in Perl 5.10) is available in PCRE since version 7.3. They are (*FAIL), (*F), (*PRUNE), (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT). Perl's corresponding use of arguments with backtracking control verbs is not generally supported. Note however that since version 8.10, PCRE supports the following verbs with a specified argument: (*MARK:markName), (*SKIP:markName), (*PRUNE:markName), and (*THEN:markName). Since version 10.32 PCRE2 has supported (*ACCEPT:markName), (*FAIL:markName), and (*COMMIT:markName). PCRE and Perl are slightly different in their tolerance of erroneous constructs Perl allows quantifiers on the (?!...) construct, which is meaningless but harmless (albeit inefficient); PCRE produces an error in versions before 8.13. PCRE has a hard limit on recursion depth, Perl does not With default build options "bbbbXcXaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" =~ /.X(.+)+X/ will fail to match due to the limit, but Perl will match this correctly. Perl uses the heap for recursion and has no hard limit for recursion depth, whereas PCRE2 has a compile-time default limit that can be adjusted up or down by the calling application. Verification With the exception of the above points, PCRE is capable of passing the tests in the Perl "t/op/re_tests" file, one of the main syntax-level regression tests for Perl's regular expression engine. Notes and references Notes References See also Pcregrep Comparison of regular expression engines External links PCRE - Development mailing list: https://groups.google.com/g/pcre2-dev PCRE - Bug Tracker: https://github.com/PCRE2Project/pcre2/issues Pattern Matching Using Regular Expressions (2010-03-02), by Nick Maclaren, Philip Hazel: https://www-uxsup.csx.cam.ac.uk/courses/moved.REs/paper.pdf pcre 8.43 (2019-04) - Windows Cygwin x86-64: https://www-uxsup.csx.cam.ac.uk/pub/windows/cygwin/x86_64/release/pcre/ Pattern matching C (programming language) libraries Perl Regular expressions Software using the BSD license