diff --git a/HACKING b/HACKING
index cad11b3..67841c7 100644
--- a/HACKING
+++ b/HACKING
@@ -8,8 +8,8 @@ library is referred to as PCRE1 below. For information about testing PCRE2, see
 the pcre2test documentation and the comment at the head of the RunTest file.
 
 PCRE1 releases were up to 8.3x when PCRE2 was developed, and later bug fix
-releases remain in the 8.xx series. PCRE2 releases started at 10.00 to avoid
-confusion with PCRE1.
+releases carried on the 8.xx series, up to the final 8.45 release. PCRE2
+releases started at 10.00 to avoid confusion with PCRE1.
 
 
 Historical note 1
@@ -38,8 +38,8 @@ Historical note 2
 By contrast, the code originally written by Henry Spencer (which was
 subsequently heavily modified for Perl) compiles the expression twice: once in
 a dummy mode in order to find out how much store will be needed, and then for
-real. (The Perl version probably doesn't do this any more; I'm talking about
-the original library.) The execution function operates by backtracking and
+real. (The Perl version may or may not still do this; I'm talking about the
+original library.) The execution function operates by backtracking and
 maximizing (or, optionally, minimizing, in Perl) the amount of the subject that
 matches individual wild portions of the pattern. This is an "NFA algorithm" in
 Friedl's terminology.
@@ -151,8 +151,8 @@ of code units in the item itself. The exception is the aforementioned large
 advance to check for such values. When auto-callouts are enabled, the generous
 assumption is made that there will be a callout for each pattern code unit
 (which of course is only actually true if all code units are literals) plus one
-at the end. There is a default parsed pattern vector on the system stack, but
-if this is not big enough, heap memory is used.
+at the end. A default parsed pattern vector is defined on the system stack, to
+minimize memory handling, but if this is not big enough, heap memory is used.
 
 As before, the actual compiling function is run twice, the first time to
 determine the amount of memory needed for the final compiled pattern. It
@@ -187,7 +187,7 @@ META_CLASS_EMPTY      [] empty class - only with PCRE2_ALLOW_EMPTY_CLASS
 META_CLASS_EMPTY_NOT  [^] negative empty class - ditto
 META_CLASS_END        ] end of non-empty class
 META_CLASS_NOT        [^ start non-empty negative class
-META_COMMIT           (*COMMIT)
+META_COMMIT           (*COMMIT) - no argument (see below for with argument)
 META_COND_ASSERT      (?(?assertion)
 META_DOLLAR           $ metacharacter
 META_DOT              . metacharacter
@@ -201,14 +201,14 @@ META_NOCAPTURE        (?: no capture parens
 META_PLUS             +
 META_PLUS_PLUS        ++
 META_PLUS_QUERY       +?
-META_PRUNE            (*PRUNE) - no argument
+META_PRUNE            (*PRUNE) - no argument (see below for with argument)
 META_QUERY            ?
 META_QUERY_PLUS       ?+
 META_QUERY_QUERY      ??
 META_RANGE_ESCAPED    hyphen in class range with at least one escape
 META_RANGE_LITERAL    hyphen in class range defined literally
-META_SKIP             (*SKIP) - no argument
-META_THEN             (*THEN) - no argument
+META_SKIP             (*SKIP) - no argument (see below for with argument)
+META_THEN             (*THEN) - no argument (see below for with argument)
 
 The two RANGE values occur only in character classes. They are positioned
 between two literals that define the start and end of the range. In an EBCDIC
@@ -229,7 +229,8 @@ If the data for META_ALT is non-zero, it is inside a lookbehind, and the data
 is the length of its branch, for which OP_REVERSE must be generated.
 
 META_BACKREF, META_CAPTURE, and META_RECURSE have the capture group number as
-their data in the lower 16 bits of the element.
+their data in the lower 16 bits of the element. META_RECURSE is followed by an
+offset, for use in error messages.
 
 META_BACKREF is followed by an offset if the back reference group number is 10
 or more. The offsets of the first ocurrences of references to groups whose
@@ -238,8 +239,6 @@ occurrence is useful). On 64-bit systems this avoids using more than two parsed
 pattern elements for items such as \3. The offset is used when an error occurs
 because the reference is to a non-existent group.
 
-META_RECURSE is always followed by an offset, for use in error messages.
-
 META_ESCAPE has an ESC_xxx value as its data. For ESC_P and ESC_p, the next
 element contains the 16-bit type and data property values, packed together.
 ESC_g and ESC_k are used only for named references - numerical ones are turned
@@ -291,9 +290,9 @@ META_LOOKBEHIND       (?<=      start of lookbehind
 META_LOOKBEHIND_NA    (*naplb:  start of non-atomic lookbehind
 META_LOOKBEHINDNOT    (?<!      start of negative lookbehind
 
-The following are followed by two elements, the minimum and maximum. Repeat
-values are limited to 65535 (MAX_REPEAT). A maximum value of "unlimited" is
-represented by UNLIMITED_REPEAT, which is bigger than MAX_REPEAT:
+The following are followed by two elements, the minimum and maximum. The
+maximum value is limited to 65535 (MAX_REPEAT). A maximum value of "unlimited"
+is represented by UNLIMITED_REPEAT, which is bigger than MAX_REPEAT:
 
 META_MINMAX           {n,m}  repeat
 META_MINMAX_PLUS      {n,m}+ repeat
@@ -347,11 +346,11 @@ support is not available for this kind of matching.
 Changeable options
 ------------------
 
-The /i, /m, or /s options (PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL, and
-others) may be changed in the middle of patterns by items such as (?i). Their
-processing is handled entirely at compile time by generating different opcodes
-for the different settings. The runtime functions do not need to keep track of
-an option's state.
+The /i, /m, or /s options (PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL) and
+some others may be changed in the middle of patterns by items such as (?i).
+Their processing is handled entirely at compile time by generating different
+opcodes for the different settings. The runtime functions do not need to keep
+track of an option's state.
 
 PCRE2_DUPNAMES, PCRE2_EXTENDED, PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE
 are tracked and processed during the parsing pre-pass. The others are handled
@@ -437,7 +436,7 @@ Backtracking control verbs
 --------------------------
 
 Verbs with no arguments generate opcodes with no following data (as listed
-in the section above). 
+in the section above).
 
 (*MARK:NAME) generates OP_MARK followed by the mark name, preceded by a
 length in one code unit, and followed by a binary zero. The name length is
@@ -468,8 +467,8 @@ Caseless matching (positive or negative) of characters that have more than two
 case-equivalent code points (which is possible only in UTF mode) is handled by
 compiling a Unicode property item (see below), with the pseudo-property
 PT_CLIST. The value of this property is an offset in a vector called
-"ucd_caseless_sets" which identifies the start of a short list of equivalent
-characters, terminated by the value NOTACHAR (0xffffffff).
+"ucd_caseless_sets" which identifies the start of a short list of case
+equivalent characters, terminated by the value NOTACHAR (0xffffffff).
 
 
 Repeating single characters
@@ -546,9 +545,9 @@ Each is followed by two code units that encode the desired property as a type
 and a value. The types are a set of #defines of the form PT_xxx, and the values
 are enumerations of the form ucp_xx, defined in the pcre2_ucp.h source file.
 The value is relevant only for PT_GC (General Category), PT_PC (Particular
-Category), PT_SC (Script), PT_BIDICL (Bidi Class), and the pseudo-property
-PT_CLIST, which is used to identify a list of case-equivalent characters when
-there are three or more.
+Category), PT_SC (Script), PT_BIDICL (Bidi Class), PT_BOOL (Boolean property),
+and the pseudo-property PT_CLIST, which is used to identify a list of
+case-equivalent characters when there are three or more (see above).
 
 Repeats of these items use the OP_TYPESTAR etc. set of opcodes, followed by
 three code units: OP_PROP or OP_NOTPROP, and then the desired property type and
@@ -666,9 +665,9 @@ a count that immediately follows the offset.
 There are several opcodes that mark the end of a subpattern group. OP_KET is
 used for subpatterns that do not repeat indefinitely, OP_KETRMIN and
 OP_KETRMAX are used for indefinite repetitions, minimally or maximally
-respectively, and OP_KETRPOS for possessive repetitions (see below for more 
+respectively, and OP_KETRPOS for possessive repetitions (see below for more
 details). All four are followed by a LINK_SIZE value giving (as a positive
-number) the offset back to the matching bracket opcode.
+number) the offset back to the matching opening bracket opcode.
 
 If a subpattern is quantified such that it is permitted to match zero times, it
 is preceded by one of OP_BRAZERO, OP_BRAMINZERO, or OP_SKIPZERO. These are
@@ -719,7 +718,7 @@ Assertions
 
 Forward assertions are also just like other subpatterns, but starting with one
 of the opcodes OP_ASSERT, OP_ASSERT_NA (non-atomic assertion), or
-OP_ASSERT_NOT. Backward assertions use the opcodes OP_ASSERTBACK, 
+OP_ASSERT_NOT. Backward assertions use the opcodes OP_ASSERTBACK,
 OP_ASSERTBACK_NA, and OP_ASSERTBACK_NOT, and the first opcode inside the
 assertion is OP_REVERSE, followed by a count of the number of characters to
 move back the pointer in the subject string. In ASCII or UTF-32 mode, the count
@@ -828,4 +827,4 @@ not a real opcode, but is used to check at compile time that tables indexed by
 opcode are the correct length, in order to catch updating errors.
 
 Philip Hazel
-December 2021
+April 2022
diff --git a/maint/README b/maint/README
index f21ff87..3d341b8 100644
--- a/maint/README
+++ b/maint/README
@@ -78,9 +78,9 @@ utf8.c
   A short, freestanding C program for converting a Unicode code point into a
   sequence of bytes in the UTF-8 encoding, and vice versa. If its argument is a
   hex number such as 0x1234, it outputs a list of the equivalent UTF-8 bytes.
-  If its argument is a sequence of concatenated UTF-8 bytes (e.g. e188b4) it
-  treats them as a UTF-8 character and outputs the equivalent code point in
-  hex. See comments at its head for details.
+  If its argument is a sequence of concatenated UTF-8 bytes (e.g. 12e188b4) it
+  treats them as a UTF-8 string and outputs the equivalent code points in hex.
+  See comments at its head for details.
 
 
 Updating to a new Unicode release
@@ -94,8 +94,9 @@ directory.
 Note: Previously, it was necessary to update lists of scripts and their 
 abbreviations by hand before running the Python scripts. This is no longer
 necessary because the scripts have been upgraded to extract this information
-themselves. Also, there used to be explicit lists of script in two of the man
-pages. This is no longer the case.
+themselves. Also, there used to be explicit lists of scripts in two of the man
+pages. This is no longer the case; the pcre2test program can now output a list 
+of supported scripts.
 
 You can give an output file name as an argument to the following scripts, but
 by default:
@@ -129,8 +130,8 @@ files should eventually be installed in the main testdata directory.
 Preparing for a PCRE2 release
 =============================
 
-This section contains a checklist of things that I consult before building a
-distribution for a new release.
+This section contains a checklist of things that I do before building a new
+release.
 
 . Ensure that the version number and version date are correct in configure.ac.
 
@@ -139,17 +140,16 @@ distribution for a new release.
 
 . If new build options or new source files have been added, ensure that they
   are added to the CMake files as well as to the autoconf files. The relevant
-  files are CMakeLists.txt and config-cmake.h.in. After making a release
-  tarball, test it out with CMake if there have been changes here.
+  files are CMakeLists.txt and config-cmake.h.in. After making a release, test
+  it out with CMake if there have been changes here.
 
 . Run ./autogen.sh to ensure everything is up-to-date.
 
 . Compile and test with many different config options, and combinations of
   options. Also, test with valgrind by running "RunTest valgrind" and
-  "RunGrepTest valgrind" (which takes quite a long time). The script
-  maint/ManyConfigTests now encapsulates this testing. It runs tests with
-  different configurations, and it also runs some of them with valgrind, all of
-  which can take quite some time.
+  "RunGrepTest valgrind". The script maint/ManyConfigTests now encapsulates
+  this testing. It runs tests with different configurations, and it also runs
+  some of them with valgrind, all of which can take quite some time.
 
 . Run tests in both 32-bit and 64-bit environments if possible. I can no longer
   run 32-bit tests.
@@ -164,7 +164,8 @@ distribution for a new release.
   -fsanitize=signed-integer-overflow
 
 . Do a test build using CMake. Remove src/config.h first, lest it override the
-  version that CMake creates. Do NOT use parallel make.
+  version that CMake creates. Also do a CMake unity build to check that it 
+  still works: [c]cmake -DCMAKE_UNITY_BUILD=ON sets up a unity build.
 
 . Run perltest.sh on the test data for tests 1 and 4. The output should match
   the PCRE2 test output, apart from the version identification at the start of
@@ -183,11 +184,12 @@ distribution for a new release.
   systems. For example, on Solaris it is helpful to test using Sun's cc
   compiler as a change from gcc. Adding -xarch=v9 to the cc options does a
   64-bit test, but it also needs -S 64 for pcre2test to increase the stack size
-  for test 2. Since I retired I can no longer do much of this, but instead I
-  rely on putting out release candidates for testing by the community.
+  for test 2. Since I retired I can no longer do much of this. There are 
+  automated tests under Ubuntu, Alpine, and Windows that are now set up as 
+  GitHub actions. Check that they are running clean.
 
 . The buildbots at http://buildfarm.opencsw.org/ do some automated testing
-  of PCRE2 and should be checked before putting out a release.
+  of PCRE2 and should also be checked before putting out a release.
 
 
 Updating version info for libtool
@@ -243,10 +245,11 @@ it reports them and then aborts. Otherwise it removes trailing spaces from
 sources and refreshes the HTML documentation. Update the GitHub repository with
 "git push".
 
-Once PrepareRelease has run clean, run "make distcheck" to create the tarball
+Once PrepareRelease has run clean, run "make distcheck" to create the tarballs
 and the zipball. I then sign these files. Double-check with "git status" that
-the repository is fully up-to-date, then create a new tag on GitHub. Upload the
-tarball, zipball, and the signatures as "assets" of the GitHub release.
+the repository is fully up-to-date, then create a new tag and a release on
+GitHub. Upload the tarballs, zipball, and the signatures as "assets" of the
+GitHub release.
 
 When the new release is out, don't forget to tell webmaster@pcre.org and the
 mailing list.
@@ -365,8 +368,6 @@ years.
 
   See Unicode TR 29. The last two are very much aimed at natural language.
 
-. (?[...]) extended classes: big project.
-
 . Allow a callout to specify a number of characters to skip. This can be done
   compatibly via an extra callout field.
 
@@ -436,13 +437,8 @@ years.
   with lookarounds for \b and \B. Ideally the setting should last till the end
   of the group, which means remembering all previous settings; maybe a fixed
   amount of stack would do - how deep would anyone want to nest these things?
-  See GitHub issue #13 for a compendium of character class issues.
-
-. Recognize the short script names. They are already listed in maint/
-  Multistage2.py because they are needed for scanning the script extensions
-  file.
-
-. Use script extensions for \p?
+  See GitHub issue #13 for a compendium of character class issues, including
+  (?[...]) extended classes.
 
 . A user suggested something like --with-build-info to set a build information
   string that could be retrieved by pcre2_config(). However, there's no
@@ -461,4 +457,4 @@ years.
 Philip Hazel
 Email local part: Philip.Hazel
 Email domain: gmail.com
-Last updated: 10 January 2022
+Last updated: 25 April 2022