          \n              reference by number (can be ambiguous)
@@ -10525,7 +10599,7 @@ AUTHOR
 
 REVISION
 
-       Last updated: 24 September 2018
+       Last updated: 10 October 2018
        Copyright (c) 1997-2018 University of Cambridge.
 ------------------------------------------------------------------------------
  
@@ -10633,6 +10707,108 @@ CASE-EQUIVALENCE IN UTF MODES
        such.
 
 
+SCRIPT RUNS
+
+       The  pattern constructs (*script_run:...) and (*atomic_script_run:...),
+       with synonyms (*sr:...) and (*asr:...), verify that the string  matched
+       within  the  parentheses is a script run. In concept, a script run is a
+       sequence of characters that are all from the same Unicode script.  How-
+       ever, because some scripts are commonly used together, and because some
+       diacritical and other marks are used with multiple scripts, it  is  not
+       that simple.
+
+       Every Unicode character has a Script property, mostly with a value cor-
+       responding to the name of a script, such as Latin, Greek, or  Cyrillic.
+       There are also three special values:
+
+       "Unknown" is used for code points that have not been assigned, and also
+       for the surrogate code points. In the PCRE2 32-bit library,  characters
+       whose  code  points  are  greater  than the Unicode maximum (U+10FFFF),
+       which are accessible only in non-UTF mode,  are  assigned  the  Unknown
+       script.
+
+       "Common"  is used for characters that are used with many scripts. These
+       include punctuation, emoji, mathematical, musical,  and  currency  sym-
+       bols, and the ASCII digits 0 to 9.
+
+       "Inherited"  is used for characters such as diacritical marks that mod-
+       ify a previous character. These are considered to take on the script of
+       the character that they modify.
+
+       Some  Inherited characters are used with many scripts, but many of them
+       are only normally used with a small number  of  scripts.  For  example,
+       U+102E0 (Coptic Epact thousands mark) is used only with Arabic and Cop-
+       tic. In order to make it possible to check  this,  a  Unicode  property
+       called  Script  Extension  exists.  Its value is a list of scripts that
+       apply to the character. For the majority of characters, the  list  con-
+       tains  just  one  script, the same one as the Script property. However,
+       for characters such as U+102E0 more than one Script  is  listed.  There
+       are  also  some Common characters that have a single, non-Common script
+       in their Script Extension list.
+
+       The next section describes the basic rules for deciding whether a given
+       string  of  characters  is  a script run. Note, however, that there are
+       some special cases involving the Chinese Han script, and an  additional
+       constraint  for  decimal  digits.  These are covered in subsequent sec-
+       tions.
+
+   Basic script run rules
+
+       A string that is less than two characters long is a script run. This is
+       the  only  case  in  which an Unknown character can be part of a script
+       run. Longer strings are checked using only the Script Extensions  prop-
+       erty, not the basic Script property.
+
+       If  a character's Script Extension property is the single value "Inher-
+       ited", it is always accepted as part of a script run. This is also true
+       for  the  property  "Common", subject to the checking of decimal digits
+       described below. All the remaining characters in a script run must have
+       at  least one script in common in their Script Extension lists. In set-
+       theoretic terminology, the intersection of all the sets of scripts must
+       not be empty.
+
+       A  simple example is an Internet name such as "google.com". The letters
+       are all in the Latin script, and the dot is Common, so this string is a
+       script run.  However, the Cyrillic letter "o" looks exactly the same as
+       the Latin "o"; a string that looks the same, but with Cyrillic "o"s  is
+       not a script run.
+
+       More  interesting examples involve characters with more than one script
+       in their Script Extension. Consider the following characters:
+
+         U+060C  Arabic comma
+         U+06D4  Arabic full stop
+
+       The first has the Script Extension list Arabic, Hanifi  Rohingya,  Syr-
+       iac,  and  Thaana; the second has just Arabic and Hanifi Rohingya. Both
+       of them could  appear  in  script  runs  of  either  Arabic  or  Hanifi
+       Rohingya.  The first could also appear in Syriac or Thaana script runs,
+       but the second could not.
+
+   The Chinese Han script
+
+       The Chinese Han script is  commonly  used  in  conjunction  with  other
+       scripts  for  writing certain languages. Japanese uses the Hiragana and
+       Katakana scripts together with Han; Korean uses Hangul  and  Han;  Tai-
+       wanese  Mandarin  uses  Bopomofo  and Han. These three combinations are
+       treated as special cases when checking script runs and are, in  effect,
+       "virtual  scripts".  Thus,  a script run may contain a mixture of Hira-
+       gana, Katakana, and Han, or a mixture of Hangul and Han, or  a  mixture
+       of  Bopomofo  and  Han,  but  not, for example, a mixture of Hangul and
+       Bopomofo and Han. PCRE2 (like Perl) follows Unicode's  Technical  Stan-
+       dard     39     ("Unicode     Security     Mechanisms",     http://uni-
+       code.org/reports/tr39/) in allowing such mixtures.
+
+   Decimal digits
+
+       Unicode contains many sets of 10 decimal digits in  different  scripts,
+       and  some  scripts  (including the Common script) contain more than one
+       set. Some of these decimal digits them are  visually  indistinguishable
+       from  the  common  ASCII  digits.  In  addition  to the script checking
+       described above, if a script run contains any decimal digits, they must
+       all come from the same set of 10 adjacent characters.
+
+
 VALIDITY OF UTF STRINGS
 
        When  the  PCRE2_UTF  option is set, the strings passed as patterns and
@@ -10788,7 +10964,7 @@ AUTHOR
 
 REVISION
 
-       Last updated: 02 September 2018
+       Last updated: 12 October 2018
        Copyright (c) 1997-2018 University of Cambridge.
 ------------------------------------------------------------------------------
  
diff --git a/doc/pcre2matching.3 b/doc/pcre2matching.3
index 81ce968..20ffac5 100644
--- a/doc/pcre2matching.3
+++ b/doc/pcre2matching.3
@@ -1,4 +1,4 @@
-.TH PCRE2MATCHING 3 "29 September 2014" "PCRE2 10.00"
+.TH PCRE2MATCHING 3 "10 October 2018" "PCRE2 10.33"
 .SH NAME
 PCRE2 - Perl-compatible regular expressions (revised API)
 .SH "PCRE2 MATCHING ALGORITHMS"
@@ -113,7 +113,8 @@ do want multiple matches in such cases, either use an ungreedy repeat
 ("a\ed+?") or set the PCRE2_NO_AUTO_POSSESS option when compiling.
 .P
 There are a number of features of PCRE2 regular expressions that are not
-supported by the alternative matching algorithm. They are as follows:
+supported or behave differently in the alternative matching function. Those
+that are not supported cause an error if encountered.
 .P
 1. Because the algorithm finds all possible matches, the greedy or ungreedy
 nature of repetition quantifiers is not relevant (though it may affect
@@ -135,24 +136,26 @@ possibilities, and PCRE2's implementation of this algorithm does not attempt to
 do this. This means that no captured substrings are available.
 .P
 3. Because no substrings are captured, backreferences within the pattern are
-not supported, and cause errors if encountered.
+not supported.
 .P
 4. For the same reason, conditional expressions that use a backreference as the
 condition or test for a specific group recursion are not supported.
 .P
-5. Because many paths through the tree may be active, the \eK escape sequence,
-which resets the start of the match when encountered (but may be on some paths
-and not on others), is not supported. It causes an error if encountered.
+5. Again for the same reason, script runs are not supported.
 .P
-6. Callouts are supported, but the value of the \fIcapture_top\fP field is
+6. Because many paths through the tree may be active, the \eK escape sequence,
+which resets the start of the match when encountered (but may be on some paths
+and not on others), is not supported.
+.P
+7. Callouts are supported, but the value of the \fIcapture_top\fP field is
 always 1, and the value of the \fIcapture_last\fP field is always 0.
 .P
-7. The \eC escape sequence, which (in the standard algorithm) always matches a
+8. The \eC escape sequence, which (in the standard algorithm) always matches a
 single code unit, even in a UTF mode, is not supported in these modes, because
 the alternative algorithm moves through the subject string one character (not
 code unit) at a time, for all active paths through the tree.
 .P
-8. Except for (*FAIL), the backtracking control verbs such as (*PRUNE) are not
+9. Except for (*FAIL), the backtracking control verbs such as (*PRUNE) are not
 supported. (*FAIL) is supported, and behaves like a failing negative assertion.
 .
 .
@@ -188,7 +191,7 @@ The alternative algorithm suffers from a number of disadvantages:
 because it has to search for all possible matches, but is also because it is
 less susceptible to optimization.
 .P
-2. Capturing parentheses and backreferences are not supported.
+2. Capturing parentheses, backreferences, and script runs are not supported.
 .P
 3. Although atomic groups are supported, their use does not provide the
 performance advantage that it does for the standard algorithm.
@@ -208,6 +211,6 @@ Cambridge, England.
 .rs
 .sp
 .nf
-Last updated: 29 September 2014
-Copyright (c) 1997-2014 University of Cambridge.
+Last updated: 10 October 2018
+Copyright (c) 1997-2018 University of Cambridge.
 .fi
diff --git a/doc/pcre2pattern.3 b/doc/pcre2pattern.3
index 5e6baef..fa84844 100644
--- a/doc/pcre2pattern.3
+++ b/doc/pcre2pattern.3
@@ -1,4 +1,4 @@
-.TH PCRE2PATTERN 3 "24 September 2018" "PCRE2 10.33"
+.TH PCRE2PATTERN 3 "12 October 2018" "PCRE2 10.33"
 .SH NAME
 PCRE2 - Perl-compatible regular expressions (revised API)
 .SH "PCRE2 REGULAR EXPRESSION DETAILS"
@@ -755,7 +755,7 @@ sequences that match characters with specific properties are available. In
 8-bit non-UTF-8 mode, these sequences are of course limited to testing
 characters whose code points are less than 256, but they do work in this mode.
 In 32-bit non-UTF mode, code points greater than 0x10ffff (the Unicode limit)
-may be encountered. These are all treated as being in the Common script and
+may be encountered. These are all treated as being in the Unknown script and
 with an unassigned type. The extra escape sequences are:
 .sp
   \ep{\fIxx\fP}   a character with the \fIxx\fP property
@@ -781,8 +781,10 @@ example:
   \ep{Greek}
   \eP{Han}
 .sp
-Those that are not part of an identified script are lumped together as
-"Common". The current list of scripts is:
+Unassigned characters (and in non-UTF 32-bit mode, characters with code points
+greater than 0x10FFFF) are assigned the "Unknown" script. Others that are not
+part of an identified script are lumped together as "Common". The current list
+of scripts is:
 .P
 Adlam,
 Ahom,
@@ -928,6 +930,7 @@ Tibetan,
 Tifinagh,
 Tirhuta,
 Ugaritic,
+Unknown,
 Vai,
 Warang_Citi,
 Yi,
@@ -2603,6 +2606,73 @@ is another pattern that matches "foo" preceded by three digits and any three
 characters that are not "999".
 .
 .
+.SH "SCRIPT RUNS"
+.rs
+.sp
+In concept, a script run is a sequence of characters that are all from the same
+Unicode script such as Latin or Greek. However, because some scripts are
+commonly used together, and because some diacritical and other marks are used
+with multiple scripts, it is not that simple. There is a full description of
+the rules that PCRE2 uses in the section entitled
+.\" HTML 
+.\" 
+"Script Runs"
+.\"
+in the
+.\" HREF
+\fBpcre2unicode\fP
+.\"
+documentation.
+.P
+If part of a pattern is enclosed between (*script_run: or (*sr: and a closing
+parenthesis, it fails if the sequence of characters that it matches are not a
+script run. After a failure, normal backtracking occurs. Script runs can be
+used to detect spoofing attacks using characters that look the same, but are
+from different scripts. The string "paypal.com" is an infamous example, where
+the letters could be a mixture of Latin and Cyrillic. This pattern ensures that
+the matched characters in a sequence of non-spaces that follow white space are
+a script run:
+.sp
+  \es+(*sr:\eS+)
+.sp
+To be sure that they are all from the Latin script (for example), a lookahead
+can be used:
+.sp
+  \es+(?=\ep{Latin})(*sr:\eS+)
+.sp
+This works as long as the first character is expected to be a character in that 
+script, and not (for example) punctuation, which is allowed with any script. If
+this is not the case, a more creative lookahead is needed. For example, if 
+digits, underscore, and dots are permitted at the start:
+.sp
+  \es+(?=[0-9_.]*\ep{Latin})(*sr:\eS+)
+.sp
+.P
+In many cases, backtracking into a script run pattern fragment is not
+desirable. The script run can employ an atomic group to prevent this. Because
+this is a common requirement, a shorthand notation is provided by
+(*atomic_script_run: or (*asr:
+.sp
+  (*asr:...) is the same as (*sr:(?>...))
+.sp
+Note that the atomic group is inside the script run. Putting it outside would
+not prevent backtracking into the script run pattern.
+.P
+Support for script runs is not available if PCRE2 is compiled without Unicode
+support. A compile-time error is given if any of the above constructs is
+encountered. Script runs are not supported by the alternate matching function,
+\fBpcre2_dfa_match()\fP because they use the same mechanism as capturing
+parentheses.
+.P
+\fBWarning:\fP The (*ACCEPT) control verb
+.\" HTML 
+.\" 
+(see below)
+.\"
+should not be used within a script run subpattern, because it causes an
+immediate exit from the subpattern, bypassing the script run checking.
+.
+.
 .\" HTML 
 .SH "CONDITIONAL SUBPATTERNS"
 .rs
@@ -3267,6 +3337,7 @@ Experiments with Perl suggest that it too has similar optimizations, and like
 PCRE2, turning them off can change the result of a match.
 .
 .
+.\" HTML 
 .SS "Verbs that act immediately"
 .rs
 .sp
@@ -3287,6 +3358,10 @@ example:
 .sp
 This matches "AB", "AAD", or "ACD"; when it matches "AB", "B" is captured by
 the outer parentheses.
+.P
+\fBWarning:\fP (*ACCEPT) should not be used within a script run subpattern,
+because it causes an immediate exit from the subpattern, bypassing the script
+run checking.
 .sp
   (*FAIL) or (*FAIL:NAME)
 .sp
@@ -3692,6 +3767,6 @@ Cambridge, England.
 .rs
 .sp
 .nf
-Last updated: 24 September 2018
+Last updated: 12 October 2018
 Copyright (c) 1997-2018 University of Cambridge.
 .fi
diff --git a/doc/pcre2syntax.3 b/doc/pcre2syntax.3
index 2daf9a9..07b7d80 100644
--- a/doc/pcre2syntax.3
+++ b/doc/pcre2syntax.3
@@ -1,4 +1,4 @@
-.TH PCRE2SYNTAX 3 "24 September 2018" "PCRE2 10.33"
+.TH PCRE2SYNTAX 3 "10 October 2018" "PCRE2 10.33"
 .SH NAME
 PCRE2 - Perl-compatible regular expressions (revised API)
 .SH "PCRE2 REGULAR EXPRESSION SYNTAX SUMMARY"
@@ -511,6 +511,16 @@ setting with a similar syntax.
 Each top-level branch of a lookbehind must be of a fixed length.
 .
 .
+.SH "SCRIPT RUNS"
+.rs
+.sp
+  (*script_run:...)           ) script run, can be backtracked into
+  (*sr:...)                   )
+.sp
+  (*atomic_script_run:...)    ) atomic script run
+  (*asr:...)                  )
+.
+.
 .SH "BACKREFERENCES"
 .rs
 .sp
@@ -633,6 +643,6 @@ Cambridge, England.
 .rs
 .sp
 .nf
-Last updated: 24 September 2018
+Last updated: 10 October 2018
 Copyright (c) 1997-2018 University of Cambridge.
 .fi
diff --git a/doc/pcre2unicode.3 b/doc/pcre2unicode.3
index 877d887..f1f5810 100644
--- a/doc/pcre2unicode.3
+++ b/doc/pcre2unicode.3
@@ -1,4 +1,4 @@
-.TH PCRE2UNICODE 3 "02 September 2018" "PCRE2 10.32"
+.TH PCRE2UNICODE 3 "12 October 2018" "PCRE2 10.33"
 .SH NAME
 PCRE - Perl-compatible regular expressions (revised API)
 .SH "UNICODE AND UTF SUPPORT"
@@ -118,6 +118,108 @@ few Unicode characters such as Greek sigma have more than two code points that
 are case-equivalent, and these are treated as such.
 .
 .
+.\" HTML 
+.SH "SCRIPT RUNS"
+.rs
+.sp
+The pattern constructs (*script_run:...) and (*atomic_script_run:...), with
+synonyms (*sr:...) and (*asr:...), verify that the string matched within the
+parentheses is a script run. In concept, a script run is a sequence of
+characters that are all from the same Unicode script. However, because some
+scripts are commonly used together, and because some diacritical and other
+marks are used with multiple scripts, it is not that simple.
+.P
+Every Unicode character has a Script property, mostly with a value 
+corresponding to the name of a script, such as Latin, Greek, or Cyrillic. There
+are also three special values:
+.P
+"Unknown" is used for code points that have not been assigned, and also for the
+surrogate code points. In the PCRE2 32-bit library, characters whose code
+points are greater than the Unicode maximum (U+10FFFF), which are accessible 
+only in non-UTF mode, are assigned the Unknown script.
+.P
+"Common" is used for characters that are used with many scripts. These include
+punctuation, emoji, mathematical, musical, and currency symbols, and the ASCII
+digits 0 to 9.
+.P
+"Inherited" is used for characters such as diacritical marks that modify a
+previous character. These are considered to take on the script of the character
+that they modify.
+.P
+Some Inherited characters are used with many scripts, but many of them are only 
+normally used with a small number of scripts. For example, U+102E0 (Coptic 
+Epact thousands mark) is used only with Arabic and Coptic. In order to make it 
+possible to check this, a Unicode property called Script Extension exists. Its 
+value is a list of scripts that apply to the character. For the majority of 
+characters, the list contains just one script, the same one as the Script
+property. However, for characters such as U+102E0 more than one Script is
+listed. There are also some Common characters that have a single, non-Common
+script in their Script Extension list.
+.P
+The next section describes the basic rules for deciding whether a given string 
+of characters is a script run. Note, however, that there are some special cases 
+involving the Chinese Han script, and an additional constraint for decimal 
+digits. These are covered in subsequent sections.
+.
+.
+.SS "Basic script run rules"
+.rs
+.sp
+A string that is less than two characters long is a script run. This is the
+only case in which an Unknown character can be part of a script run. Longer
+strings are checked using only the Script Extensions property, not the basic
+Script property.
+.P
+If a character's Script Extension property is the single value "Inherited", it
+is always accepted as part of a script run. This is also true for the property
+"Common", subject to the checking of decimal digits described below. All the
+remaining characters in a script run must have at least one script in common in
+their Script Extension lists. In set-theoretic terminology, the intersection of
+all the sets of scripts must not be empty.
+.P
+A simple example is an Internet name such as "google.com". The letters are all
+in the Latin script, and the dot is Common, so this string is a script run.
+However, the Cyrillic letter "o" looks exactly the same as the Latin "o"; a 
+string that looks the same, but with Cyrillic "o"s is not a script run.
+.P
+More interesting examples involve characters with more than one script in their 
+Script Extension. Consider the following characters:
+.sp
+  U+060C  Arabic comma
+  U+06D4  Arabic full stop
+.sp
+The first has the Script Extension list Arabic, Hanifi Rohingya, Syriac, and 
+Thaana; the second has just Arabic and Hanifi Rohingya. Both of them could
+appear in script runs of either Arabic or Hanifi Rohingya. The first could also
+appear in Syriac or Thaana script runs, but the second could not.
+.
+.
+.SS "The Chinese Han script"
+.rs
+.sp  
+The Chinese Han script is commonly used in conjunction with other scripts for 
+writing certain languages. Japanese uses the Hiragana and Katakana scripts 
+together with Han; Korean uses Hangul and Han; Taiwanese Mandarin uses Bopomofo
+and Han. These three combinations are treated as special cases when checking
+script runs and are, in effect, "virtual scripts". Thus, a script run may
+contain a mixture of Hiragana, Katakana, and Han, or a mixture of Hangul and
+Han, or a mixture of Bopomofo and Han, but not, for example, a mixture of
+Hangul and Bopomofo and Han. PCRE2 (like Perl) follows Unicode's Technical
+Standard 39 ("Unicode Security Mechanisms", http://unicode.org/reports/tr39/)
+in allowing such mixtures.
+.
+.
+.SS "Decimal digits"
+.rs
+.sp
+Unicode contains many sets of 10 decimal digits in different scripts, and some
+scripts (including the Common script) contain more than one set. Some of these
+decimal digits them are visually indistinguishable from the common ASCII
+digits. In addition to the script checking described above, if a script run
+contains any decimal digits, they must all come from the same set of 10
+adjacent characters.
+.
+.
 .SH "VALIDITY OF UTF STRINGS"
 .rs
 .sp
@@ -285,6 +387,6 @@ Cambridge, England.
 .rs
 .sp
 .nf
-Last updated: 02 September 2018
+Last updated: 12 October 2018
 Copyright (c) 1997-2018 University of Cambridge.
 .fi
diff --git a/testdata/testinput4 b/testdata/testinput4
index 7f2894b..9ab4191 100644
--- a/testdata/testinput4
+++ b/testdata/testinput4
@@ -2410,6 +2410,7 @@
     \x{3031}\x{3041}\x{30a1}\x{2e80}   [Hira Kata] Hira Kata Han
     \x{060c}\x{06d4}\x{0600}\x{10d00}\x{0700}  [Arab Rohg Syrc Thaa] [Arab Rohg] Arab Rohg Syrc
     \x{060c}\x{06d4}\x{0700}\x{0600}\x{10d00}  [Arab Rohg Syrc Thaa] [Arab Rohg] Syrc Arab Rohg
+    \x{2e80}\x{3041}\x{3001}\x{3031}\x{2e80}   Han Hira [Bopo, Han, etc] [Hira Kata] Han
 
 /(?