# pcre2syntax

## NAME



           PCRE2 - Perl-compatible regular expressions (revised API)
    


## PCRE2 REGULAR EXPRESSION SYNTAX SUMMARY



    
           The full syntax and semantics of the regular expression patterns
           that are supported by PCRE2 are described in the **pcre2pattern**
           documentation. This document contains a quick-reference summary of
           the pattern syntax followed by the syntax of replacement strings
           in substitution function.  The full description of the latter is
           in the **pcre2api** documentation.
    


## QUOTING



    
             \x         where x is non-alphanumeric is a literal x
             \Q...\E    treat enclosed characters as literal
    
           Note that white space inside \Q...\E is always treated as literal,
           even if PCRE2_EXTENDED is set, causing most other white space to
           be ignored. Note also that PCRE2's handling of \Q...\E has some
           differences from Perl's. See the **pcre2pattern** documentation for
           details.
    


## BRACED ITEMS



    
           With one exception, wherever brace characters { and } are required
           to enclose data for constructions such as \g{2} or \k{name}, space
           and/or horizontal tab characters that follow { or precede } are
           allowed and are ignored. In the case of quantifiers, they may also
           appear before or after the comma. The exception is \u{...} which
           is not Perl-compatible and is recognized only when
           PCRE2_EXTRA_ALT_BSUX is set. This is an ECMAScript compatibility
           feature, and follows ECMAScript's behaviour.
    


## ESCAPED CHARACTERS



    
           This table applies to ASCII and Unicode environments. An
           unrecognized escape sequence causes an error.
    
             \a         alarm, that is, the BEL character (hex 07)
             \cx        "control-x", where x is a non-control ASCII character
             \e         escape (hex 1B)
             \f         form feed (hex 0C)
             \n         newline (hex 0A)
             \r         carriage return (hex 0D)
             \t         tab (hex 09)
             \0dd       character with octal code 0dd
             \ddd       character with octal code ddd, or backreference
             \o{ddd..}  character with octal code ddd..
             \N{U+hh..} character with Unicode code point hh.. (Unicode mode
           only)
             \xhh       character with hex code hh
             \x{hh..}   character with hex code hh..
    
           \N{U+hh..} is synonymous with \x{hh..} but is not supported in
           environments that use EBCDIC code (mainly IBM mainframes). Note
           that \N not followed by an opening curly bracket has a different
           meaning (see below).
    
           If PCRE2_ALT_BSUX or PCRE2_EXTRA_ALT_BSUX is set ("ALT_BSUX
           mode"), the following are also recognized:
    
             \U         the character "U"
             \uhhhh     character with hex code hhhh
             \u{hh..}   character with hex code hh.. but only for
           EXTRA_ALT_BSUX
    
           When \x is not followed by {, one or two hexadecimal digits are
           read, but in ALT_BSUX mode \x must be followed by two hexadecimal
           digits to be recognized as a hexadecimal escape; otherwise it
           matches a literal "x".  Likewise, if \u (in ALT_BSUX mode) is not
           followed by four hexadecimal digits or (in EXTRA_ALT_BSUX mode) a
           sequence of hex digits in curly brackets, it matches a literal
           "u".
    
           Note that \0dd is always an octal code. The treatment of backslash
           followed by a non-zero digit is complicated; for details see the
           section "Non-printing characters" in the **pcre2pattern**
           documentation, where details of escape processing in EBCDIC
           environments are also given.
    


## CHARACTER TYPES



    
             .          any character except newline;
                          in dotall mode, any character whatsoever
             \C         one code unit, even in UTF mode (best avoided)
             \d         a decimal digit
             \D         a character that is not a decimal digit
             \h         a horizontal white space character
             \H         a character that is not a horizontal white space
           character
             \N         a character that is not a newline
             \p{_xx_}     a character with the _xx_ property
             \P{_xx_}     a character without the _xx_ property
             \R         a newline sequence
             \s         a white space character
             \S         a character that is not a white space character
             \v         a vertical white space character
             \V         a character that is not a vertical white space
           character
             \w         a "word" character
             \W         a "non-word" character
             \X         a Unicode extended grapheme cluster
    
           \C is dangerous because it may leave the current matching point in
           the middle of a UTF-8 or UTF-16 character. The application can
           lock out the use of \C by setting the PCRE2_NEVER_BACKSLASH_C
           option. It is also possible to build PCRE2 with the use of \C
           permanently disabled.
    
           By default, \d, \s, and \w match only ASCII characters, even in
           UTF-8 mode or in the 16-bit and 32-bit libraries. However, if
           locale-specific matching is happening, \s and \w may also match
           characters with code points in the range 128-255. If the PCRE2_UCP
           option is set, the behaviour of these escape sequences is changed
           to use Unicode properties and they match many more characters, but
           there are some option settings that can restrict individual
           sequences to matching only ASCII characters.
    
           Property descriptions in \p and \P are matched caselessly;
           hyphens, underscores, and ASCII white space characters are
           ignored, in accordance with Unicode's "loose matching" rules. For
           example, \p{Bidi_Class=al} is the same as \p{ bidi class = AL }.
    


## GENERAL CATEGORY PROPERTIES FOR \p and \P



    
             C          Other
             Cc         Control
             Cf         Format
             Cn         Unassigned
             Co         Private use
             Cs         Surrogate
    
             L          Letter
             Lc         Cased letter, the union of Ll, Lu, and Lt
             L&         Synonym of Lc
             Ll         Lower case letter
             Lm         Modifier letter
             Lo         Other letter
             Lt         Title case letter
             Lu         Upper case letter
    
             M          Mark
             Mc         Spacing mark
             Me         Enclosing mark
             Mn         Non-spacing mark
    
             N          Number
             Nd         Decimal number
             Nl         Letter number
             No         Other number
    
             P          Punctuation
             Pc         Connector punctuation
             Pd         Dash punctuation
             Pe         Close punctuation
             Pf         Final punctuation
             Pi         Initial punctuation
             Po         Other punctuation
             Ps         Open punctuation
    
             S          Symbol
             Sc         Currency symbol
             Sk         Modifier symbol
             Sm         Mathematical symbol
             So         Other symbol
    
             Z          Separator
             Zl         Line separator
             Zp         Paragraph separator
             Zs         Space separator
    
           From release 10.45, when caseless matching is set, Ll, Lu, and Lt
           are all equivalent to Lc.
    


## PCRE2 SPECIAL CATEGORY PROPERTIES FOR \p and \P



    
             Xan        Alphanumeric: union of properties L and N
             Xps        POSIX space: property Z or tab, NL, VT, FF, CR
             Xsp        Perl space: property Z or tab, NL, VT, FF, CR
             Xuc        Universally-named character: one that can be
                          represented by a Universal Character Name
             Xwd        Perl word: property Xan or underscore
    
           Perl and POSIX space are now the same. Perl added VT to its space
           character set at release 5.18.
    


## BINARY PROPERTIES FOR \p AND \P



    
           Unicode defines a number of binary properties, that is, properties
           whose only values are true or false. You can obtain a list of
           those that are recognized by \p and \P, along with their
           abbreviations, by running this command:
    
             pcre2test -LP
    


## SCRIPT MATCHING WITH \p AND \P



    
           Many script names and their 4-letter abbreviations are recognized
           in \p{sc:...} or \p{scx:...} items, or on their own with \p (and
           also \P of course). You can obtain a list of these scripts by
           running this command:
    
             pcre2test -LS
    


## THE BIDI_CLASS PROPERTY FOR \p AND \P



    
             \p{Bidi_Class:<class>}   matches a character with the given
           class
             \p{BC:<class>}           matches a character with the given
           class
    
           The recognized classes are:
    
             AL          Arabic letter
             AN          Arabic number
             B           paragraph separator
             BN          boundary neutral
             CS          common separator
             EN          European number
             ES          European separator
             ET          European terminator
             FSI         first strong isolate
             L           left-to-right
             LRE         left-to-right embedding
             LRI         left-to-right isolate
             LRO         left-to-right override
             NSM         non-spacing mark
             ON          other neutral
             PDF         pop directional format
             PDI         pop directional isolate
             R           right-to-left
             RLE         right-to-left embedding
             RLI         right-to-left isolate
             RLO         right-to-left override
             S           segment separator
             WS          white space
    


## CHARACTER CLASSES



    
             [...]       positive character class
             [^...]      negative character class
             [x-y]       range (can be used for hex characters)
             [[:xxx:]]   positive POSIX named set
             [[:^xxx:]]  negative POSIX named set
    
             alnum       alphanumeric
             alpha       alphabetic
             ascii       0-127
             blank       space or tab
             cntrl       control character
             digit       decimal digit
             graph       printing, excluding space
             lower       lower case letter
             print       printing, including space
             punct       printing, excluding alphanumeric
             space       white space
             upper       upper case letter
             word        same as \w
             xdigit      hexadecimal digit
    
           In PCRE2, POSIX character set names recognize only ASCII
           characters by default, but some of them use Unicode properties if
           PCRE2_UCP is set. You can use \Q...\E inside a character class.
    
           When PCRE2_ALT_EXTENDED_CLASS is set, UTS#18 extended character
           classes may be used, allowing nested character classes, combined
           using set operators.
    
             [x&&[^y]]   UTS#18 extended character class
    
             x||y        set union (OR)
             x&&y        set intersection (AND)
             x--y        set difference (AND NOT)
             x~~y        set symmetric difference (XOR)
    


## PERL EXTENDED CHARACTER CLASSES



    
             (?[...])                Perl extended character class
             (?[\p{Thai} & \p{Nd}])  operators; white space ignored
             (?[(x - y) & z])        parentheses for grouping
    
             (?[ [^3] & \p{Nd} ])    [...] is a nested ordinary class
             (?[ [:alpha:] - [z] ])  POSIX set is allowed outside [...]
             (?[ \d - [3] ])         backslash-escaped set is allowed outside
           [...]
             (?[ !\n & [:ascii:] ])  backslash-escaped character is allowed
           outside [...]
                                 all other characters or ranges must be
           enclosed in [...]
    
             x|y, x+y                set union (OR)
             x&y                     set intersection (AND)
             x-y                     set difference (AND NOT)
             x^y                     set symmetric difference (XOR)
             !x                      set complement (NOT)
    
           Inside a Perl extended character class, [...] switches mode to be
           interpreted as an ordinary character class. Outside of a nested
           [...], the only items permitted are backslash-escapes, POSIX sets,
           operators, and parentheses. Inside a nested ordinary class, ^ has
           its usual meaning (inverts the class when used as the first
           character); outside of a nested class, ^ is the XOR operator.
    


## QUANTIFIERS



    
             ?           0 or 1, greedy
             ?+          0 or 1, possessive
             ??          0 or 1, lazy
             *           0 or more, greedy
             *+          0 or more, possessive
             *?          0 or more, lazy
             +           1 or more, greedy
             ++          1 or more, possessive
             +?          1 or more, lazy
             {n}         exactly n
             {n,m}       at least n, no more than m, greedy
             {n,m}+      at least n, no more than m, possessive
             {n,m}?      at least n, no more than m, lazy
             {n,}        n or more, greedy
             {n,}+       n or more, possessive
             {n,}?       n or more, lazy
             {,m}        zero up to m, greedy
             {,m}+       zero up to m, possessive
             {,m}?       zero up to m, lazy
    


## ANCHORS AND SIMPLE ASSERTIONS



    
             \b          word boundary
             \B          not a word boundary
             ^           start of subject
                           also after an internal newline in multiline mode
                           (after any newline if PCRE2_ALT_CIRCUMFLEX is set)
             \A          start of subject
             $           end of subject
                           also before newline at end of subject
                           also before internal newline in multiline mode
             \Z          end of subject
                           also before newline at end of subject
             \z          end of subject
             \G          first matching position in subject
    


## REPORTED MATCH POINT SETTING



    
             \K          set reported start of match
    
           From release 10.38 \K is not permitted by default in lookaround
           assertions, for compatibility with Perl. However, if the
           PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK option is set, the previous
           behaviour is re-enabled. When this option is set, \K is honoured
           in positive assertions, but ignored in negative ones.
    


## ALTERNATION



    
             expr|expr|expr...
    


## CAPTURING



    
             (...)           capture group
             (?<name>...)    named capture group (Perl)
             (?'name'...)    named capture group (Perl)
             (?P<name>...)   named capture group (Python)
             (?:...)         non-capture group
             (?|...)         non-capture group; reset group numbers for
                              capture groups in each alternative
    
           In non-UTF modes, names may contain underscores and ASCII letters
           and digits; in UTF modes, any Unicode letters and Unicode decimal
           digits are permitted. In both cases, a name must not start with a
           digit.
    


## ATOMIC GROUPS



    
             (?>...)         atomic non-capture group
             (*atomic:...)   atomic non-capture group
    


## COMMENT



    
             (?#....)        comment (not nestable)
    


## OPTION SETTING



           Changes of these options within a group are automatically
           cancelled at the end of the group.
    
             (?a)            all ASCII options
             (?aD)           restrict \d to ASCII in UCP mode
             (?aS)           restrict \s to ASCII in UCP mode
             (?aW)           restrict \w to ASCII in UCP mode
             (?aP)           restrict all POSIX classes to ASCII in UCP mode
             (?aT)           restrict POSIX digit classes to ASCII in UCP
           mode
             (?i)            caseless
             (?J)            allow duplicate named groups
             (?m)            multiline
             (?n)            no auto capture
             (?r)            restrict caseless to either ASCII or non-ASCII
             (?s)            single line (dotall)
             (?U)            default ungreedy (lazy)
             (?x)            ignore white space except in classes or \Q...\E
             (?xx)           as (?x) but also ignore space and tab in classes
             (?-...)         unset the given option(s)
             (?^)            unset imnrsx options
    
           (?aP) implies (?aT) as well, though this has no additional effect.
           However, it means that (?-aP) also implies (?-aT) and disables all
           ASCII restrictions for POSIX classes.
    
           Unsetting x or xx unsets both. Several options may be set at once,
           and a mixture of setting and unsetting such as (?i-x) is allowed,
           but there may be only one hyphen. Setting (but no unsetting) is
           allowed after (?^ for example (?^in). An option setting may appear
           at the start of a non-capture group, for example (?i:...).
    
           The following are recognized only at the very start of a pattern
           or after one of the newline or \R sequences or options with
           similar syntax. More than one of them may appear. For the first
           three, d is a decimal number.
    
             (*LIMIT_DEPTH=d)     set the backtracking limit to d
             (*LIMIT_HEAP=d)      set the heap size limit to d * 1024 bytes
             (*LIMIT_MATCH=d)     set the match limit to d
             (*CASELESS_RESTRICT) set PCRE2_EXTRA_CASELESS_RESTRICT when
           matching
             (*NOTEMPTY)          set PCRE2_NOTEMPTY when matching
             (*NOTEMPTY_ATSTART)  set PCRE2_NOTEMPTY_ATSTART when matching
             (*NO_AUTO_POSSESS)   no auto-possessification
           (PCRE2_NO_AUTO_POSSESS)
             (*NO_DOTSTAR_ANCHOR) no .* anchoring (PCRE2_NO_DOTSTAR_ANCHOR)
             (*NO_JIT)            disable JIT optimization
             (*NO_START_OPT)      no start-match optimization
           (PCRE2_NO_START_OPTIMIZE)
             (*TURKISH_CASING)    set PCRE2_EXTRA_TURKISH_CASING when
           matching
             (*UTF)               set appropriate UTF mode for the library in
           use
             (*UCP)               set PCRE2_UCP (use Unicode properties for
           \d etc)
    
           Note that LIMIT_DEPTH, LIMIT_HEAP, and LIMIT_MATCH can only reduce
           the value of the limits set by the caller of **pcre2_match()** or
           **pcre2_dfa_match()** , not increase them. LIMIT_RECURSION is an
           obsolete synonym for LIMIT_DEPTH. The application can lock out the
           use of (*UTF) and (*UCP) by setting the PCRE2_NEVER_UTF or
           PCRE2_NEVER_UCP options, respectively, at compile time.
    


## NEWLINE CONVENTION



    
           These are recognized only at the very start of the pattern or
           after option settings with a similar syntax.
    
             (*CR)           carriage return only
             (*LF)           linefeed only
             (*CRLF)         carriage return followed by linefeed
             (*ANYCRLF)      all three of the above
             (*ANY)          any Unicode newline sequence
             (*NUL)          the NUL character (binary zero)
    


## WHAT \R MATCHES



    
           These are recognized only at the very start of the pattern or
           after option setting with a similar syntax.
    
             (*BSR_ANYCRLF)  CR, LF, or CRLF
             (*BSR_UNICODE)  any Unicode newline sequence
    


## LOOKAHEAD AND LOOKBEHIND ASSERTIONS



    
             (?=...)                     )
             (*pla:...)                  ) positive lookahead
             (*positive_lookahead:...)   )
    
             (?!...)                     )
             (*nla:...)                  ) negative lookahead
             (*negative_lookahead:...)   )
    
             (?<=...)                    )
             (*plb:...)                  ) positive lookbehind
             (*positive_lookbehind:...)  )
    
             (?<!...)                    )
             (*nlb:...)                  ) negative lookbehind
             (*negative_lookbehind:...)  )
    
           Each top-level branch of a lookbehind must have a limit for the
           number of characters it matches. If any branch can match a
           variable number of characters, the maximum for each branch is
           limited to a value set by the caller of **pcre2_compile()** or
           defaulted. The default is set when PCRE2 is built (ultimate
           default 255). If every branch matches a fixed number of
           characters, the limit for each branch is 65535 characters.
    


## NON-ATOMIC LOOKAROUND ASSERTIONS



    
           These assertions are specific to PCRE2 and are not Perl-
           compatible.
    
             (?*...)                                )
             (*napla:...)                           ) synonyms
             (*non_atomic_positive_lookahead:...)   )
    
             (?<*...)                               )
             (*naplb:...)                           ) synonyms
             (*non_atomic_positive_lookbehind:...)  )
    


## SUBSTRING SCAN ASSERTION



           This feature is not Perl-compatible.
    
             (*scan_substring:(grouplist)...)  scan captured substring
             (*scs:(grouplist)...)             scan captured substring
    
           The comma-separated list "grouplist" may identify groups in any of
           the following ways:
    
             n       absolute reference
             +n      relative reference
             -n      relative reference
             <name>  name
             'name'  name
    


## 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)
             \gn             reference by number
             \g{n}           reference by number
             \g+n            relative reference by number (PCRE2 extension)
             \g-n            relative reference by number
             \g{+n}          relative reference by number (PCRE2 extension)
             \g{-n}          relative reference by number
             \k<name>        reference by name (Perl)
             \k'name'        reference by name (Perl)
             \g{name}        reference by name (Perl)
             \k{name}        reference by name (.NET)
             (?P=name)       reference by name (Python)
    


## SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)



    
             (?R)            recurse whole pattern
             (?n)            call subroutine by absolute number
             (?+n)           call subroutine by relative number
             (?-n)           call subroutine by relative number
             (?&name)        call subroutine by name (Perl)
             (?P>name)       call subroutine by name (Python)
             \g<name>        call subroutine by name (Oniguruma)
             \g'name'        call subroutine by name (Oniguruma)
             \g<n>           call subroutine by absolute number (Oniguruma)
             \g'n'           call subroutine by absolute number (Oniguruma)
             \g<+n>          call subroutine by relative number (PCRE2
           extension)
             \g'+n'          call subroutine by relative number (PCRE2
           extension)
             \g<-n>          call subroutine by relative number (PCRE2
           extension)
             \g'-n'          call subroutine by relative number (PCRE2
           extension)
    
           The variants using parentheses (?...) may also specify a list of
           capture groups to return, which shall be retained in the calling
           subexpression if set during the recursion (this feature is not
           supported by Perl).
    
             (?R(grouplist))       recurse whole pattern, returning capture
           groups
                                     (PCRE2 extension)
             (?n(grouplist))       )
             (?+n(grouplist))      ) call subroutine, returning capture
           groups
             (?-n(grouplist))      )   (PCRE2 extension)
             (?&name(grouplist))   )
             (?P>name(grouplist))  )
    
           The comma-separated list "grouplist" uses the same syntax as
           (*scan_substring:(grouplist)...), and may identify groups in any
           of the following ways:
    
             n       absolute reference
             +n      relative reference
             -n      relative reference
             <name>  name
             'name'  name
    


## CONDITIONAL PATTERNS



    
             (?(condition)yes-pattern)
             (?(condition)yes-pattern|no-pattern)
    
             (?(n)               absolute reference condition
             (?(+n)              relative reference condition (PCRE2
           extension)
             (?(-n)              relative reference condition (PCRE2
           extension)
             (?(<name>)          named reference condition (Perl)
             (?('name')          named reference condition (Perl)
             (?(name)            named reference condition (PCRE2,
           deprecated)
             (?(R)               overall recursion condition
             (?(Rn)              specific numbered group recursion condition
             (?(R&name)          specific named group recursion condition
             (?(DEFINE)          define groups for reference
             (?(VERSION[>]=n.m)  test PCRE2 version
             (?(assert)          assertion condition
    
           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



    
           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 if :NAME is present. The others just
           set a name for passing back to the caller, but this is not a name
           that (*SKIP) can see. The following act immediately they are
           reached:
    
             (*ACCEPT)       force successful match
             (*FAIL)         force backtrack; synonym (*F)
             (*MARK:NAME)    set name to be passed back; synonym (*:NAME)
    
           The following act only when a subsequent match failure causes a
           backtrack to reach them. They all force a match failure, but they
           differ in what happens afterwards. Those that advance the start-
           of-match point do so only if the pattern is not anchored.
    
             (*COMMIT)       overall failure, no advance of starting point
             (*PRUNE)        advance to next starting character
             (*SKIP)         advance to current matching position
             (*SKIP:NAME)    advance to position corresponding to an earlier
                             (*MARK:NAME); if not found, the (*SKIP) is
           ignored
             (*THEN)         local failure, backtrack to next alternation
    
           The effect of one of these verbs in a group called as a subroutine
           is confined to the subroutine call.
    


## CALLOUTS



    
             (?C)            callout (assumed number 0)
             (?Cn)           callout with numerical data n
             (?C"text")      callout with string data
    
           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.
    


## REPLACEMENT STRINGS



    
           If the PCRE2_SUBSTITUTE_LITERAL option is set, a replacement
           string for **pcre2_substitute()** is not interpreted. Otherwise, by
           default, the only special character is the dollar character in one
           of the following forms:
    
             $$                  insert a dollar character
             $n or ${n}          insert the contents of group _n_
             $<name>             insert the contents of named group
             $0 or $&            insert the entire matched substring
             $`                  insert the substring that precedes the match
             $'                  insert the substring that follows the match
             $_                  insert the entire input string
             $*MARK or ${*MARK}  insert a control verb name
    
           For ${n}, n can be a name or a number. If
           PCRE2_SUBSTITUTE_EXTENDED is set, there is additional
           interpretation:
    
           1. Backslash is an escape character, and the forms described in
           "ESCAPED CHARACTERS" above are recognized. Also:
    
             \Q...\E   can be used to suppress interpretation
             \l        force the next character to lower case
             \u        force the next character to upper case
             \L        force subsequent characters to lower case
             \U        force subsequent characters to upper case
             \u\L      force next character to upper case, then all lower
             \l\U      force next character to lower case, then all upper
             \E        end \L or \U case forcing
             \b        backspace character (note: as in character class in
           pattern)
             \v        vertical tab character (note: not the same as in a
           pattern)
    
           2. The Python form \g<n>, where the angle brackets are part of the
           syntax and _n_ is either a group name or a number, is recognized as
           an alternative way of inserting the contents of a group, for
           example \g<3>.
    
           3. Capture substitution supports the following additional forms:
    
             ${n:-string}             default for unset group
             ${n:+string1:string2}    values for set/unset group
    
           The substitution strings themselves are expanded. Backslash can be
           used to escape colons and closing curly brackets.
    


## REVISION



    
           Last updated: 27 November 2024
           Copyright (c) 1997-2024 University of Cambridge.
    


* * *