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+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU General Public License is a free, copyleft license for
+software and other kinds of works.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+the GNU General Public License is intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  To protect your rights, we need to prevent others from denying you
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+you modify it: responsibilities to respect the freedom of others.
+
+  For example, if you distribute copies of such a program, whether
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+
+  Developers that use the GNU GPL protect your rights with two steps:
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+giving you legal permission to copy, distribute and/or modify it.
+
+  For the developers' and authors' protection, the GPL clearly explains
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+authors' sake, the GPL requires that modified versions be marked as
+changed, so that their problems will not be attributed erroneously to
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+
+  Some devices are designed to deny users access to install or run
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+pattern of such abuse occurs in the area of products for individuals to
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+  Finally, every program is threatened constantly by software patents.
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+  The precise terms and conditions for copying, distribution and
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+
+                       TERMS AND CONDITIONS
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+  "This License" refers to version 3 of the GNU General Public License.
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+  "Copyright" also means copyright-like laws that apply to other kinds of
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+similar laws prohibiting or restricting circumvention of such
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+circumvention of technological measures to the extent such circumvention
+is effected by exercising rights under this License with respect to
+the covered work, and you disclaim any intention to limit operation or
+modification of the work as a means of enforcing, against the work's
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+
+  You may convey verbatim copies of the Program's source code as you
+receive it, in any medium, provided that you conspicuously and
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+    "keep intact all notices".
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+    c) You must license the entire work, as a whole, under this
+    License to anyone who comes into possession of a copy.  This
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+    additional terms, to the whole of the work, and all its parts,
+    regardless of how they are packaged.  This License gives no
+    permission to license the work in any other way, but it does not
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+    d) If the work has interactive user interfaces, each must display
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+in an aggregate does not cause this License to apply to the other
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+  You may convey a covered work in object code form under the terms
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+  A "User Product" is either (1) a "consumer product", which means any
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+  If you convey an object code work under this section in, or with, or
+specifically for use in, a User Product, and the conveying occurs as
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+User Product is transferred to the recipient in perpetuity or for a
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+source code form), and must require no special password or key for
+unpacking, reading or copying.
+
+  7. Additional Terms.
+
+  "Additional permissions" are terms that supplement the terms of this
+License by making exceptions from one or more of its conditions.
+Additional permissions that are applicable to the entire Program shall
+be treated as though they were included in this License, to the extent
+that they are valid under applicable law.  If additional permissions
+apply only to part of the Program, that part may be used separately
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+this License without regard to the additional permissions.
+
+  When you convey a copy of a covered work, you may at your option
+remove any additional permissions from that copy, or from any part of
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+removal in certain cases when you modify the work.)  You may place
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+add to a covered work, you may (if authorized by the copyright holders of
+that material) supplement the terms of this License with terms:
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+  All other non-permissive additional terms are considered "further
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+received it, or any part of it, contains a notice stating that it is
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+a further restriction but permits relicensing or conveying under this
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+
+  You may not propagate or modify a covered work except as expressly
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+modify it is void, and will automatically terminate your rights under
+this License (including any patent licenses granted under the third
+paragraph of section 11).
+
+  However, if you cease all violation of this License, then your
+license from a particular copyright holder is reinstated (a)
+provisionally, unless and until the copyright holder explicitly and
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+holder fails to notify you of the violation by some reasonable means
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+  Termination of your rights under this section does not terminate the
+licenses of parties who have received copies or rights from you under
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+  9. Acceptance Not Required for Having Copies.
+
+  You are not required to accept this License in order to receive or
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+occurring solely as a consequence of using peer-to-peer transmission
+to receive a copy likewise does not require acceptance.  However,
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+covered work, you indicate your acceptance of this License to do so.
+
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+
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+any patent claim is infringed by making, using, selling, offering for
+sale, or importing the Program or any portion of it.
+
+  11. Patents.
+
+  A "contributor" is a copyright holder who authorizes use under this
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+
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+hereafter acquired, that would be infringed by some manner, permitted
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+  A patent license is "discriminatory" if it does not include within
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+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
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+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
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+
+  13. Use with the GNU Affero General Public License.
+
+  Notwithstanding any other provision of this License, you have
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+  14. Revised Versions of this License.
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+  The Free Software Foundation may publish revised and/or new versions of
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+  If the Program specifies that a proxy can decide which future
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+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
diff --git a/support/texlogsieve/README.md b/support/texlogsieve/README.md
new file mode 100644
index 0000000000..acc3204d90
--- /dev/null
+++ b/support/texlogsieve/README.md
@@ -0,0 +1,143 @@
+# texlogsieve - (yet another program to) filter and summarize LaTeX log files
+
+`texlogsieve` reads a LaTeX log file (or the standard input if no file is
+specified), filters out less relevant messages, and displays a summary
+report. It is a `texlua` script, similar in spirit to tools such as
+`texfot`, `texloganalyser`, `rubber-info`, `textlog_extract`,
+`texlogparser`, and others. Highlights:
+
+* Two reports: the most important messages from the log file followed by
+  a summary of repeated messages, undefined references etc.;
+
+* The program goes to great lengths to correctly handle TeX line wrapping
+  and does a much better job at that than existing tools;
+
+* Multiline messages are treated as a single entity;
+
+* Several options to control which messages should be filtered out;
+
+* No messages are accidentally removed;
+
+* The summary report is currently simple, but useful.
+
+`texlogsieve` **must** be run from the same directory as `[pdf|lua|xe]latex`,
+because it searches for the files used during compilation (packages loaded
+from the current directory, files included with `\input` etc.).
+
+The defaults are reasonable; hopefully, you can just do
+
+```
+[pdf|lua|xe]latex myfile.tex | texlogsieve
+```
+
+and be satisfied with the result.
+
+Since it needs to know what messages to expect, `texlogsieve` is
+currently geared towards LaTeX; I have no idea how it would work with
+ConTeXt or plain TeX. Still, adding support to them should not be
+too difficult.
+
+If you want to know more about the TeX log file and the workings of
+the program, check the initial comments in the code.
+
+## Short-term improvements
+
+ * Create tests
+
+     - Synthetic unit tests: these should systematically test the code and the
+       features it implements with small "fake" log files
+
+     - Real-world files (for example, the docs for some packages or some papers
+       from arXiv): these should help us detect important log messages and
+       changes in messages whenever new versions of LaTeX and its packages are
+       released
+
+ * Include the line number in the summary for messages that have it
+
+ * Consider messages that only differ by "on line XXX" to be repetitions
+
+ * Implement option `--collapse-lines` (show multiline messages as a single
+   line)
+
+ * Implement option `--no-redundant` (makes messages that are going to be
+   summarized, such as `undefined reference blah`, not appear in the filtered
+   report, only in the summary)
+
+## Other improvements
+
+ * Improve the final summary format - we should look at other tools for
+   inspiration
+
+ * Filter the summary report too; look at `texloganalyser` for inspiration
+
+ * Consider indicating filenames more prominently in the filtered report;
+   something like
+
+        Messages for file ./somefile.tex:
+        LaTeX Warning: File `blah.txt' already exists on the system.
+        Messages for file ./someotherfile.tex:
+        Warning: Missing character: There is no " (U+0022) in font...
+   but only when there is actually something to report for the given file
+
+ * Do something smart about LaTeX errors (maybe just detecting them and saying
+   "there was an error here" is enough) - maybe get some inspiration from
+   <https://github.com/overleaf/latex-log-parser> (the parser from overleaf).
+   This can get complicated if we account for the possibility that the user
+   interactively solved whatever was the problem, but do we really want to or
+   need to handle that?
+
+ * Add colors (see `texlog_extract`)
+
+ * Improve error handling if/where possible
+
+ * Better aggregation in the summary:
+
+     - `under/overfull boxes: p.5 (chap1.tex, L27); p.7 (chap2.tex, L37); p.19
+       (chap2.tex, L176)`
+
+     - `missing characters X, Y, Z in font blah`
+
+ * Try to figure out a way to automatically extract possible messages from
+   LaTeX packages
+
+ * Stuff like
+   `LaTeX Warning: Label(s) may have changed. Rerun to get cross-references right`
+   should trigger a specific "please rerun" message in the summary
+
+ * Maybe grep the .fls file first before trying to do `kpse.find_file()`; this
+   is probably more reliable and works even if the environment has changed,
+   but can we be sure it works correctly when reading the logfile from a pipe?
+
+## Refactorings to consider:
+
+ * Modify `heartbeat` to use `os.difftime()`
+
+ * Improve Lines:
+
+     - Eliminate `Lines.current` and instead always use `Lines.get(0)`,
+       `Lines.get(1)` etc. We might store stuff in indexes 1, 2, 3 etc. and
+       make something like `Lines:get(val) => return Lines[val +1]` (this is
+       better than actually using index 0 because the lua standard library
+       counts from one, so adhering to this convention makes using it easier)
+
+     - Reimplement the logic using <https://www.lua.org/pil/11.4.html> for a
+       small performance increase
+
+---
+
+Code etc: <https://gitlab.com/lago/texlogsieve>
+
+Copyright 2021 Nelson Lago <lago@ime.usp.br>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
diff --git a/support/texlogsieve/texlogsieve b/support/texlogsieve/texlogsieve
new file mode 100755
index 0000000000..699bfa972d
--- /dev/null
+++ b/support/texlogsieve/texlogsieve
@@ -0,0 +1,4022 @@
+#!/usr/bin/env texlua
+
+-- texlogsieve - filter and summarize LaTeX log files
+--
+-- Copyright (C) 2021 Nelson Lago <lago@ime.usp.br>
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation, either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with this program.  If not, see <https://www.gnu.org/licenses/>.
+--
+-- Code etc: https://gitlab.com/lago/texlogsieve
+
+--[[
+
+----------------
+THE TeX LOG FILE
+----------------
+
+TeX uses three low-level commands for logging:
+
+ 1. \message -> outputs to both the console and the log file (most
+    low-level TeX messages, such as open/close files, shipouts etc.
+    behave *more or less* as if they were generated by \message)
+
+ 2. \write with an unallocated stream identifier (typically, 0) ->
+    also outputs to both the console and the log file.
+
+ 2. \write with a negative stream identifier (typically, -1) -> outputs
+    to the log file only
+
+\write and \message behave differently:
+
+ * Normally, \write appends a line feed character (LF) to the text, so
+   a sequence of \write commands results in multiple lines.
+
+ * \message checks whether the last thing that was sent out was another
+   \message; if so, it adds a space character and outputs the text (both
+   the previous text and the new one are on the same line, separated by
+   a space), otherwise it just outputs the text (in this case, the new
+   text is at the beginning of a line). Note, however, that there are
+   some \message's that are not separated by spaces, such as "))".
+   Also, in most cases (I could not figure out when this fails, but it
+   happens often), if \message realizes the new text will not fit in
+   the current line (the line would exceed max_print_line characters),
+   instead of wrapping the line as usual, it may output a LF and start
+   the text on a new line.
+
+ * \write also checks if the last thing that was sent out was a message;
+   if so, it sends LF before the text, so that it starts at the
+   beginning of a line (it also sends LF after the text too, as always)
+
+Therefore, in the console, text output with \write always appears on a
+new line. A sequence of calls to \message also always starts on a new
+line, but the texts of all of them appear on the same line, separated
+by spaces.
+
+However, things get messy in the log file. Basically, \message and
+\write0 modify the same filedescriptor, while \write-1 modifies a
+different filedescriptor. This means \message and \write0 are unaware
+of \write-1 and vice-versa. As a result, the spaces and LFs that are
+added according to what is output to the console get mixed up with what
+is written only to the log file with \write-1. Therefore, there may be
+unexpected empty lines or lines that start with a space character in
+the log file.
+
+The LaTeX command \GenericInfo uses \write-1, while \GenericWarning
+uses \write0. TeX and LaTeX also define \wlog, which is an alias for
+\write-1; LaTeX defines \typeout, which is an alias for \write0. Some
+packages define their own aliases; for example, pgfcore.code.tex does
+\def\pgf@typeout{\immediate\write0}, graphics.sty does \let\Gin@log\wlog,
+etc. Package infwarerr provides a compatibility layer for the LaTeX
+standard logging commands, so that they can be used both in LaTeX and
+in plain TeX, as \@PackageInfo, \@ClassWarning etc.
+
+With that in mind, we will consider that there are five kinds of message
+in the LaTeX log file:
+
+ * Ordinary messages -> messages that start at the beginning of the line
+   and end at the end of the line (they are created with \write), such as
+
+       Document Class: book 2019/08/27 v1.4j Standard LaTeX document class
+
+       For additional information on amsmath, use the `?' option.
+
+       \openout4 = `somefile'.
+
+ * Short messages -> messages that may begin/end anywhere on a line,
+   because the line they are in may contain multiple messages of
+   this type (they are created with \message), such as
+
+       ASCII Hyphenation patterns for American English
+
+       ) (/usr/share/texlive/texmf-dist/tex/generic/iftex/iftex.sty
+       -> these mean 'close last file' and 'open file .../iftex.sty'
+
+       (/usr/share/texlive/texmf-dist/tex/latex/etoolbox/etoolbox.sty)
+       -> these mean 'open file .../etoolbox.sty' and 'close last file'
+          (which is etoolbox.sty, obviously)
+
+       ))
+       -> these mean 'close the last two files'
+
+       [1] [2] [3]
+       -> these mean 'shipout pages 1, 2, and 3'
+
+ * Multiline messages -> messages that start at the beginning of a line,
+   continue for a few lines and end at the end of a line (the programmer
+   explicitly used multiple \write commands, a single \write command
+   with embedded newline characters, or single/multiple \message
+   commands with leading/trailing newline characters), such as
+
+       Package biblatex Info: Automatic encoding selection.
+       (biblatex)             Assuming data encoding 'utf8'.
+
+       *************************************
+       * Using libertinus math *
+       *************************************
+
+       **********************
+       * No checksum found! *
+       **********************
+       (from ydoc-doc.sty)
+
+ * "Best-effort" multiline messages -> similar to the previous ones,
+   but created using multiple \message commands or a single one with
+   embedded newline characters but no leading and/or trailing newline
+   characters. They *usually* begin at the beginning of the line and
+   end at the end of the line because, as mentioned before, TeX usually
+   inserts a line break if the line would not fit otherwise. However,
+   that is not always true, especially if max_print_line is large.
+   Therefore, sometimes the message may begin in the middle of a line
+   and/or the various lines may be strung together or wrapped.
+   Examples:
+
+       *****************************************************************
+         GFS-Solomos style file by A. Tsolomitis
+       *****************************************************************
+       (from gfssolomos.sty)
+
+       =============== Entering putframe ====================
+       \pagegoal =635.97621pt, \pagetotal =368.07768pt.
+       (from exam.cls)
+
+ * Error messages TODO describe them here
+
+To complicate things, TeX by default wraps (breaks) any line longer
+than max_print_line characters (by default, 79). Since some messages
+may be output together on a single line, even short messages may be
+broken across lines. At the same time, there are quite a few ordinary
+lines that in practice happen to be max_print_line characters long,
+which makes detecting line wrapping a real challenge. Also, for no
+apparent reason, LuaTeX wraps some lines at max_print_line characters
+and others at max_print_line +1 characters. More: I have seen at least
+two cases in which TeX "forgot" to wrap a line, and sometimes there is
+a blank line between the wrapped line and its continuation line. And
+even more! LuaTeX does not break a line in the middle of a multibyte
+UTF-8 character. That is obviously a good idea, but it means some lines
+may be broken at lengths smaller than max_print_line. While this may
+seem rare, it can happen when parts of the document text are included
+in the log, as is the case with over/underfull box messages.
+
+So, if at all possible, it is a very good idea to set max_print_line
+to a really large value (such as 100,000), effectively disabling line
+wrapping. It was useful in the 1980s, but not anymore (your terminal
+or editor wraps automatically).
+
+
+----------------------
+HOW THIS PROGRAM WORKS
+----------------------
+
+To read this section, pretend for a moment that TeX does not wrap long
+lines.
+
+We have a set of handlers, i.e., objects that process specific kinds
+of message. Each handler checks if a given line matches some patterns
+to decide whether it is supposed to process it (return true) or not
+(return false).
+
+There is a loop that, at each iteration, reads a new line from the log
+file with moreData() and uses chooseHandler() to call each handler in
+turn until one of them processes that line. After the right handler
+does its thing, it sends the message to the output, erases this input
+line and returns true, which causes the loop to restart, skipping the
+remaining handlers.
+
+The loop may behave a little differently in two cases:
+
+ 1. If the handler processes just a part of the input line, which may
+    happen if the line contains multiple short messages, it removes
+    the processed data from the line and leaves the rest. At the next
+    iteration, no new data is read: the loop processes the remaining
+    material from the same line.
+
+ 2. If the handler processes the input and expects specific lines of
+    content to follow, it can preset itself as the next handler,
+    temporarily bypassing the choice step.
+
+When the line (or part of it) is not recognized by any handler, it is
+appended to unrecognizedBuffer. We may sometimes concatenate multiple
+text chunks together here because, during processing, we may break the
+line into chunks when in fact it comprises a single message. In any
+case, we know for sure that the message (or messages) currently in
+unrecognizedBuffer is complete when either (1) we identify the next
+short message in the line or (2) we proceed to the next input line.
+When either happens, we send the buffer to the output.
+
+We know most messages, but not all, start at the beginning of a line.
+Therefore, we keep two sets of handlers: beginningOfLineHandlers and
+anywhereHandlers. We use the boolean atBeginningOfLine to know when
+we may skip trying the beginningOfLineHandlers.
+
+We mentioned that the handler "sends the message to the output". The
+handler actually creates a Message object and calls the dispatch()
+function to send that object to a coroutine that handles output. The
+coroutine aggregates messages by page, generates summaries for some
+kinds of message (for example, it may list all undefined references
+together) and prints out the report in different formats.
+
+Sometimes we need to be able to check the content of the next line
+to decide what to do about the current line (for example, different
+messages may begin with a line like "**********"). So, we do not only
+read one line from the input at each iteration; instead, we have a
+buffer with the next few lines. When the current line has been
+completely processed, moreData() simply refills the buffer and calls
+Lines:gotoNextLine(), which makes the next line (line 1) become the
+current line (line 0), the following line (line 2) become the next
+line (line 1) etc.
+
+That would be all if TeX did not wrap long lines, but it does. To unwrap
+lines when needed, we (1) check that the line is max_print_lines long;
+if so, we (2) check whether the next line is the beginning of a known
+message; if it is not, we (3) check whether unwrapping lines makes us
+recognize a message that was not identified without unwrapping. Because
+of 3, we do this in each of the handlers and not beforehand. To unwrap
+a line, we simply join the current line with the next one from the
+buffer.
+
+Note that, if you reconfigure the variable max_print_line to a value
+larger than 9999 (which is a good thing to do), this program assumes
+(quite reasonably) that there is no line wrapping.
+
+
+------------
+THE HANDLERS
+------------
+
+We want to be able to explicitly recognize as much messages as possible
+(and leave the least amount possible for the unrecognizedBuffer) for at
+least three reasons:
+
+ 1. A character such as "(", ")", "[", or "]" in an unrecognized message
+    may confuse the program (these chars may indicate open/close file
+    and begin/end shipout). If it is part of a known message, it will
+    not be mistaken for an open/close file etc.
+
+ 2. By default, TeX wraps lines longer than max_print_line characters,
+    and unwrapping them involves making sure that the following line
+    is not the start of a new message. For this to be reliable,
+    unknown messages should be kept to a minimum.
+
+ 3. We can assign severity levels to known messages; unknown messages
+    must always be handled as high-severity, polluting the output.
+
+At each iteration, chooseHandler() calls doit() for every handler. The
+handler returns true to signal that chooseHandler() should proceed to
+the next iteration. It does that if it did "something" to change the
+status for the next iteration:
+
+ * It processed a complete message in this iteration (i.e., the whole
+   message was contained in the current line);
+
+ * It processed the message partially and defined nextHandler;
+
+ * It finalized the processing of a previous partial message (i.e., it
+   realized the message has ended). This only happens if the handler
+   was previously set as nextHandler. When this happens, it sometimes
+   does nothing with the content of the current line, only outputs the
+   complete message. Still, when the loop restarts, it will no longer
+   be the nextHandler (and that is "something").
+
+A handler must provide:
+
+1. A doit() method that returns true or false to indicate whether it
+   actually did something with the current line or not.
+
+2. A canDoit(position) method that returns true or false to indicate
+   whether the handler can/should process the line given by "position"
+   (we use this to identify wrapped lines, as explained later).
+
+3. An init() method to do any necessary setup after the command line
+   has been read (it is ok to do nothing). The easiest way to do this
+   is to "inherit" from HandlerPrototype.
+
+4. For handlers that deal with messages that can appear in the middle
+   of a line, a lookahead(position) method to indicate whether there is
+   a message that the handler can/should process in the line indicated
+   by "position", even if there is something else in the line before
+   that message.
+
+Besides true/false, canDoit() also returns a table with extra data. In
+some cases, this table is empty; in others, the handler's doit() method
+knows what to do with it. There are two places outside the handler
+itself where this data is used:
+
+1. In handleUnrecognizedMessage(), where we call lookahead() and use
+   the value of "first" that should be embedded in this table.
+
+2. In Lines:noHandlersForNextLine(), where we treat openParensHandler
+   and openSquareBracketHandler specially and read file/page data from
+   them.
+
+A simple handler:
+-----------------
+
+  exampleHandler = {}
+  exampleHandler.pattern = '^%s*L3 programming layer %b<> xparse %b<>'
+
+  function exampleHandler:init()
+  end
+
+  function exampleHandler:canDoit(position)
+      local line
+      if position == nil then position = 0 end
+      line = Lines:get(position)
+
+      local first, last = string.find(line, self.pattern)
+      if first == nil then return false
+      return true, {first = first, last = last}
+  end
+
+  function exampleHandler:doit()
+      local myTurn, data = self:canDoit()
+      if not myTurn then return false end
+
+      flushUnrecognizedMessages()
+      local msg = Message:new()
+      msg.severity = DEBUG
+      msg.content = string.sub(Lines.current, 1, data.last)
+      dispatch(msg)
+      Lines:handledChars(data.last)
+      return true
+  end
+
+  function exampleHandler:lookahead(position)
+      local tmp = self.pattern
+      self.pattern = string.sub(self.pattern, 2) -- remove leading '^'
+      local result, data = self:canDoit()
+      self.pattern = tmp
+      return result, data
+  end
+
+There are two special handlers, which we use as prototypes
+(https://www.lua.org/pil/16.1.html ) and derive some other handlers
+from:
+
+ - stringsHandler - handles a list of predefined multiline strings
+   that may or may not begin at the beginning of a line and may or may
+   not end at the end of a line. We identify where the last line of
+   the message ends and remove that from the input line, leaving the
+   rest for the next handler. In general, the pattern we look for in
+   each line should match the whole line and should not end with
+   something like ".*", unless we are absolutely sure that (1) each line
+   always ends at the end of the line and (2) the line is short enough
+   that it is never wrapped (which also implies that the first line
+   always starts at the start of the line). This handler is quite
+   complex because it has to deal with many different scenarios. We
+   derive other handlers from the basic prototype so that we can assign
+   different severity levels to each one. Derived handlers differ from
+   the prototype only by severity level and the set of patterns to
+   search for.
+
+ - genericLatexHandler -> handles the multiline messages generated by
+   the \PackageInfo, \ClassWarning etc. LaTeX commands. The handler
+   does not need to know in advance the text for all these messages;
+   it looks for generic patterns instead and extracts from the message
+   itself the name of the package and severity level. It is able to
+   identify multiline messages by checking if the following lines are
+   prefixed with a specific pattern, so it can also handle messages
+   with an unknown number of lines. We derive other handlers from the
+   basic prototype because, for each kind of message, we use a different
+   set of pattern captures, and we need to treat these differently.
+   Derived handlers differ from the prototype by the set of patterns
+   to search for and by the unpackData() method, which deals with the
+   specific pattern captures.
+
+
+----------------
+UNWRAPPING LINES
+----------------
+
+As mentioned, each handler has a canDoit(position) method, where
+"position" is the line number in the Lines input buffer (0 is the
+current line, 1 is the next line etc.). As expected, doit() calls
+canDoit() to check whether it should proceed of not. However, that
+is not all: if canDoit() fails to find a match, it checks whether the
+line might be a wrapped line. To detect a wrapped line, canDoit()
+uses Lines:seemsWrapped() to do three things:
+
+1. Check that the line is the "right" size (in Lines:wrappingLength())
+
+2. Check that the next line is not the beginning of a known message
+   (in Lines:noHandlersForNextLine())
+
+3. Check whether unwrapping the line actually gives us something, i.e.,
+   the unwrapped line matches something that its two separate parts
+   did not.
+
+The problem is in step (2): this entails calling canDoit() from all
+handlers on the following line, which means that it may be called many
+times and may even call itself on a different line. Therefore, it is
+essential that canDoit() have no side effects, i.e., it should not set
+any state besides the return values. For the same reason, canDoit()
+cannot alter the content of the Lines buffer when it tries to unwrap a
+line; it should only use temporary variables instead (not only that:
+if unwrapping does not yield a match, we do not want to do it either).
+
+canDoit() may, however, return a "hint" about the line wrapping - either
+the text or the pattern that finally matched. Some handlers do that and,
+in doit(), take the string or pattern found by canDoit() and unwrap
+lines until finding a match to that string or pattern. Others cannot do
+this due to various reasons and need to repeat the work already done
+by canDoit() (the code is different, however).
+
+Note also that some handlers, such as underOverFullBoxHandler and
+genericLatexHandler, cannot do (3), as they do not know in advance
+how the end of a given message should look like. The bottom line is,
+line unwrapping is done in many different ways according to context.
+
+Finally, this all means that we may call canDoit() from all handlers on
+a given line many times. This gets really bad with stringsHandler: for
+a sequence of k consecutive lines that are max_print_line long, this
+handler alone is O(n^{k+1}), where n is the number of patterns that it
+checks for (around 40). A previous implementation proved this to be
+impractical, so we work around this problem with memoization.
+
+
+-----------------------------------------
+DETAILS ABOUT UNDER/OVERFULL BOX MESSAGES
+-----------------------------------------
+
+These are actually several different messages:
+
+Overfull \[hv]box (Npt too wide) SOMEWHERE
+Underfull \[hv]box (badness N) SOMEWHERE
+
+Possible SOMEWHEREs:
+
+1. detected at line N
+   -> this is something like a makebox (horizontal) or parbox (vertical)
+      with an explicit size argument. For hboxes, this is followed by
+      the offending text.
+
+2. has occurred while \output is active
+   -> If horizontal, this is probably in a header, footer or something
+      similar; if vertical, the vertical glues got too stretched
+
+3. in alignment at lines LINE NUMBERS
+   -> the problematic box is part of a tabular or math alignment
+      environment. The lines correspond to the whole align structure,
+      not only the problematic box. This should only appear as an
+      horizontal problem. This is followed by the offending text, but
+      it is more often than not just a bunch of "[]" to indicate nested
+      boxes
+
+4. in paragraph at lines LINE NUMBERS
+   -> "Normal" text. This also only appears as an horizontal problem.
+      This is followed by the offending text, which may include a
+      few "[]" for whatsits, glues etc. In particular, the text often
+      begins with "[]", indicating the left margin glue.
+
+In the log file, all under/overfull box messages are followed by a
+description of the boxes involved. This is *not* normally included in
+the console output (but it may be, depending on \tracingonline). The
+level of detail of this description is controlled by \showboxdepth
+and \showboxbreadth. The default for these in LaTeX is -1, which means
+this description is omitted and replaced by "[]", so it looks like this:
+
+Underfull \vbox (badness 10000) detected at line 128
+ []   <-- this is the description
+
+If the message includes the offending text, the description comes
+after it:
+
+Underfull \hbox (badness 3417) in paragraph at lines 128--128
+ []\T1/LibertinusSerif-TLF/b/n/14.4 (+20) Some document text...
+ []   <-- this is the description
+
+If there is no offending text, the description may appear in the same
+line as the under/overfull box message (both are \message's). The
+offending text, if any, always starts at the beginning of a line and
+ends at the end of a line.
+
+About the description: https://tex.stackexchange.com/a/367589/217608
+
+This all means that handling these messages from a pipe is different
+than from the log file, because in the log file you know there will
+be a "[]" after the message. What we do here is check whether that
+string is there; if it is, we remove it.
+
+under/overfull messages that do not include the offending text are
+\message's and, therefore, there may be extra text (such as a shipout)
+on the same line.
+
+--]]
+
+
+--[[ ##################################################################### ]]--
+--[[ ################ INIT, MAIN LOOP, CHOOSING HANDLER ################## ]]--
+--[[ ##################################################################### ]]--
+
+   DEBUG = 0
+    INFO = 1
+ WARNING = 2
+CRITICAL = 3
+ UNKNOWN = 4
+
+function main(arg)
+  processCommandLine(arg)
+  initializeGlobals()
+  initializeKpse()
+  registerHandlers()
+  registerSummaries()
+  convertFilterStringsToPatterns()
+
+  while moreData() do
+      if nextHandler == nil then
+          chooseHandler()
+      else
+          handler = nextHandler
+          nextHandler = nil
+          handler:doit()
+      end
+  end
+
+  -- dispatch remaining messages, if any
+  epilogueHandler:flush()
+  flushUnrecognizedMessages()
+  dispatch(nil) -- end the output coroutine
+end
+
+function moreData()
+  -- if there is remaining data from the previous iteration,
+  -- we leave everything as-is for it to be processed now
+  local tmp = Lines.current
+  if tmp ~= nil and string.len(tmp) > 0 then return true end
+
+  -- Refill the buffer. A simple experiment suggests 8 lines
+  -- is enough, but why not use a higher value?
+  while Lines:numLines() < 15 do
+      tmp = logfile:read("*line")
+      if tmp == nil then break end
+      -- We *need* to remove blank lines here because
+      -- sometimes a wrapped line is followed by a blank
+      -- line, which messes our detection of wrapped lines.
+      if string.len(tmp) > 0 then Lines:append(tmp) end
+  end
+
+  -- proceed to the next line
+  flushUnrecognizedMessages()
+  Lines:gotoNextLine()
+
+  return Lines.current ~= nil
+end
+
+--[[
+chooseHandler() never tries to process more than one message in a single
+iteration for at least three reasons:
+
+ * There may be no more data available on the current line, so we
+   need to call moreData();
+
+ * Maybe the next handler is one that we have already tried in this
+   iteration; skipping it and trying others may fail;
+
+ * Maybe the handler that last processed the data predefined the next
+   handler, and we should not interfere with that.
+--]]
+
+function chooseHandler()
+  -- Some messages can only appear at the beginning of a line
+  if Lines.atBeginningOfLine then
+      for _, candidateHandler in ipairs(beginningOfLineHandlers) do
+          if candidateHandler:doit() then return end
+      end
+  end
+
+  -- Others may appear anywhere
+  for _, candidateHandler in ipairs(anywhereHandlers) do
+      if candidateHandler:doit() then return end
+  end
+
+  -- No handler succeeded, which means this is an unrecognized message
+  -- (or a fragment of one); Add to unrecognizedBuffer.
+  handleUnrecognizedMessage()
+end
+
+function handleUnrecognizedMessage()
+  -- Before sending this to the unrecognizedBuffer, check if
+  -- there is another known message later on this same line.
+
+  local last = string.len(Lines.current)
+
+  for _, handler in ipairs(anywhereHandlers) do
+      local match, data = handler:lookahead()
+      if match and data.first -1 < last then last = data.first -1 end
+  end
+
+  unrecognizedBuffer = unrecognizedBuffer .. string.sub(Lines.current, 1, last)
+  Lines:handledChars(last)
+end
+
+function flushUnrecognizedMessages()
+  unrecognizedBuffer = trim(unrecognizedBuffer)
+  if unrecognizedBuffer == "" then return end
+
+  local msg = Message:new()
+  msg.content = unrecognizedBuffer
+  dispatch(msg)
+  unrecognizedBuffer = ""
+end
+
+-- Setup initial status (lots of globals, sue me)
+function initializeGlobals()
+
+  -- Chunks of text that were not recognized by any handler
+  unrecognizedBuffer = ""
+
+  -- The user may choose to silence some files. When one of these is
+  -- opened/closed, this is set to true or false accordingly. The value
+  -- is then used by Message:new()
+  mute = false
+
+  -- List of files that TeX had open at a given time during processing
+  openFiles = Stack:new()
+
+  -- "List" of currently active shipouts. There is only ever one shipout
+  -- active at any time, but we borrow the design of openFiles because
+  -- there may be "[" and "]" characters that do not correspond to any
+  -- shipout, so we use this to keep track of them.
+  shipouts = Stack:new()
+
+  -- Counter, so we know the physical page number
+  numShipouts = 0
+
+  -- map physicalPage (from numShipouts) to latexPage (LaTeX counter)
+  latexPages = {}
+
+  -- After printing each message, the output coroutine stores them
+  -- in currentPageMessages. When it receives a shipout message,
+  -- it traverses currentPageMessages adding the page number it
+  -- just learned about to each of the messages, calls :toSummary()
+  -- for each of them and and clears currentPageMessages (we do this
+  -- so the data in the summaries may include the page numbers). The
+  -- objects representing the summary for each kind of message are
+  -- stored in summaries, so after all messages we can just traverse
+  -- this list calling :toString() and get all the summaries. The
+  -- summaries table is populated by registerSummaries().
+  currentPageMessages = {}
+  summaries = {}
+
+  -- When the same message appears several times, we only output it
+  -- once, thanks to this table. This is used by showMessage()
+  alreadySeen = {}
+
+  -- All handlers should be in either of these. They are populated by
+  -- registerHandlers().
+  beginningOfLineHandlers = {}
+  anywhereHandlers = {}
+
+  -- Does the log file have wrapped lines?
+  -- This may be changed by initializeKpse().
+  badLogFile = true
+end
+
+function initializeKpse()
+  -- In texlua, the texconfig table (the table that records some TeX
+  -- config variables) is not initialized automatically; we need to
+  -- call this to initialize it so we can read "max_print_line". If
+  -- I understand things correctly, the name used here affects the
+  -- loaded configuration options: using a name such as "texlogsieve"
+  -- would allow us to add custom options to texmf.cnf. But since
+  -- all we want to do is search for files and read the value of
+  -- "max_print_line", let's just pretend we are luatex.
+  kpse.set_program_name("luatex")
+
+  max_print_line = tonumber(kpse.var_value("max_print_line"))
+  if max_print_line ~= nil and max_print_line > 9999 then
+      badLogfile = false
+  else
+      badLogfile = true
+  end
+end
+
+function registerHandlers()
+  table.insert(beginningOfLineHandlers, citationHandler)
+  table.insert(beginningOfLineHandlers, referenceHandler)
+  table.insert(beginningOfLineHandlers, labelHandler)
+  table.insert(beginningOfLineHandlers, genericLatexHandler)
+  table.insert(beginningOfLineHandlers, latex23MessageHandler)
+  table.insert(beginningOfLineHandlers, genericLatexVariantHandler)
+  table.insert(beginningOfLineHandlers, providesHandler)
+  table.insert(beginningOfLineHandlers, geometryDetailsHandler)
+  table.insert(beginningOfLineHandlers, epilogueHandler)
+  table.insert(beginningOfLineHandlers, underOverFullBoxHandler)
+  table.insert(beginningOfLineHandlers, utf8FontMapHandler)
+  table.insert(beginningOfLineHandlers, missingCharHandler)
+  table.insert(beginningOfLineHandlers, beginningOfLineDebugStringsHandler)
+  table.insert(beginningOfLineHandlers, beginningOfLineInfoStringsHandler)
+  table.insert(beginningOfLineHandlers, beginningOfLineWarningStringsHandler)
+  table.insert(anywhereHandlers, anywhereDebugStringsHandler)
+  table.insert(anywhereHandlers, anywhereInfoStringsHandler)
+  table.insert(anywhereHandlers, anywhereWarningStringsHandler)
+  table.insert(anywhereHandlers, openParensHandler)
+  table.insert(anywhereHandlers, closeParensHandler)
+  table.insert(anywhereHandlers, openSquareBracketHandler)
+  table.insert(anywhereHandlers, closeSquareBracketHandler)
+
+  for _, handler in ipairs(beginningOfLineHandlers) do
+      handler:init()
+  end
+
+  for _, handler in ipairs(anywhereHandlers) do
+      handler:init()
+  end
+end
+
+function registerSummaries()
+  table.insert(summaries, underOverSummary)
+  table.insert(summaries, missingCharSummary)
+  table.insert(summaries, repetitionsSummary)
+  table.insert(summaries, citationsSummary)
+  table.insert(summaries, referencesSummary)
+  table.insert(summaries, labelsSummary)
+end
+
+function convertFilterStringsToPatterns()
+  local tmp = {}
+  for _, pattern in ipairs(SEMISILENCE_FILES) do
+      table.insert(tmp, globtopattern(pattern))
+  end
+  SEMISILENCE_FILES = tmp
+
+  tmp = {}
+  for _, pattern in ipairs(SILENCE_FILES_RECURSIVE) do
+        table.insert(tmp, globtopattern(pattern))
+  end
+  SILENCE_FILES_RECURSIVE = tmp
+
+  tmp = {}
+  for _, str in ipairs(SILENCE_STRINGS) do
+      local pat = stringToPattern(str)
+      table.insert(tmp, pat)
+  end
+  SILENCE_STRINGS = tmp
+
+  tmp = {}
+  for _, str in ipairs(SILENCE_PKGS) do
+      local pat = stringToPattern(str)
+      table.insert(tmp, pat)
+  end
+  SILENCE_PKGS = tmp
+end
+
+function processCommandLine(args)
+  HEARTBEAT = true
+  PAGE_DELAY = true
+  ONLY_SUMMARY = false
+  SHOW_SUMMARY = true
+  SHOW_SHIPOUTS = false
+  RAW = false
+  SILENCE_REPETITIONS = true
+  MINLEVEL = WARNING
+
+  SILENCE_STRINGS = {}
+  SILENCE_PKGS = {} -- just the package names
+  SEMISILENCE_FILES = {} -- filenames (without leading path), file globs work
+  SILENCE_FILES_RECURSIVE = {} -- same
+
+
+  -- "-l level -c configFile"
+  local optionsWithArgs = "lc"
+  local vars = simpleGetopt(args, optionsWithArgs)
+
+  --help
+  -- "-h"
+  if vars.help or vars.h then
+      local msg = [[
+Usage: texlogsieve [OPTION]... [INPUT FILE]
+texlogsieve reads a LaTeX log file (or the standard input), filters
+out less relevant messages, and displays a summary report.
+
+Options:
+  --page-delay, --no-page-delay        enable/disable grouping
+                                       messages by page before display
+  --summary, --no-summary              enable/disable final summary
+  --only-summary                       no filtering, only final summary
+  --shipouts, --no-shipouts            enable/disable reporting shipouts
+  --repetitions, --no-repetitions      allow/prevent repeated messages
+  --heartbeat, --no-heartbeat          enable/disable progress gauge
+  -l LEVEL, --minlevel=LEVEL           filter out messages with severity
+                                       level lower than [LEVEL]. Valid
+                                       levels are DEBUG, INFO, WARNING,
+                                       CRITICAL, and UNKNOWN
+  -u, --unwrap-only                    no filtering or summary, only
+                                       unwrap long, wrapped lines
+  --silence-package=PKGNAME            suppress messages from package
+                                       PKGNAME; can be used multiple times
+  --silence-string=EXCERPT             suppress messages containing text
+                                       EXCERPT; can be used multiple times
+  --silence-file=FILENAME              suppress messages generated during
+                                       processing of FILENAME; can be used
+                                       multiple times
+  --semisilence-file=FILENAME          similar to --silence-file, but not
+                                       recursive
+  --add-debug-message=MESSAGE          add new recognizable debug message
+  --add-info-message=MESSAGE           add new recognizable info message
+  --add-warning-message=MESSAGE        add new recognizable warning message
+  -c cfgfile, --config-file=cfgfile    read options from config file
+  -h, --help                           give this help list
+  --version                            print program version]]
+
+      for _, line in ipairs(linesToTable(msg)) do print(line) end
+      os.exit(0)
+  end
+
+  --version
+  if vars.version then
+      print("texlogsieve 1.0.0-beta-1")
+      print("Copyright (C) 2021 Nelson Lago <lago@ime.usp.br>")
+      print("License GPLv3+: GNU GPL version 3 or later "
+            .. "<https://gnu.org/licenses/gpl.html>.")
+      print("This is free software: you are free to change "
+            .. "and redistribute it.")
+      print("There is NO WARRANTY, to the extent permitted by law.")
+      os.exit(0)
+  end
+
+  --config-file=file
+  -- "-c file"
+  local configFileName
+  if vars['config-file'] ~= nil then configFileName = vars['config-file'] end
+  if vars.c ~= nil then configFileName = vars.c end
+  if configFileName ~= nil then
+      configFileName = configFileName[1]
+      local filevars = processConfigFile(configFileName)
+
+      -- merge filevars with vars; vars has precedence
+      for k, v in pairs(vars) do
+          if type(v) == "boolean" then
+              filevars[k] = v
+          elseif filevars[k] == nil then
+              filevars[k] = v
+          else
+              -- the value is a table, so append
+              for _, item in ipairs(v) do
+                  table.insert(filevars[k], item)
+              end
+          end
+      end
+
+      -- use the merged values
+      vars = filevars
+  end
+
+  --unwrap-only
+  -- "-u"
+  if vars['unwrap-only'] or vars.u then
+      -- these may be overriden below, so order matters
+      RAW = true
+      SHOW_SUMMARY = false
+      PAGE_DELAY = false
+      SHOW_SHIPOUTS = true
+      SILENCE_REPETITIONS = false
+      MINLEVEL = DEBUG
+  end
+
+  --page-delay
+  --no-page-delay
+  --page-delay=true/false
+  if vars['no-page-delay']
+          or vars['page-delay'] ~= nil and not vars['page-delay'] then
+
+      PAGE_DELAY = false
+      SHOW_SHIPOUTS = true -- this may be overriden below
+  end
+  if vars['page-delay'] then PAGE_DELAY = true end
+
+  --only-summary
+  if vars['only-summary'] then ONLY_SUMMARY = true end
+
+  --no-summary
+  --summary
+  --summary=true/false
+  if vars['no-summary'] or vars.summary ~= nil and not vars.summary then
+      SHOW_SUMMARY = false
+      SILENCE_REPETITIONS = false
+  end
+  if vars.summary then SHOW_SUMMARY = true end
+
+  --no-shipouts
+  --shipouts
+  --shipouts=true/false
+  if vars['no-shipouts'] or vars.shipouts ~= nil and not vars.shipouts then
+      SHOW_SHIPOUTS = false
+  end
+  if vars.shipouts then SHOW_SHIPOUTS = true end
+
+  --minlevel
+  -- "-l"
+  local level
+  if vars.minlevel ~= nil then level = vars.minlevel end
+  if vars.l ~= nil then level = vars.l end
+
+  if level ~= nil then
+      level = string.lower(level[1])
+      if     level == "debug"    then MINLEVEL = DEBUG
+      elseif level == "info"     then MINLEVEL = INFO
+      elseif level == "warning"  then MINLEVEL = WARNING
+      elseif level == "critical" then MINLEVEL = CRITICAL
+      else                            MINLEVEL = UNKNOWN
+      end
+  end
+
+  --no-repetitions
+  --repetitions
+  --repetitions=true/false
+  if vars['no-repetitions']
+                    or vars.repetitions ~= nil and not vars.repetitions then
+
+      SILENCE_REPETITIONS = true
+  end
+  if vars.repetitions then SILENCE_REPETITIONS = false end
+
+  --no-heartbeat
+  --heartbeat
+  --heartbeat=true/false
+  if vars['no-heartbeat'] or vars.heartbeat ~= nil and not vars.heartbeat then
+      HEARTBEAT = false
+  end
+  if vars.heartbeat then HEARTBEAT = true end
+
+  if vars.filename == nil then
+      logfile = io.stdin
+  else
+      logfile = assert(io.open(vars.filename, "r"))
+  end
+
+  if vars['silence-string'] then SILENCE_STRINGS = vars['silence-string'] end
+
+  if vars['silence-package'] then SILENCE_PKGS = vars['silence-package'] end
+
+  if vars['silence-file'] then SILENCE_FILES_RECURSIVE =
+                                    vars['silence-file'] end
+
+  if vars['semisilence-file'] then SEMISILENCE_FILES =
+                                    vars['semisilence-file'] end
+
+  if vars['add-debug-message'] then
+      for _, msg in ipairs(vars['add-debug-message']) do
+          local pat = stringToPattern(msg)
+          if not string.find(pat, '^', 1, true) then pat = '^%s*' .. pat end
+          pat = string.gsub(pat, '\\n', '\n')
+          table.insert(anywhereDebugStringsHandler.patterns, pat)
+      end
+  end
+
+  if vars['add-info-message'] then
+      for _, msg in ipairs(vars['add-info-message']) do
+          local pat = stringToPattern(msg)
+          if not string.find(pat, '^', 1, true) then pat = '^%s*' .. pat end
+          pat = string.gsub(pat, '\\n', '\n')
+          table.insert(anywhereInfoStringsHandler.patterns, msg)
+      end
+  end
+
+  if vars['add-warning-message'] then
+      for _, msg in ipairs(vars['add-warning-message']) do
+          local pat = stringToPattern(msg)
+          if not string.find(pat, '^', 1, true) then pat = '^%s*' .. pat end
+          pat = string.gsub(pat, '\\n', '\n')
+          table.insert(anywhereWarningStringsHandler.patterns, msg)
+      end
+  end
+end
+
+function processConfigFile(filename)
+    configfile = assert(io.open(filename, "r"))
+    local fileOptions = {}
+
+    while true do
+        local line = configfile:read("*line")
+        if line == nil then break end
+
+        line = trim(line)
+        local first = string.find(line, '^#')
+        if first == nil and string.len(line) > 0 then
+
+            local equals = string.find(line, '=', 1, true)
+            if equals ~= nil then
+                optname = string.sub(line, 1, equals -1)
+                optval = string.sub(line, equals +1)
+                optname = trim(optname)
+                optval = trim(optval)
+            else
+                optname = line
+                optval = true
+            end
+            simpleGetoptStoreVal(fileOptions, optname, optval)
+        end
+    end
+
+    return fileOptions
+end
+
+
+--[[ ##################################################################### ]]--
+--[[ ################# OUTPUT COROUTINE AND FORMATTING ################### ]]--
+--[[ ##################################################################### ]]--
+
+outputCoroutine = coroutine.create(
+  function(msg)
+      while msg ~= nil do
+          processMessage(msg)
+          msg = coroutine.yield()
+      end
+      finishProcessingMessages()
+  end
+)
+
+dispatch = function(msg) coroutine.resume(outputCoroutine, msg) end
+
+function processMessage(msg)
+  if ONLY_SUMMARY or PAGE_DELAY then
+      heartbeat:tick()
+  else
+      showMessage(msg)
+  end
+
+  -- aggregate until shipout
+  table.insert(currentPageMessages, msg)
+
+  if msg.shipout then
+      heartbeat:stop()
+
+      for _, tmp in ipairs(currentPageMessages) do
+          tmp.physicalPage = msg.physicalPage
+          tmp:toSummary()
+      end
+
+      if PAGE_DELAY and not ONLY_SUMMARY then
+          showPageMessages()
+      end
+
+      currentPageMessages = {}
+  end
+end
+
+function finishProcessingMessages()
+  heartbeat:stop()
+
+  -- messages after the last shipout
+  if PAGE_DELAY and not ONLY_SUMMARY then
+      print("")
+      print("After last page:")
+      print("")
+      showPageMessages()
+  end
+
+  -- now, the summaries
+  if SHOW_SUMMARY then showSummary() end
+end
+
+function showMessage(msg)
+  local formatted = msg:toString()
+  if string.len(trim(formatted)) == 0 then return end
+
+  if RAW then
+      for _, line in ipairs(linesToTable(formatted)) do print(line) end
+      return
+  end
+
+  local pageinfo = ""
+  if msg.physicalPage ~= nil then
+      pageinfo = 'pg ' .. msg.physicalPage .. ': '
+  end
+  local spaces = string.rep(" ", string.len(pageinfo))
+
+  if not SILENCE_REPETITIONS then
+      local lines = linesToTable(formatted)
+      for _, line in ipairs(lines) do
+          print(pageinfo .. line)
+          pageinfo = spaces
+      end
+
+      return
+  end
+
+  if alreadySeen[formatted] == nil then
+      alreadySeen[formatted] = {msg}
+      local lines = linesToTable(formatted)
+      for _, line in ipairs(lines) do
+          print(pageinfo .. line)
+          pageinfo = spaces
+      end
+  else
+      table.insert(alreadySeen[formatted], msg)
+  end
+end
+
+function showPageMessages()
+  for _, msg in ipairs(currentPageMessages) do
+      showMessage(msg)
+  end
+end
+
+function showSummary()
+  if not ONLY_SUMMARY then for i = 1, 5 do print("") end end
+
+  for _, summary in ipairs(summaries) do
+      local formatted = summary:toString()
+      local prefix = ""
+      if string.len(trim(formatted)) > 0 then
+          for _, line in ipairs(linesToTable(formatted)) do
+              print(prefix .. line)
+              prefix = '    '
+          end
+          print("")
+      end
+  end
+end
+
+heartbeat = {}
+heartbeat.chars = {'/', '-', '\\', '|'}
+heartbeat.idx = 0
+heartbeat.cnt = 0
+heartbeat.startline = true
+
+function heartbeat:tick()
+  if not HEARTBEAT then return end
+
+  if self.cnt % 5 == 0 then
+      if self.startline then
+          self.startline = false
+      else
+          io.stderr:write('\b')
+      end
+      local i = self.idx %4 +1
+      io.stderr:write(self.chars[i])
+      self.idx = self.idx +1
+  end
+  self.cnt = self.cnt +1
+end
+
+function heartbeat:stop()
+  if not HEARTBEAT or self.startline then return end
+
+  io.stderr:write('\b \b')
+  self.startline = true
+end
+
+
+--[[ ##################################################################### ]]--
+--[[ ########################### THE HANDLERS ############################ ]]--
+--[[ ##################################################################### ]]--
+
+-- datepat and filepat will come in handy later on.
+--
+-- Note that, in some cases, it may be useful to start filepat with '^[%.]?/'.
+--
+-- filepat will fail:
+--
+-- 1. If the path or filename includes weird characters, such as ":" or "|"
+-- 2. If the file has no extension or the extension has only one character
+-- 3. If the extension includes "-", "_", or spaces
+-- 4. If filepat should match the end of the message and the matching line is
+--    wrapped in the middle of the file extension, for example "myfile.pd\nf"
+--    (but we have a hack in unwrapUntilPatternMatches() to work around that)
+--
+-- More importantly, filepat allows for spaces and multiple dots in filenames,
+-- but this means it may match something that is not really a filename. Don't
+-- blindly trust it! We do not use this to detect open/close file; for that,
+-- check guessFilename().
+
+datepat = '%d%d%d%d[/%-%.]%d%d[/%-%.]%d%d'
+
+filepat = '%a?[:]?'
+          .. '[^%%:;,%=%*%?%|%&%$%#%!%@"%`\'%<%>%[%]%{%}]+'
+          .. '%.'
+          .. '[^/ %-%_%.%%:;,%=%*%?%|%&%$%#%!%@"%`\'%<%>%[%]%{%}]'
+          .. '[^/ %-%_%.%%:;,%=%*%?%|%&%$%#%!%@"%`\'%<%>%[%]%{%}]+'
+
+
+-------------------------------------------------------------------------------
+-- HandlerPrototype
+-------------------------------------------------------------------------------
+
+HandlerPrototype = {}
+
+function HandlerPrototype:new()
+    local o = {}
+    setmetatable(o, self)
+    self.__index = self
+    return o
+end
+
+-- Some handlers need an init() method; by inheriting from this,
+-- we can simply iterate over all of them calling init().
+function HandlerPrototype:init()
+end
+
+-- Only some of the handlers use this implementation
+function HandlerPrototype:unwrapLines()
+  while Lines:seemsWrapped() do Lines:unwrapOneLine() end
+end
+
+function HandlerPrototype:newMessage()
+  return Message:new()
+end
+
+
+-------------------------------------------------------------------------------
+-- epilogueHandler
+--
+-- This handles the generic messages at the end of each LaTeX run. We could
+-- handle each one with stringsHandler, but this handler allows us to treat
+-- the whole group of lines together, which means we do not need to have
+-- dedicated rules for each line in them. Also, there are some lines here
+-- that are not wrapped as the rest.
+-------------------------------------------------------------------------------
+
+epilogueHandler = HandlerPrototype:new()
+
+function epilogueHandler:canDoit(position)
+  local line
+  if position == nil then position = 0 end
+  line = Lines:get(position)
+
+  -- This appears in the logfile but not on stdout
+  local _, last = string.find(line, "^Here is how much")
+  if last == nil then
+      -- This appears on stdout (and in the log, of course)
+      _, last = string.find(line,
+              "^%(see the transcript file for additional information%)")
+  else
+      last = string.len(line)
+  end
+
+  if last == nil then
+      return false, {}
+  else
+      return true, {last = last}
+  end
+end
+
+function epilogueHandler:doit()
+  local myTurn, data = self:canDoit()
+  if not myTurn then return false end
+
+  flushUnrecognizedMessages()
+  self.message = self:newMessage()
+  self.message.content = string.sub(Lines.current, 1, data.last)
+  self.message.severity = DEBUG
+  Lines:handledChars(data.last)
+  self.doit = self.handleOtherLines
+  nextHandler = self
+  self.processingFilelist = false
+  return true
+end
+
+-- We need to "manually" unwrap the file list because some
+-- lines are wrapped at lengths different from max_print_line
+function epilogueHandler:handleOtherLines()
+  local first = string.find(Lines.current, '^Output written')
+  if first ~= nil then
+      self.processingFilelist = false
+      self.message.content = '\n' .. self.message.content
+  end
+
+  if self.processingFilelist then
+      self.message.content = self.message.content .. Lines.current
+  else
+      self:unwrapLines()
+      self.message.content = self.message.content .. '\n' .. Lines.current
+  end
+
+  first = string.find(Lines.current, '^[%<%{]')
+  if first ~= nil then self.processingFilelist = true end
+
+  Lines:handledChars()
+  nextHandler = self
+  return true
+end
+
+-- We do not know when the epilogue ends, so main()
+-- calls this after the last line is read
+function epilogueHandler:flush()
+    if self.message ~= nil then dispatch(self.message) end
+end
+
+
+-------------------------------------------------------------------------------
+-- underOverFullBoxHandler
+--
+-- Handles under/overfull multiline messages. There are usually important,
+-- so we want to be able to filter them specifically and also to present
+-- a summary about them. Besides that, they may contain spurious "(", ")",
+-- "[", and "]" characters that might confuse the program if left as
+-- "unrecognized".
+-------------------------------------------------------------------------------
+
+underOverFullBoxHandler = HandlerPrototype:new()
+
+function underOverFullBoxHandler:canDoit(position)
+  local line
+  if position == nil then position = 0 end
+  line = Lines:get(position)
+
+  local basePattern = "^([UO][nv][de][e]?r)full \\(.)box (%b())"
+  local first, last, underover,
+        verthoriz, amount = string.find(line, basePattern)
+
+  if first == nil then
+      return false, {}
+  else
+      return true, {underover = underover, verthoriz = verthoriz,
+                    amount = amount, last = last}
+  end
+end
+
+function underOverFullBoxHandler:handleFirstLine()
+  local myTurn, data = self:canDoit()
+  if not myTurn then return false end
+
+  flushUnrecognizedMessages()
+  self.message = underOverMessage:new()
+  self.message.content = string.sub(Lines.current, 1, data.last)
+  self.message.underover = data.underover
+  self.message.verthoriz = data.verthoriz
+  self.message.amount = data.amount
+  self.message.severity = WARNING
+  local first = string.find(data.amount, 'badness 10000')
+  if first ~= nil then self.message.severity = CRITICAL end
+  Lines:handledChars(data.last)
+
+  self.doit = self.handleClosing
+
+  _, last = string.find(Lines.current, "has occurred while \\output is active")
+  if last == nil then
+      _, last = string.find(Lines.current, "in %S+ at lines %d+%-%-%d+")
+      if last == nil then
+          _, last = string.find(Lines.current, "detected at line %d+")
+          if last ~= nil and data.verthoriz == 'h' then
+              self.doit = self.handleOffendingText
+          end
+      else
+          self.doit = self.handleOffendingText
+      end
+  end
+
+  if last == nil then
+      io.stderr:write("    texlogsieve: parsing error\n")
+      self.doit = self.handleFirstLine
+      dispatch(self.message)
+      return true
+  end
+
+  self.message.content = self.message.content
+                         .. string.sub(Lines.current, 1, last)
+
+  Lines:handledChars(last)
+  nextHandler = self
+
+  return true
+end
+
+underOverFullBoxHandler.doit = underOverFullBoxHandler.handleFirstLine
+
+function underOverFullBoxHandler:handleOffendingText()
+  self:unwrapLines()
+  self.message.failedText = Lines.current
+  Lines:handledChars()
+  self.doit = self.handleClosing
+  nextHandler = self
+  return true
+end
+
+function underOverFullBoxHandler:handleClosing()
+  local _, last, closing = string.find(Lines.current, '^%s*(%b[])%s*$')
+  if last ~= nil then
+      Lines:handledChars(last)
+      self.message.closing = closing
+  end
+
+  dispatch(self.message)
+  self.doit = self.handleFirstLine
+  return true
+end
+
+
+-------------------------------------------------------------------------------
+-- stringsHandler
+--
+-- This is the most complex handler. It deals with predefined strings that
+-- may span multiple lines. The message may start anywhere on the line (this
+-- handler can be in anywhereHandlers) and may end before the end of the
+-- line. In fact, depending on max_print_line, it is even possible that the
+-- many lines of the message are concatenated in a single line in the log
+-- or, conversely, that some lines are wrapped. So, for example, the
+-- developer may have envisioned a message like
+--
+-- ********************
+-- *    Hi there!     *
+-- ********************
+--
+-- but this might turn to
+--
+-- ******************** *    Hi there!     * ********************
+--
+-- or
+--
+-- ******************
+-- **
+-- *    Hi there!    
+--  *
+-- ******************
+-- **
+--
+-- or even
+--
+-- ******************
+-- ** *    Hi there! 
+--     * ************
+-- ********
+--
+-- So, what we do here is to consider every line in the search pattern as a
+-- segment of the message that may start in the middle of a line and/or may
+-- be wrapped at the end of the line. We match each of these segments in
+-- turn. Because of that, the patterns should completely match all lines in
+-- the message, not just the beginning of the line followed by ".*" or ".+".
+--
+-- Still, if you know that a specific message or line (1) always starts
+-- at the beginning of the line, (2) never gets wrapped, and (3) is never
+-- followed by another message in the same line, then you can match just
+-- the beginning of the line and use ".*" for the rest. There are a few
+-- messages below defined like this.
+--
+-- Note that, when the handler is executed, the pattern *is* at the beginning
+-- of the current line (in some cases, with leading spaces) because, if there
+-- was any leading text originally in the line, some previous handler has
+-- already removed it. This is why we can (and should!) anchor the pattern
+-- with "^%s*". As before, if you do know that the line always starts at the
+-- beginning of a line, you may instead anchor the pattern with "^". Either
+-- way, we assume we cannot know the true length of the line, so it may be
+-- wrapped at any point. Also, do not forget about lookahead(), which removes
+-- the "^" anchor.
+-------------------------------------------------------------------------------
+
+stringsHandler = HandlerPrototype:new()
+
+function stringsHandler:canDoit(position)
+  for _, pattern in ipairs(self.patterns) do
+      local success, data = self:canDoitRecursive(pattern, position, 0, 0)
+      if success then
+          data.pattern = pattern
+          return true, data
+      end
+  end
+
+  return false, {}
+end
+
+function stringsHandler:handleFirstLine()
+  local myTurn, data = self:canDoit()
+  if not myTurn then return false end
+
+  flushUnrecognizedMessages()
+  self.message = self:newMessage()
+  self.message.severity = self.severity
+
+  local _, last = string.find(Lines.current, '^%s+')
+  if last ~= nil then Lines:handledChars(last) end
+
+  self.captures = {} -- just in case we want to use captures
+  self.patternLines = data.pattern -- the table with the pattern lines
+  self.patternLineNumber = 1
+  self.doit = self.handleLines -- for the next lines, if any
+
+  -- after this initial setup, the first line is handled like the others
+  self:handleLines()
+
+  return true
+end
+
+stringsHandler.doit = stringsHandler.handleFirstLine
+
+function stringsHandler:handleLines()
+
+  local pat = self.patternLines[self.patternLineNumber]
+
+  -- unwrapUntilPatternMatches() will probably not unwrap a line if
+  -- the pattern does not represent the whole line (think about it);
+  -- even if it does, it will fail to detect the correct end of the
+  -- line (how could it?). Conversely, it may try to unwrap needlessly
+  -- if the pattern ends with something like ".+" (think about it too).
+  -- So, you should only use such patterns when the line can never be
+  -- wrapped.
+  local last, tmp = unwrapUntilPatternMatches(pat)
+  for _, val in ipairs(tmp) do table.insert(self.captures, val) end
+
+  if last == nil then
+      io.stderr:write("    texlogsieve: parsing error\n")
+      dispatch(self.message)
+      self.doit = self.handleFirstLine
+      return true
+  end
+
+  if self.patternLineNumber == 1 then
+      self.message.content = string.sub(Lines.current, 1, last)
+  else
+      self.message.content = self.message.content .. '\n'
+                             .. string.sub(Lines.current, 1, last)
+  end
+
+  Lines:handledChars(last)
+
+  if self.patternLineNumber >= #self.patternLines then
+      self:processCaptures()
+      dispatch(self.message)
+      self.doit = self.handleFirstLine
+  else
+      self.patternLineNumber = self.patternLineNumber +1
+      nextHandler = self
+  end
+
+  return true
+end
+
+-- When a pattern takes more than one line, we handle each
+-- line separately. To do that, we need to transform the
+-- multiline strings of the patterns into tables where each
+-- line is an element.
+function stringsHandler:init()
+  self.strictPatterns = {}
+  self.loosePatterns = {}
+
+  for _, pat in ipairs(self.patterns) do
+      local patternLinesAsTableItems = linesToTable(pat)
+      table.insert(self.strictPatterns, patternLinesAsTableItems)
+
+      -- remove the leading '^'
+      patternLinesAsTableItems = linesToTable(string.sub(pat, 2))
+      table.insert(self.loosePatterns, patternLinesAsTableItems)
+  end
+
+  self.patterns = self.strictPatterns
+end
+
+-- The pattern we want to check may stretch over several lines. This
+-- function recursively checks each line of the pattern against the
+-- corresponding input line, but only up to three lines, as that is
+-- enough to make sure the pattern really matches.
+function stringsHandler:canDoitRecursive(patternLines,
+                                             position, offset, depth)
+
+  local line
+  if position == nil then position = 0 end
+  line = Lines:get(position)
+
+  -- skip what was processed in a previous iteration/recursion
+  if offset > 0 then line = string.sub(line, offset +1) end
+
+  local nextline = ""
+
+  local patternLine = patternLines[1]
+
+  while true do
+      local first, last = string.find(line, patternLine)
+      local tmp = string.find(nextline, patternLine) -- see comment below
+
+      if first ~= nil and tmp == nil then
+          -- Found it!
+          if depth > 2 -- 3 lines matched, that is enough
+                       or #patternLines == 1 -- no more pattern lines
+                       or Lines:get(position +1) == nil -- no more input lines
+
+          then
+              return true, {first = first}
+          else
+              -- this line matches; check the next ones too just to make sure
+              if last < string.len(line) then
+                  -- continue on the same line, skip what we already processed
+                  offset = last + offset
+              else
+                  position = position +1 -- proceed to next line...
+                  offset = 0 -- ...starting at the beginning of the line
+              end
+
+              depth = depth +1
+              patternLines = {table.unpack(patternLines, 2)}
+
+              local success = self:canDoitRecursive(patternLines,
+                                                    position, offset, depth)
+
+              return success, {first = first}
+          end
+      end
+
+      -- no success, but can we unwrap this line?
+      if not Lines:seemsWrapped(position) then return false, {} end
+      -- yep! However, we need to be careful: if we match
+      -- on the next line by itself, then the match is not
+      -- the result of unwrapping, so we should return false.
+      -- We only return true if the match occurs only when
+      -- the lines are concatenated. Do not trust that the
+      -- pattern is anchored to the beginning of the line,
+      -- lookahead() changes this.
+      offset = -1 * string.len(line)
+      nextline = Lines:get(position +1)
+      line = line .. nextline
+      position = position +1
+  end
+end
+
+-- Just like :canDoit(), but does not anchor patterns to the
+-- beginning of the line (used by handleUnrecognizedMessage).
+-- Notice the similarity to openCloseHandlerPrototype:lookahead().
+function stringsHandler:lookahead()
+  self.patterns = self.loosePatterns
+  local match, data = self:canDoit()
+  self.patterns = self.strictPatterns
+
+  return match, data
+end
+
+function stringsHandler:processCaptures()
+    -- by default, do nothing
+end
+
+
+-------------------------------------------------------------------------------
+-- beginningOfLineDebugStringsHandler
+-- beginningOfLineInfoStringsHandler
+-- beginningOfLineWarningStringsHandler
+-- anywhereDebugStringsHandler
+-- anywhereInfoStringsHandler
+-- anywhereWarningStringsHandler
+-- (from stringsHandler)
+--
+-- they differ from the prototype only by severity level
+-- and the set of patterns to search for.
+-------------------------------------------------------------------------------
+
+-- We know these messages always start at the beginning of a line
+-- Always start these patterns with "^", see lookahead().
+-- Order matters! The first match wins, so the longer ones should come first.
+beginningOfLineDebugStringsHandler = stringsHandler:new()
+beginningOfLineDebugStringsHandler.severity = DEBUG
+beginningOfLineDebugStringsHandler.patterns = {
+  '^This is .*TeX, Version.*',
+  '^%s*restricted system commands enabled%.',
+  '^%s*entering extended mode',
+  '^%s*restricted \\write18 enabled%.',
+  '^%s*%%%&%-line parsing enabled%.',
+  '^%*%*[%w%.]+', -- "**jobname"
+  '^file:line:error style messages enabled%.',
+  '^\\[^%s=]+=[^%s=]+', -- "\c@chapter=\count174"
+  "^\\openout%d+%s*=%s*`?[^']+'?%.?",
+
+  '^LaTeX2e <' .. datepat .. '>.*',
+
+  '^Lua module: lualibs%-extended ' .. datepat
+                   .. ' %S+ ConTeXt Lua libraries %-%- extended collection%.',
+
+  '^Lua module: lualibs ' .. datepat
+                   .. ' %S+ ConTeXt Lua standard libraries%.',
+
+  '^Lua module: fontspec ' .. datepat
+                   .. ' %S+ Font selection for XeLaTeX and LuaLaTeX',
+
+  '^Lua module: lualatex%-math ' .. datepat
+                   .. ' %S+ Patches for mathematics typesetting with LuaLaTeX',
+
+  '^Lua module: luaotfload ' .. datepat
+                   .. ' %S+ Lua based OpenType font support',
+
+  '^luaotfload | init : Context OpenType loader version.*',
+
+  '^luaotfload | init : Loading fontloader '
+                   .. '["“][^"]+["”] from .-["“][^"]+["”]%.',
+
+  -- there may be dots in the path, so we need to
+  -- anchor the final dot to the end of the line
+  '^luaotfload | conf : Root cache directory is "?[^"]-"?%.$',
+  '^luaotfload | db : Font names database loaded from .-%.luc',
+  '^luaotfload | cache : Lookup cache loaded from .-%.luc%.',
+  '^luaotfload | main : initialization completed in [%d%.]+ seconds',
+
+  '^Lua%-only attribute.-=%s*%S+',
+  "^Inserting %b`' at position .- in %b`'%.",
+
+  "^For additional information on amsmath, use the `%?' option%.",
+
+  "^Loading configuration file `" .. filepat .. "'%.",
+  "^contour: Using driver file `" .. filepat .. "'%.",
+
+  '^ABD: EverySelectfont initializing macros',
+  '^ABD: EveryShipout initializing macros',
+
+  '^%[Loading MPS to PDF converter %(version ' .. datepat .. '%)%.%]',
+
+
+  '^See the caption package documentation for explanation%.',
+
+  '^Lua module: luaotfload%-main ' .. datepat
+                   .. ' [%d%.]+ luaotfload entry point',
+
+  '^Lua module: luaotfload%-init ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / initialization',
+
+  '^Lua module: luaotfload%-log ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / logging',
+
+  '^Lua module: luaotfload%-parsers ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / filelist',
+
+  '^Lua module: luaotfload%-configuration ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / config file reader',
+
+  '^Lua module: luaotfload%-loaders ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / callback handling',
+
+  '^Lua module: luaotfload%-database ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / database',
+
+  '^Lua module: luaotfload%-unicode ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / Unicode helpers',
+
+  '^Lua module: luaotfload%-colors ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / color',
+
+  '^Lua module: luaotfload%-resolvers ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / resolvers',
+
+  '^Lua module: luaotfload%-features ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / features',
+
+  '^Lua module: luaotfload%-letterspace ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / color',
+
+  '^Lua module: luaotfload%-embolden ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / color',
+
+  '^Lua module: luaotfload%-notdef ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / color',
+
+  '^Lua module: luaotfload%-auxiliary ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / auxiliary functions',
+
+  '^Lua module: luaotfload%-multiscript ' .. datepat
+                   .. ' [%d%.]+ luaotfload submodule / multiscript',
+
+  '^' .. string.rep('%*', 37) .. '\n%* Using libertinus math %*\n'
+                   .. string.rep('%*', 37),
+
+  '^`inconsolata%-zi4\' v%S-, ' .. datepat
+                   .. ' Text macros for Inconsolata %(msharpe%)',
+
+  '^Requested font ".-" at [%d%.]+pt\n %-> ' .. filepat,
+  '^Requested font ".-" scaled %d+\n %-> ' .. filepat,
+}
+
+
+-- These messages may start anywhere in a line
+-- Always start these patterns with "^%s*", see lookahead().
+-- Order matters! The first match wins, so the longer ones should come first.
+anywhereDebugStringsHandler = stringsHandler:new()
+anywhereDebugStringsHandler.severity = DEBUG
+anywhereDebugStringsHandler.patterns = {
+  '^%s*L3 programming layer %b<> xparse %b<>',
+  '^%s*%{.*pdftex%.map%}',
+
+  -- <blah.jpg, id=555, [...,] 722.7pt x 722.7pt>
+  '^%s*%<' .. filepat .. ', id=.- [%d%.]+pt x [%d%.]+pt%>',
+  '^%s*%<use ' .. filepat .. '%>', -- <use blah.jpg>
+  '^%s*%<' .. filepat .. '%>', -- <blah.jpg>
+}
+
+
+-- We know these messages always start at the beginning of a line
+-- Always start these patterns with "^", see lookahead().
+-- Order matters! The first match wins, so the longer ones should come first.
+beginningOfLineInfoStringsHandler = stringsHandler:new()
+beginningOfLineInfoStringsHandler.severity = INFO
+beginningOfLineInfoStringsHandler.patterns = {
+  "^Writing index file.*%.idx",
+  "^%*geometry%* driver:.*",
+  "^%*geometry%* detected driver:.*",
+  "^Driver file for pgf:.*%.def",
+  "^%s*file:line:error style messages enabled",
+  "^Applying: %b[] float order in 2%-column on input line .-%.",
+  "^Already applied: %b[] float order in 2%-column on input line .-%.",
+  "^\\%S+ = a dialect from .*",
+  -- TODO: we should capture the jobname and use it here
+  "^No file .-%.aux%.",
+  "^No file .-%.ind%.",
+  "^No file .-%.bbl%.",
+  "^reledmac reminder:%s*\n"
+    .. "%s*The number of the footnotes in this section "
+    .. "has changed since the last run.\n"
+    .. "%s*You will need to run LaTeX two more times "
+    .. "before the footnote placement\n"
+    .. "%s*and line numbering in this section are correct%.",
+}
+
+
+-- These messages may start anywhere in a line
+-- Always start these patterns with "^%s*", see lookahead().
+-- Order matters! The first match wins, so the longer ones should come first.
+anywhereInfoStringsHandler = stringsHandler:new()
+anywhereInfoStringsHandler.severity = INFO
+anywhereInfoStringsHandler.patterns = {
+  -- TODO: there are other "... patterns for blah blah"
+  --       in texmf-dist/tex/generic/hyph-utf8/loadhyph
+  "^%s*German Hyphenation Patterns %(Traditional Orthography%) "
+                            .. "`dehyphts?%-x' " .. datepat .. " %(WL%)",
+
+  '^%s*UTF%-8 German hyphenation patterns %(traditional orthography%)',
+  '^%s*EC German hyphenation patterns %(traditional orthography%)',
+  '^%s*German Hyphenation Patterns %(Traditional Orthography%)',
+
+  "^%s*Swiss%-German Hyphenation Patterns %(Traditional Orthography%) "
+                            .. "`dehyphts?%-x' " .. datepat .. " %(WL%)",
+
+  '^%s*UTF%-8 Swiss%-German hyphenation patterns %(traditional orthography%)',
+  '^%s*EC Swiss%-German hyphenation patterns %(traditional orthography%)',
+  '^%s*Swiss%-German Hyphenation Patterns %(Traditional Orthography%)',
+
+  '^%s*ASCII Hyphenation patterns for American English',
+  '^%s*UTF%-8 %S+ hyphenation patterns',
+  '^%s*EC %S+ hyphenation patterns',
+}
+
+
+-- We know these messages always start at the beginning of a line
+-- Always start these patterns with "^", see lookahead().
+-- Order matters! The first match wins, so the longer ones should come first.
+beginningOfLineWarningStringsHandler = stringsHandler:new()
+beginningOfLineWarningStringsHandler.severity = WARNING
+beginningOfLineWarningStringsHandler.patterns = {
+  '^luaotfload | aux : font no .- does not define feature '
+                            .. '.- for script .- with language %S+',
+
+  '^luaotfload | aux : font no .- %b() defines no feature for script %S+',
+  '^luaotfload | aux : no font with id %d+',
+
+  "^warning  %(pdf backend%): ignoring duplicate destination "
+                            .. "with the name '%-%.'",
+
+  "^Couldn't patch \\%S+",
+  "^Invalid UTF%-8 byte or sequence at line %d+ replaced by U%+FFFD%.",
+
+  '^Requested font ".-" at [%d%.]+pt\n'
+                            .. "Unknown feature %b`' in font %b`'%.\n"
+                            .. ' %-> ' .. filepat,
+}
+
+
+-- These messages may start anywhere in a line
+-- Always start these patterns with "^%s*", see lookahead().
+-- Order matters! The first match wins, so the longer ones should come first.
+anywhereWarningStringsHandler = stringsHandler:new()
+anywhereWarningStringsHandler.severity = WARNING
+anywhereWarningStringsHandler.patterns = {
+}
+
+
+-------------------------------------------------------------------------------
+-- missingCharHandler
+-- (from stringsHandler)
+--
+-- this differs from the prototype by severity level, the set of
+-- patterns to search for, and because it uses a different kind of
+-- Message object (we want to summarize missing characters specially)
+-------------------------------------------------------------------------------
+
+missingCharHandler = stringsHandler:new()
+missingCharHandler.severity = CRITICAL
+
+missingCharHandler.patterns = {
+  '^Missing character: There is no .- in font .*!',
+}
+
+function missingCharHandler:newMessage()
+  return missingCharMessage:new()
+end
+
+
+-------------------------------------------------------------------------------
+-- genericLatexHandler
+--
+-- Messages generated by GenericInfo, PackageWarning etc., such as
+--
+--   Package babel Info: \l@canadian = using hyphenrules for english
+--   (babel)             (\language0) on input line 102.
+--
+-- or
+--
+--   LaTeX Info: Redefining \setlength on input line 80.
+--
+-- These messages always start at the beginning of a line and end at the
+-- end of a line. There may be more than one line; subsequent lines have
+-- a specific prefix derived from the package/class name (which can be
+-- obtained from the first line). We look for this prefix to detect such
+-- subsequent lines.
+-------------------------------------------------------------------------------
+
+genericLatexHandler = HandlerPrototype:new()
+
+genericLatexHandler.patterns = {
+  "^(Package)%s+(%S+)%s+(%S+): ",
+  "^(Class)%s+(%S+)%s+(%S+): ",
+  "^(LaTeX)%s+(%S+)%s+(%S+): ",
+  "^(Module)%s+(%S+)%s+(%S+): ", -- Only ever saw "Module microtype Info"
+  "^(Package)%s+(%S+)%s+(notification) ", -- pgfplots does this
+}
+
+function genericLatexHandler:canDoit(position)
+  local line
+  if position == nil then position = 0 end
+  line = Lines:get(position)
+
+  local last, data
+
+  for _,pattern in ipairs(self.patterns) do
+      -- Because this is a prototype that may be used with
+      -- other patterns, we do not know how many captures
+      -- are there in the pattern; put them all in a table
+      data = {string.find(line, pattern)}
+      table.remove(data, 1) -- remove "first"
+      last = data[1]
+      if last ~= nil then break end
+  end
+
+  if last == nil then
+      return false, {}
+  else
+      return true, data
+  end
+end
+
+function genericLatexHandler:unpackData(data)
+  local last = data[1]
+  local what = data[2]
+  local name = data[3]
+  local severity = data[4]
+  self.message.what = what
+  self.message.name = name
+  self.message.severity = self:parseSeverity(severity)
+  self.message.content = Lines.current
+
+  self:findPrefix(last, name, what)
+  self.message.prefix = self.prefix
+end
+
+function genericLatexHandler:handleFirstLine()
+  local myTurn, data = self:canDoit()
+  if not myTurn then return false end
+
+  flushUnrecognizedMessages()
+  self:unwrapLines()
+
+  -- erase any previous values; nil is not a good idea! If one of these
+  -- is nil in a derived object, the object may grab the value of the
+  -- parent object from some previous message.
+  self.linenum = ""
+  self.prefix = ""
+
+  self.message = self:newMessage()
+  self.message.content = ""
+  self.message.severity = self.severity
+  self:unpackData(data) -- process whatever canDoit() gave us
+
+  self:extractLinenum()
+  Lines:handledChars()
+
+  self.doit = self.handleOtherLines
+  nextHandler = self
+  return true
+end
+
+genericLatexHandler.doit = genericLatexHandler.handleFirstLine
+
+function genericLatexHandler:handleOtherLines()
+  local _, last = string.find(Lines.current, '^' .. self.prefix)
+
+  if last ~= nil then
+      self:unwrapLines()
+      Lines:handledChars(last)
+      self:extractLinenum()
+
+      self.message.content = self.message.content .. '\n' .. Lines.current
+
+      Lines:handledChars()
+      nextHandler = self
+  else
+      self.doit = self.handleFirstLine
+      if self.linenum ~= "" then
+          self.message.linenum = self.linenum
+      end
+      self:adjustSeverity()
+      dispatch(self.message)
+  end
+
+  return true
+end
+
+function genericLatexHandler:findPrefix(lastcol, name, what)
+  -- continuation lines look like
+  -- ^(pkgname) [padding spaces] blah blah
+  -- let's find out how many spaces and
+  -- build the pattern for the prefix
+
+  local numspaces
+
+  if name ~= nil then
+      name = "(" .. name .. ")"
+      numspaces = lastcol - string.len(name)
+      self.prefix = protect_metachars(name)
+  else
+      self.prefix = ""
+      numspaces = lastcol
+  end
+
+  self.prefix = self.prefix .. string.rep(" ", numspaces)
+end
+
+function genericLatexHandler:extractLinenum()
+  if self.linenum ~= "" then return end
+
+  _, _, self.linenum = string.find(Lines.current, "on input line (%d+)%.")
+  if self.linenum ~= "" then return end
+
+  -- LaTeX3-style messages (with \msg_something)
+  _, _, self.linenum = string.find(Lines.current, "on line (%d+)$")
+end
+
+function genericLatexHandler:parseSeverity(severity)
+  if severity == nil or severity == "" then return self.severity end
+
+  severity = string.lower(severity)
+
+   -- tocbibind uses "Note"
+  if severity == 'info'
+          or severity == 'notification'
+          or severity == 'note'
+  then
+      return INFO
+  else
+      return WARNING
+  end
+end
+
+-- similar to HandlerPrototype:unwrapLines(), but with extra checks
+function genericLatexHandler:unwrapLines()
+  while Lines:seemsWrapped() do
+      -- The current line is the right length and other handlers do
+      -- not know how to handle the next line, but we still need to
+      -- check another possibility: the next line might be a "normal"
+      -- continuation line
+      local first = string.find(Lines:get(1), '^' .. self.prefix)
+      if first ~= nil then break end
+
+      -- Ok, this is almost certainly a wrapped line, but it does
+      -- not hurt to also check this just in case
+      first = string.find(Lines.current, 'on input line %d+%.$')
+      if first ~= nil then break end
+
+      Lines:unwrapOneLine()
+  end
+end
+
+-- LaTeX only uses severity "INFO" and "WARNING", which
+-- is very limited. Let's demote some warnings to INFO
+-- and promote some others to CRITICAL.
+function genericLatexHandler:adjustSeverity()
+  for _, pat in ipairs(self.downgradePatterns) do
+      local first = string.find(self.message.content, pat)
+      if first ~= nil then
+          self.message.severity = INFO
+          break
+      end
+  end
+
+  for _, pat in ipairs(self.upgradePatterns) do
+      local first = string.find(self.message.content, pat)
+      if first ~= nil then
+          self.message.severity = CRITICAL
+          break
+      end
+  end
+end
+
+genericLatexHandler.downgradePatterns = {
+    -- No need to include the full message
+    "File %b`' already exists on the system%."
+            .. "%s*Not generating it from",
+    "You have requested package %b`',"
+            .. "%s*but the package provides",
+    "Writing file %b`'",
+    "Form Feed has been converted to Blank",
+    "Tab has been converted to Blank",
+    "The morewrites package is unnecessary",
+    'Unused \\captionsetup%b[]',
+}
+
+genericLatexHandler.upgradePatterns = {
+    "Label %b`' multiply defined",
+    "Command .- invalid in math mode",
+    "Optional argument of \\twocolumn too tall on page",
+    "Marginpar on page %S- moved",
+    "Some font shapes were not available, defaults substituted%.",
+    "Font shape %b`' in size %b<> not available"
+            .. "%s+Font shape %b`' tried instead",
+    "Font shape %b`' in size %S+ not available"
+            .. "%s+external font %b`' used",
+    "Font shape %b`' undefined"
+            .. "%s+using %b`' instead",
+}
+
+
+-------------------------------------------------------------------------------
+-- latex23MessageHandler
+-- genericLatexVariantHandler
+-- (from genericLatexHandler)
+--
+-- They differ from the prototype by the set of patterns to search for and by
+-- the unpackData() method, which deals with the specific pattern captures
+-- defined in the search patterns.
+-------------------------------------------------------------------------------
+
+latex23MessageHandler = genericLatexHandler:new()
+
+latex23MessageHandler.patterns = {
+  "^(LaTeX3?)%s+(%S+): "
+}
+
+function latex23MessageHandler:unpackData(data)
+  local last = data[1]
+  local what = data[2]
+  local severity = data[3]
+  self.message.severity = self:parseSeverity(severity)
+  self.message.what = what
+  self.message.content = Lines.current
+
+  local name
+  -- When the message looks like "LaTeX...", there is no package
+  -- name, but with "LaTeX3...", that is used as the name
+  if what == 'LaTeX3' then name = 'LaTeX3' end
+
+  self:findPrefix(last, name, what)
+  self.message.prefix = self.prefix
+end
+
+genericLatexVariantHandler = genericLatexHandler:new()
+
+genericLatexVariantHandler.patterns = {
+  "^(Package) (%S+) (%S+) on input line (%S+): ",
+}
+
+function genericLatexVariantHandler:unpackData(data)
+  local last = data[1]
+  local what = data[2]
+  local name = data[3]
+  local severity = data[4]
+  self.linenum = data[5]
+  self.message.what = what
+  self.message.name = name
+  self.message.severity = self:parseSeverity(severity)
+  self.message.content = Lines.current
+
+  self:findPrefix(last, name, what)
+  self.message.prefix = self.prefix
+end
+
+
+-------------------------------------------------------------------------------
+-- citationHandler
+-- referenceHandler
+-- labelHandler
+-- (from genericLatexHandler)
+--
+-- They differ from the prototype by the set of patterns to search for, by
+-- the unpackData() method, and by the message type generated, because we
+-- want to generate dedicated summaries for them
+-------------------------------------------------------------------------------
+citationHandler = genericLatexHandler:new()
+
+citationHandler.patterns = {
+  "^(LaTeX)%s+(Warning): (Citation) (%b`') on page (.-) undefined",
+  "^(LaTeX)%s+(Warning): (Citation) (%b`') undefined",
+}
+
+function citationHandler:unpackData(data)
+  local last = data[1]
+  local what = data[2]
+  local severity = data[3]
+  local name = data[4]
+  local key = string.sub(data[5], 2, -2) -- remove quotes
+  local page = data[6] -- may be null
+
+  self.message.what = what
+  self.message.name = name
+  self.message.severity = self:parseSeverity(severity)
+  self.message.key = key
+  self.message.page = page
+  self.message.content = Lines.current
+  self:findPrefix(last, nil, what)
+  self.message.prefix = self.prefix
+end
+
+function citationHandler:newMessage()
+  return citationMessage:new()
+end
+
+referenceHandler = citationHandler:new()
+
+referenceHandler.patterns = {
+  "^(LaTeX)%s+(Warning): (Reference) (%b`') on page (.-) undefined",
+}
+
+function referenceHandler:newMessage()
+  return referenceMessage:new()
+end
+
+labelHandler = citationHandler:new()
+
+labelHandler.patterns = {
+  "^(LaTeX)%s+(Warning): (Label) (%b`') multiply defined",
+}
+
+function labelHandler:newMessage()
+  return labelMessage:new()
+end
+
+
+-------------------------------------------------------------------------------
+-- providesHandler
+-- (from genericLatexHandler)
+--
+-- Handles the lines generated by the \Provides* LaTeX commands, such as:
+--
+--   Package: etoolbox 2020/10/05 v2.5k e-TeX tools for LaTeX (JAW)
+--
+-- or
+--
+--   File: size11.clo 2020/04/10 v1.4m Standard LaTeX file (size option)
+--
+-- There is code to specifically handle a hardcoded line break
+-- in a few packages (atbegshi-ltx, atveryend-ltx etc.)
+-------------------------------------------------------------------------------
+
+providesHandler = genericLatexHandler:new()
+providesHandler.severity = INFO
+
+providesHandler.patterns = {
+  "^(Document Class):%s+(%S+)%s+",
+  "^(Package):%s+(%S+)%s+",
+  "^(File):%s+(%S+)%s+",
+  "^(Language):%s+(%S+)%s+", -- this and the next come from babel
+  "^(Dictionary):%s+(%S+)%s+"
+}
+
+function providesHandler:unpackData(data)
+  local last = data[1]
+  local what = data[2]
+  local name = data[3]
+
+  self.message.what = what
+  self.message.name = name
+  self.message.content = Lines.current
+
+  -- There are no continuation lines of this kind for
+  -- these messages, but the generic code still wants
+  -- to check for the prefix.
+  self.prefix = '[^%s%S]+' -- nothing matches
+
+  if not Lines:empty() then
+      local first = string.find(Lines:get(1), 'with kernel methods')
+      if first ~= nil then
+          self.message.content = self.message.content .. ' ' .. Lines:get(1)
+          Lines:gotoNextLine()
+      end
+  end
+  self.message.content = string.gsub(self.message.content,
+                        '%s*with kernel methods', ' with kernel methods')
+end
+
+
+-------------------------------------------------------------------------------
+-- geometryDetailsHandler
+-- (from genericLatexHandler)
+--
+-- Handles the output from the geometry package with the "verbose" option.
+-- Iinheriting from genericLatexHandler is a little hackish, since
+-- the message does not really fit the "standard" message format (we define
+-- the prefix statically instead of computing it from the message itself),
+-- but works well and is simple.
+-------------------------------------------------------------------------------
+
+geometryDetailsHandler = genericLatexHandler:new()
+geometryDetailsHandler.severity = INFO
+
+geometryDetailsHandler.patterns = {
+    '^%*geometry%* verbose mode',
+}
+
+function geometryDetailsHandler:unpackData(data)
+  self.message.name = 'geometry'
+  self.message.content = Lines.current
+  self.prefix = '* '
+  self.message.prefix = self.prefix
+end
+
+-------------------------------------------------------------------------------
+-- openParensHandler
+-- closeParensHandler
+-- openSquareBracketHandler
+-- closeSquareBracketHandler
+--
+-- These determine whether the chars "(", ")", "[", and "]" are ordinary
+-- characters or if they indicate open/close file or begin/end shipout.
+-- Detecting files allows us to filter the output according to which file
+-- is being processed; detecting shipouts allows us to indicate the page
+-- that a message originated from.
+--
+-- Although openParensHandler is very similar to openSquareBracketsHandler
+-- and closeParensHandler is very similar to closeSquareBracketsHandler,
+-- we decided not to use inheritance to reuse the code (except for the
+-- lookahead() method). We would avoid a little repetition, but the code
+-- size would probably be the same and it would be more complex.
+--
+-- The fact that the code is similar may seem a little odd at first: While
+-- the openFiles stack may contain many entries (because an open file may
+-- request to open another file etc.), the same is obviously not true for
+-- the shipouts stack. Still, we use a stack too because we need to handle
+-- "[" and "]" characters that do not correspond to real shipouts, just
+-- like we do with "(" and ")".
+-------------------------------------------------------------------------------
+
+openCloseHandlerPrototype = HandlerPrototype:new()
+
+-- Just like :canDoit(), but does not anchor patterns to the
+-- beginning of the line (used by handleUnrecognizedMessage).
+-- Notice the similarity to stringsHandler:lookahead().
+function openCloseHandlerPrototype:lookahead()
+    self.pattern = self.loosePattern
+    match, data = self:canDoit()
+    self.pattern = self.strictPattern
+
+    return match, data
+end
+
+openParensHandler = openCloseHandlerPrototype:new()
+
+openParensHandler.strictPattern = "^(%s*)%("
+openParensHandler.loosePattern = "%s*%("
+openParensHandler.pattern = openParensHandler.strictPattern
+
+function openParensHandler:canDoit(position)
+  local line
+  if position == nil then position = 0 end
+  line = Lines:get(position)
+
+  local first, last = string.find(line, self.pattern)
+  if first == nil then return false, {} end
+
+  line = string.sub(line, last +1)
+
+  local filename = guessFilename(position)
+
+  return true, {first = first, filename = filename} -- might be nil
+end
+
+function openParensHandler:doit()
+  local myTurn, data = self:canDoit()
+  if not myTurn then return false end
+
+  local _, last, spaces = string.find(Lines.current, self.pattern)
+  unrecognizedBuffer = unrecognizedBuffer .. spaces
+
+  -- skip the spaces and the open parens character
+  Lines:handledChars(last)
+
+  if data.filename ~= nil then
+      flushUnrecognizedMessages()
+      local last = unwrapUntilStringMatches(data.filename)
+      if last == nil then
+          io.stderr:write("    texlogsieve: parsing error\n")
+      else
+          Lines:handledChars(last)
+      end
+      openFiles:push(data.filename)
+      mute = currentFileIsSilenced()
+      local msg = openFileMessage:new()
+      msg.severity = DEBUG
+      msg.filename = data.filename
+      msg.content = "Open file " .. data.filename
+      dispatch(msg)
+  else
+      openFiles:push("DUMMY")
+      unrecognizedBuffer = unrecognizedBuffer .. "("
+  end
+
+  return true
+end
+
+closeParensHandler = openCloseHandlerPrototype:new()
+
+closeParensHandler.strictPattern = "^(%s*)%)"
+closeParensHandler.loosePattern = "%s*%)"
+closeParensHandler.pattern = closeParensHandler.strictPattern
+
+function closeParensHandler:canDoit(position)
+  local line
+  if position == nil then position = 0 end
+  line = Lines:get(position)
+
+  local first = string.find(line, self.pattern)
+  if first == nil then return false, {} end
+
+  return true, {first = first}
+end
+
+function closeParensHandler:doit()
+  local myTurn = self:canDoit()
+  if not myTurn then return false end
+
+  local _, last, spaces = string.find(Lines.current, self.pattern)
+  unrecognizedBuffer = unrecognizedBuffer .. spaces
+
+  -- skip the spaces and the close parens character
+  Lines:handledChars(last)
+
+  local filename = openFiles:pop()
+  if filename == nil or filename == "DUMMY" then
+      unrecognizedBuffer = unrecognizedBuffer .. ")"
+  else
+      flushUnrecognizedMessages()
+      local msg = closeFileMessage:new()
+      msg.severity = DEBUG
+      msg.content = "Close file " .. filename
+      dispatch(msg)
+      mute = currentFileIsSilenced()
+  end
+
+  return true
+end
+
+openSquareBracketHandler = openCloseHandlerPrototype:new()
+
+openSquareBracketHandler.strictPattern = "^(%s*)%["
+openSquareBracketHandler.loosePattern = "%s*%["
+openSquareBracketHandler.pattern = openSquareBracketHandler.strictPattern
+
+function openSquareBracketHandler:canDoit(position)
+  local line
+  if position == nil then position = 0 end
+  line = Lines:get(position)
+
+  local first, last = string.find(line, self.pattern)
+  if first == nil then return false, {} end
+
+  line = string.sub(line, last +1)
+
+  local latexPage = guessShipoutPage(position)
+
+  return true, {first = first, latexPage = latexPage} -- may be nil
+end
+
+function openSquareBracketHandler:doit()
+  local myTurn, data = self:canDoit()
+  if not myTurn then return false end
+
+  local _, last, spaces = string.find(Lines.current, self.pattern)
+  unrecognizedBuffer = unrecognizedBuffer .. spaces
+
+  -- skip the spaces and the open square bracket character
+  Lines:handledChars(last)
+
+  if data.latexPage ~= nil then
+      flushUnrecognizedMessages()
+      local last = unwrapUntilStringMatches(data.latexPage)
+      if last == nil then
+          io.stderr:write("    texlogsieve: parsing error\n")
+      else
+          Lines:handledChars(last)
+      end
+      shipouts:push(data.latexPage)
+      numShipouts = numShipouts +1
+      table.insert(latexPages, numShipouts, data.latexPage)
+      local msg = beginShipoutMessage:new()
+      msg.physicalPage = numShipouts
+      dispatch(msg)
+  else
+      shipouts:push("DUMMY")
+      unrecognizedBuffer = unrecognizedBuffer .. "["
+  end
+
+  return true
+end
+
+closeSquareBracketHandler = openCloseHandlerPrototype:new()
+
+closeSquareBracketHandler.strictPattern = "^(%s*)%]"
+closeSquareBracketHandler.loosePattern = "%s*%]"
+closeSquareBracketHandler.pattern = closeSquareBracketHandler.strictPattern
+
+function closeSquareBracketHandler:canDoit(position)
+  local line
+  if position == nil then position = 0 end
+  line = Lines:get(position)
+
+  local first = string.find(line, self.pattern)
+  if first == nil then return false, {} end
+
+  return true, {first = first}
+end
+
+function closeSquareBracketHandler:doit()
+  local myTurn = self:canDoit()
+  if not myTurn then return false end
+
+  local _, last, spaces = string.find(Lines.current, self.pattern)
+  unrecognizedBuffer = unrecognizedBuffer .. spaces
+
+  -- skip the spaces and the close square bracket character
+  Lines:handledChars(last)
+
+  local latexPage = shipouts:pop()
+  if latexPage == nil or latexPage == "DUMMY" then
+      unrecognizedBuffer = unrecognizedBuffer .. "]"
+  else
+      flushUnrecognizedMessages()
+      local msg = endShipoutMessage:new()
+      msg.physicalPage = numShipouts
+      dispatch(msg)
+  end
+end
+
+
+-------------------------------------------------------------------------------
+-- utf8FontMapHandler
+--
+-- This handles the encoding-related multi-line messages generated by
+-- inputenc/fontenc with pdftex and utf8, similar to:
+--
+--   Now handling font encoding LS1 ...
+--   ... no UTF-8 mapping file for font encoding LS1
+--
+-- or
+--
+--   Now handling font encoding LY1 ...
+--   ... processing UTF-8 mapping file for font encoding LY1
+--      defining Unicode char U+00A0 (decimal 160)
+--
+-- We could handle these by inheriting from genericLatexHandler, which
+-- might be a good idea as this handler is quite complex. Still, the
+-- advantage of this handler is that it groups the first lines (that
+-- indicate the encoding) and the continuation lines as a unit, even
+-- though there are other messages in between that are handled by other
+-- handlers. We use two strategies to deal with continuation lines to
+-- accomplish this:
+--
+--  1. After the first line, we change the self.doit method and define
+--     ourselves as nextHandler, because we know the next line "belongs"
+--     to us (nothing new here, genericLatexHandler does this too)
+--
+--  2. After the second line, we do not know whether the next line "belongs"
+--     to us (actually, it most likely does not). So, we just change the
+--     self.doit method and wait to be called by chooseHandler() again a
+--     few lines down the road. When one of the patterns we are looking for
+--     matches, we are back in business. This is why handleOtherLines must
+--     check for the base "Now handling font encoding" pattern too: there
+--     might not be continuation lines and we need to handle a new message
+--     instead at some other point in the input file.
+-------------------------------------------------------------------------------
+
+utf8FontMapHandler = HandlerPrototype:new()
+
+-- we repeat here the tests we make on the other methods of this
+-- object, which is somewhat dirty.
+function utf8FontMapHandler:canDoit(position)
+  local line
+  if position == nil then position = 0 end
+  line = Lines:get(position)
+
+  local first, encoding
+  if self.doit == self.handleFirstLine then
+      first, _, encoding = string.find(line,
+              "^Now handling font encoding (%S+) %.%.%.")
+  elseif self.doit == self.handleSecondLine then
+      first = string.find(line,
+              "^%.%.%. no UTF%-8 mapping file for font encoding")
+
+      if first == nil then
+          first = string.find(
+                  "^%.%.%. processing UTF%-8 mapping file for font encoding")
+      end
+  else
+      first = string.find(line, "^%s*defining Unicode char")
+  end
+
+  if first == nil then
+      return false, {}
+  else
+      return true, {encoding = encoding}
+  end
+end
+
+function utf8FontMapHandler:handleFirstLine()
+  local myTurn, data = self:canDoit()
+  if not myTurn then return false end
+
+  flushUnrecognizedMessages()
+  self.message = Message:new()
+  self.message.severity = DEBUG
+  self.message.content = Lines.current
+  self.message.encoding = data.encoding
+  Lines:handledChars()
+  self.encoding = data.encoding
+  self.doit = self.handleSecondLine
+  nextHandler = self
+  return true
+end
+
+utf8FontMapHandler.doit = utf8FontMapHandler.handleFirstLine
+
+function utf8FontMapHandler:handleSecondLine()
+  local first = string.find(Lines.current,
+                      "^%.%.%. no UTF%-8 mapping file for font encoding")
+
+  if first ~= nil then
+      self.message.content = self.message.content .. '\n' .. Lines.current
+      Lines:handledChars()
+      dispatch(self.message)
+      self.doit = self.handleFirstLine
+      return true
+  end
+
+  first = string.find(Lines.current,
+                "^%.%.%. processing UTF%-8 mapping file for font encoding")
+
+  if first ~= nil then
+      self.message.content = self.message.content .. '\n' .. Lines.current
+      Lines:handledChars()
+      self.doit = self.handleOtherLines
+      self.numTries = 0
+      self.foundOtherLines = false
+      return true
+  end
+
+  -- The second line was neither "no UTF-8 mapping..." nor
+  -- "processing UTF-8 mapping" - this should never happen
+  dispatch(self.message)
+  io.stderr:write("    texlogsieve: parsing error\n")
+  Lines:handledChars()
+  self.doit = self.handleFirstLine
+  return true
+end
+
+-- Between handleSecondLine and handleOtherLines there usually are two
+-- messages: "open file ENCenc.dfu" and "ProvidesFile ENCenc.dfu".
+-- Therefore, we try to find the first "...defining Unicode char"
+-- message for the following 4 lines before giving up.
+function utf8FontMapHandler:handleOtherLines()
+  local first = string.find(Lines.current, "^%s*defining Unicode char")
+
+  if first ~= nil then
+      flushUnrecognizedMessages()
+      self.foundOtherLines = true
+      self.message.content = self.message.content .. '\n' .. Lines.current
+      Lines:handledChars()
+      nextHandler = self
+      return true
+  end
+
+  -- this line does not match; why? First possibility: there are no
+  -- "...defining Unicode char" lines to be found; instead, there is
+  -- another encoding being defined. This obviously should not happen
+  first = string.find(Lines.current,
+                   "^Now handling font encoding (%S+) %.%.%.")
+
+  if first ~=nil then
+      -- give up and start processing the new message (should not happen)
+      dispatch(self.message)
+      flushUnrecognizedMessages()
+      io.stderr:write("    texlogsieve: parsing error\n")
+
+      self.numTries = 0
+      self.foundOtherLines = false
+      self.doit = self.handleFirstLine
+      return self:handleFirstLine()
+  end
+
+  -- second possibility: we have not yet reached the first "...defining
+  -- Unicode char" message, but we want to try again in the next line
+  if not self.foundOtherLines and self.numTries < 4 then
+      self.numTries = self.numTries +1
+      return false, {} -- we will try again later; for now, call chooseHandler()
+  end
+
+  -- third possibility: we never reached any "...defining Unicode char" line
+  -- but we already tried for too many lines (more than 4), so give up and
+  -- do nothing (we might output a "parsing error" message, but that is
+  -- probably unnecessary)
+
+  -- fourth possibility: we already found all lines, so
+  -- we are done and there is no need to do anything else
+
+  -- wrap up for the third and fourth possibilities
+  dispatch(self.message)
+  self.doit = self.handleFirstLine
+  self.numTries = 0
+  self.foundOtherLines = false
+  return true
+end
+
+
+--[[ ##################################################################### ]]--
+--[[ ############################# MESSAGES ############################## ]]--
+--[[ ##################################################################### ]]--
+
+Message = {}
+
+function Message:new()
+  local o = {}
+  setmetatable(o, self)
+  self.__index = self
+  o.mute = mute
+  o.content = ""
+  o.prefix = ""
+  if openFiles ~= nil and not openFiles:empty() then
+      o.filename = openFiles:peek()
+  end
+  return o
+end
+
+Message.severity = UNKNOWN
+
+function Message:toString()
+    if self.mute then return "" end
+
+    -- If we've already been here, just output the previous result
+    if self.formatted ~= nil then return self.formatted end
+
+    self.formatted = self:realToString()
+    if trim(self.formatted) == "" then self.formatted = "" return "" end
+
+    for _, val in ipairs(SILENCE_STRINGS) do
+        local first = string.find(self.formatted, val)
+        local other = string.find(self.content, val)
+        if first ~= nil or other ~= nil then self.formatted = "" return "" end
+    end
+
+    if self.name ~= nil then
+        for _, val in ipairs(SILENCE_PKGS) do
+            if self.name == val then self.formatted = "" return "" end
+        end
+    end
+
+    if self.severity < MINLEVEL then self.formatted = "" return "" end
+
+    return self.formatted
+end
+
+function Message:realToString()
+  if self.prefix == "" then return self.content end
+
+  local lines = linesToTable(self.content)
+  local msg = table.remove(lines, 1)
+  for _, line in ipairs(lines) do
+      msg = msg .. '\n' .. unprotect_metachars(self.prefix) .. line
+  end
+  return msg
+end
+
+function Message:toSummary()
+  local formatted = self:toString()
+  if string.len(trim(formatted)) == 0 then return end
+
+  repetitionsSummary:add(self)
+end
+
+
+function currentFileIsSilenced()
+  if openFiles:empty() then return false end
+
+  local filename = openFiles:peek()
+  local _, last = string.find(filename, '^.*/') -- get just the basename
+  if last ~= nil then filename = string.sub(filename, last +1) end
+  for _, pattern in ipairs(SEMISILENCE_FILES) do
+      local first = string.find(filename, pattern)
+      if first ~= nil then return true end
+  end
+
+  -- This is O(n*m) and gets executed for every message,
+  -- but "n" and "m" are unlikely to grow much beyond 10.
+  for _, filename in ipairs(openFiles) do
+      -- get just the basename
+      local basename = filename
+      local _, last = string.find(basename, '^.*/')
+      if last ~= nil then basename = string.sub(basename, last +1) end
+
+      for _, pattern in ipairs(SILENCE_FILES_RECURSIVE) do
+          _, last = string.find(basename, pattern)
+          if last ~= nil then return true end
+      end
+  end
+
+  return false
+end
+
+
+beginShipoutMessage = Message:new()
+function beginShipoutMessage:realToString()
+  if not SHOW_SHIPOUTS then return "" end
+
+  if RAW then return '[' .. latexPages[self.physicalPage] end
+
+  return ""
+end
+
+
+endShipoutMessage = Message:new()
+endShipoutMessage.shipout = true
+function endShipoutMessage:realToString()
+  if not SHOW_SHIPOUTS then return "" end
+
+  if RAW then return ']' end
+
+  -- print counter as [cnt], just as LaTeX does. With that, if a program is
+  -- monitoring output, it can show some sort of progress bar to the user
+  local msg = 'shipout - physical page ' .. self.physicalPage
+              .. ', LaTeX page counter ['
+              .. latexPages[self.physicalPage] .. ']'
+
+  return msg
+end
+
+
+openFileMessage = Message:new()
+function openFileMessage:realToString()
+  if RAW then return "(" .. self.filename end
+
+  return Message.realToString(self)
+end
+
+
+closeFileMessage = Message:new()
+function closeFileMessage:realToString()
+  if RAW then return ")" end
+
+  return Message.realToString(self)
+end
+
+
+underOverMessage = Message:new()
+underOverMessage.severity = WARNING
+function underOverMessage:realToString()
+    local tmp = self.content
+    if self.failedText ~= nil then
+        if not RAW then tmp = tmp .. '\nOffending text:' end
+        tmp = tmp .. '\n' .. self.failedText .. '\n'
+    end
+
+    -- in raw mode, add the final "[]"
+    if RAW and self.closing ~= nil then
+        tmp = tmp .. ' ' .. self.closing .. '\n'
+    end
+
+    return tmp
+end
+
+function underOverMessage:toSummary()
+    underOverSummary:add(self)
+end
+
+
+missingCharMessage = Message:new()
+
+-- This is a hack: it would be too painful to define
+-- pattern captures in the handler, so we do this here
+function missingCharMessage:realToString()
+  if self.char == nil then
+      _, _, self.char, self.font = string.find(self.content,
+                        '^Missing character: There is no (.-) in font (.*)!')
+  end
+
+  return self.content
+end
+
+function missingCharMessage:toSummary()
+  missingCharSummary:add(self)
+end
+
+
+citationMessage = Message:new()
+function citationMessage:toSummary()
+  citationsSummary:add(self)
+end
+
+referenceMessage = Message:new()
+function referenceMessage:toSummary()
+  referencesSummary:add(self)
+end
+
+labelMessage = Message:new()
+function labelMessage:toSummary()
+  labelsSummary:add(self)
+end
+
+
+--[[ ##################################################################### ]]--
+--[[ ############################ SUMMARIES ############################## ]]--
+--[[ ##################################################################### ]]--
+
+-- A Summary handles a class of messages (for example, undefined citations).
+-- Some of these messages may be repeated (such as one specicic undefined
+-- citation that appears multiple times). We want to mention each repeated
+-- group as a single item ("citation blah undefined in pages X, Y, and Z").
+-- Therefore, we make self.messages a list of lists: Each "sub-list" holds
+-- the messages that correspond to a specific message content (such as a
+-- specific undefined citation).
+SummaryPrototype = {}
+
+function SummaryPrototype:new()
+  local o = {}
+  setmetatable(o, self)
+  self.__index = self
+  o.messages = {}
+  o.header = ""
+  return o
+end
+
+function SummaryPrototype:add(msg)
+  -- group messages by message content
+  local formatted = msg:toString()
+
+  if self.messages[formatted] == nil then
+      self.messages[formatted] = {}
+  end
+
+  table.insert(self.messages[formatted], msg)
+end
+
+function SummaryPrototype:toString()
+  -- check if the table is empty - https://stackoverflow.com/a/1252776
+  if next(self.messages) == nil then return "" end
+
+  local text = self:processAllMessages()
+
+  if text == "" then return "" end -- happens with repetitionsSummary
+
+  return self.header .. text
+end
+
+-- as mentioned above, self.messages holds a list of lists, such as
+-- all the "undefined reference blah" messages in one sublist and
+-- all the "undefined reference bleh" messages in another; process
+-- each sublist separately and concatenate the results. We sort
+-- because otherwise the order of the reports changes with each
+-- execution, which makes comparing outputs harder.
+function SummaryPrototype:processAllMessages()
+  local allText = ""
+  for _, messagesSublist in pairsSortedByKeys(self.messages) do
+      local tmp = self:processSingleMessageList(messagesSublist)
+      if tmp ~= "" then
+          allText = allText .. '\n\n' .. tmp
+      end
+  end
+
+  -- remove leading '\n\n'
+  return string.sub(allText, 3)
+end
+
+-- This is where we process each individual sublist, generating
+-- something like "undefined reference blah in pages X, Y Z".
+-- This obviously depends on the type of summary.
+function SummaryPrototype:processSingleMessageList(messages)
+  return ""
+end
+
+-- This receives a list of (equal) messages and returns
+-- the list of pages and files where they were found.
+function SummaryPrototype:pageAndFileList(messages)
+
+    -- Build a Set with the page numbers to eliminate repetitions...
+    local pages = {}
+    local files = {}
+    for _, msg in ipairs(messages) do
+        pages[msg.physicalPage] = true
+        if msg.filename ~= nil then
+            files[msg.filename] = true
+        end
+    end
+
+    -- and convert it to a "normal" table so we can sort it
+    local tmp = {}
+    for page, _ in pairs(pages) do -- not ipairs!
+        table.insert(tmp, page)
+    end
+    pages = tmp
+    table.sort(pages)
+
+    tmp = {}
+    for file, _ in pairs(files) do
+        table.insert(tmp, file)
+    end
+    files = tmp
+    table.sort(files)
+
+    -- Now turn these into strings
+    tmp = ""
+    for _, page in ipairs(pages) do
+        tmp = tmp .. ", " .. page
+    end
+    pages = tmp
+
+    local _, last = string.find(pages, '^, ')
+    if last ~= nil then pages = string.sub(pages, last +1) end
+
+    local tmp = ""
+    for _, file in ipairs(files) do
+        tmp = tmp .. ", " .. file
+    end
+    files = tmp
+
+    local _, last = string.find(files, '^, ')
+    if last ~= nil then files = string.sub(files, last +1) end
+
+    return pages, files
+end
+
+
+repetitionsSummary = SummaryPrototype:new()
+repetitionsSummary.header = 'Repeated messages:\n'
+
+function repetitionsSummary:toString()
+  if not SILENCE_REPETITIONS then return "" end
+
+  return SummaryPrototype.toString(self)
+end
+
+function repetitionsSummary:processSingleMessageList(messages)
+  local text = ""
+  if #messages > 1 then
+      local pages, files = self:pageAndFileList(messages)
+      local content = messages[1]:toString()
+
+      text = content .. '\n'
+             .. 'in pages ' .. pages
+             .. " (files " .. files .. ") - "
+             .. #messages .. ' repetitions'
+  end
+
+  return text
+end
+
+
+missingCharSummary = SummaryPrototype:new()
+missingCharSummary.header = 'Missing characters:\n'
+
+function missingCharSummary:processSingleMessageList(messages)
+  local text = ""
+  local pages, files = self:pageAndFileList(messages)
+  local char = messages[1].char
+  local font = messages[1].font
+
+  text = 'char ' .. char .. ', font ' .. font .. '\n'
+         .. 'in pages ' .. pages .. " (files " .. files .. ")"
+
+  return text
+end
+
+
+citationsSummary = SummaryPrototype:new()
+citationsSummary.header = 'Undefined citations:\n'
+
+function citationsSummary:add(msg)
+  -- group messages by problem key. We do not use msg:toString()
+  -- here because some messages may include the page number, making
+  -- messages that are otherwise the same appear to be different.
+  local key = msg.key
+
+  if self.messages[key] == nil then
+      self.messages[key] = {}
+  end
+
+  table.insert(self.messages[key], msg)
+end
+
+function citationsSummary:processSingleMessageList(messages)
+  local text = ""
+  local pages, files = self:pageAndFileList(messages)
+  local key = messages[1].key
+
+  text = key .. '\n'
+         .. 'in pages ' .. pages .. " (files " .. files .. ")"
+
+  return text
+end
+
+
+referencesSummary = citationsSummary:new()
+referencesSummary.header = 'Undefined references:\n'
+
+
+labelsSummary = citationsSummary:new()
+labelsSummary.header = 'Multiply defined labels:\n'
+
+
+-- This is a little different from the others; we do not want to
+-- treat different messages differently, only report that there were
+-- under/overfull boxes in pages X, Y, and Z. So we store messages
+-- directly in self.messages instead of using sublists.
+underOverSummary = SummaryPrototype:new()
+
+function underOverSummary:add(msg)
+  table.insert(self.messages, msg)
+end
+
+function underOverSummary:toString()
+  if #self.messages == 0 then return "" end
+
+  local pages, files = self:pageAndFileList(self.messages)
+
+  return "Under/overfull boxes in pages "
+             .. pages .. " (files " .. files .. ")"
+end
+
+
+--[[ ##################################################################### ]]--
+--[[ ########################## AUXILIARY STUFF ########################## ]]--
+--[[ ##################################################################### ]]--
+
+function protect_metachars(s)
+  s = string.gsub(s, "%%", "%%%%")
+  s = string.gsub(s, "%(", "%%(")
+  s = string.gsub(s, "%)", "%%)")
+  s = string.gsub(s, "%.", "%%.")
+  s = string.gsub(s, "%+", "%%+")
+  s = string.gsub(s, "%-", "%%-")
+  s = string.gsub(s, "%*", "%%*")
+  s = string.gsub(s, "%?", "%%?")
+  s = string.gsub(s, "%[", "%%[")
+  s = string.gsub(s, "%^", "%%^")
+  s = string.gsub(s, "%$", "%%$")
+  return s
+end
+
+function unprotect_metachars(s)
+  s = string.gsub(s, "%%%$", "$")
+  s = string.gsub(s, "%%%^", "^")
+  s = string.gsub(s, "%%%[", "[")
+  s = string.gsub(s, "%%%?", "?")
+  s = string.gsub(s, "%%%*", "*")
+  s = string.gsub(s, "%%%-", "-")
+  s = string.gsub(s, "%%%+", "+")
+  s = string.gsub(s, "%%%.", ".")
+  s = string.gsub(s, "%%%)", ")")
+  s = string.gsub(s, "%%%(", "(")
+  s = string.gsub(s, "%%%%", "%%")
+  return s
+end
+
+function trim(s) return (string.gsub(s, '^%s*(.-)%s*$', '%1')) end
+
+function stringToPattern(s)
+  local first, _ = string.find(s, '^////')
+  local pat
+  if first ~= nil then
+      pat = string.sub(s, 5)
+  else
+      pat = protect_metachars(s)
+      pat = string.gsub(pat, "%s+", "%%s+")
+  end
+
+  return pat
+end
+
+-- Given a string with multiple lines, returns
+-- a table in which each line is an element
+function linesToTable(s)
+  local size = string.len(s)
+  local i = 1
+  local lines = {}
+  while i < size do
+      -- check \r in case the user added to this file a pattern
+      -- with an embedded dos-style "CR LF" sequence.
+      local first, last, line = string.find(s, '(.-)[\r]?\n', i)
+
+      if first == nil then
+          table.insert(lines, string.sub(s, i))
+          i = size
+      else
+          table.insert(lines, line)
+          i = last +1
+      end
+  end
+  return lines
+end
+
+-- copied verbatim from https://www.lua.org/pil/19.3.html
+function pairsSortedByKeys (t, f)
+      local a = {}
+      for n in pairs(t) do table.insert(a, n) end
+      table.sort(a, f)
+      local i = 0      -- iterator variable
+      local iter = function ()   -- iterator function
+        i = i + 1
+        if a[i] == nil then return nil
+        else return a[i], t[a[i]]
+        end
+      end
+      return iter
+    end
+
+
+--[[ ##### STACK ##### ]]--
+
+Stack = {}
+
+function Stack:new()
+  local o = {}
+  setmetatable(o, self)
+  self.__index = self
+  return o
+end
+
+function Stack:push(val)
+  table.insert(self, val)
+end
+
+function Stack:pop()
+  if #self > 0 then
+      return table.remove(self)
+  else
+      return nil
+  end
+end
+
+function Stack:peek()
+  return self[#self]
+end
+
+function Stack:size()
+  return #self
+end
+
+function Stack:empty()
+    return #self == 0
+end
+
+
+--[[ ##### GLOBTOPATTERN ##### ]]--
+
+-- convert a file glob to a lua pattern
+
+-- globtopattern (c) 2008-2011 David Manura.  Licensed under the same terms as Lua (MIT).
+-- copied verbatim from https://github.com/davidm/lua-glob-pattern
+
+function globtopattern(g)
+  -- Some useful references:
+  -- - apr_fnmatch in Apache APR.  For example,
+  --   http://apr.apache.org/docs/apr/1.3/group__apr__fnmatch.html
+  --   which cites POSIX 1003.2-1992, section B.6.
+
+  local p = "^"  -- pattern being built
+  local i = 0    -- index in g
+  local c        -- char at index i in g.
+
+  -- unescape glob char
+  local function unescape()
+    if c == '\\' then
+      i = i + 1; c = g:sub(i,i)
+      if c == '' then
+        p = '[^]'
+        return false
+      end
+    end
+    return true
+  end
+
+  -- escape pattern char
+  local function escape(c)
+    return c:match("^%w$") and c or '%' .. c
+  end
+
+  -- Convert tokens at end of charset.
+  local function charset_end()
+    while 1 do
+      if c == '' then
+        p = '[^]'
+        return false
+      elseif c == ']' then
+        p = p .. ']'
+        break
+      else
+        if not unescape() then break end
+        local c1 = c
+        i = i + 1; c = g:sub(i,i)
+        if c == '' then
+          p = '[^]'
+          return false
+        elseif c == '-' then
+          i = i + 1; c = g:sub(i,i)
+          if c == '' then
+            p = '[^]'
+            return false
+          elseif c == ']' then
+            p = p .. escape(c1) .. '%-]'
+            break
+          else
+            if not unescape() then break end
+            p = p .. escape(c1) .. '-' .. escape(c)
+          end
+        elseif c == ']' then
+          p = p .. escape(c1) .. ']'
+          break
+        else
+          p = p .. escape(c1)
+          i = i - 1 -- put back
+        end
+      end
+      i = i + 1; c = g:sub(i,i)
+    end
+    return true
+  end
+
+  -- Convert tokens in charset.
+  local function charset()
+    i = i + 1; c = g:sub(i,i)
+    if c == '' or c == ']' then
+      p = '[^]'
+      return false
+    elseif c == '^' or c == '!' then
+      i = i + 1; c = g:sub(i,i)
+      if c == ']' then
+        -- ignored
+      else
+        p = p .. '[^'
+        if not charset_end() then return false end
+      end
+    else
+      p = p .. '['
+      if not charset_end() then return false end
+    end
+    return true
+  end
+
+  -- Convert tokens.
+  while 1 do
+    i = i + 1; c = g:sub(i,i)
+    if c == '' then
+      p = p .. '$'
+      break
+    elseif c == '?' then
+      p = p .. '.'
+    elseif c == '*' then
+      p = p .. '.*'
+    elseif c == '[' then
+      if not charset() then break end
+    elseif c == '\\' then
+      i = i + 1; c = g:sub(i,i)
+      if c == '' then
+        p = p .. '\\$'
+        break
+      end
+      p = p .. escape(c)
+    else
+      p = p .. escape(c)
+    end
+  end
+  return p
+end
+
+
+--[[ ##### PARSING THE COMMAND LINE ##### ]]--
+
+-- loosely inspired by http://lua-users.org/wiki/AlternativeGetOpt
+
+function simpleGetopt(args, optionsWithArgs)
+  local userOptions = {} -- results will be stored here
+
+  if optionsWithArgs == nil then optionsWithArgs = "" end
+
+  i = 1
+  while i <= #args do
+
+    -- lua does not have "continue", so we put the loop body
+    -- in a "repeat/until true" block and use break instead.
+    repeat
+        local optname, optval
+
+        -- this handles "--option=blah", "--option = blah",
+        --              "--option= blah" and "--option =blah"
+        if string.sub(args[i], 1, 2) == "--" then
+            optname = string.sub(args[i], 3)
+
+            -- check for "--option=..."
+            local equals = string.find(optname, "=", 1, true)
+            if equals ~= nil then
+                optval = string.sub(optname, equals +1)
+                optname = string.sub(optname, 1, equals -1)
+
+            -- check for "--option =..."
+            elseif i +1 <= #args and string.sub(args[i +1], 1, 1) == '=' then
+                optval = string.sub(args[i +1], 2)
+                i = i +1  -- do not process this again later on
+            end
+
+            if optval ~= nil then
+                if optval == "" then -- check for "...= blah"
+                    optval = args[i +1]
+                    i = i +1 -- do not process this again later on
+                end
+            else
+                -- check for "--option" without "="
+                optval = true
+            end
+
+            simpleGetoptStoreVal(userOptions, optname, optval)
+
+            break
+        end
+
+        -- this handles "-a -b", "-ab", "-cVAL", "-c VAL", "-abcVAL",
+        -- and "-abc VAL". Obviously, "-cVALab" does not work (where
+        -- does "VAL" end?).
+        --
+        -- To decide whether "-cVAL" means "c with param VAL" or
+        -- "options c, V, A, and L", we check optionsWithArgs.
+        if string.sub(args[i], 1, 1) == "-" then
+            local j = 2
+            local length = string.len(args[i])
+
+            while (j <= length) do
+                local optname = string.sub(args[i], j, j) -- a single letter
+                if string.find(optionsWithArgs, optname, 1, true) then
+                    if j < length then
+                        optval = string.sub(args[i], j +1)
+                        j = length
+                    else
+                        optval = args[i +1]
+                        i = i +1 -- do not process this again later on
+                    end
+                else
+                    optval = true
+                end
+
+                simpleGetoptStoreVal(userOptions, optname, optval)
+
+                j = j + 1 -- next letter
+            end
+
+            break
+        end
+
+        -- the filename is the only argument that does not start with "-"
+        userOptions['filename'] = args[i]
+    until true
+
+    i = i +1 -- next arg
+
+  end -- while i <= #args
+
+  return userOptions
+end
+
+function simpleGetoptStoreVal(userOptions, optname, optval)
+  if type(optval) == 'boolean' then
+      userOptions[optname] = optval
+      return
+  end
+
+  local tmp = string.lower(optval)
+    if tmp == "y" or tmp == "true" then
+        userOptions[optname] = true
+    elseif tmp == "n" or tmp == "false" then
+        userOptions[optname] = false
+    else
+        if type(userOptions[optname]) ~= 'table' then
+            userOptions[optname] = {}
+        end
+        table.insert(userOptions[optname], optval)
+    end
+end
+
+--[[
+-- TESTING THE COMMAND LINE PARSER --
+
+optionsWithArgs = 'abdg' -- these are followed by a parameter: "-b5", "-a true"
+
+args = {
+  '--should-be-true',
+  '-a', 'param-for-a',
+  '-bparam-for-b',
+  '-cdparam-for-d', -- c should be true
+  '-e', -- e should be true
+  '-fg', 'param-for-g', -- f should be true
+  '--opt1', '=', 'param-for-opt1',
+  '--opt2=', 'param-for-opt2',
+  '--opt3', '=param-for-opt3',
+  '--opt4=param-for-opt4',
+  '--also-should-be-true'
+}
+
+for k, v in pairs(simpleGetopt(args, optionsWithArgs)) do
+    print("Option " .. k .. ': ', v)
+end
+--]]
+
+
+--[[ ##################################################################### ]]--
+--[[ ######################### INPUT LINES BUFFER ######################## ]]--
+--[[ ##################################################################### ]]--
+
+--[[
+This is a buffer of lines from the logfile. The first line in the
+buffer (self.current) is treated specially: we may alter its content
+during processing and, therefore, we record its original size so
+later we can detect if it may be a wrapped line (i.e., if its
+original length was max_print_line characters).
+--]]
+
+Lines = {}
+Lines.wrapped = {} -- memoization
+
+function Lines:gotoNextLine()
+  self.current = table.remove(self, 1)
+  self.currentWrapped = table.remove(self.wrapped, 1)
+  self.atBeginningOfLine = true
+
+  -- When unwrapping lines, we need to check whether a line is of
+  -- the "right" size. However, we modify the content of currentLine
+  -- during processing, so we capture its initial length here
+  if self.current ~= nil then
+      self.currentLineInitialLength = string.len(self.current)
+  else
+      self.currentLineInitialLength = 0
+      self.currentWrapped = false
+  end
+end
+
+function Lines:handledChars(n)
+  -- After a handler processes currentLine, it indicates how much
+  -- from the line it processed, either leaving some trailing text
+  -- for the next handler or leaving nothing, indicating that it is
+  -- time to get more data and call gotoNextLine().
+  if n == nil then
+      self.current = nil
+  else
+      self.current = string.sub(self.current, n +1)
+      self.atBeginningOfLine = false
+  end
+
+end
+
+function Lines:len(n)
+  local n = n or 0
+  if n == 0 then return self.currentLineInitialLength end
+  return string.len(self[n])
+end
+
+function Lines:append(x)
+    table.insert(self, x)
+    table.insert(self.wrapped, "unknown") -- cannot use "nil"
+end
+
+function Lines:get(n)
+    local n = n or 0
+    if n == 0 then return self.current end
+    return self[n]
+end
+
+function Lines:empty()
+    return #self == 0
+end
+
+function Lines:numLines()
+    return #self
+end
+
+
+--[[ ##### UNWRAPPING LINES ##### ]]--
+
+function Lines:seemsWrappedMemo(n)
+    if n == 0 then
+        return self.currentWrapped
+    else
+        return self.wrapped[n]
+    end
+end
+
+function Lines:setWrappedMemo(n, val)
+    if n == 0 then
+        self.currentWrapped = val
+    else
+        self.wrapped[n] = val
+    end
+end
+
+function Lines:unwrapOneLine()
+  -- We trust the caller to check :seemsWrapped() before
+  -- calling this!
+  local old = self.current
+  self:gotoNextLine() -- this also updates currentLineInitialLength
+  self.current = old .. self.current
+end
+
+function Lines:seemsWrapped(position)
+  if not badLogfile then return false end
+
+  if position == nil then position = 0 end
+
+  if self:seemsWrappedMemo(position) ~= 'unknown' then
+      return self:seemsWrappedMemo(position)
+  end
+
+  -- No next line, so the current line cannot be a wrapped line.
+  -- The buffer should be large enough to guarantee this will
+  -- only happen when we are actually at the end of the input
+  if self:get(position +1) == nil then
+      -- BUT, just in case the buffer does get
+      -- empty before EOF, do not memoize
+      --self:setWrappedMemo(position, false)
+      return false
+  end
+
+  if not self:wrappingLength(position) then
+      self:setWrappedMemo(position, false)
+      return false
+  end
+
+  -- ok, the line length suggests this line continues on the
+  -- next, but we need to be sure; let's check if there are
+  -- no handlers that can manage the next line
+  local result = self:noHandlersForNextLine(position)
+  self:setWrappedMemo(position, result)
+  return result
+end
+
+function Lines:wrappingLength(position)
+  local line = self:get(position)
+  local n = self:len(position)
+
+  -- I have seen at least two cases where TeX "forgot" to
+  -- wrap a line. In this happens, the line is not wrapped.
+  if n > max_print_line +1 then return false end
+
+  -- Is the line the "right" length?
+  -- (max_print_line or max_print_line +1)
+  if n >= max_print_line then return true end
+
+  -- Ok, n < max_print_line, so it looks like this is not
+  -- a wrapped line. BUT! LuaTeX does not break a multibyte
+  -- UTF-8 character, which means some lines may be broken
+  -- at lengths < max_print_line; let's check for this.
+
+  -- Get the length of the first UTF-8 character on the next line:
+  -- https://www.lua.org/manual/5.3/manual.html#pdf-utf8.charpattern
+  local _, nextcharsize = string.find(self:get(position +1),
+                                      '^' .. utf8.charpattern)
+
+  -- if it is not a multibyte char, the line really is not wrapped
+  if nextcharsize == 1 then return false end
+
+  -- Some *very* simplistic experiments tell me that if a
+  -- multibyte UTF-8 character in the last position of a line
+  -- would make that line exactly max_print_line long, LuaTeX
+  -- still breaks the line, even though the character would fit.
+  -- This is why we do "+1" here.
+
+  -- If the multibyte char would fit, the line really is not wrapped
+  if n + nextcharsize +1 <= max_print_line then return false end
+
+  -- The line is shorter because of an UTF-8 multibyte
+  -- char, so it seems like a wrapped line
+  return true
+end
+
+function Lines:noHandlersForNextLine(position)
+  local line = self:get(position)
+
+  local wrapped = true
+  for _, candidateHandler in ipairs(beginningOfLineHandlers) do
+      if candidateHandler:canDoit(position +1) then wrapped = false break end
+  end
+
+  for _, candidateHandler in ipairs(anywhereHandlers) do
+      if candidateHandler:canDoit(position +1) then wrapped = false break end
+  end
+
+  if wrapped then return true end
+
+  -- TODO: the way we deal with these special cases is lame...
+
+  -- a close parens at the beginning of the next line might not be
+  -- a "close file" message, but instead refer to an open parens in
+  -- the current line; let's check for this exceptional case. We
+  -- traverse the current line looking for open/close parens and pair
+  -- every close parens to the corresponding open parens. A dangling
+  -- close parens is probably a continuation too, so we ignore it.
+  if closeParensHandler:canDoit(position +1) then
+      -- We previously decided the line is not wrapped because
+      -- there is a close parens in the following line; let's
+      -- revise that decision
+      local unpaired = 0
+      local i = 1
+      local size = string.len(line)
+      while i <= size do
+          local j = string.find(line, '[%(%)]', i)
+          if j ~= nil then
+              local open = string.find(line, '%(', i)
+              if open then
+                  unpaired = unpaired +1
+              elseif unpaired > 0 then
+                  unpaired = unpaired -1
+              end
+              i = j +1
+          else
+              i = size +1
+          end
+      end
+
+      if unpaired > 0 then return true end
+  end
+
+  -- Same thing for close square bracket
+  if closeSquareBracketHandler:canDoit(position +1) then
+      -- We previously decided the line is not wrapped because
+      -- there is a close square bracket in the following line;
+      -- let's revise that decision
+      local unpaired = 0
+      local i = 1
+      local size = string.len(line)
+      while i <= size do
+          local j = string.find(line, '[%[%]]', i)
+          if j ~= nil then
+              local open = string.find(line, '%[', i)
+              if open then
+                  unpaired = unpaired +1
+              elseif unpaired > 0 then
+                  unpaired = unpaired -1
+              end
+              i = j +1
+          else
+              i = size +1
+          end
+      end
+
+      if unpaired > 0 then return true end
+  end
+
+  local parens, data = openParensHandler:canDoit(position +1)
+  local filename = data[1]
+  if parens and filename == nil then
+      -- Next line could be handled as an "open parens" message, but
+      -- there is no filename, so the message is only "(". There is
+      -- a good chance that is just the continuation of a previous
+      -- wrapped message. If there is a close parens character on the
+      -- line too, we'll assume that is true and ignore the handler
+      local first = string.find(self:get(position +1), "%)")
+      if first ~= nil then return true end
+  end
+
+  local bracket, data = openSquareBracketHandler:canDoit(position +1)
+  local page = data[1]
+  if bracket and page == nil then
+      -- Next line could be handled as an "open square bracket" message,
+      -- but there is no page number, so the message is only "[". There
+      -- is a good chance that is just the continuation of a previous
+      -- wrapped message. If there is a close square bracket character on
+      -- the line too, we'll assume that is true and ignore the handler
+      local first = string.find(self:get(position +1), "%]")
+      if first ~= nil then return true end
+  end
+
+  return false
+end
+
+function unwrapUntilPatternMatches(pat)
+  local last, tmp
+  while true do
+      matches = {string.find(Lines.current, pat)}
+      table.remove(matches, 1) -- remove "first"
+      last = table.remove(matches, 1) -- remove "last"
+
+      if last ~= nil then break end
+
+      if Lines:seemsWrapped() then
+          Lines:unwrapOneLine()
+      else
+          io.stderr:write("    texlogsieve: parsing error\n")
+      end
+  end
+
+  -- We matched the given pattern. However, if the pattern ends with
+  -- something like ".+", it is possible that there is still some more
+  -- relevant material in the next line (this is why we should not use
+  -- such patterns). There is not much we can do about that in general,
+  -- but if the next line is really short, this is probably why, so we
+  -- might as well try to unwrap once more. This is obviously a hack,
+  -- but it saves us from problems with a couple of messages that use
+  -- "filepat" at the end of the pattern.
+
+  -- these might fit in 2 chars, so do not consider lines with that
+  local realMessage = string.find(Lines:get(1), '[%)%[%]]')
+  if string.len(Lines:get(1)) < 3 and not realMessage then
+      local together = Lines.current .. Lines:get(1)
+      local candidateMatches = {string.find(together, pat)}
+      table.remove(candidateMatches, 1)
+      local candidateLast = table.remove(candidateMatches, 1)
+      if candidateLast ~= nil then
+          Lines:unwrapOneLine()
+          last = candidateLast
+          matches = candidateMatches
+      end
+  end
+
+  return last, matches
+end
+
+function unwrapUntilStringMatches(s)
+  return unwrapUntilPatternMatches(protect_metachars(s))
+end
+
+
+--[[ ##################################################################### ]]--
+--[[ ################## GUESSING FILENAMES AND SHIPOUTS ################## ]]--
+--[[ ##################################################################### ]]--
+
+--[[
+To find the full path of a file in the TeX search path, we may use
+
+thepath = kpse.find_file("article")
+thepath = kpse.find_file("/usr/share/texlive/texmf-dist/tex/latex/base/article.cls")
+thepath = kpse.find_file("latex/base/article.cls")
+thepath = kpse.find_file("texmf.cnf", "cnf")
+
+The filename may or may not include the extension; kpathsea adds the
+extension if necessary according to the specified format (default is
+"tex", which means extensions .tex, .sty, .cls and some others). This
+is problematic, because (1) it does not recognize filenames with an
+unknown extension and (2) if there is a file named "what.ever.tex" and
+another one called "what.ever", it may find the wrong file.
+
+We want to check whether a string from the log file corresponds to the
+complete path of an existing filename, which means we already know the
+extension. Therefore, we will use the type "other text files". This
+prevents kpathsea from adding the extension automatically (which is what
+we want) and also prevents kpathsea from searching the standard TeX path,
+which is also nice because we are checking a complete path.
+--]]
+
+function guessFilename(position)
+  if position == nil then position = 0 end
+  local line = Lines:get(position)
+  local _, last = string.find(line, '^%s*%(')
+  if last ~= nil then line = string.sub(line, last +1) end
+
+  local quotes, filename = guessQuotedFilename(line, position)
+
+  if filename ~= nil then return filename end
+
+  if quotes then return nil end
+
+  return guessUnquotedFilename(line, position)
+end
+
+function guessShipoutPage(position)
+  -- In general, a shipout is identified by "[\count0.\count1.\count2..."
+  -- followed by a space or "]". However, there are complications:
+  --
+  -- 1. Dates, such as [2020/10/03] or [2020-10-03]
+  --
+  -- 2. Files added to the shipout, such as
+  --    "[3{somefile.tex}" or "[3<somefile.pdf>"
+  --
+  -- We can either:
+  --
+  -- 1. Specify what is allowed: "^(%d+[%d%.]*)[ %]<{]" or "^(%d+[%d%.]*)$"
+  --
+  -- 2. Exclude what is forbidden: "^(%d+[%d%.]*)[^/-]"
+  --
+  -- Let's go with option 1.
+
+  local patterns = {
+      "^(%d+[%d%.]*)[ %]<{]",
+      "^(%d+[%d%.]*)$"
+  }
+
+  if position == nil then position = 0 end
+  local line = Lines:get(position)
+  local _, last = string.find(line, '^%s*%[')
+  if last ~= nil then line = string.sub(line, last +1) end
+
+  while true do
+      for _, pattern in ipairs(patterns) do
+          _, _, page = string.find(line, pattern)
+          if page ~= nil then
+              -- just the number, please
+              local _, last = string.find(page, '^%d+[%d%.]*')
+              page = string.sub(page, 1, last)
+              break
+          end
+      end
+
+      if not Lines:seemsWrapped(position) then break end
+
+      local nextline = Lines:get(1)
+      line = line .. nextline
+      position = position +1
+  end
+
+  return page -- may be nil
+end
+
+function guessQuotedFilename(line, position)
+  -- luatex puts quotes around filenames with spaces, which makes things easier
+  while true do
+      local _, last = string.find(line, '^"')
+      if string.len(line) > 0 and last == nil then return false end -- no quotes
+
+      last = string.find(line, '^"[%.]?/') -- relative path or unix-style path
+      if last == nil then
+          last = string.find(line, '^"%a:/') -- windows-style path
+      end
+      -- there are quotes, but what follows is not a filename
+      if string.len(line) >= 4 and last == nil then return true, nil end
+
+      _, last = string.find(line, '^"%a?[:]?[%.]?/[^"%(%)%[%]]+"')
+      if last ~= nil then
+          local filename = string.sub(line, 2, last -1) -- remove quotes
+          if kpse.find_file(filename, 'other text files') == nil then
+              return true, nil -- there are quotes, but no filename
+          else
+              return true, '"' .. filename .. '"'
+          end
+      end
+
+      -- no closing quote or the line is too short; can we unwrap this line?
+      if not Lines:seemsWrapped(position) then
+          io.stderr:write("    texlogsieve: parsing error\n")
+          return true, nil
+      end
+
+      -- yep!
+      line = line .. Lines:get(position +1)
+      position = position +1
+  end
+end
+
+-- no quotes; let's exhaustively extract the substrings of currentLine
+-- and use kpse.find_file() to check if any of them is an existing
+-- filename.
+function guessUnquotedFilename(line, position)
+  -- In subsequent iterations, we do not check the smaller strings
+  -- we already checked in the previous ones.
+  local alreadyCheckedIdx = 0
+
+  while true do
+      local first = string.find(line, '^[%.]?/') -- relative or unix-style path
+      if first == nil then
+          first = string.find(line, '^%a:/') -- windows-style path
+      end
+      -- this does not look like a filename
+      if string.len(line) >= 3 and first == nil then return nil end
+
+      local longest = string.len(line)
+
+      -- if there is a ")", "(", "[", or "]" char, stop before that
+      first = string.find(line, "[%)%(%[%]]")
+      if first ~= nil then longest = first -1 end
+
+      -- From longest to shortest, to avoid problems if there is a
+      -- substring in the filename that matches some other filename.
+      for i = longest, alreadyCheckedIdx +1, -1 do
+          local filename = string.sub(line, 1, i)
+          if kpse.find_file(filename, 'other text files') ~= nil then
+              return filename
+          end
+      end
+
+      -- we did not find the filename; can we unwrap this line?
+      if not Lines:seemsWrapped(position) then return nil end
+      first = string.find(line, "[%)%(%[%]]")
+      if first ~= nil then return nil end
+
+      -- yep!
+      alreadyCheckedIdx = longest
+      line = line .. Lines:get(position +1)
+      position = position +1
+  end
+end
+
+--[[ ###################################################################### ]]--
+--[[ ######################## BEGINNING OF SCRIPT ######################### ]]--
+--[[ ###################################################################### ]]--
+
+
+main(arg)
diff --git a/support/texlogsieve/texlogsieve.1 b/support/texlogsieve/texlogsieve.1
new file mode 100644
index 0000000000..79cdbc68d1
--- /dev/null
+++ b/support/texlogsieve/texlogsieve.1
@@ -0,0 +1,229 @@
+.TH TEXLOGSIEVE "1" "December 2021" "texlogsieve 1.0.0-beta-1" "User Commands"
+
+.SH NAME
+
+texlogsieve \- filter and summarize LaTeX log files
+
+.SH SYNOPSIS
+
+\fBtexlogsieve\fR [\fI\,OPTION\/\fR]... [\fI\,INPUT FILE\/\fR]
+
+.SH DESCRIPTION
+
+texlogsieve reads a LaTeX log file (or the standard input if no file is
+specified), filters out less relevant messages, and displays a summary
+report.
+
+texlogsieve \fBmust\fR be run from the same directory as [pdf|lua|xe]latex,
+because it searches for the files used during compilation (packages loaded
+from the current directory, files included with \einput etc.).
+
+The program goes to great lengths to correctly handle TeX line wrapping. It
+understands the \fI\,max_print_line\/\fR TeX configuration variable and reads
+its value from the same places as TeX. Setting \fI\,max_print_line\/\fR to a
+value larger than 9999 makes texlogsieve ignore line wrapping.
+
+The defaults are reasonable; hopefully, you can just do
+
+.RS 3
+.EX
+[pdf|lua|xe]latex myfile.tex | texlogsieve
+.EE
+.RE
+
+and be satisfied with the result.
+
+.SH OPTIONS
+
+.TP
+\fB\-\-page\-delay\fR, \fB\-\-no\-page\-delay\fR
+Enable/disable grouping messages by page before display. When enabled,
+messages are only output after the current page is finished (shipout). \
+The advantage is that the page number is included in the message (default
+enabled).
+
+.TP
+\fB\-\-summary\fR, \fB\-\-no\-summary\fR
+Enable/disable final summary (default enabled).
+
+.TP
+\fB\-\-only\-summary\fR
+No messages, show only the final summary (default disabled).
+
+.TP
+\fB\-\-shipouts\fR, \fB\-\-no\-shipouts\fR
+Enable/disable reporting shipouts (default disabled with page-delay,
+enabled with no-page-delay).
+
+.TP
+\fB\-\-repetitions\fR, \fB\-\-no\-repetitions\fR
+Allow/prevent repeated messages (default disabled, i.e., repeated messages
+are supressed).
+
+.TP
+\fB\-\-heartbeat\fR, \fB\-\-no\-heartbeat\fR
+Enable/disable progress gauge in page-delay mode (default enabled).
+
+.TP
+\fB\-l\fR \fI\,LEVEL\/\fR, \fB\-\-minlevel\fR=\fI\,LEVEL\/\fR
+Filter out messages with severity level lower than LEVEL. Valid levels
+are DEBUG (no filtering), INFO, WARNING, CRITICAL, and UNKNOWN (default
+WARNING).
+
+.TP
+\fB\-u\fR, \fB\-\-unwrap\-only\fR
+Do not filter messages and do not output the summary, only unwrap long,
+wrapped lines. The output should be very similar (but not equal) to the
+input file, but with wrapped lines reconstructed. This activates \-l debug,
+\-\-no\-summary, \-\-no\-page\-delay, \-\-repetitions, and \-\-shipouts, and
+also supresses the verbose \[lq]open/close file\[rq] and \[lq]shipout\[rq]
+messages, simulating instead the TeX format, with parens and square brackets. \
+This is useful if you prefer the reports generated by some other tool but want
+to benefit from texlogsieve's line unwrapping algorithm; the output generated
+by this option should be parseable by other tools (but you probably need to
+coerce the other tool not to try to unwrap lines).
+
+.TP
+\fB\-\-silence\-package\fR=\fI\,PKGNAME\/\fR
+Filter out messages that can be identified as coming from the given package. \
+Use this option multiple times to suppress messages from several different
+packages.
+
+.TP
+\fB\-\-silence\-string\fR=\fI\,EXCERPT OF UNWANTED MESSAGE\/\fR
+Filter out messages that contain the given string (you only need to provide
+part of the message text for the whole message to be suppressed). Use this
+option multiple times to suppress several different messages. The string
+should be a single line, but that is not a problem for multiline log messages:
+space characters in the provided string match any sequence of whitespace
+characters in the message, including newlines. If needed, you may precede the
+string with \[lq]////\[rq], in which case you can use lua-style pattern matching
+(\c
+.UR https://www.lua.org/pil/20.2.html
+.UE ). Note that the string is used verbatim: you need not (and should not)
+enclose it in quotes nor escape special characters such as \[lq]\e\[rq].
+
+.TP
+\fB\-\-silence\-file\fR=\fI\,FILENAME OR FILE GLOB\/\fR
+Filter out messages that have been generated while the given file was being
+processed. Do \fBnot\fR use absolute or relative paths, only filenames. Simple
+file globs, such as \[lq]*.cls\[rq], work as expected. Use this option multiple
+times to suppress messages from several different files.
+
+.TP
+\fB\-\-semisilence\-file\fR=\fI\,FILENAME OR FILE GLOB\/\fR
+Just like the previous option, but non-recursive. This means that messages
+generated while the given file was being processed are excluded, but messages
+generated by some other file that was opened by it are not. For example, if
+\[lq]chapters.tex\[rq] includes (with \einput) the files \[lq]chapter1.tex\[rq]
+and \[lq]chapter2.tex\[rq], using \[lq]\-\-silence\-file=chapters.tex\[rq]
+will prevent messages generated by any of the three files from being
+displayed. If, however, you use \[lq]\-\-semisilence\-file=chapters.tex\[rq],
+messages generated by chapters.tex will be suppressed, but messages generated
+by chapter1.tex or chapter2.tex will not.
+
+.TP
+\fB\-\-add\-[debug|info|warning]\-message\fR=\fI\,MESSAGE\/\fR
+Add MESSAGE to the list of messages known to the program with the given
+severity level; see Section UNRECOGNIZED MESSAGES below for more information
+about this. Like \-\-silence\-string, these should be a single line; unlike
+\-\-silence\-string, you need to embed \en explicitly to indicate line
+breaks. You may precede the string with \[lq]////\[rq] to use lua-style
+pattern matching, but embedding \en to indicate line breaks is unavoidable.
+Use these options multiple times to add many different messages.
+
+.TP
+\fB\-c\fR \fI\,CFGFILE\/\fR, \fB\-\-config\-file\fR=\fI\,CFGFILE\/\fR
+Read options from the given configuration file. Options are exactly the
+same as the long command-line options, but without the preceding \[lq]\-\-\[rq]
+characters. Lines starting with a \[lq]#\[rq] sign are comments. An example
+configuration file:
+
+.RS
+.RS 3
+.EX
+no\-page\-delay
+.br
+# no\-page\-delay enables shipouts, but we do not want that
+.br
+no\-shipouts
+.br
+silence\-string = Hyperreferences in rotated content will be misplaced
+.br
+# no need to escape the \[dq]\e\[dq] (or any other) character
+.br
+silence\-string = Using \eoverbracket and \eunderbracket from \[ga]mathtools\[aq]
+.br
+# silence a string using lua pattern matching
+.br
+silence\-string = ////luaotfload | aux : font no %d+ %(.\-%)
+.br
+silence\-files = *.cls
+.EE
+.RE
+.RE
+
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+Show concise options description.
+
+.TP
+\fB\-\-version\fR
+Print program version.
+
+.SH UNRECOGNIZED MESSAGES
+
+texlogsieve automatically handles messages such as \[lq]Package blah
+Info:...\[rq] or \[lq]LaTeX Warning:...\[rq]. However, many messages do not
+follow this pattern. To do its thing, texlogsieve should know about these
+other messages beforehand. This is important for three reasons:
+
+.IP 1. 3
+Unknown messages are given maximum priority; if you do not want to see them,
+you have to use \-\-silence\-string;
+.IP 2. 3
+If the message has more than one line, each line is treated as an independent
+message. This means you need to use \-\-silence\-string multiple times;
+.IP 3. 3
+In some rare cases, the line unwrapping algorithm may fail near an
+unrecognized message.
+
+.PP
+While texlogsieve recognizes quite a few messages out of the box, you may run
+into a message generated by some package that it does not know about (you can
+check for this using \[lq]\-l unknown\[rq]). If that is the case, you can use
+the \-\-add\-[debug|info|warning]\-message options to add it to the list of
+messages known to the program.
+
+.SH LIMITATIONS
+
+texlogsieve does not try to do anything smart about error messages (at least
+for now); if there is an error, you probably want to take a look directly
+at the log file anyway.
+
+Since it needs to know what messages to expect, texlogsieve is currently
+geared towards LaTeX; I have no idea how it would work with ConTeXt or plain
+TeX. Still, adding support to them should not be too difficult.
+
+.SH SEE ALSO
+
+The pdf documentation (in TeXLive, try \fI\,texdoc texlogsieve\/\fR).
+
+If you want to know more about the TeX log file and the workings of the
+program, check the initial comments in the code.
+
+.SH BUGS AND DEVELOPMENT
+
+.UR https://gitlab.com/lago/texlogsieve
+.UE
+
+.SH COPYRIGHT
+
+Copyright \[co] 2021 Nelson Lago <lago@ime.usp.br>
+.br
+License GPLv3+: GNU GPL version 3 or later
+.UR https://gnu.org/licenses/gpl.html
+.UE .
+
+This is free software: you are free to change and redistribute it. \
+There is NO WARRANTY, to the extent permitted by law.
diff --git a/support/texlogsieve/texlogsieve.pdf b/support/texlogsieve/texlogsieve.pdf
new file mode 100644
index 0000000000..80c47a3037
--- /dev/null
+++ b/support/texlogsieve/texlogsieve.pdf
diff --git a/support/texlogsieve/texlogsieve.tex b/support/texlogsieve/texlogsieve.tex
new file mode 100644
index 0000000000..4d29abf8cc
--- /dev/null
+++ b/support/texlogsieve/texlogsieve.tex
@@ -0,0 +1,312 @@
+% texlogsieve - filter and summarize LaTeX log files
+%
+% Copyright (C) 2021 Nelson Lago <lago@ime.usp.br>
+%
+% This program is free software: you can redistribute it and/or modify
+% it under the terms of the GNU General Public License as published by
+% the Free Software Foundation, either version 3 of the License, or
+% (at your option) any later version.
+%
+% This program is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with this program.  If not, see <https://www.gnu.org/licenses/>.
+%
+% Code etc: https://gitlab.com/lago/texlogsieve
+
+\documentclass{ltxdoc}
+
+\usepackage[hyperref,svgnames,x11names,table]{xcolor}
+\usepackage{url}
+\urlstyle{sf}
+\usepackage{hyperref}
+\hypersetup{
+  colorlinks=true,
+  citecolor=DarkGreen,
+  linkcolor=NavyBlue,
+  urlcolor=DarkRed,
+  filecolor=green,
+  anchorcolor=black,
+}
+
+\usepackage{libertinus}
+\usepackage[scale=.85]{sourcecodepro}
+
+\RecordChanges
+
+\changes{v1.0.0-beta-1}{2021/12/16}{first public prerelease}
+
+\begin{document}
+
+\title{\textsf{texlogsieve}:\thanks{This document
+corresponds to \textsf{texlogsieve}~1.0.0-beta-1,
+dated~2021-12-16.}\\[.3\baselineskip]
+{\normalsize(yet another program to)\\[-.6\baselineskip]}
+{\large filter and summarize \LaTeX\ log files}
+}
+
+\author{
+Nelson Lago\\
+\texttt{lago@ime.usp.br}\\
+~\\
+\url{https://gitlab.com/lago/texlogsieve}
+}
+
+\maketitle
+
+\begin{abstract}
+
+\texttt{texlogsieve} reads a \LaTeX\ log file (or the standard input if
+no file is specified), filters out less relevant messages, and displays
+a summary report. Highlights:
+
+\begin{itemize}
+  \item Two reports: the most important messages from the log file
+        followed by a summary of repeated messages, undefined
+        references etc.;
+  \item The program goes to great lengths to correctly handle \TeX\ line
+        wrapping and does a much better job at that than existing tools;
+  \item Multiline messages are treated as a single entity;
+  \item Several options to control which messages should be filtered out;
+  \item No messages are accidentally removed;
+  \item The summary report is currently simple, but useful.
+\end{itemize}
+
+\end{abstract}
+
+\section{Introduction}
+
+The \LaTeX\ log file is very verbose, which is useful when debugging but
+a hindrance during document preparation, as warnings such as ``missing
+character'', ``undefined reference'', and others become buried among lots
+of less relevant messages. This program filters out such less relevant
+messages and outputs the rest, together with a final summary for the
+specially important ones. It is a \texttt{texlua} script, similar in
+spirit to tools such as \texttt{texfot}, \texttt{texloganalyser},
+\texttt{rubber-info}, \texttt{textlog\_extract}, \texttt{texlogparser},
+and others. Note that it does not try to do anything smart about error
+messages (at least for now); if there is an error, you probably want to
+take a look directly at the log file anyway.
+
+\texttt{texlogsieve} \textbf{must} be run from the same directory as
+\verb/[pdf|lua|xe]latex/, because it searches for the files used during
+compilation (packages loaded from the current directory, files included
+with \verb|\input| etc.).
+
+\pagebreak[1]
+The defaults are reasonable; hopefully, you can just do
+
+\begin{quote}
+\verb/[pdf|lua|xe]latex myfile.tex | texlogsieve/
+\end{quote}
+
+and be satisfied with the result.
+
+Since it needs to know what messages to expect, \texttt{texlogsieve} is
+currently geared towards \LaTeX; I have no idea how it would work with
+Con\TeX{}t or plain \TeX. Still, adding support to them should not be
+too difficult.
+
+If you want to know more about the \TeX\ log file and the workings of the
+program, check the initial comments in the code.
+
+\section{Unwrapping long lines}
+
+\TeX\ wraps (breaks) lines longer than \texttt{max\_print\_line} (by
+default, 79 characters). Most tools detect lines that are exactly 79
+characters long and treat the next line as a continuation, but that fails
+in quite a few cases (check the comments in the \texttt{texlogsieve} code
+for a discussion on that). So, if at all possible, it is a very good idea
+to set \texttt{max\_print\_line} to a really large value (such as 100,000),
+effectively disabling line wrapping. It was useful in the 1980s, but not
+anymore (your terminal or editor wraps automatically).
+
+Still, \texttt{texlogsieve} goes to great lengths to correctly handle
+\TeX{} line wrapping and does a pretty good job at that. It understands
+the \texttt{max\_print\_line} \TeX{} configuration variable and reads its
+value from the same places as \TeX. Setting \texttt{max\_print\_line} to
+a value larger than 9999 makes \texttt{texlogsieve} ignore line wrapping.
+
+\section{Options}
+
+\begin{description}
+\item[\texttt{-\/-page-delay}, \texttt{-\/-no-page-delay}]~\\
+Enable/disable grouping messages by page before display. When enabled, messages
+are only output after the current page is finished (shipout). The advantage is
+that the page number is included in the message (default enabled).
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-summary}, \texttt{-\/-no-summary}]~\\
+Enable/disable final summary (default enabled).
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-only-summary}]~\\
+No messages, show only the final summary (default disabled).
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-shipouts}, \texttt{-\/-no-shipouts}]~\\
+Enable/disable reporting shipouts (default disabled with page-delay, enabled
+with no-page-delay).
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-repetitions}, \texttt{-\/-no-repetitions}]~\\
+Allow/prevent repeated messages (default disabled, i.e., repeated messages
+are supressed).
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-heartbeat}, \texttt{-\/-no-heartbeat}]~\\
+Enable/disable progress gauge in page-delay mode (default enabled).
+\end{description}
+
+\begin{description}
+\item[\texttt{-l LEVEL}, \texttt{-\/-minlevel=LEVEL}]~\\
+Filter out messages with severity level lower than \texttt{LEVEL}. Valid
+levels are \texttt{DEBUG} (no filtering), \texttt{INFO}, \texttt{WARNING},
+\texttt{CRITICAL}, and \texttt{UNKNOWN} (default \texttt{WARNING}).
+\end{description}
+
+\begin{description}
+\item[\texttt{-u}, \texttt{-\/-unwrap-only}]~\\
+Do not filter messages and do not output the summary, only unwrap long,
+wrapped lines. The output should be very similar (but not equal) to the
+input file, but with wrapped lines reconstructed. This activates \texttt{-l
+debug}, \texttt{-\/-no-summary}, \texttt{-\/-no-page-delay},
+\texttt{-\/-repetitions}, and \texttt{-\/-shipouts}, and also supresses the
+verbose ``open/close file'' and ``shipout'' messages, simulating instead
+the \TeX{} format, with parens and square brackets. This is useful if you
+prefer the reports generated by some other tool but want to benefit from
+texlogsieve's line unwrapping algorithm; the output generated by this option
+should be parseable by other tools (but you probably need to coerce the other
+tool not to try to unwrap lines).
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-silence-package=PKGNAME}]~\\
+Filter out messages that can be identified as coming from the given package.
+Use this option multiple times to suppress messages from several different
+packages.
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-silence-string=EXCERPT OF UNWANTED MESSAGE}]~\\
+Filter out messages that contain the given string (you only need to provide
+part of the message text for the whole message to be suppressed). Use this
+option multiple times to suppress several different messages. The string
+should be a single line, but that is not a problem for multiline log
+messages: space characters in the provided string match any sequence of
+whitespace characters in the message, including newlines. If needed, you
+may precede the string with ``////'', in which case you can use lua-style
+pattern matching (\url{https://www.lua.org/pil/20.2.html}). Note that the
+string is used verbatim: you need not (and should not) enclose it in quotes
+nor escape special characters such as ``\textbackslash''.
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-silence-file=FILENAME OR FILE GLOB}]~\\
+Filter out messages that have been generated while the given file was being
+processed. Do \textbf{not} use absolute or relative paths, only filenames.
+Simple file globs, such as ``\texttt{*.cls}'', work as expected. Use this
+option multiple times to suppress messages from several different files.
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-semisilence-file=FILENAME OR FILE GLOB}]~\\
+Just like the previous option, but non-recursive. This means that messages
+generated while the given file was being processed are excluded, but messages
+generated by some other file that was opened by it are not. For example,
+if ``\texttt{chapters.tex}'' includes (with \textbackslash input) the
+files ``\texttt{chapter1.tex}'' and ``\texttt{chapter2.tex}'', using
+``\texttt{-\/-silence-file=chapters.tex}'' will prevent messages generated
+by any of the three files from being displayed. If, however, you use
+``\texttt{-\/-semisilence-file=chapters.tex}'', messages generated by
+\texttt{chapters.tex} will be suppressed, but messages generated by
+\texttt{chapter1.tex} or \texttt{chapter2.tex} will not.
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-add-[debug\textbar info\textbar warning]-message=MESSAGE}]~\\
+Add \texttt{MESSAGE} to the list of messages known to the program with the given
+severity level; see Section \ref{unrecognized} below for more information
+about this. Like \texttt{-\/-silence-string}, these should be a single line;
+unlike \texttt{-\/-silence-string}, you need to embed  \verb|\n|  explicitly
+to indicate line breaks. You may precede the string with ``////'' to use
+lua-style pattern matching, but embedding \verb|\n| to indicate line breaks
+is unavoidable. Use these options multiple times to add many different
+messages.
+\end{description}
+
+\begin{description}
+\item[\texttt{-c CFGFILE}, \texttt{-\/-config-file=CFGFILE}]~\\
+Read options from the given configuration file. Options are exactly the
+same as the long command-line options, but without the preceding ``-\/-''
+characters. Lines starting with a ``\#'' sign are comments. An example
+configuration file:
+
+\begin{quote}
+\begin{verbatim}
+no-page-delay
+# no-page-delay enables shipouts, but we do not want that
+no-shipouts
+silence-string = Hyperreferences in rotated content will be misplaced
+# no need to escape the "\" (or any other) character
+silence-string = Using \overbracket and \underbracket from `mathtools'
+# silence a string using lua pattern matching
+silence-string = ////luaotfload | aux : font no %d+ %(.-%)
+silence-files = *.cls
+\end{verbatim}
+\end{quote}
+\end{description}
+
+\begin{description}
+\item[\texttt{-h}, \texttt{-\/-help}]
+Show concise options description.
+\end{description}
+
+\begin{description}
+\item[\texttt{-\/-version}]
+Print program version.
+\end{description}
+
+\section{Unrecognized Messages}
+\label{unrecognized}
+
+\texttt{texlogsieve} automatically handles messages such as ``Package blah
+Info:\dots'' or ``LaTeX Warning:\dots''. However, many  messages do not
+follow this pattern. To do its thing, \texttt{texlogsieve} should know about
+these other messages beforehand. This is important for three reasons:
+
+\begin{enumerate}
+  \item Unknown messages are given maximum priority; if you do not want to
+        see them, you have to use -\/-silence-string;
+  \item If the message has more than one line, each line is treated as an
+        independent message. This means you need to use -\/-silence-string
+        multiple times;
+  \item In some rare cases, the line unwrapping algorithm may fail near an
+        unrecognized message.
+\end{enumerate}
+
+While \texttt{texlogsieve} recognizes quite a few messages out of the box,
+you may run into a message generated by some package that it does not know
+about (you can check for this using \texttt{-l unknown}). If that is the
+case, you can use the \verb/--add-[debug|info|warning]-message/ options to
+add it to the list of messages known to the program.
+
+\section{License}
+
+Copyright © 2021 Nelson Lago \textless lago@ime.usp.br\textgreater\\
+License GPLv3+: GNU GPL version 3 or later
+\url{https://gnu.org/licenses/gpl.html}.\\
+This is free software: you are free to change and redistribute it.\\
+There is NO WARRANTY, to the extent permitted by law.
+
+\PrintChanges
+
+\end{document}