install new script latexdiff

git-svn-id: svn://tug.org/texlive/trunk@16379 c570f23f-e606-0410-a88d-b1316a301751

11 files changed, 7076 insertions, 0 deletions

diff --git a/Master/texmf-dist/doc/latex/latexdiff/CHANGES b/Master/texmf-dist/doc/latex/latexdiff/CHANGES
new file mode 100644
index 00000000000..18853d35f76
--- /dev/null
+++ b/Master/texmf-dist/doc/latex/latexdiff/CHANGES
@@ -0,0 +1,138 @@
+Version 0.5 
+===========
+
+- add \protect in front of all changebar package commands.  These prevents error messages
+  when changes are made to section titles in any styles making use of changebar package
+
+- For a changed section, the deletion is now reported before the insertion, in common
+  with standard practice for diff programs
+
+- "\begin{equation}%" and similar constructs no longer confuse latexdiff
+
+- deals correctly with some fairly pathological cases of math mode switching - code 
+  should parse but equation numbers and linebreaks might be changed
+
+- \\[..] is now left alone (previously, this got erroneously interpreted as \ \begin{displaymath})
+
+- \(..\) is recognised as a synonym for $...$
+
+- introduce new subclasses of textcmd
+   context1cmd  are text commands which should be disabled in a deleted block, as they
+                are only meaningful in certain contexts (e.g. \caption).  However, their
+                argument is still marked up as deleted (plain) text, surrounded by a pair of braces.
+   context2cmd  behave like text commands except that they are completely disabled in deleted blocks,
+                including their arguments.
+
+- array environments within in-lined maths are now underlined correctly
+
+- if endfloat package is inferred from preamble, then make sure \begin{figure} and \end{figure}
+  are always on a line by themselves, similarly for table enviroment
+
+- if hyperref package is used, make wrapper for \DIFadd and \DIFdel which protects markup from becoming 
+  part of link texts where it causes an error
+
+- if amsmath package is used, then default eqnarray environement (Variable MATHARRREPL) is set to align
+  (Default: eqnarray).  Also, the standard amsmath equation array environments are now recognised as such.
+
+- new option --packages
+
+Version 0.42 November 2006
+==========================
+
+- the auxiliary commands put in to bring latexdiff into and out of 
+  math mode correctly would sometimes not be consistent. This is no longer the 
+  case
+
+- If a comment was put between two commands within a deleted block, the 
+  latter command would not be disabled by a DIFDELCMD
+
+
+
+Version 0.4 January 2006
+========================
+
+- $$ $$ usually accepted for displayed equations (but less robust than \[ \] or displaymath environment)
+
+- For commands which are in textcmd list but not in safecmd list (e.g. \footnote and \section commands) the content is now marked up if they are added or deleted. (Thanks to S. Utcke for alerting me to this shortcoming of previous versions).  The downside of this change is that deleted section heads are now shown, messing up the section numbering
+
+- added RCS and SVN support to latexdiff-vc (previous name latexdiff-cvs)
+
+- a fast version (latexdiff-fast) uses the UNIX diff command to speed up the differencing phases.
+
+Minor bug fixes:
+
+- Improved parsing of textcmd and safecmd lists, some clarification in manual (Thanks to V. Kuhlmann for fix)
+
+- All \color commands now \protect'ed (V. Kuhlmann)
+
+- Picture environment within floats now is cleared up properly (Thanks to V. Kuhlmann for fix)
+
+- non-matching textcommands right before \end{document} are now parsed correctly
+
+- updates to textcmd (emph, text..) and safecmd lists (emph)
+
+- fixed \par bug.  Previously, this bug resulted new paragraphs to be merged with the following paragraph.
+
+- better error checking in latexdiff-vc
+
+- can specify arbitrary number of files in latexdiff-vc
+
+- can choose output directory in latexdiff-vc
+
+Version 0.3 August 2005
+==========================
+
+- fixed bug where a deleted displayed equation would result in math mode commands 
+  being processed in text mode (the "! Missing $ inserted" error). 
+ 
+- Improved parsing in math mode: Superscript and subscript and \left,\right are now parsed correctly
+
+- shell script for providing CVS support
+
+Minor:
+
+- fixed a bug in utf8 mode that resulted in many warning messages and
+  failure to parse properly words with national characters
+
+- Now works with the latest version of Algorithm::Diff (version 1.19)
+
+- new options "--allow-spaces" and "--ignore-warnings"
+
+- Better wording and enhanced context for warning messages 
+
+- '|' character is now recognised as valid math mode character
+
+- Fixed a bug whereby \begin{document} and \end{document} in comments are nevertheless treated as real begin and end points
+
+- add \protect in front of \nogroupcolor command in DVIPSCOL subtype (old version broke sometimes according to bug reports although I could not replicate the problem) 
+
+- replace \uline by \uwave in CUNDERLINE style, such that added and deleted text parts look different even in math mode
+
+- Markup within DIFnomarkup enviroment is removed by latexdiff. This can be used to protect parts
+  for which latexdiff has trouble creating proper latex code. 
+
+- new markup type FONTSTRIKE
+
+
+Version 0.2  September 2004
+===========================
+
+- introduced subtype DVIPSCOL (coloring changed blocks for dvips converter)
+
+- support for utf8 and other encodings 
+
+Minor:
+
+- removed buggy COLOR subtype
+
+- Usage information no longer printed automatically after certain syntactic error messages
+
+- short options -a, -A, -x, -X now really do what is claimed in the manual
+
+- bug in failback splitting of input was fixed
+
+- options --exclude-textcmd, --append-textcmd, --exclude-safecmd, and --append-safecmd
+  can now take comma-separated list as well as a file as argument.
+
+
+
diff --git a/Master/texmf-dist/doc/latex/latexdiff/LICENSE b/Master/texmf-dist/doc/latex/latexdiff/LICENSE
new file mode 100644
index 00000000000..960fe7469fe
--- /dev/null
+++ b/Master/texmf-dist/doc/latex/latexdiff/LICENSE
@@ -0,0 +1,280 @@
+		    GNU GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+                       59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+			    Preamble
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diff --git a/Master/texmf-dist/doc/latex/latexdiff/Makefile b/Master/texmf-dist/doc/latex/latexdiff/Makefile
new file mode 100644
index 00000000000..45467307879
--- /dev/null
+++ b/Master/texmf-dist/doc/latex/latexdiff/Makefile
@@ -0,0 +1,64 @@
+# Modify these paths to the requirements of your own system
+# For the current setting you will need root permission but 
+# it is perfectly acceptable to choose user directories 
+#
+INSTALLPATH = /usr/local
+INSTALLMANPATH = $(INSTALLPATH)/man
+INSTALLEXECPATH = $(INSTALLPATH)/bin
+
+default:
+	@echo "To install stand-alone version type:    make install"
+	@echo "  (Note the standard version requires prior installation"
+	@echo "   of the PERL package Algorithm::Diff available from "
+	@echo "   the PERL archive www.cpan.org)"
+	@echo " "
+	@echo "To install fast version (using UNIX diff) type: make install fast "
+	@echo " "
+	@echo "To install the version which uses the system Algorithm::Diff package type: make install-ext"
+	@echo " "
+
+install: install-so
+
+install-ext: install-latexdiff install-latexrevise install-latexdiff-vc install-man
+
+install-so: install-latexdiff-so install-latexrevise install-latexdiff-vc install-man
+
+install-fast: install-latexdiff-fast install-latexrevise install-latexdiff-vc install-man
+
+install-man:
+	install latexrevise.1 latexdiff.1 latexdiff-vc.1 $(INSTALLMANPATH)/man1
+
+install-latexdiff:
+	install latexdiff $(INSTALLEXECPATH)
+
+install-latexdiff-so:
+	if [ -e $(INSTALLEXECPATH)/latexdiff ]; then rm $(INSTALLEXECPATH)/latexdiff; fi
+	install latexdiff-so $(INSTALLEXECPATH)
+	cd $(INSTALLEXECPATH); ln -s latexdiff-so latexdiff
+
+install-latexdiff-fast:
+	if [ -e $(INSTALLEXECPATH)/latexdiff ]; then rm $(INSTALLEXECPATH)/latexdiff; fi
+	install latexdiff-fast $(INSTALLEXECPATH)
+	cd $(INSTALLEXECPATH); ln -s latexdiff-fast latexdiff
+
+install-latexrevise:
+	install latexrevise $(INSTALLEXECPATH)
+
+install-latexdiff-vc:
+	install latexdiff-vc $(INSTALLEXECPATH)
+	cd $(INSTALLEXECPATH); for vcs in cvs rcs svn ; do if [ -e latexdiff-$$vcs ]; then rm latexdiff-$$vcs; fi; ln -s latexdiff-vc latexdiff-$$vcs ; done
+
+test-ext: 
+	@echo "latexdiff example/example-draft.tex example/example-rev.tex (system Algorithm::Diff)"
+	./latexdiff -V example/example-draft.tex example/example-rev.tex > example/example-diff.tex
+	@echo "Difference file created: example/example-diff.tex"
+
+test-so: 
+	@echo "latexdiff example/example-draft.tex example/example-rev.tex (stand-alone version)"
+	./latexdiff-so -V example/example-draft.tex example/example-rev.tex > example/example-diff.tex
+	@echo "Difference file created: example/example-diff.tex"
+
+test-fast: 
+	@echo "latexdiff example/example-draft.tex example/example-rev.tex (stand-alone version)"
+	./latexdiff-fast -V example/example-draft.tex example/example-rev.tex > example/example-diff.tex
+	@echo "Difference file created: example/example-diff.tex"
diff --git a/Master/texmf-dist/doc/latex/latexdiff/README b/Master/texmf-dist/doc/latex/latexdiff/README
new file mode 100644
index 00000000000..78adffb533a
--- /dev/null
+++ b/Master/texmf-dist/doc/latex/latexdiff/README
@@ -0,0 +1,98 @@
+
+INTRODUCTION
+
+latexdiff is a Perl script, which compares two latex files and marks
+up significant differences between them (i.e. a diff for latex files).
+  Various options are available for visual markup using standard latex 
+packages such as "color.sty". Changes not directly affecting visible 
+text, for example in formatting commands, are still marked in 
+the latex source.
+ 
+A rudimentary revision facilility is provided by another Perl script,
+latexrevise, which accepts or rejects all changes.  Manual
+editing of the difference file can be used to override this default
+behaviour and accept or reject selected changes only.  
+
+The author is F Tilmann.
+
+
+REQUIREMENTS
+
+Perl 5.8 or higher must be installed.
+  The latexdiff script makes use of the Perl package Algorithm::Diff (available 
+from www.cpan.org, current version 1.19). You can either install this package, or
+use the standalone version of latexdiff, latexdiff-so, which has version 1.15 of 
+this package inlined and does not require external installation of
+the package. Because latexdiff uses internal functions of Algorithm:Diff whose 
+calling format or availability can change without notice, the preferred method is
+now to use the standalone version.
+
+As an alternative, latexdiff-fast has a modified version of Algorithm::Diff inlined,
+which internally uses the UNIX diff command.  This version is much faster but is dependent
+on an external "diff" command.  Subtle differences in the algorithm of Algorithm::Diff and 
+UNIX-diff mean that the resulting set of differences will generally not be the same as
+for the standard latexdiff.  In most practical cases, these differences are minor, though.
+
+INSTALLATION UNIX/LINUX
+
+The basic installation procedure is almost trivial:
+
+1. Copy latexdiff, latexrevise and latexdiff-vc into a directory which
+   is in the search path and make them executable.  If the Algorithm::Diff
+   package is not installed, use latexdiff-so instead of latexdiff. 
+
+2. Copy latexdiff.1 and latexrevise.1 into the correct man directory
+
+3. Optionally create soft links latexdiff-cvs latexdiff-rcs, and
+   latexdiff-svn for latexdiff-vc.
+
+The attached Makefile contains example commands to carry out above 
+steps as root for a typical UNIX installation. Type 
+
+  make install          (for the stand alone version)
+or
+  make install-ext      (for the version using the external Algorithm::Diff)
+or
+  make install-fast     (for the version using the UNIX 'diff' function for fast differencing)
+
+to get it rolling.  You can type
+
+  make test
+or
+  make test-ext
+or
+  make test-fast
+
+to test the respective versions on a brief example before installation
+
+
+DOCUMENTATION:
+
+Usage instructions are in the manual latexdiff-man.pdf as well as the 
+man pages.
+
+CONTRIBUTIONS
+
+The directory contrib contains code written by others relating to latexdiff.  
+Currently this directory contains:
+
+latexdiff-wrap (Author: V. Kuhlmann) An alternative wrapper script which can be used
+  instead of latexdiff-vc.  Its main use is as a template for customised wrapper scripts.
+
+latexdiff.spec (Author: T. Doerges) spec file for RPM generation
+
+The following contributions were incorporated into the latexdiff code, or inspired me to 
+extend latexdiff in a similar way: J. Paisley, N. Becker, K. Huebner
+
+LICENSE
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License Version 2 as published by
+the Free Software Foundation.
+
+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 (file LICENSE in the
+distribution).
+
diff --git a/Master/texmf-dist/doc/latex/latexdiff/contrib/latexdiff-wrap b/Master/texmf-dist/doc/latex/latexdiff/contrib/latexdiff-wrap
new file mode 100755
index 00000000000..894b424de36
--- /dev/null
+++ b/Master/texmf-dist/doc/latex/latexdiff/contrib/latexdiff-wrap
@@ -0,0 +1,192 @@
+#!/bin/bash
+#
+# latexdiff-wrap
+#
+# Wrapper for latexdiff, to
+#   * provide support for documents consiting of more than 1 latex file
+#   * provide my common arguments
+#
+# Copyright (C) by Volker Kuhlmann <VolkerKuhlmann@gmx.de>
+# Released under the terms of the GNU General Public License (GPL) Version 2.
+# See http://www.gnu.org/ for details.
+#
+# Volker Kuhlmann
+#   5, 6, 7, 12, 16, 17 Oct 2005
+#   31 Jan; 5, 7, 13, 15 Feb 2006
+#
+
+VERSION="0.6, 15 Feb 2006"
+AUTHOR="Volker Kuhlmann <VolkerKuhlmann@gmx.de>"
+COPYRIGHT="Copyright (C) 2005-2006"
+
+
+####
+#### Constants and initialised variables
+#
+diffcmd="latexdiff"
+diffrc="$HOME/texmf/latexdiff"
+#diffargs="-e latin1 --ignore-warnings -p latexdiff-preamble.sty"
+diffargs="-e latin1 --ignore-warnings"
+diffargs="$diffargs --append-safecmd $diffrc/safe-cmds"
+diffargs="$diffargs --append-textcmd $diffrc/text-cmds"
+# Note: Can't use multiple --append-safecmd
+# show current command lists:
+#diffcmd="$diffcmd --show-safecmd --show-textcmd --show-config"
+
+
+####
+#### Version, Usage, Help
+#
+show_version() {
+    echo "${0##*/} version $VERSION
+$COPYRIGHT by $AUTHOR"
+}
+
+show_usage() {
+    echo "
+Usage: ${0##*/} OLDDIR NEWDIR DIFFDIR [DIFFARGS --] FILE.tex [...]
+       ${0##*/} --show [DIFFARGS]
+Version $VERSION
+$COPYRIGHT by $AUTHOR
+"
+}
+
+show_help() {
+    show_usage
+    echo "\
+For each FILE.tex, build a new file DIFFDIR/FILE.tex with markup of the changes
+which were made from OLDDIR/FILE.tex to NEWDIR/FILE.tex.
+Any path given with FILE.tex is stripped off.
+Any DIFFARGS are added to the latexdiff call, if present (remember to follow
+them with a double-hyphen on its own before the FILE arguments).
+
+With --show, shows the settings latexdiff would be running with, including the
+changes applied by the user.
+"
+}
+
+# For scripts not using function library only:
+Version() { show_version; exitwith ErrVersion; }
+Usage() { show_help; exitwith ErrUsage; }
+Help() { test "$1" && exitwith ErrHelp show_help; show_help; exitwith ErrOK; }
+
+
+####
+#### Error/Exit codes
+#
+exitwith() {
+    exec 1>&2  # write stdout on stderr instead
+  case "$1" in
+    ErrOK)
+    	exit 0;;
+    ErrVersion|ErrUsage|ErrHelp)
+	# Output generated by function (program) $2, if given
+	test -n "$2" && "$2"
+	exit 1;;
+ # more codes in here
+ # more codes in here
+    ErrBadoption)
+    	echo "Bad option '$2'."
+	echo "Call with -h for help."
+	exit 9;;
+    ErrMissingParameter)
+	echo "A required parameter for option $2 is missing."
+	echo "Call with -h for help."
+	exit 9;;
+    *)
+	echo "Internal error: exitwith() called with illegal error code '$1'."
+	exit 19;;
+  esac
+}
+
+
+####
+#### Parse command line parameters
+#
+
+# If the next arg starts with a "-", collect additional argument for latexdiff
+# until "--".
+scanextraargs() {
+    addargs=()
+    case "$1" in -*)
+	while [ $# -gt 0 -a "$1" != "--" ]; do
+    	    addargs=( "${addargs[@]}" "$1" )
+	    shift
+	done
+	test "$1" == "--" && shift
+    ;; esac
+    fileargs=( "$@" )
+}
+
+case "$1" in
+    --version)	    	Version;;
+    --usage)	    	Usage;;
+    --help|-h|-help)	Help;;
+    --show)
+        shift
+	scanextraargs "$@"
+	(set -x
+	$diffcmd $diffargs "${addargs[@]}" \
+	    --show-safecmd --show-textcmd --show-config 
+	) | fmt
+    	exit $? ;;
+esac
+
+olddir="${1%/}"
+newdir="${2%/}"
+diffdir="${3%/}"
+
+if ! [ -d "$olddir" -a -d "$newdir" -a -d "$diffdir" ]; then
+    Help 1>&2 err
+fi
+
+shift 3
+
+scanextraargs "$@"
+set -- "${fileargs[@]}"
+
+
+
+####
+#### Functions
+#
+#set -x
+Log() { echo 1>&2 "+ $@"; "$@"; }
+
+
+####
+#### Main
+#
+
+# Create output directory, just in case.
+(set -x
+mkdir -p "$diffdir"
+)
+while [ $# -gt 0 ]; do
+    file="${1##*/}"
+    echo Examining: "$file"
+    # No point running latexdiff if both files are identical,
+    # but run latexdiff on top-level LaTeX file in any case.
+    if cmp --quiet "$olddir/$file" "$newdir/$file" \
+	&& ! grep -lq '\\begin.*{document}' "$newdir/$file"; then
+	(set -x
+	cp -p "$olddir/$file" "$diffdir"
+	)
+    else
+    	# Delete file, to make sure it's not clobbered by redirecting stdout
+	# in case it's a symlink to te original.
+	test -f "$diffdir/$file" && (set -x
+	rm "$diffdir/$file"
+	)
+	# Run latexdiff if both input files are present.
+	run=1
+	test -f "$olddir/$file" || { echo 1>&2 "No file: $olddir/$file"; run=; }
+	test -f "$newdir/$file" || { echo 1>&2 "No file: $newdir/$file"; run=; }
+	test -n "$run" && \
+	(set -x
+	$diffcmd $diffargs "${addargs[@]}" \
+	    "$olddir/$file" "$newdir/$file"  > "$diffdir/$file"
+	)
+    fi
+    shift
+done
diff --git a/Master/texmf-dist/doc/latex/latexdiff/contrib/latexdiff.spec b/Master/texmf-dist/doc/latex/latexdiff/contrib/latexdiff.spec
new file mode 100644
index 00000000000..9255a69fea9
--- /dev/null
+++ b/Master/texmf-dist/doc/latex/latexdiff/contrib/latexdiff.spec
@@ -0,0 +1,58 @@
+Summary: Diff for LaTeX files
+Name: latexdiff
+Version: 0.5
+Release: 1
+License: GPL
+Group: Productivity/Publishing/TeX/Utilities
+URL: http://www.tug.org/tex-archive/help/Catalogue/entries/latexdiff.html
+Source0: %{name}.zip
+BuildArch: noarch
+BuildRoot: %{_tmppath}/%{name}-%{version}-%{release}-root
+# only required for 'make install-ext'
+# Requires: perl-Algorithm-Diff
+
+
+%description
+latexdiff is a Perl script, which compares two latex files and marks
+up significant differences between them (i.e. a diff for latex files).
+  Various options are available for visual markup using standard latex
+packages such as "color.sty". Changes not directly affecting visible
+text, for example in formatting commands, are still marked in
+the latex source.
+
+(C) 2004 Frederik Tilmann <tilmann@esc.cam.ac.uk>
+
+
+%prep
+%setup -n %{name}
+
+
+%build
+# quick had to adapt the Makefile
+%{__mv} Makefile Makefile.old
+%{__sed} \
+  -e "s;INSTALLPATH = /usr/local;INSTALLPATH = \${DESTDIR}%{_prefix};" \
+  -e "s;INSTALLMANPATH = \$(INSTALLPATH)/man;INSTALLMANPATH = \${DESTDIR}%{_mandir};" \
+  Makefile.old > Makefile
+
+
+%install
+%{__mkdir_p} $RPM_BUILD_ROOT%{_bindir}
+%{__mkdir_p} $RPM_BUILD_ROOT%{_mandir}/man1
+
+%makeinstall
+
+
+%clean
+[ "${RPM_BUILD_ROOT}" != "/" ] && [ -d "${RPM_BUILD_ROOT}" ] && %{__rm} -rf "${RPM_BUILD_ROOT}"
+
+
+%files
+%defattr(-,root,root)
+%doc example CHANGES LICENSE README
+%{_bindir}/*
+%{_mandir}/man*/*
+
+%changelog
+* Thu Jan  4 2007 Till Dörges <till@doerges.net> - 0.5-1
+- Initial build.
diff --git a/Master/texmf-dist/doc/latex/latexdiff/example/example-draft.tex b/Master/texmf-dist/doc/latex/latexdiff/example/example-draft.tex
new file mode 100644
index 00000000000..593a1707121
--- /dev/null
+++ b/Master/texmf-dist/doc/latex/latexdiff/example/example-draft.tex
@@ -0,0 +1,59 @@
+\documentclass[12pt,a4paper]{article}
+
+\setlength{\topmargin}{-0.2in}
+\setlength{\textheight}{9.5in}
+\setlength{\oddsidemargin}{0.0in}
+
+\setlength{\textwidth}{6.5in}
+
+\title{latexdiff Example - Draft version}
+\author{F Tilmann}
+
+\begin{document}
+\maketitle
+
+\section*{Introduction}
+
+This is an extremely simple document that showcases some of latexdiff features.
+Type
+\begin{verbatim}
+latexdiff -t UNDERLINE example-draft.tex example-rev.tex > example-diff.tex
+\end{verbatim}
+to create the difference file.  You can inspect this file directly. Then run either 
+\begin{verbatim}
+pdflatex example-diff.tex
+xpdf example-diff.pdf
+\end{verbatim}
+or
+\begin{verbatim}
+latex example-diff.tex
+dvips -o example-diff.ps example-diff.dvi
+gv example-diff.ps
+\end{verbatim}
+to display the markup.
+
+\section*{Another section title}
+
+A paragraph with a line only in the draft document.  More things could be said 
+were it not for the constraints of time and space.
+
+More things could be said were it not for the constraints of time and space.
+
+And here is a tipo. 
+
+Here is a table:
+
+\begin{tabular}{ll}
+Name & Description \\
+\hline
+Gandalf & Grey \\
+Saruman & White
+\end{tabular}
+
+And sometimes a whole paragraph gets completely rewritten. In this
+case latexdiff marks up the whole paragraph even if some words in it
+are identical.
+No change, no markup!
+\end{document}
+
+
diff --git a/Master/texmf-dist/doc/latex/latexdiff/example/example-rev.tex b/Master/texmf-dist/doc/latex/latexdiff/example/example-rev.tex
new file mode 100644
index 00000000000..4bcaf156272
--- /dev/null
+++ b/Master/texmf-dist/doc/latex/latexdiff/example/example-rev.tex
@@ -0,0 +1,60 @@
+\documentclass[12pt,a4paper]{article}
+
+\setlength{\topmargin}{-0.2in}
+\setlength{\textheight}{9.5in}
+\setlength{\oddsidemargin}{0.0in}
+
+\setlength{\textwidth}{6in}
+
+\title{latexdiff Example - Revised version}
+\author{F Tilmann}
+% Note how in the preamble visual markup is never used (even
+% if some preamble might eventually end up as visible text.)
+
+\begin{document}
+\maketitle
+
+\section*{Introduction}
+
+This is an extremely simple document that showcases some of the latexdiff features.
+Type
+\begin{verbatim}
+latexdiff -t UNDERLINE example-draft.tex example-rev.tex > example-diff.tex
+\end{verbatim}
+to create the difference file.  You can inspect this file directly. Then run either 
+\begin{verbatim}
+pdflatex example-diff.tex
+xpdf example-diff.pdf
+\end{verbatim}
+or
+\begin{verbatim}
+latex example-diff.tex
+dvips -o example-diff.ps example-diff.dvi
+gv example-diff.ps
+\end{verbatim}
+to display the markup.
+
+\section*{Yet another section title}
+
+ More things could be said were it not for the constraints of time and space.
+
+A paragraph with a line only in the revised document.  More things could be 
+said were it not for the constraints of time and space.
+
+And here is a typo. 
+
+Here is a table:
+
+\begin{tabular}{ll}
+Name & Description \\
+\hline
+Gandalf & White \\
+Saruman & Evil
+\end{tabular}
+
+And now for something completely different, with not a paragraph in sight.
+No change, 
+no markup!
+\end{document}
+
+
diff --git a/Master/texmf-dist/doc/latex/latexdiff/latexdiff b/Master/texmf-dist/doc/latex/latexdiff/latexdiff
new file mode 100755
index 00000000000..efceea4c2ee
--- /dev/null
+++ b/Master/texmf-dist/doc/latex/latexdiff/latexdiff
@@ -0,0 +1,2783 @@
+#!/usr/bin/perl -w
+# latexdiff - differences two latex files on the word level
+#             and produces a latex file with the differences marked up.
+#
+#   Copyright (C) 2004-2007  F J Tilmann (tilmann@esc.cam.ac.uk)
+#
+#    This program is free software; you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License Version 2 as published by
+#    the Free Software Foundation.
+#
+#    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, write to the Free Software
+#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+# Detailed usage information at the end of the file
+#
+# Version 0.5  A number of minor improvements based on feedback
+#              Deleted blocks are now shown before added blocks
+#              Package specific processing
+#
+# Version 0.43 unreleased typo in list of styles at the end
+#              Add protect to all \cbstart, \cbend commands
+#              More robust substitution of deleted math commands
+#
+# Version 0.42 November 06  Bug fixes only
+#
+# Version 0.4   March 06 option for fast differencing using UNIX diff command, several minor bug fixes (\par bug, improved highlighting of textcmds)
+#
+# Version 0.3   August 05 improved parsing of displayed math, --allow-spaces 
+#               option, several minor bug fixes
+#
+# Version 0.25  October 04 Fix bug with deleted equations, add math mode commands to safecmd, add | to allowed interpunctuation signs
+# Version 0.2   September 04 extension to utf-8 and variable encodings
+# Version 0.1   August 04    First public release
+
+use Algorithm::Diff qw(traverse_sequences);
+
+use Getopt::Long ;
+use strict ;
+use utf8 ;
+
+my ($algodiffversion)=split(/ /,$Algorithm::Diff::VERSION);
+
+
+my ($versionstring)=<<EOF ;
+This is LATEXDIFF 0.5  (Algorithm::Diff $Algorithm::Diff::VERSION)
+  (c) 2004-2007 F J Tilmann
+EOF
+
+# Configuration variables: these have to be visible from the subroutines
+my $MINWORDSBLOCK=3; # minimum number of tokens to form an independent block
+                     # shorter identical blocks will be merged to the previous word
+my $FLOATENV='(?:figure|table|plate)[\w\d*@]*' ;   # Environments in which FL variants of defined commands are used
+my $PICTUREENV='(?:picture|DIFnomarkup)[\w\d*@]*' ;   # Environments in which all change markup is removed
+my $MATHENV='(?:equation|displaymath|DOLLARDOLLAR)' ;           # Environments turning on display math mode (code also knows about \[ and \]
+my $MATHREPL='displaymath';  # Environment introducing deleted maths blocks
+my $MATHARRENV='(?:eqnarray|align|gather|multiline|flalign)[*]?' ;           # Environments turning on eqnarray math mode
+my $MATHARRREPL='eqnarray*';  # Environment introducing deleted maths blocks
+my $ARRENV='(?:array|[pbvBV]matrix)'; # Enviroments making arrays in math mode.  The underlining style does not cope well with those - as a result in-text math environments are surrounded by \mbox{ } if any of these commands is used in an inline math block
+my $COUNTERCMD='(?:footnote|part|section|subsection|subsubsection|paragraph|subparagraph)';  # textcmds which are associated with a counter
+                                        # If any of these commands occur in a deleted block
+                                        # they will be succeeded by an \addtocounter{...}{-1}
+                                        # for the associated counter such that the overall numbers
+                                        # should be the same as in the new file
+
+# Markup strings
+# If at all possible, do not change these as parts of the program
+# depend on the actual name (particularly post-processing)
+# At the very least adapt subroutine postprocess to new tokens.
+my $ADDMARKOPEN='\DIFaddbegin ';   # Token to mark begin of appended text
+my $ADDMARKCLOSE='\DIFaddend ';   # Token to mark end of appended text
+my $ADDOPEN='\DIFadd{';  # To mark begin of added text passage
+my $ADDCLOSE='}';        # To mark end of added text passage
+my $ADDCOMMENT='DIF > ';   # To mark added comment line
+my $DELMARKOPEN='\DIFdelbegin ';   # Token to mark begin of deleted text
+my $DELMARKCLOSE='\DIFdelend ';   # Token to mark end of deleted text
+my $DELOPEN='\DIFdel{';  # To mark begin of deleted text passage
+my $DELCLOSE='}';        # To mark end of deleted text passage
+my $DELCMDOPEN='%DIFDELCMD < ';  # To mark begin of deleted commands (must begin with %, i.e., be a comment
+my $DELCMDCLOSE="%%%\n";    # To mark end of deleted commands (must end with a new line)
+my $AUXCMD='%DIFAUXCMD' ; #  follows auxiliary commands put in by latexdiff to make difference file legal
+                          # auxiliary commands must be on a line of their own
+my $DELCOMMENT='DIF < ';   # To mark deleted comment line
+
+
+# main local variables:
+my @TEXTCMDLIST=();  # array containing patterns of commands with text arguments
+my @TEXTCMDEXCL=();  # array containing patterns of commands without text arguments (if a pattern
+                     # matches both TEXTCMDLIST and TEXTCMDEXCL it is excluded)
+my @CONTEXT1CMDLIST=();  # array containing patterns of commands with text arguments (subset of text commands),
+                         # but which cause confusion if used out of context (e.g. \caption). 
+                         # In deleted passages, the command will be disabled but its argument is marked up
+                         # Otherwise they behave exactly like TEXTCMD's 
+my @CONTEXT1CMDEXCL=();  # exclude list for above, but always empty
+my @CONTEXT2CMDLIST=();  # array containing patterns of commands with text arguments, but which fail cause confusion
+                         # if used out of context (e.g. \title). They and their arguments will be disabled in deleted
+                         # passages
+my @CONTEXT2CMDEXCL=();  # exclude list for above, but always empty
+
+my @SAFECMDLIST=();  # array containing patterns of safe commands (which do not break when in the argument of DIFadd or DIFDEL)
+my @SAFECMDEXCL=();
+
+my ($i,$j,$l);
+my ($old,$new);
+my ($line);
+my ($newpreamble,$oldpreamble);
+my (@newpreamble,@oldpreamble,@diffpreamble,@diffbody);
+my ($latexdiffpreamble);
+my ($oldbody, $newbody, $diffbo);
+my ($oldpost, $newpost);
+my ($diffall);
+# Option names
+my ($type,$subtype,$floattype,$config,$preamblefile,$encoding,
+    $showpreamble,$showsafe,$showtext,$showconfig,$showall,
+    $replacesafe,$appendsafe,$excludesafe,
+    $replacetext,$appendtext,$excludetext,
+    $replacecontext1,$appendcontext1,
+    $replacecontext2,$appendcontext2,
+    $help,$verbose,$version,$ignorewarnings,$allowspaces,$flatten,$debug);
+my (@configlist,
+    @appendsafelist,@excludesafelist,
+    @appendtextlist,@excludetextlist,
+    @appendcontext1list,@appendcontext2list,
+    @packagelist);
+my ($assign,@config);
+# Hash where keys corresponds to the names of  all included packages (including the documentclass as another package
+# the optional arguments to the package are the values of the hash elements
+my ($pkg,%packages);
+# Defaults
+$type='UNDERLINE';
+$subtype='SAFE';
+$floattype='FLOATSAFE';
+
+$verbose=0;
+$debug=1; 
+# define character properties
+sub IsNonAsciiPunct { return <<'END'    # Unicode punctuation but excluding ASCII punctuation
++utf8::IsPunct
+-utf8::IsASCII
+END
+}
+sub IsNonAsciiS { return <<'END'       # Unicode symbol but excluding ASCII
++utf8::IsS
+-utf8::IsASCII
+END
+}
+
+
+
+  my %verbhash;
+
+Getopt::Long::Configure('bundling');
+GetOptions('type|t=s' => \$type, 
+	   'subtype|s=s' => \$subtype, 
+	   'floattype|f=s' => \$floattype, 
+	   'config|c=s' => \@configlist,
+	   'preamble|p=s' => \$preamblefile,
+	   'encoding|e=s' => \$encoding,
+	   'exclude-safecmd|A=s' => \@excludesafelist,
+	   'replace-safecmd=s' => \$replacesafe,
+	   'append-safecmd|a=s' => \@appendsafelist,
+	   'exclude-textcmd|X=s' => \@excludetextlist,
+	   'replace-textcmd=s' => \$replacetext,
+	   'append-textcmd|x=s' => \@appendtextlist,
+	   'replace-context1cmd=s' => \$replacecontext1,
+	   'append-context1cmd=s' => \@appendcontext1list,
+	   'replace-context2cmd=s' => \$replacecontext2,
+	   'append-context2cmd=s' => \@appendcontext2list,
+	   'show-preamble' => \$showpreamble,
+	   'show-safecmd' => \$showsafe,
+	   'show-textcmd' => \$showtext,
+	   'show-config' => \$showconfig,
+	   'show-all' => \$showall,
+           'packages=s' => \@packagelist,
+	   'verbose|V' => \$verbose,
+	   'ignore-warnings' => \$ignorewarnings,
+	   'allow-spaces' => \$allowspaces,
+	   'flatten' => \$flatten,
+	   'version' => \$version,
+	   'help|h|H' => \$help);
+
+if ( $help ) {
+  usage() ;
+}
+
+
+if ( $version ) {
+  die $versionstring ; 
+}
+
+print STDERR $versionstring if $verbose; 
+
+if (defined($showall)){
+  $showpreamble=$showsafe=$showtext=$showconfig=1;
+}
+
+# setting extra preamble commands
+if (defined($preamblefile)) {
+  $latexdiffpreamble=join "\n",(extrapream($preamblefile),"");
+} else {
+  $latexdiffpreamble=join "\n",(extrapream($type,$subtype,$floattype),"");
+}
+
+# setting up @SAFECMDLIST and @SAFECMDEXCL
+if (defined($replacesafe)) {
+  init_regex_arr_ext(\@SAFECMDLIST,$replacesafe);
+} else {
+  init_regex_arr_data(\@SAFECMDLIST, "SAFE COMMANDS");
+}
+foreach $appendsafe ( @appendsafelist ) {
+  init_regex_arr_ext(\@SAFECMDLIST, $appendsafe);
+}
+foreach $excludesafe ( @excludesafelist ) {
+  init_regex_arr_ext(\@SAFECMDEXCL, $excludesafe);
+}
+
+# Special: treat all cite commands as safe except in UNDERLINE and FONTSTRIKE mode
+# (there is a conflict between citation and ulem package, see
+# package documentation)
+if ( uc($type) ne "UNDERLINE" && uc($type) ne "FONTSTRIKE" && uc($type) ne "CULINECHBAR" ) {
+  push (@SAFECMDLIST, qr/^cite.*$/);
+}
+
+# setting up @TEXTCMDLIST and @TEXTCMDEXCL
+if (defined($replacetext)) {
+  init_regex_arr_ext(\@TEXTCMDLIST,$replacetext);
+} else {
+  init_regex_arr_data(\@TEXTCMDLIST, "TEXT COMMANDS");
+}
+foreach $appendtext ( @appendtextlist ) {
+  init_regex_arr_ext(\@TEXTCMDLIST, $appendtext);
+}
+foreach $excludetext ( @excludetextlist ) {
+  init_regex_arr_ext(\@TEXTCMDEXCL, $excludetext);
+}
+
+
+# setting up @CONTEXT1CMDLIST ( @CONTEXT1CMDEXCL exist but is always empty )
+if (defined($replacecontext1)) {
+  init_regex_arr_ext(\@CONTEXT1CMDLIST,$replacecontext1);
+} else {
+  init_regex_arr_data(\@CONTEXT1CMDLIST, "CONTEXT1 COMMANDS");
+}
+foreach $appendcontext1 ( @appendcontext1list ) {
+  init_regex_arr_ext(\@CONTEXT1CMDLIST, $appendcontext1);
+}
+
+
+# setting up @CONTEXT2CMDLIST ( @CONTEXT2CMDEXCL exist but is always empty )
+if (defined($replacecontext2)) {
+  init_regex_arr_ext(\@CONTEXT2CMDLIST,$replacecontext2);
+} else {
+  init_regex_arr_data(\@CONTEXT2CMDLIST, "CONTEXT2 COMMANDS");
+}
+foreach $appendcontext2 ( @appendcontext2list ) {
+  init_regex_arr_ext(\@CONTEXT2CMDLIST, $appendcontext2);
+}
+
+
+
+
+# setting configuration variables
+@config=();
+foreach $config ( @configlist ) {
+  if (-f $config ) {
+    open(FILE,$config) or die ("Couldn't open configuration file $config: $!");
+    while (<FILE>) {
+      chomp;
+      next if /^\s*#/ || /^\s*%/ || /^\s*$/ ;
+      push (@config,$_);
+    }
+    close(FILE);
+  }
+  else {
+#    foreach ( split(",",$config) ) {
+#      push @config,$_;
+#    }
+     push @config,split(",",$config)
+  }
+}
+foreach $assign ( @config ) {
+  $assign=~ m/\s*(\w*)\s*=\s*(\S*)\s*$/ or die "Illegal assignment $assign in configuration list (must be variable=value)";  
+  if ( $1 eq "MINWORDSBLOCK" ) { $MINWORDSBLOCK = $2; }
+  elsif ( $1 eq "FLOATENV" ) { $FLOATENV = $2 ; }
+  elsif ( $1 eq "PICTUREENV" ) { $PICTUREENV = $2 ; }
+  elsif ( $1 eq "MATHENV" ) { $MATHENV = $2 ; }
+  elsif ( $1 eq "MATHREPL" ) { $MATHREPL = $2 ; }
+  elsif ( $1 eq "MATHARRENV" ) { $MATHARRENV = $2 ; }
+  elsif ( $1 eq "MATHARRREPL" ) { $MATHARRREPL = $2 ; }
+  elsif ( $1 eq "ARRENV" ) { $ARRENV = $2 ; }
+  elsif ( $1 eq "COUNTERCMD" ) { $COUNTERCMD = $2 ; }
+  else { die "Unknown variable $1 in assignment.";}
+}
+
+
+foreach $pkg ( @packagelist ) {
+  map { $packages{$_}="" } split(/,/,$pkg) ;
+}
+
+if ($showpreamble) {
+  print "\nPreamble commands:\n";
+  print $latexdiffpreamble ;
+}
+
+if ($showsafe) {
+  print "\nCommands safe within scope of $ADDOPEN $ADDCLOSE and $DELOPEN $DELCLOSE (unless excluded):\n";
+  print_regex_arr(@SAFECMDLIST);
+  print "\nCommands not safe within scope of $ADDOPEN $ADDCLOSE and $DELOPEN $DELCLOSE :\n";
+  print_regex_arr(@SAFECMDEXCL);
+}
+
+if ($showtext) {
+  print "\nCommands with last argument textual (unless excluded) and safe in every context:\n";
+  print_regex_arr(@TEXTCMDLIST);
+  print "\nContext1 commands (last argument textual, command will be disabled in deleted passages, last argument will be shown as plain text):\n";
+  print_regex_arr(@CONTEXT1CMDLIST);
+  print "\nContext2 commands (last argument textual, command ant its argument will be disabled in deleted passages):\n";
+  print_regex_arr(@CONTEXT2CMDLIST);  
+  print "\nExclude list of Commands with last argument not textual (overrides patterns above):\n";
+  print_regex_arr(@TEXTCMDEXCL);
+}
+
+if ($showconfig) {
+  print "Configuration variables:\n";
+  print "MINWORDSBLOCK=$MINWORDSBLOCK\n";
+  print "FLOATENV=$FLOATENV\n";
+  print "PICTUREENV=$PICTUREENV\n";
+  print "MATHENV=$MATHENV\n";
+  print "MATHREPL=$MATHREPL\n";
+  print "MATHARRENV=$MATHARRENV\n";
+  print "MATHARRREPL=$MATHARRREPL\n";
+  print "ARRENV=$ARRENV\n";
+  print "COUNTERCMD=$COUNTERCMD\n";
+}
+if ($showconfig || $showtext || $showsafe || $showpreamble) {
+  exit 0; }
+if ( @ARGV != 2 ) { 
+  print STDERR "2 and only 2 non-option arguments required.  Write latexdiff -h to get help\n";
+  exit(2);
+}
+
+# Are extra spaces between command arguments permissible?
+my $extraspace;
+if ($allowspaces) {
+  $extraspace='\s*'; 
+} else {
+  $extraspace='';
+}
+
+# append context lists to text lists (as text property is implied)
+push @TEXTCMDLIST, @CONTEXT1CMDLIST;
+push @TEXTCMDLIST, @CONTEXT2CMDLIST;
+
+
+# Patterns. These are used by some of the subroutines, too
+# I can only define them down here because value of extraspace depends on an option
+  my $pat0 = '(?:[^{}]|\\\{|\\\})*';
+  my $pat1 = '(?:[^{}]|\\\{|\\\}|\{'.$pat0.'\})*';
+  my $pat2 = '(?:[^{}]|\\\{|\\\}|\{'.$pat1.'\})*'; # 
+  my $pat3 = '(?:[^{}]|\\\{|\\\}|\{'.$pat2.'\})*';
+  my $pat4 = '(?:[^{}]|\\\{|\\\}|\{'.$pat3.'\})*';
+  my $brat0 = '(?:[^\[\]]|\\\[|\\\])*'; 
+
+  my $quotemarks = '(?:\'\')|(?:\`\`)';
+  my $punct='[0.,\/\'\`:;\"\?\(\)\[\]!~\p{IsNonAsciiPunct}\p{IsNonAsciiS}]';
+  my $number='-?\d*\.\d*';
+  my $mathpunct='[+=<>\-\|]';
+  my $and = '&';
+  my $coords= '[\-.,\s\d]*';
+# word: sequence of letters or accents followed by letter
+  my $word='(?:[-\w\d*]|\\\\[\"\'\`~^][A-Za-z\*])+';
+  my $cmdleftright='\\\\(?:left|right)\s*(?:[()\[\]|]|\\\\(?:[|{}]|\w+))';
+
+  my $cmdoptseq='\\\\[\w\d\*]+'.$extraspace.'(?:(?:\['.$brat0.'\]|\{'. $pat4 . '\}|\(' . $coords .'\))'.$extraspace.')*';
+  my $oneletcmd='\\\\.(?:\['.$brat0.'\]|\{'. $pat4 . '\})*';
+  my $math='\$(?:[^$]|\\\$)*?\$|\\\\[(].*?\\\\[)]';
+#  my $math='\$(?:[^$]|\\\$)*\$';
+  my $comment='%.*?\n';
+  my $pat=qr/(?:\A\s*)?(?:${and}|${quotemarks}|${number}|${word}|$cmdleftright|${cmdoptseq}|${math}|${oneletcmd}|${comment}|${punct}|${mathpunct}|\{|\})\s*/ ;
+
+
+
+# now we are done setting up and can start working   
+my ($oldfile, $newfile) = @ARGV;
+
+$encoding=guess_encoding($newfile) unless defined($encoding);
+
+$encoding = "utf8" if $encoding =~ m/^utf8/i ;
+if (lc($encoding) eq "utf8" ) {
+  binmode(STDOUT, ":utf8");
+  binmode(STDERR, ":utf8");
+}
+
+$old=read_file_with_encoding($oldfile,$encoding);
+$new=read_file_with_encoding($newfile,$encoding);
+
+
+
+
+# reset time
+exetime(1);
+($oldpreamble,$oldbody,$oldpost)=splitdoc($old,'\\\\begin\{document\}','\\\\end\{document\}');
+
+
+($newpreamble,$newbody,$newpost)=splitdoc($new,'\\\\begin\{document\}','\\\\end\{document\}');
+
+
+if ($flatten) {
+  $oldbody=flatten($oldbody,$oldpreamble,$oldfile,$encoding);
+  $newbody=flatten($newbody,$newpreamble,$newfile,$encoding);
+}
+
+if ( length $oldpreamble && length $newpreamble ) {
+  @oldpreamble = split /\n/, $oldpreamble;
+  @newpreamble = split /\n/, $newpreamble;
+  
+  %packages=list_packages(@newpreamble) unless %packages;
+  if (defined $packages{"hyperref"} ) {
+    print STDERR "hyperref package detected.\n" if $verbose ;
+    $latexdiffpreamble =~ s/\{\\DIFadd\}/{\\DIFaddtex}/g;
+    $latexdiffpreamble =~ s/\{\\DIFdel\}/{\\DIFdeltex}/g;
+    $latexdiffpreamble .= join "\n",(extrapream("HYPERREF"),"");
+  }
+  # insert dummy first line such that line count begins with line 1 (rather than perl's line 0) - just so that line numbers inserted by linediff are correct
+  unshift @newpreamble,'';
+  unshift @oldpreamble,'';
+  print STDERR "Differencing preamble.\n" if $verbose;
+  @diffpreamble = linediff(\@oldpreamble, \@newpreamble);
+  # remove dummy line again
+  shift @diffpreamble; 
+  push @diffpreamble,$latexdiffpreamble;
+  push @diffpreamble,'\begin{document}';
+}
+elsif ( !length $oldpreamble && !length $newpreamble ) {
+  @diffpreamble=();
+} else {
+  print STDERR "Either both texts must have preamble or neither text must have the preamble.\n";
+  exit(2);
+}
+
+if (defined $packages{"amsmath"} ) {
+  print STDERR "amsmath package detected.\n" if $verbose ;
+  $MATHARRREPL='align*';
+}
+
+print STDERR "Preprocessing body.  " if $verbose;
+my ($oldleadin,$newleadin)=preprocess($oldbody,$newbody);
+
+
+# run difference algorithm
+@diffbody=bodydiff($oldbody, $newbody);
+$diffbo=join("",@diffbody);
+print STDERR "(",exetime()," s)\n","Postprocessing body. \n " if $verbose;
+postprocess($diffbo);
+$diffall =join("\n",@diffpreamble) ;
+$diffall .= "$newleadin$diffbo" ;
+$diffall .= "\\end{document}$newpost" if length $newpreamble ;
+if ( lc($encoding) ne "utf8" && lc($encoding) ne "ascii" ) {
+  print STDERR "Encoding output file to $encoding\n" if $verbose;
+  $diffall=Encode::encode($encoding,$diffall);
+  binmode STDOUT;
+}
+print $diffall;
+
+
+print STDERR "(",exetime()," s)\n","Done.\n" if $verbose;
+
+
+
+## guess_encoding(filename)
+## reads the first 20 lines of filename and looks for call of inputenc package
+## if found, return the option of this package (encoding), otherwise return ascii
+sub guess_encoding {
+  my ($filename)=@_;
+  my ($i,$enc);
+  open (FH, $filename) or die("Couldn't open $filename: $!");
+  $i=0;
+  while (<FH>) {
+    next if /^\s*%/;    # skip comment lines
+    if (m/\\usepackage\[(\w*?)\]\{inputenc\}/) {
+      close(FH);
+      return($1);
+    }
+    last if (++$i > 20 ); # scan at most 20 non-comment lines
+  }
+  close(FH);
+  return("ascii");
+}
+
+
+sub read_file_with_encoding {
+  my ($output);
+  my ($filename, $encoding) = @_;
+
+  if (lc($encoding) eq "utf8" ) {
+    open (FILE, "<:utf8",$filename) or die("Couldn't open $filename: $!");
+    local $/ ; # locally set record operator to undefined, ie. enable whole-file mode
+    $output=<FILE>;
+  } elsif ( lc($encoding) eq "ascii") {
+    open (FILE, $filename) or die("Couldn't open $filename: $!");
+    local $/ ; # locally set record operator to undefined, ie. enable whole-file mode
+    $output=<FILE>;
+  } else {
+    require Encode;
+    open (FILE, "<",$filename) or die("Couldn't open $filename: $!");
+    local $/ ; # locally set record operator to undefined, ie. enable whole-file mode
+    $output=<FILE>;
+    print STDERR "Converting $filename from $encoding to utf8\n" if $verbose;
+    $output=Encode::decode($encoding,$output);
+  }
+  close FILE;
+  return $output;
+}
+
+# %packages=list_packages(@preamble)
+# scans the arguments for \documentclass and \usepackage statements and constructs a hash
+# whose keys are the included packages, and whose values are the associated optional arguments
+sub list_packages {
+  my (@preamble)=@_;
+  my %packages=();
+  foreach $line ( @preamble ) {
+    # get rid of comments
+    $line=~s/(?<!\\)%.*$// ;
+    if ( $line =~ m/\\(?:documentclass|usepackage)(?:\[(.+?)\])?\{(.*?)\}/ ) {
+#      print STDERR "Found something: |$line|\n";
+      if (defined($1)) {
+	$packages{$2}=$1;
+      } else {
+	$packages{$2}="";
+      }
+    }
+  }
+  return (%packages);
+}
+
+# flatten($text,$preamble,$filename,$encoding)
+# expands \input and \include commands within text
+# premable is scanned for includeonly commands
+# encoding is the encoding
+sub flatten {
+  my ($text,$preamble,$filename,$encoding)=@_;
+  my ($includeonly,$dirname,$fname,$newpage,$replacement);
+  require File::Basename ; 
+  require File::Spec ; 
+  $dirname = File::Basename::dirname($filename);
+
+  if ( ($includeonly) = ($preamble =~ m/\\includeonly{(.*?)}/ ) ) {
+    $includeonly =~ s/,/|/g;
+  } else {
+    $includeonly = '.*?';
+  }
+
+  print STDERR "DEBUG: includeonly $includeonly\n";
+
+  $text=~s/\\input{(.*?)}|\\include{(${includeonly}(?:\.tex)?)}/{ 
+	    $fname = $1 if defined($1)  ;
+	    $fname = $2 if defined($2) ;       
+            #      # add tex extension unless there is a three letter extension already 
+            $fname .= ".tex" unless $fname =~ m|\.\w{3}|;
+            print STDERR "Include file $fname\n" if $verbose;
+            print STDERR "DEBUG looking for file ",File::Spec->catfile($dirname,$fname), "\n";
+            # content of file becomes replacement value, add \newpage if the command was include
+            $replacement=read_file_with_encoding(File::Spec->catfile($dirname,$fname), $encoding) or die
+                "Couldn't find file ",File::Spec->catfile($dirname,$fname),": $!";
+	    $newpage=(defined($2)? " \\newpage " : "") ;
+	    "$newpage$replacement$newpage";
+          }/exg;
+
+  return($text);
+}
+
+
+# print_regex_arr(@arr)
+# prints regex array without x-ism expansion put in by pearl to stdout
+sub print_regex_arr {
+  my $dumstring;
+  $dumstring = join(" ",@_);     # PERL generates string (?-xism:^ref$) for quoted refex ^ref$
+  $dumstring =~ s/\(\?-xism:\^(.*?)\$\)/$1/g;   # remove string and ^,$ marks before output
+  print $dumstring,"\n";
+}
+
+
+# @lines=extrapream($type)
+# reads line from appendix (end of file after __END__ token)
+sub extrapream {
+  my $type;
+  my @retval=("%DIF PREAMBLE EXTENSION ADDED BY LATEXDIFF") ;
+  my ($copy);
+
+  while (@_) {
+    $copy=0;
+    $type=shift ;
+    if ( -f $type ) {
+      open (FILE,$type) or die "Cannot open preamble file $type: $!";
+      print STDERR "Reading preamble file $type\n" if $verbose ;
+      while (<FILE>) {
+	chomp ;
+	if ( $_ =~ m/%DIF PREAMBLE/ ) {
+	  push (@retval,"$_"); 
+	} else {
+	  push (@retval,"$_ %DIF PREAMBLE"); 
+	}
+      }
+    } 
+    else {    # not (-f $type)
+      $type=uc($type);   # upcase argument
+      print STDERR "Preamble Internal Type $type\n" if $verbose;
+      while (<DATA>) {
+	if ( m/^%DIF $type/ ) {
+	  $copy=1; }
+	elsif ( m/^%DIF END $type/ ) {
+	  last; }
+	chomp;
+	push (@retval,"$_ %DIF PREAMBLE") if $copy;
+      }
+      if ( $copy == 0 ) {
+	print STDERR "\nPreamble style $type not implemented.\n";
+        print STDERR "Write latexdiff -h to get help with available styles\n";
+        exit(2);
+      }
+      seek DATA,0,0;    # rewind DATA handle to file begin
+    }
+  }
+  push (@retval,"%DIF END PREAMBLE EXTENSION ADDED BY LATEXDIFF")  ;
+  return @retval;
+}
+
+
+# ($part1,$part2,$part3)=splitdoc($text,$word1,$word2)
+# splits $text into 3 parts at $word1 and $word2.
+# if neither $word1 nor $word2 exist, $part1 and $part3 are empty, $part2 is $text
+# If only $word1 or $word2 exist but not the other, output an error message.
+
+# NB this version avoids $` and $' for performance reason although it only makes a tiny difference
+# (in one test gain a tenth of a second for a 30s run)
+sub splitdoc {
+  my ($text,$word1,$word2)=@_;
+  my ($part1,$part2,$part3)=("","","");
+  my ($rest,$pos);
+
+  if ( $text =~ m/(^[^%]*)($word1)/mg ) {
+    $pos=pos $text;
+    $part1=substr($text,0,$pos-length($2));
+    $rest=substr($text,$pos);
+    if ( $rest =~ m/(^[^%]*)($word2)/mg ) {
+      $pos=pos $rest;
+      $part2=substr($rest,0,$pos-length($2));
+      $part3=substr($rest,$pos);
+    } 
+    else {
+      die "$word1 and $word2 not in the correct order or not present as a pair." ;
+    }
+  } else {
+    $part2=$text;
+    die "$word2 present but not $word1." if ( $text =~ m/(^[^%]*)$word2/ms );
+  }
+  return ($part1,$part2,$part3);
+}
+
+
+
+
+
+# bodydiff($old,$new)
+sub bodydiff {
+  my ($oldwords, $newwords) = @_;
+  my @retwords;
+
+  print STDERR "(",exetime()," s)\n","Splitting into latex tokens \n" if $verbose;
+  print STDERR "Parsing $oldfile \n" if $verbose;
+  my @oldwords = splitlatex($oldwords);
+  print STDERR "Parsing $newfile \n" if $verbose;
+  my @newwords = splitlatex($newwords);
+  my $token;
+
+  print STDERR "(",exetime()," s)\n","Pass 1: Expanding text commands and merging isolated identities with changed blocks  " if $verbose;
+  pass1(\@oldwords, \@newwords);
+
+
+  print STDERR "(",exetime()," s)\n","Pass 2: inserting DIF tokens and mark up.  " if $verbose;
+
+  @retwords=pass2(\@oldwords, \@newwords);
+
+  return(@retwords);
+}
+
+
+
+
+# @words=splitlatex($string)
+# split string according to latex rules
+# Each element of words is either
+# a word (including trailing spaces and punctuation)
+# a latex command
+sub splitlatex {
+  my ($string) = @_ ;
+  my @retval=($string =~ m/$pat/osg);  
+
+  if (length($string) != length(join("",@retval))) {
+    print STDERR "\nWARNING: Inconsistency in length of input string and parsed string:\n     This often indicates faulty or non-standard latex code.\n     In many cases you can ignore this and the following warning messages.\n Note that character numbers in the following are counted beginning after \\begin{document} and are only approximate." unless $ignorewarnings;
+    print STDERR "DEBUG Original length ",length($string),"  Parsed length ",length(join("",@retval)),"\n" if $debug;
+    print STDERR "DEBUG Input string:  |$string|\n" if (length($string)<500) && $debug;
+    print STDERR "DEBUG Token parsing: |",join("+",@retval),"|\n" if (length($string)<500) && $debug ;
+    @retval=();
+    # slow way only do this if other m//sg method fails
+    my $last = 0;
+    while ( $string =~ m/$pat/osg ) {
+      my $match=$&;
+      if ($last + length $& != pos $string  ) {
+	my $pos=pos($string);
+	my $offset=30<$last ? 30 : $last;
+	my $dum=substr($string,$last-$offset,$pos-$last+2*$offset);
+	my $dum1=$dum;
+	my $cnt=$#retval;
+	my $i;
+	$dum1 =~ s/\n/ /g;
+	unless ($ignorewarnings) {
+	  print STDERR "\n$dum1\n";
+	  print STDERR " " x 30,"^" x ($pos-$last)," " x 30,"\n";
+	  print STDERR "Missing characters near word " . (scalar @retval) . " character index: " . $last . "-" .  pos($string) . " Length: " . length($match) . " Match: |$match| (expected match marked above).\n";
+	}
+	  # put in missing characters `by hand'
+	push (@retval, substr($dum,$offset,$pos-$last-length($match)));
+#       Note: there seems to be a bug in substr with utf8 that made the following line output substr which were too long,
+#             using dum instead appears to work
+#	push (@retval, substr($string,$last, pos($string)-$last-length($match)));
+      }
+      push (@retval, $match);
+      $last=pos $string;
+    }
+
+  }
+  return @retval;
+}
+
+
+# pass1( \@seq1,\@seq2)
+# Look for differences between seq1 and seq2.
+# Where an common-subsequence block is flanked by deleted or appended blocks, 
+# and is shorter than $MINWORDSBLOCK words it is appended
+# to the last deleted or appended word.  If the block contains tokens other than words 
+# or punctuation it is not merged.
+# Deleted or appended block consisting of words and safe commands only are
+# also merged, to prevent break-up in pass2 (after previous isolated words have been removed)
+# If there are commands with textual arguments (e.g. \caption) both in corresponding 
+# appended and deleted blocks split them such that the command and opening bracket 
+# are one token, then the rest is split up following standard rules, and the closing 
+# bracket is a separate token, ie. turn
+# "\caption{This is a textual argument}" into 
+# ("\caption{","This ","is ","a ","textual ","argument","}")
+# No return value.  Destructively changes sequences
+sub pass1 {
+  my $seq1 = shift ;
+  my $seq2 = shift ;
+
+  my $len1 = scalar @$seq1;
+  my $len2 = scalar @$seq2;
+  my $wpat=qr/^(?:[a-zA-Z.,'`:;?()!]*)[\s~]*$/;   #'
+
+  my ($last1,$last2)=(-1,-1) ;
+  my $cnt=0;
+  my $block=[];
+  my $addblock=[];
+  my $delblock=[];
+  my $todo=[];
+  my $instruction=[];
+  my $i;
+  my (@delmid,@addmid,@dummy);
+
+  my ($addcmds,$delcmds,$matchindex);
+  my ($addtextblocks,$deltextblocks);
+  my ($addtokcnt,$deltokcnt,$mattokcnt)=(0,0,0);
+  my ($addblkcnt,$delblkcnt,$matblkcnt)=(0,0,0);
+
+  my $adddiscard = sub {
+                      if ($cnt > 0 ) {
+			$matblkcnt++;
+			# just after an unchanged block 
+#			print STDERR "Unchanged block $cnt, $last1,$last2 \n";
+                        if ($cnt < $MINWORDSBLOCK 
+			    && $cnt==scalar (
+				     grep { /^$wpat/ || ( /^\\([\w\d\*]+)((?:\[$brat0\]|\{$pat4\})*)/o 
+							   && iscmd($1,\@SAFECMDLIST,\@SAFECMDEXCL) 
+							   && scalar(@dummy=split(" ",$2))<3 ) }
+					     @$block) )  {
+			  # merge identical blocks shorter than $MINWORDSBLOCK 
+			  # and only containing ordinary words
+			  # with preceding different word
+			  # We cannot carry out this merging immediately as this
+			  # would change the index numbers of seq1 and seq2 and confuse
+			  # the algorithm, instead we store in @$todo where we have to merge
+                          push(@$todo, [ $last1,$last2,$cnt,@$block ]);
+			}
+			$block = []; 
+			$cnt=0; $last1=-1; $last2=-1;
+		      }
+		    };
+  my $discard=sub { $deltokcnt++;
+                    &$adddiscard; #($_[0],$_[1]);
+		    push(@$delblock,[ $seq1->[$_[0]],$_[0] ]);
+		    $last1=$_[0] };		      
+
+  my $add =   sub { $addtokcnt++;
+                    &$adddiscard; #($_[0],$_[1]);
+		    push(@$addblock,[ $seq2->[$_[1]],$_[1] ]);
+		    $last2=$_[1] };		      
+
+  my $match = sub { $mattokcnt++;
+                    if ($cnt==0) {   # first word of matching sequence after changed sequence or at beginning of word sequence
+		      $deltextblocks = extracttextblocks($delblock); 
+		      $delblkcnt++ if scalar @$delblock;
+		      $addtextblocks = extracttextblocks($addblock);
+		      $addblkcnt++ if scalar @$addblock;
+
+		      $delcmds = extractcommands($delblock);
+      		      $addcmds = extractcommands($addblock);
+		      # keygen(third argument of _longestCommonSubsequence) implies to sort on command (0th elements of $addcmd elements)
+		      # the calling format for longestCommonSubsequence has changed between versions of
+		      # Algorithm::Diff so we need to check which one we are using
+		      if ( $algodiffversion  > 1.15 ) {
+			### Algorithm::Diff 1.19
+			$matchindex=Algorithm::Diff::_longestCommonSubsequence($delcmds,$addcmds, 0, sub { $_[0]->[0] } );
+		      } else {
+			### Algorithm::Diff 1.15	
+			$matchindex=Algorithm::Diff::_longestCommonSubsequence($delcmds,$addcmds, sub { $_[0]->[0] } );
+		      }
+
+		      for ($i=0 ; $i<=$#$matchindex ; $i++) {
+			if (defined($matchindex->[$i])){
+			  $j=$matchindex->[$i];
+			  @delmid=splitlatex($delcmds->[$i][3]);
+			  @addmid=splitlatex($addcmds->[$j][3]);
+			  while (scalar(@$deltextblocks)  && $deltextblocks->[0][0]<$delcmds->[$i][1]) {
+			    my ($index,$block,$cnt)=@{ shift(@$deltextblocks) };
+			    push(@$todo, [$index,-1,$cnt,@$block]);
+			  }
+			  push(@$todo, [ $delcmds->[$i][1],-1,-1,$delcmds->[$i][2],@delmid,$delcmds->[$i][4]]);
+
+			  while (scalar(@$addtextblocks) && $addtextblocks->[0][0]<$addcmds->[$j][1]) {
+			    my ($index,$block,$cnt)=@{ shift(@$addtextblocks) };
+			    push(@$todo, [-1,$index,$cnt,@$block]);
+			  }
+			  push(@$todo, [ -1,$addcmds->[$j][1],-1,$addcmds->[$j][2],@addmid,$addcmds->[$j][4]]);
+			}
+		      }
+		      # mop up remaining textblocks
+		      while (scalar(@$deltextblocks)) {
+			my ($index,$block,$cnt)=@{ shift(@$deltextblocks) } ;
+			push(@$todo, [$index,-1,$cnt,@$block]);
+		      }
+		      while (scalar(@$addtextblocks)) {
+			my ($index,$block,$cnt)=@{ shift(@$addtextblocks) };
+			push(@$todo, [-1,$index,$cnt,@$block]);
+		      }
+		      
+		      $addblock=[];
+		      $delblock=[];
+		    }
+		    push(@$block,$seq2->[$_[1]]);  
+		    $cnt++  };
+
+  my $keyfunc = sub { join("  ",split(" ",shift())) };
+
+  traverse_sequences($seq1,$seq2, { MATCH=>$match, DISCARD_A=>$discard, DISCARD_B=>$add }, $keyfunc );
+
+
+  # now carry out the merging/splitting.  Refer to elements relative from 
+  # the end (with negative indices) as these offsets don't change before the instruction is executed
+  # cnt>0: merged small unchanged groups with previous changed blocks
+  # cnt==-1: split textual commands into components
+  foreach $instruction ( @$todo) {
+    ($last1,$last2,$cnt,@$block)=@$instruction ;
+    if ($cnt>=0) {
+      splice(@$seq1,$last1-$len1,1+$cnt,join("",$seq1->[$last1-$len1],@$block)) if $last1>=0;
+      splice(@$seq2,$last2-$len2,1+$cnt,join("",$seq2->[$last2-$len2],@$block)) if $last2>=0;
+    } else {
+      splice(@$seq1,$last1-$len1,1,@$block) if $last1>=0;
+      splice(@$seq2,$last2-$len2,1,@$block) if $last2>=0;
+    }
+  }
+
+  if ($verbose) { 
+    print STDERR "\n";
+    print STDERR "  $mattokcnt matching  tokens in $matblkcnt blocks.\n";
+    print STDERR "  $deltokcnt discarded tokens in $delblkcnt blocks.\n";
+    print STDERR "  $addtokcnt appended  tokens in $addblkcnt blocks.\n";
+  }
+}
+
+
+# extracttextblocks(\@blockindex)
+# $blockindex has the following format 
+# [ [ token1, index1 ], [token2, index2],.. ] 
+# where index refers to the index in the original old or new word sequence 
+# Returns: reference to an array of the form  
+# [[ $index, $textblock, $cnt ], ..
+# where $index index of block to be merged
+#       $textblock contains all the words to be merged with the word at $index (but does not contain this word)
+#       $cnt   is length of block
+#
+# requires: iscmd
+#
+sub extracttextblocks { 
+  my $block=shift;
+  my ($i,$token,$index);
+  my $textblock=[];
+  my $last=-1;
+  my $wpat=qr/^(?:[a-zA-Z.,'`:;?()!]*)[\s~]*$/;  #'
+  my $retval=[];
+
+  for ($i=0;$i< scalar @$block;$i++) {
+    ($token,$index)=@{ $block->[$i] };
+    # store pure text blocks
+    if ($token =~ /$wpat/ ||  ( $token =~/^\\([\w\d\*]+)((?:${extraspace}\[$brat0\]${extraspace}|${extraspace}\{$pat4\})*)/o 
+				&& iscmd($1,\@SAFECMDLIST,\@SAFECMDEXCL) 
+				&& !iscmd($1,\@TEXTCMDLIST,\@TEXTCMDEXCL))) {
+      # we have text or a command which can be treated as text
+      if ($last<0) {
+	# new pure-text block
+	$last=$index;
+      } else {
+	# add to pure-text block
+	push(@$textblock, $token); 
+      }
+    } else {
+      # it is not text
+      if (scalar(@$textblock)) {
+	push(@$retval,[ $last, $textblock, scalar(@$textblock) ]);
+      }
+      $textblock=[];
+      $last=-1;
+    }
+  }
+  # finish processing a possibly unfinished block before returning
+  if (scalar(@$textblock)) {
+    push(@$retval,[ $last, $textblock, scalar(@$textblock) ]);
+  }
+  return($retval)
+}
+
+
+
+# extractcommands( \@blockindex )
+# $blockindex has the following format 
+# [ [ token1, index1 ], [token2, index2],.. ] 
+# where index refers to the index in the original old or new word sequence 
+# Returns: reference to an array of the form  
+# [ [ "\cmd1", index, "\cmd1[optarg]{arg1}{", "arg2" ,"} " ],.. 
+# where index is just taken from input array 
+# command must have a textual argument as last argument 
+# 
+# requires: iscmd 
+# 
+sub extractcommands { 
+  my $block=shift;
+  my ($i,$token,$index,$cmd,$open,$mid,$closing);
+  my $retval=[];
+
+  for ($i=0;$i< scalar @$block;$i++) {
+    ($token,$index)=@{ $block->[$i] };
+    # check if token is an alphanumeric command sequence with at least one non-optional argument
+    # \cmd[...]{...}{last argument}  
+    # Capturing in the following results in these associations
+    # $1: \cmd[...]{...}{
+    # $2: \cmd
+    # $3: last argument
+    # $4: }  + trailing spaces
+    if ( ( $token =~ m/^(\\([\w\d\*]+)(?:${extraspace}\[$brat0\]|${extraspace}\{$pat4\})*${extraspace}\{)($pat4)(\}\s*)$/so )
+	 && iscmd($2,\@TEXTCMDLIST,\@TEXTCMDEXCL) ) {
+      #      push(@$retval,[ $2,$index,$1,$3,$4 ]);
+      ($cmd,$open,$mid,$closing) = ($2,$1,$3,$4) ;
+      $closing =~ s/\}/\\RIGHTBRACE/ ;
+      push(@$retval,[ $cmd,$index,$open,$mid,$closing ]);
+    }
+  }
+  return $retval;
+}
+
+# iscmd($cmd,\@regexarray,\@regexexcl) checks
+# return 1 if $cmd matches any of the patterns in the 
+# array $@regexarray, and none of the patterns in \@regexexcl, otherwise return 0
+sub iscmd {
+  my ($cmd,$regexar,$regexexcl)=@_;
+  my ($ret)=0;
+  foreach $pat ( @$regexar ) {
+    if ( $cmd =~ m/^${pat}$/ ) {
+      $ret=1 ; 
+      last;
+    }
+  }
+  return 0 unless $ret;
+  foreach $pat ( @$regexexcl ) {
+    return 0 if ( $cmd =~ m/^${pat}$/ );
+  }
+  return 1;
+}
+
+
+# pass2( \@seq1,\@seq2)
+# Look for differences between seq1 and seq2.  
+# Mark begin and end of deleted and appended sequences with tags $DELOPEN and $DELCLOSE
+# and $ADDOPEN and $ADDCLOSE, respectively, however exclude { } & and all comands, unless
+# they match an element of the whitelist (SAFECMD)
+# For words in TEXTCMD but not in SAFECMD, enclose interior with $ADDOPEN and $ADDCLOSE brackets
+# Deleted comment lines are marked with %DIF < 
+# Added comment lines are marked with %DIF > 
+sub pass2 {
+  my $seq1 = shift ;
+  my $seq2 = shift ;
+
+  my ($addtokcnt,$deltokcnt,$mattokcnt)=(0,0,0);
+  my ($addblkcnt,$delblkcnt,$matblkcnt)=(0,0,0);
+
+  my $retval = [];
+  my $delhunk   = [];
+  my $addhunk   = [];
+
+  my $discard = sub { $deltokcnt++;
+                      push ( @$delhunk, $seq1->[$_[0]]) };
+
+  my $add = sub { $addtokcnt++;
+                  push ( @$addhunk, $seq2->[$_[1]]) };
+
+  my $match = sub { $mattokcnt++;
+		    if ( scalar @$delhunk ) {
+                      $delblkcnt++;
+		      # mark up changes, but comment out commands
+                      push @$retval,marktags($DELMARKOPEN,$DELMARKCLOSE,$DELOPEN,$DELCLOSE,$DELCMDOPEN,$DELCMDCLOSE,$DELCOMMENT,$delhunk);
+		      $delhunk = [];
+		    }
+                    if ( scalar @$addhunk ) {
+                      $addblkcnt++;
+                      # we mark up changes, but simply quote commands
+                      push @$retval,marktags($ADDMARKOPEN,$ADDMARKCLOSE,$ADDOPEN,$ADDCLOSE,"","",$ADDCOMMENT,$addhunk);
+		      $addhunk = [];
+		    }
+		    push(@$retval,$seq2->[$_[1]]) };
+ 
+  my $keyfunc = sub { join("  ",split(" ",shift())) };
+
+  traverse_sequences($seq1,$seq2, { MATCH=>$match, DISCARD_A=>$discard, DISCARD_B=>$add }, $keyfunc );
+  # clear up unprocessed hunks
+  push @$retval,marktags($DELMARKOPEN,$DELMARKCLOSE,$DELOPEN,$DELCLOSE,$DELCMDOPEN,$DELCMDCLOSE,$DELCOMMENT,$delhunk) if scalar @$delhunk;
+  push @$retval,marktags($ADDMARKOPEN,$ADDMARKCLOSE,$ADDOPEN,$ADDCLOSE,"","",$ADDCOMMENT,$addhunk) if scalar @$addhunk;
+
+
+  if ($verbose) { 
+    print STDERR "\n";
+    print STDERR "  $mattokcnt matching  tokens. \n";
+    print STDERR "  $deltokcnt discarded tokens in $delblkcnt blocks.\n";
+    print STDERR "  $addtokcnt appended  tokens in $addblkcnt blocks.\n";
+  }
+
+  return(@$retval);
+}
+
+# marktags($openmark,$closemark,$open,$close,$opencmd,$closecmd,$comment,\@block)
+# returns ($openmark,$open,$block,$close,$closemark) if @block only contains no commands (except white-listed ones),
+# braces, ampersands, or comments
+# mark comments with $comment
+# exclude all other exceptions from scope of open, close like this
+# ($openmark, $open,...,$close, $opencomd,command, command,$closecmd, $open, ..., $close, $closemark)
+# If $opencmd begins with "%" marktags assumes it is operating on a deleted block, otherwise on an added block
+sub marktags {
+  my ($openmark,$closemark,$open,$close,$opencmd,$closecmd,$comment,$block)=@_;
+  my $word;
+  my (@argtext);
+  my $retval=[];
+  my $noncomment=0;
+  my $cmd=-1;    # -1 at beginning 0: last token written is a ordinary word 
+                 # 1: last token written is a command
+                # for keeping track whether we are just in a command sequence or in a word sequence
+  my $cmdcomment= ($opencmd =~ m/^%/);  # Flag to indicate whether opencmd is a comment (i.e. if we intend to simply comment out changed commands)
+  my ($command,$commandword,$closingbracket) ; # temporary variables needed below to remember sub-pattern matches
+
+# split this block to flatten out sequences joined in pass1
+  @$block=splitlatex(join "",@$block);
+  foreach (@$block) {
+    $word=$_; 
+    if ( $word =~ s/^%/%$comment/ ) {
+      # a comment
+      if ($cmd==1) {
+	push (@$retval,$closecmd) ;
+	$cmd=-1;
+      }
+      push (@$retval,$word); 
+      next;
+    }
+    if (! $noncomment) {
+      push (@$retval,$openmark); 
+      $noncomment=1;
+    }
+    # negative lookahead pattern (?!) in second clause is put in to avoid mathcing \( .. \) patterns
+    if ( $word =~ /^[&{}\[\]]/ || ( $word =~ /^\\(?!\()([\w*@]*)/ && !iscmd($1,\@SAFECMDLIST,\@SAFECMDEXCL)) ) {
+      # word is a command or other significant token (not in SAFECMDLIST)
+	## same conditions as in subroutine extractcommand:
+	# check if token is an alphanumeric command sequence with at least one non-optional argument
+	# \cmd[...]{...}{last argument}  
+	# Capturing in the following results in these associations
+	# $1: \cmd[...]{...}{
+	# $2: \cmd
+	# $3: last argument
+	# $4: }  + trailing spaces
+	### pre-0.3    if ( ( $token =~ m/^(\\([\w\d\*]+)(?:\[$brat0\]|\{$pat4\})*\{)($pat4)(\}\s*)$/so )
+      if ( ( $word =~ m/^(\\([\w\d\*]+)(?:${extraspace}\[$brat0\]|${extraspace}\{$pat4\})*${extraspace}\{)($pat4)(\}\s*)$/so )
+	   && iscmd($2,\@TEXTCMDLIST,\@TEXTCMDEXCL)  && ( !$cmdcomment || !iscmd($2,\@CONTEXT2CMDLIST, \@CONTEXT2CMDEXCL) )  ) {	 
+	# word is a text command - we mark up the interior of the word. But if we are in a deleted block ($cmdcomment=1) and
+        # $2 (the command) is in context2, just treat it as an ordinary command (i.e. comment it open with $opencmd)
+        # Because we do not want to disable this command
+	# here we do not use $opencmd and $closecmd($opencmd is empty) 
+	if ($cmd==1) {
+	  push (@$retval,$closecmd) ;
+	} elsif ($cmd==0) { 
+	  push (@$retval,$close) ;
+	}
+        $command=$1; $commandword=$2; $closingbracket=$4;
+	@argtext=splitlatex($3);   # split textual argument into tokens
+	# and mark it up (but we do not need openmark and closemark)
+        # insert command with initial arguments, marked-up final argument, and closing bracket
+	if ( $cmdcomment && iscmd($commandword,\@CONTEXT1CMDLIST, \@CONTEXT1CMDEXCL) ) {
+	  # context1cmd in a deleted environment; delete command itself but keep last argument, marked up
+	  push (@$retval,$opencmd);
+	  $command =~ s/\n/\n${opencmd}/sg ; # repeat opencmd at the beginning of each line
+	  # argument, note that the additional comment character is included
+          # to suppress linebreak after opening parentheses, which is important
+          # for latexrevise
+          push (@$retval,$command,"%\n{$AUXCMD\n",marktags("","",$open,$close,$opencmd,$closecmd,$comment,\@argtext),$closingbracket);
+	} else {
+	  # normal textcmd or context1cmd in an added block
+	  push (@$retval,$command,marktags("","",$open,$close,$opencmd,$closecmd,$comment,\@argtext),$closingbracket);  
+	}
+	push (@$retval,$AUXCMD,"\n") if $cmdcomment ;
+	$cmd=-1 ;
+      } else {
+	# ordinary command
+	push (@$retval,$opencmd) if $cmd==-1 ;
+	push (@$retval,$close,$opencmd) if $cmd==0 ;
+	$word =~ s/\n/\n${opencmd}/sg if $cmdcomment ;   # if opencmd is a comment, repeat this at the beginning of every line
+	push (@$retval,$word);
+	$cmd=1;
+      }
+    } else {
+      # just an ordinary word or word in SAFECMD
+      push (@$retval,$open) if $cmd==-1 ;
+      push (@$retval,$closecmd,$open) if $cmd==1 ;
+      push (@$retval,$word);
+      $cmd=0;
+    }
+  }
+  push (@$retval,$close) if $cmd==0;
+  push (@$retval,$closecmd) if $cmd==1;
+
+  push (@$retval,$closemark) if ($noncomment);
+  return @$retval;
+}
+
+# preprocess($string, ..)
+# carry out the following pre-processing steps for all arguments:
+# 1. Remove leading white-space
+# 2. mark all first empty line (in block of several) with \PAR tokens
+# 3. Convert all '\%' into '\PERCENTAGE ' to make parsing regular expressions easier
+# 4. Convert all \verb|some verbatim text| commands (where | can be an arbitrary character)
+#    into \verb{hash}
+# 5. Convert \begin{verbatim} some verbatim text \end{verbatim} into \verbatim{hash}
+# 6. Convert _n into \SUBSCRIPTNB{n} and _{nnn} into \SUBSCRIPT{nn}
+# 7. Convert ^n into \SUPERSCRIPTNB{n} and ^{nnn} into \SUPERSCRIPT{nn}
+# 8. a. Convert $$ $$ into \begin{DOLLARDOLLAR} \end{DOLLARDOLLAR}
+#    b. Convert \[ \] into \begin{SQUAREBRACKET} \end{SQUAREBRACKET}
+
+# 9. Add final token STOP to the very end.  This is put in because the algorithm works better if the last token is identical.  This is removed again in postprocessing.
+#
+# NB: step 6 and 7 is likely to  convert some "_" inappropriately, e.g. in file
+#     names or labels but it does not matter because they are converted back in the postprocessing step
+# Returns: leading white space removed in step 1
+sub preprocess {
+  my @leadin=() ;
+  for (@_) { 
+    s/^(\s*)//s;
+    push(@leadin,$1);
+    s/\n(\s*?)\n((?:\s*\n)*)/\n$1\\PAR\n$2/g ;
+    s/(?<!\\)\\%/\\PERCENTAGE /g ;  # (?<! is negative lookbehind assertion to prevent \\% from being converted
+    s/(\\verb\*?)(\S)(.*?)\2/"${1}{". tohash(\%verbhash,"${2}${3}${2}") ."}"/esg;
+    s/\\begin\{(verbatim\*?)\}(.*?)\\end\{\1\}/"\\${1}{". tohash(\%verbhash,"${2}") . "}"/esg;
+    # Convert _n or _\cmd into \SUBSCRIPTNB{n} or \SUBSCRIPTNB{\cmd} and _{nnn} into \SUBSCRIPT{nn}
+    s/_([^{\\]|\\\w+)/\\SUBSCRIPTNB{$1}/g ;
+    s/_{($pat4)}/\\SUBSCRIPT{$1}/g ;
+    # Convert ^n into \SUPERSCRIPTNB{n} and ^{nnn} into \SUPERSCRIPT{nn}
+    s/\^([^{\\]|\\\w+)/\\SUPERSCRIPTNB{$1}/g ;
+    s/\^{($pat4)}/\\SUPERSCRIPT{$1}/g ;
+    # Convert $$ $$ into \begin{DOLLARDOLLAR} \end{DOLLARDOLLAR}
+    s/\$\$(.*?)\$\$/\\begin{DOLLARDOLLAR}$1\\end{DOLLARDOLLAR}/sg;
+    # Convert \[ \] into \begin{SQUAREBRACKET} \end{SQUAREBRACKET}
+    s/(?<!\\)\\\[/\\begin{SQUAREBRACKET}/sg;
+    s/\\\]/\\end{SQUAREBRACKET}/sg;
+    # add final token " STOP"
+    $_ .= " STOP"
+  }
+  return(@leadin);
+}
+
+#hashstring=tohash(\%hash,$string)
+# creates a hash value based on string and stores in %hash
+sub tohash {
+  my ($hash,$string)=@_;
+  my (@arr,$val);
+  my ($sum,$i)=(0,1);
+  my ($hstr);
+
+  @arr=unpack('c*',$string);
+
+  foreach $val (@arr) {
+    $sum += $i*$val;
+    $i++;
+  }
+  $hstr= "$sum";
+  if (defined($hash->{$hstr}) && $string ne $hash->{$hstr}) {
+    warn "Repeated hash value for verbatim mode in spite of different content.";
+    $hstr="-$hstr";
+  }
+  $hash->{$hstr}=$string;
+  return($hstr);
+}
+
+#string=fromhash(\%hash,$fromstring)
+# restores string value stored in hash
+#string=fromhash(\%hash,$fromstring,$prependstring)
+# additionally begins each line with prependstring
+sub fromhash {
+  my ($hash,$hstr)=($_[0],$_[1]);
+  my $retstr=$hash->{$hstr};
+  if ( $#_ >= 2) {
+    $retstr =~ s/^/$_[2]/mg;
+  }
+  return $retstr;
+}
+
+
+# postprocess($string, ..)
+# carry out the following post-processing steps for all arguments:
+# * Remove STOP token from the end
+# * Replace \RIGHTBRACE by }
+# 1. Check all deleted blocks: 
+#    a.where a deleted block contains a matching \begin and
+#      \end environment (these will be disabled by a %DIFDELCMD statements), for selected environment enable enable
+#      these commands again (such that for example displayed math in a deleted equation
+#      is properly within math mode.  For math mode environments replace numbered equation
+#      environments with their display only variety (so that equation numbers in new file and
+#      diff file are identical).  Where the correct type of math environment cannot be determined
+#      use a place holder MATHMODE
+#    b.where one of the commands matching $COUNTERCMD is used as a DIFAUXCMD, add a statement
+#      subtracting one from the respective counter to keep numbering consistent with new file
+#    Replace all MATHMODE environment commands by the correct environment to achieve matching
+#    pairs
+#    c. If in-line math mode contains array environment, enclose the whole environment in \mbox'es
+# 2. Remove DIFadd, DIFdel, DIFFaddbegin , ... from picture environments
+# 3. Convert DIFadd, DIFdel, DIFFaddbegin , ... into FL varieties
+#    within floats (currently recognised float environments: plate,table,figure
+#    plus starred varieties).
+# 4. Remove empty %DIFDELCMD < lines 
+# 4. Convert \begin{SQUAREBRACKET} \end{SQUAREBRACKET} into \[ \]
+#    Convert \begin{DOLLARDOLLAR} \end{DOLLARDOLLAR} into $$ $$
+# 5. Convert  \SUPERSCRIPTNB{n} into ^n  and  \SUPERSCRIPT{nn} into ^{nnn}
+# 6. Convert  \SUBSCRIPTNB{n} into _n  and  \SUBCRIPT{nn} into _{nnn}
+# 7. Expand hashes of verb and verbatim environments
+# 8. Convert '\PERCENTAGE ' back into '\%'
+# 9.. remove all \PAR tokens
+# 10.  package specific processing:  endfloat: make sure \begin{figure} and \end{figure} are always
+#      on a line by themselves, similarly for table environment
+#  4, undo renaming of the \begin and \end in comments
+
+#
+# Note have to manually synchronize substitution commands below and 
+# DIF.. command names in the header
+sub postprocess {
+  my ($begin,$len,$cnt,$float,$delblock,$addblock);
+  # second level blocks
+  my ($begin2,$cnt2,$len2,$eqarrayblock,$mathblock);
+
+  for (@_) { 
+
+    # change $'s in comments to something harmless
+    1 while s/(%.*)\$/$1DOLLARDIF/mg ;
+
+    # Remove final STOP token
+    s/ STOP$//;
+    # Replace \RIGHTBRACE by }    
+    s/\\RIGHTBRACE/}/g;
+    # Check all deleted blocks: where a deleted block contains a matching \begin and
+    #    \end environment (these will be disabled by a %DIFDELCMD statements), enable
+    #    these commands again (such that for example displayed math in a deleted equation
+    #    is properly within math mode.  For math mode environments replace numbered equation
+    #    environments with their display only variety (so that equation numbers in new file and
+    #    diff file are identical
+    while ( m/\\DIFdelbegin.*?\\DIFdelend/sg ) {
+      $cnt=0;
+      $len=length($&);
+      $begin=pos($_) - $len;
+      $delblock=$&;
+
+
+      ### (.*?[^\n]?)\n? construct is necessary to avoid empty lines in math mode, which result in
+      ### an error
+      # displayed math environments
+      $delblock=~ s/(\%DIFDELCMD < \s*\\begin\{((?:$MATHENV)|SQUAREBRACKET)\}\s*?(?:$DELCMDCLOSE|\n))(.*?[^\n]?)\n?(\%DIFDELCMD < \s*\\end\{\2\})/\\begin{$MATHREPL}$AUXCMD\n$1$3\n\\end{$MATHREPL}$AUXCMD\n$4/sg;
+      # also transform the opposite pair \end{displaymath} .. \begin{displaymath} but we have to be careful not to interfere with the results of the transformation in the line directly above
+      $delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\end\{((?:$MATHENV)|SQUAREBRACKET)\}\s*?(?:$DELCMDCLOSE|\n))(.*?[^\n]?)\n?(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\begin\{\2\})/\\end{MATHMODE}$AUXCMD\n$1$3\n\\begin{MATHMODE}$AUXCMD\n$4/sg;
+
+      # now look for unpaired %DIFDELCMD < \begin{MATHENV}; if found add \begin{$MATHREPL} and insert \end{$MATHREPL} 
+      # just before end of block; again we use look-behind assertion to avoid matching constructions which have already been converted
+      if ($delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\begin\{((?:$MATHENV)|SQUAREBRACKET)\}\s*?(?:$DELCMDCLOSE|\n))/$1\\begin{$MATHREPL}$AUXCMD\n/sg ) {
+	$delblock =~ s/(\\DIFdelend$)/\\end{$MATHREPL}$AUXCMD\n$1/s ;
+      }
+      # now look for unpaired %DIFDELCMD < \end{MATHENV}; if found add \end{MATHMODE} and insert \begin{MATHMODE} 
+      # just before end of block; again we use look-behind assertion to avoid matching constructions which have already been converted
+      if ($delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\end\{((?:$MATHENV)|SQUAREBRACKET)\}\s*?(?:$DELCMDCLOSE|\n))/$1\\end{MATHMODE}$AUXCMD\n/sg ) {
+	$delblock =~ s/(\\DIFdelend$)/\\begin{MATHMODE}$AUXCMD\n$1/s ;
+      }
+
+
+      # equation array environment
+      $delblock=~ s/(\%DIFDELCMD < \s*\\begin\{($MATHARRENV)\}\s*?(?:$DELCMDCLOSE|\n))(.*?[^\n]?)\n?(\%DIFDELCMD < \s*\\end\{\2\})/\\begin{$MATHARRREPL}$AUXCMD\n$1$3\n\\end{$MATHARRREPL}$AUXCMD\n$4/sg;
+      $delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\end\{($MATHARRENV)\}\s*?(?:$DELCMDCLOSE|\n))(.*?[^\n]?)\n?(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\begin\{\2\})/\\end{MATHMODE}$AUXCMD\n$1$3\n\\begin{MATHMODE}$AUXCMD\n$4/sg;
+
+      # now look for unpaired %DIFDELCMD < \begin{MATHARRENV}; if found add \begin{$MATHARRREPL} and insert \end{$MATHARRREPL} 
+      # just before end of block; again we use look-behind assertion to avoid matching constructions which have already been converted
+      if ($delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\begin\{($MATHARRENV)\}\s*?(?:$DELCMDCLOSE|\n))/$1\\begin{$MATHARRREPL}$AUXCMD\n/sg ) {
+	$delblock =~ s/(\\DIFdelend$)/\\end{$MATHARRREPL}$AUXCMD\n$1/s ;
+      }
+      # now look for unpaired %DIFDELCMD < \end{MATHENV}; if found add \end{MATHMODE} and insert \begin{MATHMODE} 
+      # just before end of block; again we use look-behind assertion to avoid matching constructions which have already been converted
+      if ($delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\end\{($MATHARRENV)\}\s*?(?:$DELCMDCLOSE|\n))/$1\\end{MATHMODE}$AUXCMD\n/sg ) {
+	$delblock =~ s/(\\DIFdelend$)/\\begin{MATHMODE}$AUXCMD\n$1/s ;
+      }
+
+      # parse $delblock for deleted and reinstated eqnarray* environments - within those reinstate \\ and & commands
+      while ( $delblock =~ m/\\begin\Q{$MATHARRREPL}$AUXCMD\E\n.*?\n\\end\Q{$MATHARRREPL}$AUXCMD\E\n/sg ) {
+	$cnt2=0;
+	$len2=length($&);
+	$begin2=pos($delblock) - $len2;
+	$eqarrayblock=$&;
+	# reinstate deleted & and \\ commands
+	$eqarrayblock=~ s/(\%DIFDELCMD < \s*(\&|\\\\)\s*?(?:$DELCMDCLOSE|\n))/$1$2$AUXCMD\n/sg ;
+
+	substr($delblock,$begin2,$len2)=$eqarrayblock;
+	pos($delblock) = $begin2 + length($eqarrayblock);
+      }
+
+
+
+#    b.where one of the commands matching $COUNTERCMD is used as a DIFAUXCMD, add a statement
+#      subtracting one from the respective counter to keep numbering consistent with new file
+      $delblock=~ s/\\($COUNTERCMD)((?:${extraspace}\[$brat0\]${extraspace}|${extraspace}\{$pat4\})*\s*${AUXCMD}\n)/\\$1$2\\addtocounter{$1}{-1}${AUXCMD}\n/sg ;
+#     c. If in-line math mode contains array environment, enclose the whole environment in \mbox'es
+      while ( $delblock =~ m/($math)(\s*)/sg ) {
+	$cnt2=0;
+	$len2=length($&);
+	$begin2=pos($delblock) - $len2;
+	$mathblock="%\n\\mbox{$AUXCMD\n$1\n}$AUXCMD\n";
+        next unless $mathblock =~ m/\{$ARRENV\}/ ;
+	substr($delblock,$begin2,$len2)=$mathblock;
+	pos($delblock) = $begin2 + length($mathblock);
+      }
+
+#     splice in modified delblock
+      substr($_,$begin,$len)=$delblock;
+      pos = $begin + length($delblock);
+    }
+    # make the array modification in added blocks
+    while ( m/\\DIFaddbegin.*?\\DIFaddend/sg ) {
+      $cnt=0;
+      $len=length($&);
+      $begin=pos($_) - $len;
+      $addblock=$&;
+      while ( $addblock =~ m/($math)(\s*)/sg ) {
+	$cnt2=0;
+	$len2=length($&);
+	$begin2=pos($addblock) - $len2;
+	$mathblock="%\n\\mbox{$AUXCMD\n$1\n}$AUXCMD\n";
+        next unless $mathblock =~ m/\{$ARRENV\}/ ;
+	substr($addblock,$begin2,$len2)=$mathblock;
+	pos($addblock) = $begin2 + length($mathblock);
+      }
+
+#     splice in modified addblock
+      substr($_,$begin,$len)=$addblock;
+      pos = $begin + length($addblock);
+    }
+
+
+    ### old place for BEGINDIF, ENDDIF replacement
+    # change begin and end commands  within comments such that they
+    # don't disturb the pattern matching (if there are several \begin or \end in one line
+    # this substitution is insufficient but that appears unlikely)
+    s/(%.*)\\begin\{(.*)$/$1\\BEGINDIF\{$2/mg ;
+    s/(%.*)\\end\{(.*)$/$1\\ENDDIF\{$2/mg ;
+
+    # Replace MATHMODE environments from step 1a above by the correct Math environment
+
+    # The next line is complicated.  The negative look-ahead insertion makes sure that no \end{$MATHENV} (or other mathematical
+    # environments) are between the \begin{$MATHENV} and \end{MATHMODE} commands. This is necessary as the minimal matching 
+    # is not globally minimal but only 'locally' (matching is beginning from the left side of the string)
+    1 while s/\\begin{((?:$MATHENV)|(?:$MATHARRENV)|SQUAREBRACKET)}((?:.(?!(?:\\end{(?:(?:$MATHENV)|(?:$MATHARRENV)|SQUAREBRACKET)}|\\begin{MATHMODE})))*?)\\end{MATHMODE}/\\begin{$1}$2\\end{$1}/s;
+    1 while s/\\begin{MATHMODE}((?:.(?!\\end{MATHMODE}))*?)\\end{((?:$MATHENV)|(?:$MATHARRENV)|SQUAREBRACKET)}/\\begin{$2}$1\\end{$2}/s;
+    # convert remaining \begin{MATHMODE} \end{MATHMODE} (and not containing & or \\ )into MATHREPL environments
+    s/\\begin{MATHMODE}((?:(.(?!(?<!\\)\&|\\\\))*)?)\\end{MATHMODE}/\\begin{$MATHREPL}$1\\end{$MATHREPL}/sg;
+    # others into MATHARRREPL
+    s/\\begin{MATHMODE}(.*?)\\end{MATHMODE}/\\begin{$MATHARRREPL}$1\\end{$MATHARRREPL}/sg;
+
+    # now look for AUXCMD math-mode pairs which have only comments (or empty lines between them), and remove the added commands
+    s/\\begin{((?:$MATHENV)|(?:$MATHARRENV)|SQUAREBRACKET)}$AUXCMD\n((?:\s*%.[^\n]*\n)*)\\end{\1}$AUXCMD\n/$2/sg; 
+
+
+    # Remove all mark up within picture environments
+    while ( m/\\begin\{($PICTUREENV)\}.*?\\end\{\1\}/sg ) {
+      $cnt=0;
+      $len=length($&);
+      $begin=pos($_) - $len;
+      $float=$&;
+      $float =~ s/\\DIFaddbegin //g;
+      $float =~ s/\\DIFaddend //g;
+      $float =~ s/\\DIFadd\{($pat4)\}/$1/g;
+      $float =~ s/\\DIFdelbegin //g;
+      $float =~ s/\\DIFdelend //g;
+      $float =~ s/\\DIFdel\{($pat4)\}//g;
+      substr($_,$begin,$len)=$float;
+      pos = $begin + length($float);
+    }
+    # Convert DIFadd, DIFdel, DIFFaddbegin , ... into  varieties
+    #    within floats (currently recognised float environments: plate,table,figure
+    #    plus starred varieties).
+    while ( m/\\begin\{($FLOATENV)\}.*?\\end\{\1\}/sg ) {
+      $cnt=0;
+      $len=length($&);
+      $begin=pos($_) - $len;
+      $float=$&;
+      $float =~ s/\\DIFaddbegin /\\DIFaddbeginFL /g;
+      $float =~ s/\\DIFaddend /\\DIFaddendFL /g;
+      $float =~ s/\\DIFadd\{/\\DIFaddFL{/g;
+      $float =~ s/\\DIFdelbegin /\\DIFdelbeginFL /g;
+      $float =~ s/\\DIFdelend /\\DIFdelendFL /g;
+      $float =~ s/\\DIFdel\{/\\DIFdelFL{/g;
+      substr($_,$begin,$len)=$float;
+      pos = $begin + length($float);
+    }
+    ### former location of undo renaming of \begin and \end in comments
+
+    # remove empty DIFCMD < lines
+    s/^\Q${DELCMDOPEN}\E\n//msg;
+
+    # Expand hashes of verb and verbatim environments (note negative look behind assertion to not leak out of DIFDELCMD comments
+    s/(\\verb\*?)\{([-\d]*?)\}/"${1}". fromhash(\%verbhash,$2)/esg;
+    s/${DELCMDOPEN}\\(verbatim\*?)\{([-\d]*?)\}/"${DELCMDOPEN}\\begin{${1}}".fromhash(\%verbhash,$2,$DELCMDOPEN)."${DELCMDOPEN}\\end{${1}}"/esg;
+    s/\\(verbatim\*?)\{([-\d]*?)\}/"\\begin{${1}}".fromhash(\%verbhash,$2)."\\end{${1}}"/esg;
+    # Convert '\PERCENTAGE ' back into '\%'			       
+    s/\\PERCENTAGE /\\%/g;
+    # remove all \PAR tokens (taking care to properly keep commented out PAR's
+    # from introducing uncommented newlines - next line)
+    s/(%DIF < )([^\n]*?)\\PAR\n/$1$2\n$1\n/sg;
+    # convert PAR commands which are on a line by themselves
+    s/\n(\s*?)\\PAR\n/\n\n/sg;
+    # convert remaining PAR commands (which are preceded by non-white space characters, usually "}" ($ADDCLOSE)
+    s/\\PAR\n/\n\n/sg;
+
+    #  package specific processing: 
+    if ( defined($packages{"endfloat"})) {
+      #endfloat: make sure \begin{figure} and \end{figure} are always
+      #      on a line by themselves, similarly for table environment
+      print STDERR "endfloat package detected.\n" if $verbose ;
+      # eliminate whitespace before and after
+      s/^(\s*)(\\(?:begin|end)\{(?:figure|table)\})(\s*)$/$2/mg;
+      # split lines with remaining characters before float enviroment conmmand
+      s/^(.+)(\\(?:begin|end)\{(?:figure|table)\})/$1\n$2/mg;
+      # split lines with remaining characters after float enviroment conmmand
+      s/(\\(?:begin|end)\{(?:figure|table)\})(.+)$/$1\n$2/mg;
+    }
+    # undo renaming of the \begin and \end  and dollars in comments 
+    s/(%.*)\\BEGINDIF\{(.*)$/$1\\begin\{$2/mg ;
+    s/(%.*)\\ENDDIF\{(.*)$/$1\\end\{$2/mg ;
+    1 while s/(%.*)DOLLARDIF/$1\$/mg ;
+#   Convert \begin{SQUAREBRACKET} \end{SQUAREBRACKET} into \[ \]
+    s/\\end{SQUAREBRACKET}/\\\]/sg;
+    s/\\begin{SQUAREBRACKET}/\\\[/sg;
+# 4. Convert \begin{DOLLARDOLLAR} \end{DOLLARDOLLAR} into $$ $$
+    s/\\begin\{DOLLARDOLLAR\}(.*?)\\end\{DOLLARDOLLAR\}/\$\$$1\$\$/sg;
+# 5. Convert  \SUPERSCRIPTNB{n} into ^n  and  \SUPERSCRIPT{nn} into ^{nnn}
+    s/\\SUPERSCRIPTNB{($pat0)}/^$1/g ;
+    s/\\SUPERSCRIPT{($pat4)}/^{$1}/g ;
+    # Convert  \SUBSCRIPNB{n} into _n  and  \SUBCRIPT{nn} into _{nnn}
+    s/\\SUBSCRIPTNB{($pat0)}/_$1/g ;
+    s/\\SUBSCRIPT{($pat4)}/_{$1}/g ;
+
+  return;
+  }
+}
+
+
+# @diffs=linediff(\@seq1, \@seq2)
+# mark up lines like this
+#%DIF mm-mmdnn
+#%< old deleted line(s)
+#%DIF -------
+#%DIF mmann-nn
+#new appended line %< 
+#%DIF -------
+# Future extension: mark change explicitly
+# Assumes: traverse_sequence traverses deletions before insertions in changed sequences
+#          all line numbers relative to line 0 (first line of real file)
+sub linediff {
+  my $seq1 = shift ;
+  my $seq2 = shift ;
+
+  my $block = [];
+  my $retseq = [];
+  my @begin=('','',''); # dummy initialisation
+  my $instring ; 
+
+  my $discard = sub { @begin=('d',$_[0],$_[1]) unless scalar @$block ; 
+                      push(@$block, "%DIF < " . $seq1->[$_[0]]) };
+  my $add = sub { if (! scalar  @$block) {
+		    @begin=('a',$_[0],$_[1]) ;}
+		  elsif ( $begin[0] eq 'd' ) {
+                    $begin[0]='c'; $begin[2]=$_[1];
+		    push(@$block, "%DIF -------") }
+                  push(@$block,  $seq2->[$_[1]] . " %DIF > " ) };
+  my $match = sub { if ( scalar @$block ) {
+                      if ( $begin[0] eq 'd' && $begin[1]!=$_[0]-1) {
+			$instring = sprintf "%%DIF %d-%dd%d",$begin[1],$_[0]-1,$begin[2]; }
+		      elsif ( $begin[0] eq 'a' && $begin[2]!=$_[1]-1) {
+			$instring = sprintf "%%DIF %da%d-%d",$begin[1],$begin[2],$_[1]-1; }
+		      elsif ( $begin[0] eq 'c' ) {
+			$instring = sprintf "%%DIF %sc%s",
+			                     ($begin[1]==$_[0]-1) ? "$begin[1]" : $begin[1]."-".($_[0]-1)  , 
+			                     ($begin[2]==$_[1]-1) ? "$begin[2]" : $begin[2]."-".($_[1]-1)  ; }
+		      else {
+			$instring = sprintf "%%DIF %d%s%d",$begin[1],$begin[0],$begin[2]; }
+		      push @$retseq, $instring,@$block, "%DIF -------" ; 
+		      $block = []; 
+		    }
+		    push @$retseq, $seq2->[$_[1]]
+		  };
+  # key function: remove multiple spaces (such that insertion or deletion of redundant white space is not reported)
+  my $keyfunc = sub { join("  ",split(" ",shift())) };
+
+  traverse_sequences($seq1,$seq2, { MATCH=>$match, DISCARD_A=>$discard, DISCARD_B=>$add }, $keyfunc );
+  push @$retseq, @$block if scalar @$block; 
+
+  return wantarray ? @$retseq : $retseq ;
+}
+
+
+
+# init_regex_arr_data(\@array,"TOKEN INIT")
+# scans DATA file handel for line "%% TOKEN INIT" line
+# then appends each line not beginning with % into array (as a quoted regex)
+sub init_regex_arr_data {
+  my ($arr,$token)=@_;
+  my ($copy);
+  while (<DATA>) {
+    if ( m/^%%BEGIN $token\s*$/ ) {
+      $copy=1; }
+    elsif ( m/^%%END $token\s*/ )  {
+      last; }
+    chomp;
+    push (@$arr,qr/^$_$/) if ( $copy && !/^%/ ) ;
+  }
+  seek DATA,0,0;    # rewind DATA handle to file begin
+}
+
+
+# init_regex_arr_ext(\@array,$arg)
+# fills array with regular expressions.
+# if arg is a file name, then read in list of regular expressions from that file
+# (one expression per line)
+# Otherwise treat arg as a comma separated list of regular expressions
+sub init_regex_arr_ext {
+  my ($arr,$arg)=@_;
+  my $regex;
+  if ( -f $ arg ) {
+    open(FILE,"$arg") or die ("Couldn't open $arg: $!");
+    while (<FILE>) {
+      chomp;
+      next if /^\s*#/ || /^\s*%/ || /^\s*$/ ;
+      push (@$arr,qr/^$_$/);
+    }
+    close(FILE);
+  }
+  else {
+    # assume it is a comma-separated list of reg-ex
+    foreach $regex (split(qr/(?<!\\),/,$arg)) {
+      $regex =~ s/\\,/,/g;
+      push (@$arr,qr/^$regex$/);
+    }
+  }
+}
+
+#exetime() returns time since last execution of this command
+#exetime(1) resets this time
+my $lasttime=-1;   # global variable for persistence
+sub exetime {
+  my $reset=0;
+  my $retval;
+  if ((scalar @_) >=1) {
+    $reset=shift;
+  }
+  if ($reset) {
+    $lasttime=times();
+  }
+  else {
+    $retval=times()-$lasttime;
+    $lasttime=$lasttime+$retval;
+    return($retval);
+  }
+}
+
+
+sub usage {
+  die <<"EOF"; 
+Usage: $0 [options] old.tex new.tex > diff.tex
+
+Compares two latex files and writes tex code to stdout, which has the same
+format as new.tex but has all changes relative to old.tex marked up or commented.
+
+--type=markupstyle
+-t markupstyle         Add code to preamble for selected markup style
+                       Available styles: UNDERLINE CTRADITIONAL TRADITIONAL CFONT FONTSTRIKE INVISIBLE 
+                                         CHANGEBAR CCHANGEBAR CULINECHBAR CFONTCBHBAR
+                       [ Default: UNDERLINE ]
+
+--subtype=markstyle
+-s markstyle           Add code to preamble for selected style for bracketing
+                       commands (e.g. to mark changes in  margin)
+                       Available styles: SAFE MARGINAL DVIPSCOL
+                       [ Default: SAFE ]
+
+--floattype=markstyle
+-f markstyle           Add code to preamble for selected style which 
+                       replace standard marking and markup commands within floats
+                       (e.g., marginal remarks cause an error within floats
+                       so marginal marking can be disabled thus)
+                       Available styles: FLOATSAFE IDENTICAL
+                       [ Default: FLOATSAFE ]
+
+--encoding=enc
+-e enc                 Specify encoding of old.tex and new.tex. Typical encodings are
+                       ascii, utf8, latin1, latin9.  A list of available encodings can be 
+                       obtained by executing 
+                       perl -MEncode -e 'print join ("\\n",Encode->encodings( ":all" )) ;'
+                       [Default encoding is utf8 unless the first few lines of the preamble contain
+                       an invocation "\\usepackage[..]{inputenc} in which case the 
+                       encoding chosen by this command is asssumed. Note that ASCII (standard
+                       latex) is a subset of utf8]
+
+--preamble=file
+-p file                Insert file at end of preamble instead of auto-generating
+                       preamble.  The preamble must define the following commands
+                       \\DIFaddbegin,\\DIFaddend,\\DIFadd{..},
+                       \\DIFdelbegin,\\DIFdelend,\\DIFdel{..},
+                       and varieties for use within floats
+                       \\DIFaddbeginFL,\\DIFaddendFL,\\DIFaddFL{..},
+                       \\DIFdelbeginFL,\\DIFdelendFL,\\DIFdelFL{..}
+                       (If this option is set -t, -s, and -f options
+                       are ignored.)
+
+--exclude-safecmd=exclude-file
+--exclude-safecmd="cmd1,cmd2,..."
+-A exclude-file 
+--replace-safecmd=replace-file
+--append-safecmd=append-file
+--append-safecmd="cmd1,cmd2,..."
+-a append-file         Exclude from, replace or append to the list of regex
+                       matching commands which are safe to use within the 
+                       scope of a \\DIFadd or \\DIFdel command.  The file must contain
+                       one Perl-RegEx per line (Comment lines beginning with # or % are
+                       ignored). A literal comma within the comma-separated list must be
+                       escaped thus "\\,",   Note that the RegEx needs to match the whole of 
+                       the token, i.e., /^regex\$/ is implied and that the initial
+                       "\\" of the command is not included. The --exclude-safecmd
+                       and --append-safecmd options can be combined with the --replace-safecmd 
+                       option and can be used repeatedly to add cumulatively to the lists.
+
+--exclude-textcmd=exclude-file 
+--exclude-textcmd="cmd1,cmd2,..."
+-X exclude-file
+--replace-textcmd=replace-file
+--append-textcmd=append-file
+--append-textcmd="cmd1,cmd2,..."
+-x append-file         Exclude from, replace or append to the list of regex
+                       matching commands whose last argument is text.  See
+                       entry for --exclude-safecmd directly above for further details.
+
+--replace-context1cmd=replace-file
+--append-context1cmd=append-file
+--append-context1cmd="cmd1,cmd2,..."
+                       Replace or append to the list of regex matching commands
+                       whose last argument is text but which require a particular
+                       context to work, e.g. \\caption will only work within a figure
+                       or table.  These commands behave like text commands, except when 
+                       they occur in a deleted section, when they are disabled, but their
+                       argument is shown as deleted text.
+
+--replace-context2cmd=replace-file
+--append-context2cmd=append-file
+--append-context2cmd="cmd1,cmd2,..."
+                       As corresponding commands for context1.  The only difference is that
+                       context2 commands are completely disabled in deleted sections, including
+                       their arguments.
+
+
+--config var1=val1,var2=val2,...
+-c var1=val1,..        Set configuration variables.
+-c configfile           Available variables: 
+                          MINWORDSBLOCK (integer)
+                          FLOATENV (RegEx)
+                          PICTUREENV (RegEx)
+                          MATHENV (RegEx)
+                          MATHREPL (String)
+                          MATHARRENV (RegEx)
+                          MATHARRREPL (String)
+                          ARRENV (RegEx)
+                          COUNTERCMD (RegEx)
+                       This option can be repeated.
+
+
+--packages=pkg1,pkg2,..
+                       Tell latexdiff that .tex file is processed with the packages in list 
+                       loaded.  This is normally not necessary if the .tex file includes the
+                       preamble, as the preamble is automatically scanned for \\usepackage commands.
+                       Use of the --packages option disables automatic scanning, so if for any
+                       reason package specific parsing needs to be switched off, use --packages=none.
+                       The following packages trigger special behaviour:
+                       endfloat hyperref amsmath
+                       [ Default: scan the preamble for \\usepackage commands to determine
+                         loaded packages.]
+
+--show-preamble        Print generated or included preamble commands to stdout.
+
+--show-safecmd         Print list of regex matching and excluding safe commands.
+
+--show-textcmd         Print list of regex matching and excluding commands with text argument.
+
+--show-config          Show values of configuration variables
+
+--show-all             Show all of the above
+
+   NB For all --show commands, no old.tex or new.tex file needs to be given, and no 
+      differencing takes place.
+
+--allow-spaces         Allow spaces between bracketed or braced arguments to commands
+                       [Default requires arguments to directly follow each other without 
+                                intervening spaces]
+
+--flatten              Replace \\input and \\include commands within body by the content
+                       of the files in their argument.  If \\includeonly is present in the
+                       preamble, only those files are expanded into the document. However, 
+                       no recursion is done, i.e. \\input and \\include commands within 
+                       included sections are not expanded.  The included files are assumed to 
+                       be located in the same directories as the old and new master files,
+                       respectively, making it possible to organise files into old and new directories.
+
+--help
+-h                     Show this help text.
+
+--ignore-warnings      Suppress warnings about inconsistencies in length between input
+                       and parsed strings and missing characters. 
+
+--verbose
+-V                     Output various status information to stderr during processing.
+                       Default is to work silently.
+
+--version              Show version number.
+EOF
+}
+
+=head1 NAME
+
+latexdiff - determine and markup differences between two latex files
+
+=head1 SYNOPSIS
+
+B<latexdiff> [ B<OPTIONS> ] F<old.tex> F<new.tex> > F<diff.tex>
+
+=head1 DESCRIPTION
+
+Briefly, I<latexdiff> is a utility program to aid in the management of
+revisions of latex documents. It compares two valid latex files, here
+called C<old.tex> and C<new.tex>, finds significant differences
+between them (i.e., ignoring the number of white spaces and position
+of line breaks), and adds special commands to highlight the
+differences.  Where visual highlighting is not possible, e.g. for changes
+in the formatting, the differences are
+nevertheless marked up in the source.
+
+The program treats the preamble differently from the main document.
+Differences between the preambles are found using line-based
+differencing (similarly to the Unix diff command, but ignoring white
+spaces).  A comment, "S<C<%DIF E<gt>>>" is appended to each added line, i.e. a 
+line present in C<new.tex> but not in C<old.tex>.  Discarded lines 
+ are deactivated by prepending "S<C<%DIF E<lt>>>". Changed blocks are preceded  by
+comment lines giving information about line numbers in the original files.  Where there are insignificant
+differences, the resulting file C<diff.tex> will be similar to
+C<new.tex>.  At the end of the preamble, the definitions for I<latexdiff> markup commands are inserted.
+In differencing the main body of the text, I<latexdiff> attempts to
+satisfy the following guidelines (in order of priority):
+
+=over 3
+
+=item 1
+
+If both C<old.tex> and C<new.tex> are valid LaTeX, then the resulting
+C<diff.tex> should also be valid LateX. (NB If a few plain TeX commands
+are used within C<old.tex> or C<new.tex> then C<diff.tex> is not
+guaranteed to work but usually will).
+
+=item 2
+
+Significant differences are determined on the level of
+individual words. All significant differences, including differences
+between comments should be clearly marked in the resulting source code
+C<diff.tex>.
+
+=item 3
+
+If a changed passage contains text or text-producing commands, then
+running C<diff.tex> through LateX should produce output where added
+and discarded passages are highlighted.
+
+=item 4
+
+Where there are insignificant differences, e.g. in the positioning of
+line breaks, C<diff.tex> should follow the formatting of C<new.tex>
+
+=back
+
+For differencing the same algorithm as I<diff> is used but words
+instead of lines are compared.  An attempt is made to recognize
+blocks which are completely changed such that they can be marked up as a unit.
+Comments are differenced line by line
+but the number of spaces within comments is ignored. Commands including
+all their arguments are generally compared as one unit, i.e., no mark-up
+is inserted into the arguments of commands.  However, for a selected
+number of commands (for example, C<\caption> and all sectioning
+commands) the last argument is known to be text. This text is
+split into words and differenced just as ordinary text (use options to
+show and change the list of text commands, see below). As the
+algorithm has no detailed knowledge of LaTeX, it assumes all pairs of
+curly braces immediately following a command (i.e. a sequence of
+letters beginning with a backslash) are arguments for that command.
+As a restriction to condition 1 above it is thus necessary to surround
+all arguments with curly braces, and to not insert
+extraneous spaces.  For example, write 
+
+  \section{\textem{This is an emphasized section title}}
+
+and not
+
+  \section {\textem{This is an emphasized section title}}
+
+or
+
+  \section\textem{This is an emphasized section title}
+
+even though all varieties are the same to LaTeX (but see
+B<--allow-spaces> option which allows the second variety).
+
+For environments whose content does not conform to standard LaTeX or
+where graphical markup does not make sense all markup commands can be
+removed by setting the PICTUREENV configuration variable, set by
+default to C<picture> and C<DIFnomarkup> environments; see B<--config>
+option).  The latter environment (C<DIFnomarkup>) can be used to
+protect parts of the latex file where the markup results in illegal
+markup. You have to surround the offending passage in both the old and
+new file by C<\begin{DIFnomarkup}> and C<\end{DIFnomarkup}>. You must
+define the environment in the preambles of both old and new
+documents. I prefer to define it as a null-environment,
+
+C<\newenvironment{DIFnomarkup}{}{}>
+
+but the choice is yours.  Any markup within the environment will be
+removed, and generally everything within the environment will just be
+taken from the new file.
+
+It is also possible to difference files which do not have a preamble. 
+ In this case, the file is processed in the main document
+mode, but the definitions of the markup commands are not inserted.
+
+All markup commands inserted by I<latexdiff> begin with "C<\DIF>".  Added
+blocks containing words, commands or comments which are in C<new.tex>
+but not in C<old.tex> are marked by C<\DIFaddbegin> and C<\DIFaddend>.
+Discarded blocks are marked by C<\DIFdelbegin> and C<\DIFdelend>.
+Within added blocks all text is highlighted with C<\DIFadd> like this:
+C<\DIFadd{Added text block}>
+Selected `safe' commands can be contained in these text blocks as well
+(use options to show and change the list of safe commands, see below).
+All other commands as well as braces "{" and "}" are never put within
+the scope of C<\DIFadd>.  Added comments are marked by prepending
+"S<C<%DIF E<gt> >>".
+
+Within deleted blocks text is highlighted with C<\DIFdel>.  Deleted
+comments are marked by prepending "S<C<%DIF E<lt> >>".  Non-safe command
+and curly braces within deleted blocks are commented out with 
+"S<C<%DIFDELCMD E<lt> >>".
+
+
+
+=head1 OPTIONS
+
+=head2 Preamble
+
+The following options determine the visual markup style by adding the appropriate
+command definitions to the preamble. See the end of this section for a description of 
+available styles.
+
+=over 4
+
+=item B<--type=markupstyle> or
+B<-t markupstyle>
+
+Add code to preamble for selected markup style. This option defines
+C<\DIFadd> and C<\DIFdel> commands.
+Available styles: 
+
+C<UNDERLINE CTRADITIONAL TRADITIONAL CFONT FONTSTRIKE INVISIBLE 
+CHANGEBAR CCHANGEBAR CULINECHBAR CFONTCBHBAR>
+
+[ Default: C<UNDERLINE> ]
+
+=item B<--subtype=markstyle> or
+B<-s markstyle> 
+
+Add code to preamble for selected style for bracketing
+commands (e.g. to mark changes in  margin). This option defines
+C<\DIFaddbegin>, C<\DIFaddend>, C<\DIFdelbegin> and C<\DIFdelend> commands.
+Available styles: C<SAFE MARGINAL DVIPSCOL>
+
+[ Default: C<SAFE> ]
+
+=item B<--floattype=markstyle> or
+B<-f markstyle>
+
+Add code to preamble for selected style which 
+replace standard marking and markup commands within floats
+(e.g., marginal remarks cause an error within floats
+so marginal marking can be disabled thus). This option defines all 
+C<\DIF...FL> commands.
+Available styles: C<FLOATSAFE TRADITIONALSAFE IDENTICAL>
+
+[ Default: C<FLOATSAFE> ]
+
+=item B<--encoding=enc> or 
+B<-e enc>
+
+Specify encoding of old.tex and new.tex. Typical encodings are
+C<ascii>, C<utf8>, C<latin1>, C<latin9>.  A list of available encodings can be 
+obtained by executing 
+
+C<perl -MEncode -e 'print join ("\n",Encode->encodings( ":all" )) ;' >
+
+[Default encoding is utf8 unless the first few lines of the preamble contain
+an invocation C<\usepackage[..]{inputenc}> in which case the 
+encoding chosen by this command is asssumed. Note that ASCII (standard
+latex) is a subset of utf8]
+
+=item B<--preamble=file> or
+B<-p file>
+
+Insert file at end of preamble instead of generating
+preamble.  The preamble must define the following commands
+C<\DIFaddbegin, \DIFaddend, \DIFadd{..},
+\DIFdelbegin,\DIFdelend,\DIFdel{..},>
+and varieties for use within floats
+C<\DIFaddbeginFL, \DIFaddendFL, \DIFaddFL{..},
+\DIFdelbeginFL, \DIFdelendFL, \DIFdelFL{..}>
+(If this option is set B<-t>, B<-s>, and B<-f> options
+are ignored.)
+
+=item B<--packages=pkg1,pkg2,..> 
+
+Tell latexdiff that .tex file is processed with the packages in list
+loaded.  This is normally not necessary if the .tex file includes the
+preamble, as the preamble is automatically scanned for C<\usepackage> commands.
+Use of the B<--packages> option disables automatic scanning, so if for any
+reason package specific parsing needs to be switched off, use B<--packages=none>.
+The following packages trigger special behaviour:
+
+=over 8
+
+=item C<amsmath> 
+
+Configuration variable amsmath is set to C<align*> (Default: C<eqnarray*>)
+
+=item C<endfloat> 
+
+Ensure that C<\begin{figure}> and C<\end{figure}> always appear by themselves on a line.
+
+=item C<hyperref>
+
+Change name of C<\DIFadd> and C<\DIFdel> commands to C<\DIFaddtex> and C<\DIFdeltex> and 
+define new C<\DIFadd> and C<\DIFdel> commands, which provide a wrapper for these commands,
+using them for the text but not for the link defining command (where any markup would cause
+errors).
+
+=back
+
+[ Default: scan the preamble for C<\\usepackage> commands to determine
+  loaded packages.]
+
+
+
+=item B<--show-preamble>
+
+Print generated or included preamble commands to stdout.
+
+=back
+
+=head2 Configuration
+
+=over 4
+
+=item B<--exclude-safecmd=exclude-file> or
+B<-A exclude-file> or  B<--exclude-safecmd="cmd1,cmd2,...">
+
+=item B<--replace-safecmd=replace-file>
+
+=item B<--append-safecmd=append-file> or 
+B<-a append-file> or B<--append-safecmd="cmd1,cmd2,...">
+
+Exclude from, replace or append to the list of regular expressions (RegEx)
+matching commands which are safe to use within the 
+scope of a C<\DIFadd> or C<\DIFdel> command.  The file must contain
+one Perl-RegEx per line (Comment lines beginning with # or % are
+ignored).  Note that the RegEx needs to match the whole of 
+the token, i.e., /^regex$/ is implied and that the initial
+"\" of the command is not included. 
+The B<--exclude-safecmd> and B<--append-safecmd> options can be combined with the -B<--replace-safecmd> 
+option and can be used repeatedly to add cumulatively to the lists.
+ B<--exclude-safecmd>
+and B<--append-safecmd> can also take a comma separated list as input. If a
+comma for one of the regex is required, escape it thus "\,". In most cases it
+will be necessary to protect the comma-separated list from the shell by putting
+it in quotation marks.
+
+=item B<--exclude-textcmd=exclude-file> or
+B<-X exclude-file> or B<--exclude-textcmd="cmd1,cmd2,...">
+
+=item B<--replace-textcmd=replace-file>
+
+=item B<--append-textcmd=append-file> or 
+B<-x append-file> or B<--append-textcmd="cmd1,cmd2,...">
+
+Exclude from, replace or append to the list of regular expressions
+matching commands whose last argument is text.  See
+entry for B<--exclude-safecmd> directly above for further details.
+
+
+=item B<--replace-context1cmd=replace-file> 
+
+=item B<--append-context1cmd=append-file> or
+=item B<--append-context1cmd="cmd1,cmd2,...">
+
+Replace or append to the list of regex matching commands
+whose last argument is text but which require a particular
+context to work, e.g. \caption will only work within a figure
+or table.  These commands behave like text commands, except when 
+they occur in a deleted section, when they are disabled, but their
+argument is shown as deleted text.
+
+=item B<--replace-context1cmd=replace-file> 
+
+=item B<--append-context2cmd=append-file> or
+=item B<--append-context2cmd="cmd1,cmd2,...">
+As corresponding commands for context1.  The only difference is that
+context2 commands are completely disabled in deleted sections, including
+their arguments.
+
+
+
+=item B<--config var1=val1,var2=val2,...> or B<-c var1=val1,..>
+
+=item B<-c configfile>
+
+Set configuration variables.  The option can be repeated to set different
+variables (as an alternative to the comma-separated list).
+Available variables (see below for further explanations): 
+
+C<MINWORDSBLOCK> (integer)
+
+C<FLOATENV> (RegEx)
+
+C<PICTUREENV> (RegEx)
+
+C<MATHENV> (RegEx)
+
+C<MATHREPL> (String)
+
+C<MATHARRENV> (RegEx)
+
+C<MATHARRREPL> (String)
+
+C<ARRENV> (RegEx)
+
+C<COUNTERCMD> (RegEx)
+
+=item B<--show-safecmd>
+
+Print list of RegEx matching and excluding safe commands.
+
+=item B<--show-textcmd>
+
+Print list of RegEx matching and excluding commands with text argument.
+
+=item B<--show-config>
+
+Show values of configuration variables.
+
+=item B<--show-all>
+
+Combine all --show commands.
+
+NB For all --show commands, no C<old.tex> or C<new.tex> file needs to be specified, and no 
+differencing takes place.
+
+
+=back
+
+=head2 Miscellaneous
+
+=over 4
+
+=item B<--verbose> or B<-V>
+
+Output various status information to stderr during processing.
+Default is to work silently.
+
+=item B<--ignore-warnings>
+
+Suppress warnings about inconsistencies in length between input and
+parsed strings and missing characters.  These warning messages are
+often related to non-standard latex or latex constructions with a
+syntax unknown to C<latexdiff> but the resulting difference argument
+is often fully functional anyway, particularly if the non-standard
+latex only occurs in parts of the text which have not changed.
+
+=item B<--allow-spaces>
+
+Allow spaces between bracketed or braced arguments to commands.  Note
+that this option might have undesirable side effects (unrelated scope
+might get lumpeded with preceding commands) so should only be used if the
+default produces erroneous results.  (Default requires arguments to
+directly follow each other without intervening spaces).
+
+=item B<--flatten>
+
+Replace C<\input> and C<\include> commands within body by the content
+of the files in their argument.  If C<\includeonly> is present in the
+preamble, only those files are expanded into the document. However, 
+no recursion is done, i.e. C<\input> and C<\include> commands within 
+included sections are not expanded.  The included files are assumed to 
+ be located in the same directories as the old and new master files,
+respectively, making it possible to organise files into old and new directories. 
+
+Use of this option is not recommended
+primarily the processing time for the large documents is prohibitive, and
+the resulting difference document no longer reflects the structure of the 
+input documents. 
+
+=item B<--help> or
+B<-h>
+
+Show help text
+
+=item B<--version>
+
+Show version number
+
+=back
+
+=head2 Predefined styles 
+
+=head2 Major types
+
+The major type determine the markup of plain text and some selected latex commands outside floats by defining the markup commands C<\DIFadd{...}> and C<\DIFdel{...}> .
+
+=over 10
+
+=item C<UNDERLINE>
+
+Added text is wavy-underlined and blue, discarded text is struck out and red
+(Requires color and ulem packages).  Overstriking does not work in displayed math equations such that deleted parts of equation are underlined, not struck out (this is a shortcoming inherent to the ulem package).
+
+=item C<CTRADITIONAL>
+
+Added text is blue and set in sans-serif, and a red footnote is created for each discarded 
+piece of text. (Requires color package)
+
+=item C<TRADITIONAL>
+
+Like C<CTRADITIONAL> but without the use of color.
+
+=item C<CFONT>
+
+Added text is blue and set in sans-serif, and discarded text is red and very small size.
+
+=item C<FONTSTRIKE>
+
+Added tex is set in sans-serif, discarded text small and struck out
+
+=item C<CCHANGEBAR>
+
+Added text is blue, and discarded text is red.  Additionally, the changed text is marked with a bar in the margin (Requires color and changebar packages).
+
+=item C<CFONTCHBAR>
+
+Like C<CFONT> but with additional changebars (Requires color and changebar packages).
+
+=item C<CULINECHBAR>
+
+Like C<UNDERLINE> but with additional changebars (Requires color, ulem and changebar packages).
+
+=item C<CHANGEBAR>
+
+No mark up of text, but mark margins with changebars (Requires changebar package).
+
+=item C<INVISIBLE>
+
+No visible markup (but generic markup commands will still be inserted.
+
+=back
+
+=head2 Subtypes
+
+The subtype defines the commands that are inserted at the begin and end of added or discarded blocks, irrespectively of whether these blocks contain text or commands (Defined commands: C<\DIFaddbegin, \DIFaddend, \DIFdelbegin, \DIFdelend>) 
+
+=over 10
+
+=item C<SAFE>
+
+No additional markup (Recommended choice)
+
+=item C<MARGIN>
+
+Mark beginning and end of changed blocks with symbols in the margin nearby (using
+the standard C<\marginpar> command - note that this sometimes moves somewhat
+from the intended position.
+
+=item C<DVIPSCOL>
+
+An alternative way of marking added passages in blue, and deleted ones in red. Note
+that C<DVIPSCOL> only works with the dvips converter, e.g. not pdflatex.
+(it is recommeneded to use instead the main types to effect colored markup,
+although in some cases coloring with dvipscol can be more complete).
+
+=back
+
+=head2 Float Types
+
+Some of the markup used in the main text might cause problems when used within 
+floats (e.g. figures or tables).  For this reason alternative versions of all
+markup commands are used within floats. The float type defines these alternative commands.
+
+=over 10
+
+=item C<FLOATSAFE>
+
+Use identical markup for text as in the main body, but set all commands marking the begin and end of changed blocks to null-commands.  You have to choose this float type if your subtype is C<MARGIN> as C<\marginpar> does not work properly within floats.
+
+=item C<TRADITIONALSAFE>
+
+Mark additions the same way as in the main text.  Deleted environments are marked by angular brackets \[ and \] and the deleted text is set in scriptscript size. This float type should always be used with the C<TRADITIONAL> and  C<CTRADITIONAL> markup types as the \footnote command does not work properly in floating environments.
+
+=item C<IDENTICAL>
+
+Make no difference between the main text and floats.
+
+=back
+
+
+=head2 Configuration Variables
+
+=over 10
+
+=item C<MINWORDSBLOCK>
+
+Minimum number of tokens required to form an independent block. This value is
+used in the algorithm to detect changes of complete blocks by merging identical text parts of less than C<MINWORDSBLOCK> to the preceding added and discarded parts.
+
+[ Default: 3 ]
+
+=item C<FLOATENV>
+
+Environments whose name matches the regular expression in C<FLOATENV> are 
+considered floats.  Within these environments, the I<latexdiff> markup commands
+are replaced by their FL variaties.
+
+[ Default: S<C<(?:figure|table|plate)[\w\d*@]*> >]
+
+=item C<PICTUREENV>
+
+Within environments whose name matches the regular expression in C<PICTUREENV>
+all latexdiff markup is removed (in pathologic cases this might lead to
+ inconsistent markup but this situation should be rare).
+
+[ Default: S<C<(?:picture|DIFnomarkup)[\w\d*@]*> >]
+
+=item C<MATHENV>,C<MATHREPL>
+
+If both \begin and \end for a math environment (environment name matching C<MATHENV>
+or \[ and \])
+are within the same deleted block, they are replaced by a \begin and \end commands for C<MATHREPL>
+rather than being commented out.
+
+[ Default: C<MATHENV>=S<C<(?:displaymath|equation)> >, C<MATHREPL>=S<C<displaymath> >]
+
+=item C<MATHARRENV>,C<MATHARRREPL>
+
+as C<MATHENV>,C<MATHREPL> but for equation arrays
+
+[ Default: C<MATHARRENV>=S<C<eqnarray\*?> >, C<MATHREPL>=S<C<eqnarray> >]
+
+=item C<ARRENV>
+
+If a match to C<ARRENV> is found within an inline math environment within a deleted or added block, then the inlined math 
+is surrounded by C<\mbox{>...C<}>.  This is necessary as underlining does not work within inlined array environments.
+
+[ Default: C<ARRENV>=S<C<(?:array|[pbvBV]matrix)> >
+
+=item C<COUNTERCMD>
+
+If a command in a deleted block which is also in the textcmd list matches C<COUNTERCMD> then an
+additional command C<\addtocounter{>F<cntcmd>C<}{-1}>, where F<cntcmd> is the matching command, is appended in the diff file such that the numbering in the diff file remains synchronized with the
+numbering in the new file.
+
+[ Default: C<COUNTERCMD>=C<(?:footnote|part|section|subsection> ...
+
+C<|subsubsection|paragraph|subparagraph)>  ]
+
+=back
+
+=head1 BUGS
+
+UTF-8 support requires a relatively new version of perl (5.8.0 is sufficient 
+but 5.6.2 up would work OK, too).
+
+Option allow-spaces not implemented entirely consistently. It breaks
+the rules that number and type of white space does not matter, as
+different numbers of inter-argument spaces are treated as significant.
+
+Please send bug reports
+to I<tilmann@esc.cam.ac.uk>.  Include the serial number of I<latexdiff>
+(from comments at the top of the source or use B<--version>).  If you come across latex
+files that are error-free and conform to the specifications set out
+above, and whose differencing still does not result in error-free
+latex, please send me those files, ideally edited to only contain the
+offending passage as long as that still reproduces the problem. 
+
+=head1 SEE ALSO
+
+L<latexrevise>
+
+=head1 PORTABILITY
+
+I<latexdiff> does not make use of external commands and thus should run
+on any platform  supporting Perl 5.6 or higher.  If files with encodings 
+other than ASCII or UTF-8 are processed, Perl 5.8 or higher is required.
+
+The standard version of I<latexdiff> requires installation of the Perl package
+C<Algorithm::Diff> (available from I<www.cpan.org> - 
+I<http://search.cpan.org/~nedkonz/Algorithm-Diff-1.15>) but a stand-alone
+version, I<latexdiff-so>, which has this package inlined, is available, too.
+I<latexdiff-fast> requires the I<diff> command to be present.
+
+=head1 AUTHOR
+
+Copyright (C) 2004-2007 Frederik Tilmann
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License Version 2
+
+Contributors of fixes and additions: V. Kuhlmann, J. Paisley, N. Becker, T. Doerges, K. Huebner
+Thanks to everyone who send in bug reports.
+
+=cut
+
+__END__
+%%BEGIN SAFE COMMANDS
+% Regex matching commands which can safely be in the
+% argument of a \DIFadd or \DIFdel command (leave out the \)
+arabic
+dashbox
+emph
+fbox
+framebox
+hspace
+math.*
+makebox
+mbox
+pageref
+ref
+symbol
+raisebox
+rule
+text.*
+shortstack
+usebox
+dag
+ddag
+copyright
+pounds
+S
+P
+oe
+OE
+ae
+AE
+aa
+AA
+o
+O
+l
+L
+frac
+ss
+sqrt
+ldots
+cdots
+vdots
+ddots
+alpha
+beta
+gamma
+delta
+epsilon
+varepsilon
+zeta
+eta
+theta
+vartheta
+iota
+kappa
+lambda
+mu
+nu
+xi
+pi
+varpi
+rho
+varrho
+sigma
+varsigma
+tau
+upsilon
+phi
+varphi
+chi
+psi
+omega
+Gamma
+Delta
+Theta
+Lambda
+Xi
+Pi
+Sigma
+Upsilon
+Phi
+Psi
+Omega
+ps
+mp
+times
+div
+ast
+star
+circ
+bullet
+cdot
+cap
+cup
+uplus
+sqcap
+vee
+wedge
+setminus
+wr
+diamond
+(?:big)?triangle.*
+lhd
+rhd
+unlhd
+unrhd
+oplus
+ominus
+otimes
+oslash
+odot
+bigcirc
+d?dagger
+amalg
+leq
+prec
+preceq
+ll
+(?:sq)?su[bp]set(?:eq)?
+in
+vdash
+geq
+succ(?:eq)?
+gg
+ni
+dashv
+equiv
+sim(?:eq)?
+asymp
+approx
+cong
+neq
+doteq
+propto
+models
+perp
+mid
+parallel
+bowtie
+Join
+smile
+frown
+.*arrow
+(?:long)?mapsto
+.*harpoon.*
+leadsto
+aleph
+hbar
+imath
+jmath
+ell
+wp
+Re
+Im
+mho
+prime
+emptyset
+nabla
+surd
+top
+bot
+angle
+forall
+exists
+neg
+flat
+natural
+sharp
+backslash
+partial
+infty
+Box
+Diamond
+triangle
+clubsuit
+diamondsuit
+heartsuit
+spadesuit
+sum
+prod
+coprod
+int
+oint
+big(?:sq)?c[au]p
+bigvee
+bigwedge
+bigodot
+bigotimes
+bigoplus
+biguplus
+(?:arc)?(?:cos|sin|tan|cot)h?
+csc
+arg
+deg
+det
+dim
+exp
+gcd
+hom
+inf
+ker
+lg
+lim
+liminf
+limsup
+ln
+log
+max
+min
+Pr
+sec
+sup
+(SUPER|SUB)SCRIPTNB
+(SUPER|SUB)SCRIPT
+%%END SAFE COMMANDS
+
+%%BEGIN TEXT COMMANDS
+% Regex matching commands with a text argument (leave out the \)
+addcontents.*
+cc
+closing
+chapter
+dashbox
+emph
+encl
+fbox
+framebox
+footnote
+footnotetext
+framebox
+part
+(sub){0,2}section\*?
+(sub)?paragraph\*?
+makebox
+mbox
+opening
+parbox
+raisebox
+savebox
+sbox
+shortstack
+signature
+text.*
+value
+underline
+sqrt
+(SUPER|SUB)SCRIPT
+%%END TEXT COMMANDS 
+
+%%BEGIN CONTEXT1 COMMANDS
+% Regex matching commands with a text argument (leave out the \), which will fail out of context, but who's arguemtn should be printed as plain text
+caption
+%%END CONTEXT1 COMMANDS 
+
+%%BEGIN CONTEXT2 COMMANDS
+% Regex matching commands with a text argument (leave out the \), which will fail out of context, but who's arguemtn should be printed as plain text
+title
+author
+%%END CONTEXT2 COMMANDS 
+
+
+%% TYPES (Commands for highlighting changed blocks)
+
+%DIF UNDERLINE PREAMBLE
+\RequirePackage[normalem]{ulem}
+\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
+\providecommand{\DIFadd}[1]{{\protect\color{blue}\uwave{#1}}}
+\providecommand{\DIFdel}[1]{{\protect\color{red}\sout{#1}}}                     
+%DIF END UNDERLINE PREAMBLE
+
+%DIF CTRADITIONAL PREAMBLE
+\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
+\RequirePackage[stable]{footmisc}
+\providecommand{\DIFadd}[1]{{\protect\color{blue} \sf #1}}
+\providecommand{\DIFdel}[1]{{\protect\color{red} [..\footnote{removed: #1} ]}}
+%DIF END CTRADITIONAL PREAMBLE
+
+%DIF TRADITIONAL PREAMBLE
+\RequirePackage[stable]{footmisc}
+\providecommand{\DIFadd}[1]{{\sf #1}}
+\providecommand{\DIFdel}[1]{{[..\footnote{removed: #1} ]}}
+%DIF END TRADITIONAL PREAMBLE
+
+%DIF CFONT PREAMBLE
+\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
+\providecommand{\DIFadd}[1]{{\protect\color{blue} \sf #1}}
+\providecommand{\DIFdel}[1]{{\protect\color{red} \scriptsize #1}}
+%DIF END CFONT PREAMBLE
+
+%DIF FONTSTRIKE PREAMBLE
+\RequirePackage[normalem]{ulem}
+\providecommand{\DIFadd}[1]{{\sf #1}}
+\providecommand{\DIFdel}[1]{{\footnotesize \sout{#1}}}
+%DIF END FONTSTRIKE PREAMBLE
+
+%DIF CCHANGEBAR PREAMBLE
+\RequirePackage[dvips]{changebar}
+\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
+\providecommand{\DIFadd}[1]{\protect\cbstart{\protect\color{blue}#1}\protect\cbend}
+\providecommand{\DIFdel}[1]{\protect\cbdelete{\protect\color{red}#1}\protect\cbdelete}
+%DIF END CCHANGEBAR PREAMBLE
+
+%DIF CFONTCHBAR PREAMBLE
+\RequirePackage[dvips]{changebar}
+\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
+\providecommand{\DIFadd}[1]{\protect\cbstart{\protect\color{blue}\sf #1}\protect\cbend}
+\providecommand{\DIFdel}[1]{\protect\cbdelete{\protect\color{red}\scriptsize #1}\protect\cbdelete}
+%DIF END CFONTCHBAR PREAMBLE
+
+%DIF CULINECHBAR PREAMBLE
+\RequirePackage[normalem]{ulem}
+\RequirePackage[dvips]{changebar}
+\RequirePackage{color}
+\providecommand{\DIFadd}[1]{\protect\cbstart{\protect\color{blue}\uwave{#1}}\protect\cbend}
+\providecommand{\DIFdel}[1]{\protect\cbdelete{\protect\color{red}\sout{#1}}\protect\cbdelete}
+%DIF END CULINECHBAR PREAMBLE
+
+%DIF CHANGEBAR PREAMBLE
+\RequirePackage[dvips]{changebar}
+\providecommand{\DIFadd}[1]{\protect\cbstart{#1}\protect\cbend}
+\providecommand{\DIFdel}[1]{\protect\cbdelete}
+%DIF END CHANGEBAR PREAMBLE
+
+%DIF INVISIBLE PREAMBLE
+\providecommand{\DIFadd}[1]{#1}
+\providecommand{\DIFdel}[1]{}
+%DIF END INVISIBLE PREAMBLE
+
+
+%% SUBTYPES (Markers for beginning and end of changed blocks)
+
+%DIF SAFE PREAMBLE
+\providecommand{\DIFaddbegin}{}
+\providecommand{\DIFaddend}{}
+\providecommand{\DIFdelbegin}{}
+\providecommand{\DIFdelend}{}
+%DIF END SAFE PREAMBLE
+
+%DIF MARGIN PREAMBLE
+\providecommand{\DIFaddbegin}{\protect\marginpar{a[}}
+\providecommand{\DIFaddend}{\protect\marginpar{]}}
+\providecommand{\DIFdelbegin}{\protect\marginpar{d[}}
+\providecommand{\DIFdelend}{\protect\marginpar{]}}
+%DIF END BRACKET PREAMBLE
+
+%DIF DVIPSCOL PREAMBLE
+%Note: only works with dvips converter
+\RequirePackage{color}
+\RequirePackage{dvipscol}
+\providecommand{\DIFaddbegin}{\protect\nogroupcolor{blue}}
+\providecommand{\DIFaddend}{\protect\nogroupcolor{black}}
+\providecommand{\DIFdelbegin}{\protect\nogroupcolor{red}}
+\providecommand{\DIFdelend}{\protect\nogroupcolor{black}}
+%DIF END DVIPSCOL PREAMBLE
+
+
+%% FLOAT TYPES 
+
+%DIF FLOATSAFE PREAMBLE
+\providecommand{\DIFaddFL}[1]{\DIFadd{#1}}
+\providecommand{\DIFdelFL}[1]{\DIFdel{#1}}
+\providecommand{\DIFaddbeginFL}{}
+\providecommand{\DIFaddendFL}{}
+\providecommand{\DIFdelbeginFL}{}
+\providecommand{\DIFdelendFL}{}
+%DIF END FLOATSAFE PREAMBLE
+
+%DIF IDENTICAL PREAMBLE
+\providecommand{\DIFaddFL}[1]{\DIFadd{#1}}
+\providecommand{\DIFdelFL}[1]{\DIFdel{#1}}
+\providecommand{\DIFaddbeginFL}{\DIFaddbegin}
+\providecommand{\DIFaddendFL}{\DIFaddend}
+\providecommand{\DIFdelbeginFL}{\DIFdelbegin}
+\providecommand{\DIFdelendFL}{\DIFdelend}
+%DIF END IDENTICAL PREAMBLE
+
+%DIF TRADITIONALSAFE PREAMBLE
+% procidecommand color to make this work for TRADITIONAL and CTRADITIONAL
+\providecommand{\color}[1]{}
+\providecommand{\DIFaddFL}[1]{\DIFadd{#1}}
+\providecommand{\DIFdel}[1]{{\protect\color{red}[..{\scriptsize {removed: #1}} ]}}
+\providecommand{\DIFaddbeginFL}{}
+\providecommand{\DIFaddendFL}{}
+\providecommand{\DIFdelbeginFL}{}
+\providecommand{\DIFdelendFL}{}
+%DIF END FLOATSAFE PREAMBLE
+
+%% SPECIAL PACKAGE PREAMBLE COMMANDS
+
+% Standard \DIFadd and \DIFdel are redefined as \DIFaddtex and \DIFdeltex
+% when hyperref package is included.
+%DIF HYPERREF PREAMBLE
+\providecommand{\DIFadd}[1]{\texorpdfstring{\DIFaddtex{#1}}{#1}}
+\providecommand{\DIFdel}[1]{\texorpdfstring{\DIFdeltex{#1}}{}}
+%DIF END HYPERREF PACKAGE
diff --git a/Master/texmf-dist/doc/latex/latexdiff/latexdiff-fast b/Master/texmf-dist/doc/latex/latexdiff/latexdiff-fast
new file mode 100755
index 00000000000..ee6c7419ac9
--- /dev/null
+++ b/Master/texmf-dist/doc/latex/latexdiff/latexdiff-fast
@@ -0,0 +1,3344 @@
+#!/usr/bin/perl -w
+# latexdiff - differences two latex files on the word level
+#             and produces a latex file with the differences marked up.
+#
+#   Copyright (C) 2004-2007  F J Tilmann (tilmann@esc.cam.ac.uk)
+#
+#    This program is free software; you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License Version 2 as published by
+#    the Free Software Foundation.
+#
+#    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, write to the Free Software
+#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+# Detailed usage information at the end of the file
+#
+# Version 0.5  A number of minor improvements based on feedback
+#              Deleted blocks are now shown before added blocks
+#              Package specific processing
+#
+# Version 0.43 unreleased typo in list of styles at the end
+#              Add protect to all \cbstart, \cbend commands
+#              More robust substitution of deleted math commands
+#
+# Version 0.42 November 06  Bug fixes only
+#
+# Version 0.4   March 06 option for fast differencing using UNIX diff command, several minor bug fixes (\par bug, improved highlighting of textcmds)
+#
+# Version 0.3   August 05 improved parsing of displayed math, --allow-spaces 
+#               option, several minor bug fixes
+#
+# Version 0.25  October 04 Fix bug with deleted equations, add math mode commands to safecmd, add | to allowed interpunctuation signs
+# Version 0.2   September 04 extension to utf-8 and variable encodings
+# Version 0.1   August 04    First public release
+
+# Inserted block for differenceing 
+# use Algorithm::Diff qw(traverse_sequences);
+# in standard version
+# The following BEGIN block contains a verbatim copy of
+# Ned Konz' Algorithm::Diff package version 1.15 except
+# that subroutine _longestCommonSubsequence has been replace by 
+# a routine which internally uses the UNIX diff command for
+# the differencing rather than the Perl routines if the 
+# length of the sequences exceeds some threshold.
+# Also, all POD documentation has been stripped out.
+#
+# (the distribution on which this modification is based is available
+#  from http://search.cpan.org/~nedkonz/Algorithm-Diff-1.15
+#  the most recent version can be found via  http://search.cpan.org/search?module=Algorithm::Diff )
+# Please note that the LICENCSE for Algorithm::Diff :
+#   "Copyright (c) 2000-2002 Ned Konz.  All rights reserved.
+#    This program is free software;
+#    you can redistribute it and/or modify it under the same terms
+#    as Perl itself."
+# The fast-differencing version of latexdiff is provided as a convenience
+# for latex users under Unix-like systems which have a 'diff' command.
+# If you believe
+# the inlining of Algorithm::Diff violates its license please contact
+# me and I will modify the latexdiff distribution accordingly.
+# Frederik Tilmann (tilmann@esc.cam.ac.uk)
+# Jonathan Paisley is acknowledged for the idea of using the system diff
+# command to achieve shorter running times
+BEGIN { 
+package Algorithm::Diff;
+use strict;
+use vars qw($VERSION @EXPORT_OK @ISA @EXPORT);
+use integer;    # see below in _replaceNextLargerWith() for mod to make
+                # if you don't use this
+require Exporter;
+@ISA       = qw(Exporter);
+@EXPORT    = qw();
+@EXPORT_OK = qw(LCS diff traverse_sequences traverse_balanced sdiff);
+$VERSION = sprintf('%d.%02d fast', (q$Revision: 1.15 $ =~ /\d+/g));
+
+# Global parameters
+
+use File::Temp qw/tempfile/;
+# if larger number of elements in longestCommonSubsequence smaller than
+# this number, then use internal algorithm, otherwise use UNIX diff
+use constant THRESHOLD => 100 ; 
+# Detect whether diff --minimal option is available
+# if yes we use it
+use constant MINIMAL => ( system('diff','--minimal','/dev/null','/dev/null') >> 8 ==0 ? "--minimal" : "" ) ;
+
+
+
+# McIlroy-Hunt diff algorithm
+# Adapted from the Smalltalk code of Mario I. Wolczko, <mario@wolczko.com>
+# by Ned Konz, perl@bike-nomad.com
+
+
+# Create a hash that maps each element of $aCollection to the set of positions
+# it occupies in $aCollection, restricted to the elements within the range of
+# indexes specified by $start and $end.
+# The fourth parameter is a subroutine reference that will be called to
+# generate a string to use as a key.
+# Additional parameters, if any, will be passed to this subroutine.
+#
+# my $hashRef = _withPositionsOfInInterval( \@array, $start, $end, $keyGen );
+
+sub _withPositionsOfInInterval
+{
+	my $aCollection = shift;    # array ref
+	my $start       = shift;
+	my $end         = shift;
+	my $keyGen      = shift;
+	my %d;
+	my $index;
+	for ( $index = $start ; $index <= $end ; $index++ )
+	{
+		my $element = $aCollection->[$index];
+		my $key = &$keyGen( $element, @_ );
+		if ( exists( $d{$key} ) )
+		{
+			unshift ( @{ $d{$key} }, $index );
+		}
+		else
+		{
+			$d{$key} = [$index];
+		}
+	}
+	return wantarray ? %d : \%d;
+}
+
+# Find the place at which aValue would normally be inserted into the array. If
+# that place is already occupied by aValue, do nothing, and return undef. If
+# the place does not exist (i.e., it is off the end of the array), add it to
+# the end, otherwise replace the element at that point with aValue.
+# It is assumed that the array's values are numeric.
+# This is where the bulk (75%) of the time is spent in this module, so try to
+# make it fast!
+
+sub _replaceNextLargerWith
+{
+	my ( $array, $aValue, $high ) = @_;
+	$high ||= $#$array;
+
+	# off the end?
+	if ( $high == -1 || $aValue > $array->[-1] )
+	{
+		push ( @$array, $aValue );
+		return $high + 1;
+	}
+
+	# binary search for insertion point...
+	my $low = 0;
+	my $index;
+	my $found;
+	while ( $low <= $high )
+	{
+		$index = ( $high + $low ) / 2;
+
+		#		$index = int(( $high + $low ) / 2);		# without 'use integer'
+		$found = $array->[$index];
+
+		if ( $aValue == $found )
+		{
+			return undef;
+		}
+		elsif ( $aValue > $found )
+		{
+			$low = $index + 1;
+		}
+		else
+		{
+			$high = $index - 1;
+		}
+	}
+
+	# now insertion point is in $low.
+	$array->[$low] = $aValue;    # overwrite next larger
+	return $low;
+}
+
+# This method computes the longest common subsequence in $a and $b.
+
+# Result is array or ref, whose contents is such that
+# 	$a->[ $i ] == $b->[ $result[ $i ] ]
+# foreach $i in ( 0 .. $#result ) if $result[ $i ] is defined.
+
+# An additional argument may be passed; this is a hash or key generating
+# function that should return a string that uniquely identifies the given
+# element.  It should be the case that if the key is the same, the elements
+# will compare the same. If this parameter is undef or missing, the key
+# will be the element as a string.
+
+# By default, comparisons will use "eq" and elements will be turned into keys
+# using the default stringizing operator '""'.
+
+# Additional parameters, if any, will be passed to the key generation routine.
+
+sub _longestCommonSubsequence
+{
+	my $a      = shift;    # array ref
+	my $b      = shift;    # array ref
+	my $keyGen = shift;    # code ref
+	my $compare;           # code ref
+
+	# set up code refs
+	# Note that these are optimized.
+	if ( !defined($keyGen) )    # optimize for strings
+	{
+		$keyGen = sub { $_[0] };
+		$compare = sub { my ( $a, $b ) = @_; $a eq $b };
+	}
+	else
+	{
+		$compare = sub {
+			my $a = shift;
+			my $b = shift;
+			&$keyGen( $a, @_ ) eq &$keyGen( $b, @_ );
+		};
+	}
+
+	my ( $aStart, $aFinish, $bStart, $bFinish, $matchVector ) =
+	  ( 0, $#$a, 0, $#$b, [] );
+
+	# Check whether to use internal routine (small number of elements)
+	# or use it as a wrapper for UNIX diff
+	if ( ( $#$a > $#$b ?  $#$a : $#$b) < THRESHOLD ) {
+	  ###	  print STDERR "DEBUG: regular longestCommonSubsequence\n";
+	  # First we prune off any common elements at the beginning
+	  while ( $aStart <= $aFinish
+		  and $bStart <= $bFinish
+		  and &$compare( $a->[$aStart], $b->[$bStart], @_ ) )
+	    {
+	      $matchVector->[ $aStart++ ] = $bStart++;
+	    }
+
+	  # now the end
+	  while ( $aStart <= $aFinish
+		and $bStart <= $bFinish
+		and &$compare( $a->[$aFinish], $b->[$bFinish], @_ ) )
+	    {
+	      $matchVector->[ $aFinish-- ] = $bFinish--;
+	    }
+
+	  # Now compute the equivalence classes of positions of elements
+	  my $bMatches =
+	    _withPositionsOfInInterval( $b, $bStart, $bFinish, $keyGen, @_ );
+	  my $thresh = [];
+	  my $links  = [];
+	  
+	  my ( $i, $ai, $j, $k );
+	  for ( $i = $aStart ; $i <= $aFinish ; $i++ )
+	    {
+	      $ai = &$keyGen( $a->[$i], @_ );
+	      if ( exists( $bMatches->{$ai} ) )
+		{
+		  $k = 0;
+		  for $j ( @{ $bMatches->{$ai} } )
+		    {
+		      
+		      # optimization: most of the time this will be true
+		      if ( $k and $thresh->[$k] > $j and $thresh->[ $k - 1 ] < $j )
+			{
+			  $thresh->[$k] = $j;
+			}
+		      else
+			{
+			  $k = _replaceNextLargerWith( $thresh, $j, $k );
+			}
+		      
+		      # oddly, it's faster to always test this (CPU cache?).
+		      if ( defined($k) )
+			{
+			  $links->[$k] =
+			    [ ( $k ? $links->[ $k - 1 ] : undef ), $i, $j ];
+			}
+		    }
+		}
+	    }
+
+	  if (@$thresh)
+	    {
+	      for ( my $link = $links->[$#$thresh] ; $link ; $link = $link->[0] )
+		{
+		  $matchVector->[ $link->[1] ] = $link->[2];
+		}
+	    }
+	}
+	else {
+	  my ($fha,$fhb,$fna,$fnb,$ele,$key);
+	  my ($alines,$blines,$alb,$alf,$blb,$blf);
+	  my ($minimal)=MINIMAL;
+	  # large number of elements, use system diff
+	  ###	  print STDERR "DEBUG: fast (diff) longestCommonSubsequence\n";
+
+	  ($fha,$fna)=tempfile("DiffA-XXXX") or die "_longestCommonSubsequence: Cannot open tempfile for sequence A";
+	  ($fhb,$fnb)=tempfile("DiffB-XXXX") or die "_longestCommonSubsequence: Cannot open tempfile for sequence B";
+	  # prepare sequence A
+	  foreach $ele ( @$a ) {
+	    $key=&$keyGen( $ele, @_ );
+	    $key =~ s/\\/\\\\/g ;
+	    $key =~ s/\n/\\n/sg ;
+	    print $fha "$key\n" ;
+	  }
+	  close($fha);
+	  # prepare sequence B
+	  foreach $ele ( @$b ) {
+	    $key=&$keyGen( $ele, @_ );
+	    $key =~ s/\\/\\\\/g ;
+	    $key =~ s/\n/\\n/sg ;
+	    print $fhb "$key\n" ;
+	  }
+	  close($fhb);
+	  
+	  open(DIFFPIPE, "diff $minimal $fna $fnb |") or die "_longestCommonSubsequence: Cannot launch diff process. $!" ;
+	  # The diff line numbering begins with 1, but Perl subscripts start with 0
+	  # We follow the diff numbering but substract 1 when assigning to matchVector
+	  $aStart++; $bStart++ ; $aFinish++ ; $bFinish++ ;
+	  while( <DIFFPIPE> ) {
+	    if ( ($alines,$blines) = ( m/^(\d*(?:,\d*)?)?c(\d*(?:,\d*)?)?$/ ) ) {
+	      ($alb,$alf)=split(/,/,$alines);
+	      ($blb,$blf)=split(/,/,$blines);
+	      $alf=$alb unless defined($alf);
+	      $blf=$blb unless defined($blf);
+	      while($aStart < $alb ) {
+		$matchVector->[ -1 + $aStart++ ] = -1 + $bStart++ ;
+	      }
+	      # check for consistency
+	      $bStart==$blb or die "_longestCommonSubsequence: Fatal error in interpreting diff output: Inconsistency in changed sequence";
+	      $aStart=$alf+1;
+	      $bStart=$blf+1;
+	    }
+	    elsif ( ($alb,$blines) = ( m/^(\d*)a(\d*(?:,\d*)?)$/ ) ) {
+	      ($blb,$blf)=split(/,/,$blines);
+	      $blf=$blb unless defined($blf);
+	      while ( $bStart < $blb ) {
+		$matchVector->[ -1 + $aStart++ ] = -1 + $bStart++ ;
+	      }
+	      $aStart==$alb+1 or die "_longestCommonSubsequence: Fatal error in interpreting diff output: Inconsistency in appended sequence near elements $aStart and $bStart";
+	      $bStart=$blf+1;
+	    }
+	    elsif ( ($alines,$blb) = ( m/^(\d*(?:,\d*)?)d(\d*)$/ ) ) {
+	      ($alb,$alf)=split(/,/,$alines);
+	      $alf=$alb unless defined($alf);
+	      while ( $aStart < $alb ) {
+		$matchVector->[ -1 + $aStart++ ] = -1 + $bStart++ ;
+	      }
+	      $bStart==$blb+1 or die "_longestCommonSubsequence: Fatal error in interpreting diff output: Inconsistency in deleted sequence near elements $aStart and $bStart";
+	      $aStart=$alf+1;
+	    }
+	    elsif ( m/^Binary files/ ) {
+	      # if diff reports it is a binary file force --text mode. I do not like
+	      # to always use this option because it is probably only available in GNU diff
+	      open(DIFFPIPE, "diff --text $fna $fnb |") or die "Cannot launch diff process. $!" ;
+	    }
+	    # Default: just skip line
+	  }
+	  while ($aStart <= $aFinish ) {
+	    $matchVector->[ -1 + $aStart++ ] = -1 + $bStart++ ;
+	  }
+	  $bStart==$bFinish+1  or die "_longestCommonSubsequence: Fatal error in interpreting diff output: Inconsistency at end";
+	  close DIFFPIPE;
+	  # check whether a system error has occurred or return status is greater than or equal to 5
+	  if ( $! || ($? >> 8) > 5) {
+	    print STDERR "diff process failed with exit code ", ($? >> 8), " $!\n";
+	    die;
+	  }
+	  unlink $fna,$fnb ;
+	}
+	return wantarray ? @$matchVector : $matchVector;
+}
+
+sub traverse_sequences
+{
+	my $a                 = shift;                                  # array ref
+	my $b                 = shift;                                  # array ref
+	my $callbacks         = shift || {};
+	my $keyGen            = shift;
+	my $matchCallback     = $callbacks->{'MATCH'} || sub { };
+	my $discardACallback  = $callbacks->{'DISCARD_A'} || sub { };
+	my $finishedACallback = $callbacks->{'A_FINISHED'};
+	my $discardBCallback  = $callbacks->{'DISCARD_B'} || sub { };
+	my $finishedBCallback = $callbacks->{'B_FINISHED'};
+	my $matchVector = _longestCommonSubsequence( $a, $b, $keyGen, @_ );
+
+	# Process all the lines in @$matchVector
+	my $lastA = $#$a;
+	my $lastB = $#$b;
+	my $bi    = 0;
+	my $ai;
+
+	for ( $ai = 0 ; $ai <= $#$matchVector ; $ai++ )
+	{
+		my $bLine = $matchVector->[$ai];
+		if ( defined($bLine) )    # matched
+		{
+			&$discardBCallback( $ai, $bi++, @_ ) while $bi < $bLine;
+			&$matchCallback( $ai,    $bi++, @_ );
+		}
+		else
+		{
+			&$discardACallback( $ai, $bi, @_ );
+		}
+	}
+
+	# The last entry (if any) processed was a match.
+	# $ai and $bi point just past the last matching lines in their sequences.
+
+	while ( $ai <= $lastA or $bi <= $lastB )
+	{
+
+		# last A?
+		if ( $ai == $lastA + 1 and $bi <= $lastB )
+		{
+			if ( defined($finishedACallback) )
+			{
+				&$finishedACallback( $lastA, @_ );
+				$finishedACallback = undef;
+			}
+			else
+			{
+				&$discardBCallback( $ai, $bi++, @_ ) while $bi <= $lastB;
+			}
+		}
+
+		# last B?
+		if ( $bi == $lastB + 1 and $ai <= $lastA )
+		{
+			if ( defined($finishedBCallback) )
+			{
+				&$finishedBCallback( $lastB, @_ );
+				$finishedBCallback = undef;
+			}
+			else
+			{
+				&$discardACallback( $ai++, $bi, @_ ) while $ai <= $lastA;
+			}
+		}
+
+		&$discardACallback( $ai++, $bi, @_ ) if $ai <= $lastA;
+		&$discardBCallback( $ai, $bi++, @_ ) if $bi <= $lastB;
+	}
+
+	return 1;
+}
+
+sub traverse_balanced
+{
+	my $a                 = shift;                                  # array ref
+	my $b                 = shift;                                  # array ref
+	my $callbacks         = shift || {};
+	my $keyGen            = shift;
+	my $matchCallback     = $callbacks->{'MATCH'} || sub { };
+	my $discardACallback  = $callbacks->{'DISCARD_A'} || sub { };
+	my $discardBCallback  = $callbacks->{'DISCARD_B'} || sub { };
+	my $changeCallback    = $callbacks->{'CHANGE'};
+	my $matchVector = _longestCommonSubsequence( $a, $b, $keyGen, @_ );
+
+	# Process all the lines in match vector
+	my $lastA = $#$a;
+	my $lastB = $#$b;
+	my $bi    = 0;
+	my $ai    = 0;
+	my $ma    = -1;
+	my $mb;
+
+	while (1)
+	{
+
+		# Find next match indices $ma and $mb
+		do { $ma++ } while ( $ma <= $#$matchVector && !defined $matchVector->[$ma] );
+
+		last if $ma > $#$matchVector;    # end of matchVector?
+		$mb = $matchVector->[$ma];
+
+		# Proceed with discard a/b or change events until
+		# next match
+		while ( $ai < $ma || $bi < $mb )
+		{
+
+			if ( $ai < $ma && $bi < $mb )
+			{
+
+				# Change
+				if ( defined $changeCallback )
+				{
+					&$changeCallback( $ai++, $bi++, @_ );
+				}
+				else
+				{
+					&$discardACallback( $ai++, $bi, @_ );
+					&$discardBCallback( $ai, $bi++, @_ );
+				}
+			}
+			elsif ( $ai < $ma )
+			{
+				&$discardACallback( $ai++, $bi, @_ );
+			}
+			else
+			{
+
+				# $bi < $mb
+				&$discardBCallback( $ai, $bi++, @_ );
+			}
+		}
+
+		# Match
+		&$matchCallback( $ai++, $bi++, @_ );
+	}
+
+	while ( $ai <= $lastA || $bi <= $lastB )
+	{
+		if ( $ai <= $lastA && $bi <= $lastB )
+		{
+
+			# Change
+			if ( defined $changeCallback )
+			{
+				&$changeCallback( $ai++, $bi++, @_ );
+			}
+			else
+			{
+				&$discardACallback( $ai++, $bi, @_ );
+				&$discardBCallback( $ai, $bi++, @_ );
+			}
+		}
+		elsif ( $ai <= $lastA )
+		{
+			&$discardACallback( $ai++, $bi, @_ );
+		}
+		else
+		{
+
+			# $bi <= $lastB
+			&$discardBCallback( $ai, $bi++, @_ );
+		}
+	}
+
+	return 1;
+}
+
+sub LCS
+{
+	my $a = shift;                                           # array ref
+	my $matchVector = _longestCommonSubsequence( $a, @_ );
+	my @retval;
+	my $i;
+	for ( $i = 0 ; $i <= $#$matchVector ; $i++ )
+	{
+		if ( defined( $matchVector->[$i] ) )
+		{
+			push ( @retval, $a->[$i] );
+		}
+	}
+	return wantarray ? @retval : \@retval;
+}
+
+sub diff
+{
+	my $a      = shift;    # array ref
+	my $b      = shift;    # array ref
+	my $retval = [];
+	my $hunk   = [];
+	my $discard = sub { push ( @$hunk, [ '-', $_[0], $a->[ $_[0] ] ] ) };
+	my $add = sub { push ( @$hunk, [ '+', $_[1], $b->[ $_[1] ] ] ) };
+	my $match = sub { push ( @$retval, $hunk ) if scalar(@$hunk); $hunk = [] };
+	traverse_sequences( $a, $b,
+		{ MATCH => $match, DISCARD_A => $discard, DISCARD_B => $add }, @_ );
+	&$match();
+	return wantarray ? @$retval : $retval;
+}
+
+sub sdiff
+{
+	my $a      = shift;    # array ref
+	my $b      = shift;    # array ref
+	my $retval = [];
+	my $discard = sub { push ( @$retval, [ '-', $a->[ $_[0] ], "" ] ) };
+	my $add = sub { push ( @$retval, [ '+', "", $b->[ $_[1] ] ] ) };
+	my $change = sub {
+		push ( @$retval, [ 'c', $a->[ $_[0] ], $b->[ $_[1] ] ] );
+	};
+	my $match = sub {
+		push ( @$retval, [ 'u', $a->[ $_[0] ], $b->[ $_[1] ] ] );
+	};
+	traverse_balanced(
+		$a,
+		$b,
+		{
+			MATCH     => $match,
+			DISCARD_A => $discard,
+			DISCARD_B => $add,
+			CHANGE    => $change,
+		},
+		@_
+	);
+	return wantarray ? @$retval : $retval;
+}
+
+1;
+}
+import Algorithm::Diff qw(traverse_sequences);
+# End of inserted block for stand-alone version
+
+
+use Getopt::Long ;
+use strict ;
+use utf8 ;
+
+my ($algodiffversion)=split(/ /,$Algorithm::Diff::VERSION);
+
+
+my ($versionstring)=<<EOF ;
+This is LATEXDIFF 0.5  (Algorithm::Diff $Algorithm::Diff::VERSION)
+  (c) 2004-2007 F J Tilmann
+EOF
+
+# Configuration variables: these have to be visible from the subroutines
+my $MINWORDSBLOCK=3; # minimum number of tokens to form an independent block
+                     # shorter identical blocks will be merged to the previous word
+my $FLOATENV='(?:figure|table|plate)[\w\d*@]*' ;   # Environments in which FL variants of defined commands are used
+my $PICTUREENV='(?:picture|DIFnomarkup)[\w\d*@]*' ;   # Environments in which all change markup is removed
+my $MATHENV='(?:equation|displaymath|DOLLARDOLLAR)' ;           # Environments turning on display math mode (code also knows about \[ and \]
+my $MATHREPL='displaymath';  # Environment introducing deleted maths blocks
+my $MATHARRENV='(?:eqnarray|align|gather|multiline|flalign)[*]?' ;           # Environments turning on eqnarray math mode
+my $MATHARRREPL='eqnarray*';  # Environment introducing deleted maths blocks
+my $ARRENV='(?:array|[pbvBV]matrix)'; # Enviroments making arrays in math mode.  The underlining style does not cope well with those - as a result in-text math environments are surrounded by \mbox{ } if any of these commands is used in an inline math block
+my $COUNTERCMD='(?:footnote|part|section|subsection|subsubsection|paragraph|subparagraph)';  # textcmds which are associated with a counter
+                                        # If any of these commands occur in a deleted block
+                                        # they will be succeeded by an \addtocounter{...}{-1}
+                                        # for the associated counter such that the overall numbers
+                                        # should be the same as in the new file
+
+# Markup strings
+# If at all possible, do not change these as parts of the program
+# depend on the actual name (particularly post-processing)
+# At the very least adapt subroutine postprocess to new tokens.
+my $ADDMARKOPEN='\DIFaddbegin ';   # Token to mark begin of appended text
+my $ADDMARKCLOSE='\DIFaddend ';   # Token to mark end of appended text
+my $ADDOPEN='\DIFadd{';  # To mark begin of added text passage
+my $ADDCLOSE='}';        # To mark end of added text passage
+my $ADDCOMMENT='DIF > ';   # To mark added comment line
+my $DELMARKOPEN='\DIFdelbegin ';   # Token to mark begin of deleted text
+my $DELMARKCLOSE='\DIFdelend ';   # Token to mark end of deleted text
+my $DELOPEN='\DIFdel{';  # To mark begin of deleted text passage
+my $DELCLOSE='}';        # To mark end of deleted text passage
+my $DELCMDOPEN='%DIFDELCMD < ';  # To mark begin of deleted commands (must begin with %, i.e., be a comment
+my $DELCMDCLOSE="%%%\n";    # To mark end of deleted commands (must end with a new line)
+my $AUXCMD='%DIFAUXCMD' ; #  follows auxiliary commands put in by latexdiff to make difference file legal
+                          # auxiliary commands must be on a line of their own
+my $DELCOMMENT='DIF < ';   # To mark deleted comment line
+
+
+# main local variables:
+my @TEXTCMDLIST=();  # array containing patterns of commands with text arguments
+my @TEXTCMDEXCL=();  # array containing patterns of commands without text arguments (if a pattern
+                     # matches both TEXTCMDLIST and TEXTCMDEXCL it is excluded)
+my @CONTEXT1CMDLIST=();  # array containing patterns of commands with text arguments (subset of text commands),
+                         # but which cause confusion if used out of context (e.g. \caption). 
+                         # In deleted passages, the command will be disabled but its argument is marked up
+                         # Otherwise they behave exactly like TEXTCMD's 
+my @CONTEXT1CMDEXCL=();  # exclude list for above, but always empty
+my @CONTEXT2CMDLIST=();  # array containing patterns of commands with text arguments, but which fail cause confusion
+                         # if used out of context (e.g. \title). They and their arguments will be disabled in deleted
+                         # passages
+my @CONTEXT2CMDEXCL=();  # exclude list for above, but always empty
+
+my @SAFECMDLIST=();  # array containing patterns of safe commands (which do not break when in the argument of DIFadd or DIFDEL)
+my @SAFECMDEXCL=();
+
+my ($i,$j,$l);
+my ($old,$new);
+my ($line);
+my ($newpreamble,$oldpreamble);
+my (@newpreamble,@oldpreamble,@diffpreamble,@diffbody);
+my ($latexdiffpreamble);
+my ($oldbody, $newbody, $diffbo);
+my ($oldpost, $newpost);
+my ($diffall);
+# Option names
+my ($type,$subtype,$floattype,$config,$preamblefile,$encoding,
+    $showpreamble,$showsafe,$showtext,$showconfig,$showall,
+    $replacesafe,$appendsafe,$excludesafe,
+    $replacetext,$appendtext,$excludetext,
+    $replacecontext1,$appendcontext1,
+    $replacecontext2,$appendcontext2,
+    $help,$verbose,$version,$ignorewarnings,$allowspaces,$flatten,$debug);
+my (@configlist,
+    @appendsafelist,@excludesafelist,
+    @appendtextlist,@excludetextlist,
+    @appendcontext1list,@appendcontext2list,
+    @packagelist);
+my ($assign,@config);
+# Hash where keys corresponds to the names of  all included packages (including the documentclass as another package
+# the optional arguments to the package are the values of the hash elements
+my ($pkg,%packages);
+# Defaults
+$type='UNDERLINE';
+$subtype='SAFE';
+$floattype='FLOATSAFE';
+
+$verbose=0;
+$debug=1; 
+# define character properties
+sub IsNonAsciiPunct { return <<'END'    # Unicode punctuation but excluding ASCII punctuation
++utf8::IsPunct
+-utf8::IsASCII
+END
+}
+sub IsNonAsciiS { return <<'END'       # Unicode symbol but excluding ASCII
++utf8::IsS
+-utf8::IsASCII
+END
+}
+
+
+
+  my %verbhash;
+
+Getopt::Long::Configure('bundling');
+GetOptions('type|t=s' => \$type, 
+	   'subtype|s=s' => \$subtype, 
+	   'floattype|f=s' => \$floattype, 
+	   'config|c=s' => \@configlist,
+	   'preamble|p=s' => \$preamblefile,
+	   'encoding|e=s' => \$encoding,
+	   'exclude-safecmd|A=s' => \@excludesafelist,
+	   'replace-safecmd=s' => \$replacesafe,
+	   'append-safecmd|a=s' => \@appendsafelist,
+	   'exclude-textcmd|X=s' => \@excludetextlist,
+	   'replace-textcmd=s' => \$replacetext,
+	   'append-textcmd|x=s' => \@appendtextlist,
+	   'replace-context1cmd=s' => \$replacecontext1,
+	   'append-context1cmd=s' => \@appendcontext1list,
+	   'replace-context2cmd=s' => \$replacecontext2,
+	   'append-context2cmd=s' => \@appendcontext2list,
+	   'show-preamble' => \$showpreamble,
+	   'show-safecmd' => \$showsafe,
+	   'show-textcmd' => \$showtext,
+	   'show-config' => \$showconfig,
+	   'show-all' => \$showall,
+           'packages=s' => \@packagelist,
+	   'verbose|V' => \$verbose,
+	   'ignore-warnings' => \$ignorewarnings,
+	   'allow-spaces' => \$allowspaces,
+	   'flatten' => \$flatten,
+	   'version' => \$version,
+	   'help|h|H' => \$help);
+
+if ( $help ) {
+  usage() ;
+}
+
+
+if ( $version ) {
+  die $versionstring ; 
+}
+
+print STDERR $versionstring if $verbose; 
+
+if (defined($showall)){
+  $showpreamble=$showsafe=$showtext=$showconfig=1;
+}
+
+# setting extra preamble commands
+if (defined($preamblefile)) {
+  $latexdiffpreamble=join "\n",(extrapream($preamblefile),"");
+} else {
+  $latexdiffpreamble=join "\n",(extrapream($type,$subtype,$floattype),"");
+}
+
+# setting up @SAFECMDLIST and @SAFECMDEXCL
+if (defined($replacesafe)) {
+  init_regex_arr_ext(\@SAFECMDLIST,$replacesafe);
+} else {
+  init_regex_arr_data(\@SAFECMDLIST, "SAFE COMMANDS");
+}
+foreach $appendsafe ( @appendsafelist ) {
+  init_regex_arr_ext(\@SAFECMDLIST, $appendsafe);
+}
+foreach $excludesafe ( @excludesafelist ) {
+  init_regex_arr_ext(\@SAFECMDEXCL, $excludesafe);
+}
+
+# Special: treat all cite commands as safe except in UNDERLINE and FONTSTRIKE mode
+# (there is a conflict between citation and ulem package, see
+# package documentation)
+if ( uc($type) ne "UNDERLINE" && uc($type) ne "FONTSTRIKE" && uc($type) ne "CULINECHBAR" ) {
+  push (@SAFECMDLIST, qr/^cite.*$/);
+}
+
+# setting up @TEXTCMDLIST and @TEXTCMDEXCL
+if (defined($replacetext)) {
+  init_regex_arr_ext(\@TEXTCMDLIST,$replacetext);
+} else {
+  init_regex_arr_data(\@TEXTCMDLIST, "TEXT COMMANDS");
+}
+foreach $appendtext ( @appendtextlist ) {
+  init_regex_arr_ext(\@TEXTCMDLIST, $appendtext);
+}
+foreach $excludetext ( @excludetextlist ) {
+  init_regex_arr_ext(\@TEXTCMDEXCL, $excludetext);
+}
+
+
+# setting up @CONTEXT1CMDLIST ( @CONTEXT1CMDEXCL exist but is always empty )
+if (defined($replacecontext1)) {
+  init_regex_arr_ext(\@CONTEXT1CMDLIST,$replacecontext1);
+} else {
+  init_regex_arr_data(\@CONTEXT1CMDLIST, "CONTEXT1 COMMANDS");
+}
+foreach $appendcontext1 ( @appendcontext1list ) {
+  init_regex_arr_ext(\@CONTEXT1CMDLIST, $appendcontext1);
+}
+
+
+# setting up @CONTEXT2CMDLIST ( @CONTEXT2CMDEXCL exist but is always empty )
+if (defined($replacecontext2)) {
+  init_regex_arr_ext(\@CONTEXT2CMDLIST,$replacecontext2);
+} else {
+  init_regex_arr_data(\@CONTEXT2CMDLIST, "CONTEXT2 COMMANDS");
+}
+foreach $appendcontext2 ( @appendcontext2list ) {
+  init_regex_arr_ext(\@CONTEXT2CMDLIST, $appendcontext2);
+}
+
+
+
+
+# setting configuration variables
+@config=();
+foreach $config ( @configlist ) {
+  if (-f $config ) {
+    open(FILE,$config) or die ("Couldn't open configuration file $config: $!");
+    while (<FILE>) {
+      chomp;
+      next if /^\s*#/ || /^\s*%/ || /^\s*$/ ;
+      push (@config,$_);
+    }
+    close(FILE);
+  }
+  else {
+#    foreach ( split(",",$config) ) {
+#      push @config,$_;
+#    }
+     push @config,split(",",$config)
+  }
+}
+foreach $assign ( @config ) {
+  $assign=~ m/\s*(\w*)\s*=\s*(\S*)\s*$/ or die "Illegal assignment $assign in configuration list (must be variable=value)";  
+  if ( $1 eq "MINWORDSBLOCK" ) { $MINWORDSBLOCK = $2; }
+  elsif ( $1 eq "FLOATENV" ) { $FLOATENV = $2 ; }
+  elsif ( $1 eq "PICTUREENV" ) { $PICTUREENV = $2 ; }
+  elsif ( $1 eq "MATHENV" ) { $MATHENV = $2 ; }
+  elsif ( $1 eq "MATHREPL" ) { $MATHREPL = $2 ; }
+  elsif ( $1 eq "MATHARRENV" ) { $MATHARRENV = $2 ; }
+  elsif ( $1 eq "MATHARRREPL" ) { $MATHARRREPL = $2 ; }
+  elsif ( $1 eq "ARRENV" ) { $ARRENV = $2 ; }
+  elsif ( $1 eq "COUNTERCMD" ) { $COUNTERCMD = $2 ; }
+  else { die "Unknown variable $1 in assignment.";}
+}
+
+
+foreach $pkg ( @packagelist ) {
+  map { $packages{$_}="" } split(/,/,$pkg) ;
+}
+
+if ($showpreamble) {
+  print "\nPreamble commands:\n";
+  print $latexdiffpreamble ;
+}
+
+if ($showsafe) {
+  print "\nCommands safe within scope of $ADDOPEN $ADDCLOSE and $DELOPEN $DELCLOSE (unless excluded):\n";
+  print_regex_arr(@SAFECMDLIST);
+  print "\nCommands not safe within scope of $ADDOPEN $ADDCLOSE and $DELOPEN $DELCLOSE :\n";
+  print_regex_arr(@SAFECMDEXCL);
+}
+
+if ($showtext) {
+  print "\nCommands with last argument textual (unless excluded) and safe in every context:\n";
+  print_regex_arr(@TEXTCMDLIST);
+  print "\nContext1 commands (last argument textual, command will be disabled in deleted passages, last argument will be shown as plain text):\n";
+  print_regex_arr(@CONTEXT1CMDLIST);
+  print "\nContext2 commands (last argument textual, command ant its argument will be disabled in deleted passages):\n";
+  print_regex_arr(@CONTEXT2CMDLIST);  
+  print "\nExclude list of Commands with last argument not textual (overrides patterns above):\n";
+  print_regex_arr(@TEXTCMDEXCL);
+}
+
+if ($showconfig) {
+  print "Configuration variables:\n";
+  print "MINWORDSBLOCK=$MINWORDSBLOCK\n";
+  print "FLOATENV=$FLOATENV\n";
+  print "PICTUREENV=$PICTUREENV\n";
+  print "MATHENV=$MATHENV\n";
+  print "MATHREPL=$MATHREPL\n";
+  print "MATHARRENV=$MATHARRENV\n";
+  print "MATHARRREPL=$MATHARRREPL\n";
+  print "ARRENV=$ARRENV\n";
+  print "COUNTERCMD=$COUNTERCMD\n";
+}
+if ($showconfig || $showtext || $showsafe || $showpreamble) {
+  exit 0; }
+if ( @ARGV != 2 ) { 
+  print STDERR "2 and only 2 non-option arguments required.  Write latexdiff -h to get help\n";
+  exit(2);
+}
+
+# Are extra spaces between command arguments permissible?
+my $extraspace;
+if ($allowspaces) {
+  $extraspace='\s*'; 
+} else {
+  $extraspace='';
+}
+
+# append context lists to text lists (as text property is implied)
+push @TEXTCMDLIST, @CONTEXT1CMDLIST;
+push @TEXTCMDLIST, @CONTEXT2CMDLIST;
+
+
+# Patterns. These are used by some of the subroutines, too
+# I can only define them down here because value of extraspace depends on an option
+  my $pat0 = '(?:[^{}]|\\\{|\\\})*';
+  my $pat1 = '(?:[^{}]|\\\{|\\\}|\{'.$pat0.'\})*';
+  my $pat2 = '(?:[^{}]|\\\{|\\\}|\{'.$pat1.'\})*'; # 
+  my $pat3 = '(?:[^{}]|\\\{|\\\}|\{'.$pat2.'\})*';
+  my $pat4 = '(?:[^{}]|\\\{|\\\}|\{'.$pat3.'\})*';
+  my $brat0 = '(?:[^\[\]]|\\\[|\\\])*'; 
+
+  my $quotemarks = '(?:\'\')|(?:\`\`)';
+  my $punct='[0.,\/\'\`:;\"\?\(\)\[\]!~\p{IsNonAsciiPunct}\p{IsNonAsciiS}]';
+  my $number='-?\d*\.\d*';
+  my $mathpunct='[+=<>\-\|]';
+  my $and = '&';
+  my $coords= '[\-.,\s\d]*';
+# word: sequence of letters or accents followed by letter
+  my $word='(?:[-\w\d*]|\\\\[\"\'\`~^][A-Za-z\*])+';
+  my $cmdleftright='\\\\(?:left|right)\s*(?:[()\[\]|]|\\\\(?:[|{}]|\w+))';
+
+  my $cmdoptseq='\\\\[\w\d\*]+'.$extraspace.'(?:(?:\['.$brat0.'\]|\{'. $pat4 . '\}|\(' . $coords .'\))'.$extraspace.')*';
+  my $oneletcmd='\\\\.(?:\['.$brat0.'\]|\{'. $pat4 . '\})*';
+  my $math='\$(?:[^$]|\\\$)*?\$|\\\\[(].*?\\\\[)]';
+#  my $math='\$(?:[^$]|\\\$)*\$';
+  my $comment='%.*?\n';
+  my $pat=qr/(?:\A\s*)?(?:${and}|${quotemarks}|${number}|${word}|$cmdleftright|${cmdoptseq}|${math}|${oneletcmd}|${comment}|${punct}|${mathpunct}|\{|\})\s*/ ;
+
+
+
+# now we are done setting up and can start working   
+my ($oldfile, $newfile) = @ARGV;
+
+$encoding=guess_encoding($newfile) unless defined($encoding);
+
+$encoding = "utf8" if $encoding =~ m/^utf8/i ;
+if (lc($encoding) eq "utf8" ) {
+  binmode(STDOUT, ":utf8");
+  binmode(STDERR, ":utf8");
+}
+
+$old=read_file_with_encoding($oldfile,$encoding);
+$new=read_file_with_encoding($newfile,$encoding);
+
+
+
+
+# reset time
+exetime(1);
+($oldpreamble,$oldbody,$oldpost)=splitdoc($old,'\\\\begin\{document\}','\\\\end\{document\}');
+
+
+($newpreamble,$newbody,$newpost)=splitdoc($new,'\\\\begin\{document\}','\\\\end\{document\}');
+
+
+if ($flatten) {
+  $oldbody=flatten($oldbody,$oldpreamble,$oldfile,$encoding);
+  $newbody=flatten($newbody,$newpreamble,$newfile,$encoding);
+}
+
+if ( length $oldpreamble && length $newpreamble ) {
+  @oldpreamble = split /\n/, $oldpreamble;
+  @newpreamble = split /\n/, $newpreamble;
+  
+  %packages=list_packages(@newpreamble) unless %packages;
+  if (defined $packages{"hyperref"} ) {
+    print STDERR "hyperref package detected.\n" if $verbose ;
+    $latexdiffpreamble =~ s/\{\\DIFadd\}/{\\DIFaddtex}/g;
+    $latexdiffpreamble =~ s/\{\\DIFdel\}/{\\DIFdeltex}/g;
+    $latexdiffpreamble .= join "\n",(extrapream("HYPERREF"),"");
+  }
+  # insert dummy first line such that line count begins with line 1 (rather than perl's line 0) - just so that line numbers inserted by linediff are correct
+  unshift @newpreamble,'';
+  unshift @oldpreamble,'';
+  print STDERR "Differencing preamble.\n" if $verbose;
+  @diffpreamble = linediff(\@oldpreamble, \@newpreamble);
+  # remove dummy line again
+  shift @diffpreamble; 
+  push @diffpreamble,$latexdiffpreamble;
+  push @diffpreamble,'\begin{document}';
+}
+elsif ( !length $oldpreamble && !length $newpreamble ) {
+  @diffpreamble=();
+} else {
+  print STDERR "Either both texts must have preamble or neither text must have the preamble.\n";
+  exit(2);
+}
+
+if (defined $packages{"amsmath"} ) {
+  print STDERR "amsmath package detected.\n" if $verbose ;
+  $MATHARRREPL='align*';
+}
+
+print STDERR "Preprocessing body.  " if $verbose;
+my ($oldleadin,$newleadin)=preprocess($oldbody,$newbody);
+
+
+# run difference algorithm
+@diffbody=bodydiff($oldbody, $newbody);
+$diffbo=join("",@diffbody);
+print STDERR "(",exetime()," s)\n","Postprocessing body. \n " if $verbose;
+postprocess($diffbo);
+$diffall =join("\n",@diffpreamble) ;
+$diffall .= "$newleadin$diffbo" ;
+$diffall .= "\\end{document}$newpost" if length $newpreamble ;
+if ( lc($encoding) ne "utf8" && lc($encoding) ne "ascii" ) {
+  print STDERR "Encoding output file to $encoding\n" if $verbose;
+  $diffall=Encode::encode($encoding,$diffall);
+  binmode STDOUT;
+}
+print $diffall;
+
+
+print STDERR "(",exetime()," s)\n","Done.\n" if $verbose;
+
+
+
+## guess_encoding(filename)
+## reads the first 20 lines of filename and looks for call of inputenc package
+## if found, return the option of this package (encoding), otherwise return ascii
+sub guess_encoding {
+  my ($filename)=@_;
+  my ($i,$enc);
+  open (FH, $filename) or die("Couldn't open $filename: $!");
+  $i=0;
+  while (<FH>) {
+    next if /^\s*%/;    # skip comment lines
+    if (m/\\usepackage\[(\w*?)\]\{inputenc\}/) {
+      close(FH);
+      return($1);
+    }
+    last if (++$i > 20 ); # scan at most 20 non-comment lines
+  }
+  close(FH);
+  return("ascii");
+}
+
+
+sub read_file_with_encoding {
+  my ($output);
+  my ($filename, $encoding) = @_;
+
+  if (lc($encoding) eq "utf8" ) {
+    open (FILE, "<:utf8",$filename) or die("Couldn't open $filename: $!");
+    local $/ ; # locally set record operator to undefined, ie. enable whole-file mode
+    $output=<FILE>;
+  } elsif ( lc($encoding) eq "ascii") {
+    open (FILE, $filename) or die("Couldn't open $filename: $!");
+    local $/ ; # locally set record operator to undefined, ie. enable whole-file mode
+    $output=<FILE>;
+  } else {
+    require Encode;
+    open (FILE, "<",$filename) or die("Couldn't open $filename: $!");
+    local $/ ; # locally set record operator to undefined, ie. enable whole-file mode
+    $output=<FILE>;
+    print STDERR "Converting $filename from $encoding to utf8\n" if $verbose;
+    $output=Encode::decode($encoding,$output);
+  }
+  close FILE;
+  return $output;
+}
+
+# %packages=list_packages(@preamble)
+# scans the arguments for \documentclass and \usepackage statements and constructs a hash
+# whose keys are the included packages, and whose values are the associated optional arguments
+sub list_packages {
+  my (@preamble)=@_;
+  my %packages=();
+  foreach $line ( @preamble ) {
+    # get rid of comments
+    $line=~s/(?<!\\)%.*$// ;
+    if ( $line =~ m/\\(?:documentclass|usepackage)(?:\[(.+?)\])?\{(.*?)\}/ ) {
+#      print STDERR "Found something: |$line|\n";
+      if (defined($1)) {
+	$packages{$2}=$1;
+      } else {
+	$packages{$2}="";
+      }
+    }
+  }
+  return (%packages);
+}
+
+# flatten($text,$preamble,$filename,$encoding)
+# expands \input and \include commands within text
+# premable is scanned for includeonly commands
+# encoding is the encoding
+sub flatten {
+  my ($text,$preamble,$filename,$encoding)=@_;
+  my ($includeonly,$dirname,$fname,$newpage,$replacement);
+  require File::Basename ; 
+  require File::Spec ; 
+  $dirname = File::Basename::dirname($filename);
+
+  if ( ($includeonly) = ($preamble =~ m/\\includeonly{(.*?)}/ ) ) {
+    $includeonly =~ s/,/|/g;
+  } else {
+    $includeonly = '.*?';
+  }
+
+  print STDERR "DEBUG: includeonly $includeonly\n";
+
+  $text=~s/\\input{(.*?)}|\\include{(${includeonly}(?:\.tex)?)}/{ 
+	    $fname = $1 if defined($1)  ;
+	    $fname = $2 if defined($2) ;       
+            #      # add tex extension unless there is a three letter extension already 
+            $fname .= ".tex" unless $fname =~ m|\.\w{3}|;
+            print STDERR "Include file $fname\n" if $verbose;
+            print STDERR "DEBUG looking for file ",File::Spec->catfile($dirname,$fname), "\n";
+            # content of file becomes replacement value, add \newpage if the command was include
+            $replacement=read_file_with_encoding(File::Spec->catfile($dirname,$fname), $encoding) or die
+                "Couldn't find file ",File::Spec->catfile($dirname,$fname),": $!";
+	    $newpage=(defined($2)? " \\newpage " : "") ;
+	    "$newpage$replacement$newpage";
+          }/exg;
+
+  return($text);
+}
+
+
+# print_regex_arr(@arr)
+# prints regex array without x-ism expansion put in by pearl to stdout
+sub print_regex_arr {
+  my $dumstring;
+  $dumstring = join(" ",@_);     # PERL generates string (?-xism:^ref$) for quoted refex ^ref$
+  $dumstring =~ s/\(\?-xism:\^(.*?)\$\)/$1/g;   # remove string and ^,$ marks before output
+  print $dumstring,"\n";
+}
+
+
+# @lines=extrapream($type)
+# reads line from appendix (end of file after __END__ token)
+sub extrapream {
+  my $type;
+  my @retval=("%DIF PREAMBLE EXTENSION ADDED BY LATEXDIFF") ;
+  my ($copy);
+
+  while (@_) {
+    $copy=0;
+    $type=shift ;
+    if ( -f $type ) {
+      open (FILE,$type) or die "Cannot open preamble file $type: $!";
+      print STDERR "Reading preamble file $type\n" if $verbose ;
+      while (<FILE>) {
+	chomp ;
+	if ( $_ =~ m/%DIF PREAMBLE/ ) {
+	  push (@retval,"$_"); 
+	} else {
+	  push (@retval,"$_ %DIF PREAMBLE"); 
+	}
+      }
+    } 
+    else {    # not (-f $type)
+      $type=uc($type);   # upcase argument
+      print STDERR "Preamble Internal Type $type\n" if $verbose;
+      while (<DATA>) {
+	if ( m/^%DIF $type/ ) {
+	  $copy=1; }
+	elsif ( m/^%DIF END $type/ ) {
+	  last; }
+	chomp;
+	push (@retval,"$_ %DIF PREAMBLE") if $copy;
+      }
+      if ( $copy == 0 ) {
+	print STDERR "\nPreamble style $type not implemented.\n";
+        print STDERR "Write latexdiff -h to get help with available styles\n";
+        exit(2);
+      }
+      seek DATA,0,0;    # rewind DATA handle to file begin
+    }
+  }
+  push (@retval,"%DIF END PREAMBLE EXTENSION ADDED BY LATEXDIFF")  ;
+  return @retval;
+}
+
+
+# ($part1,$part2,$part3)=splitdoc($text,$word1,$word2)
+# splits $text into 3 parts at $word1 and $word2.
+# if neither $word1 nor $word2 exist, $part1 and $part3 are empty, $part2 is $text
+# If only $word1 or $word2 exist but not the other, output an error message.
+
+# NB this version avoids $` and $' for performance reason although it only makes a tiny difference
+# (in one test gain a tenth of a second for a 30s run)
+sub splitdoc {
+  my ($text,$word1,$word2)=@_;
+  my ($part1,$part2,$part3)=("","","");
+  my ($rest,$pos);
+
+  if ( $text =~ m/(^[^%]*)($word1)/mg ) {
+    $pos=pos $text;
+    $part1=substr($text,0,$pos-length($2));
+    $rest=substr($text,$pos);
+    if ( $rest =~ m/(^[^%]*)($word2)/mg ) {
+      $pos=pos $rest;
+      $part2=substr($rest,0,$pos-length($2));
+      $part3=substr($rest,$pos);
+    } 
+    else {
+      die "$word1 and $word2 not in the correct order or not present as a pair." ;
+    }
+  } else {
+    $part2=$text;
+    die "$word2 present but not $word1." if ( $text =~ m/(^[^%]*)$word2/ms );
+  }
+  return ($part1,$part2,$part3);
+}
+
+
+
+
+
+# bodydiff($old,$new)
+sub bodydiff {
+  my ($oldwords, $newwords) = @_;
+  my @retwords;
+
+  print STDERR "(",exetime()," s)\n","Splitting into latex tokens \n" if $verbose;
+  print STDERR "Parsing $oldfile \n" if $verbose;
+  my @oldwords = splitlatex($oldwords);
+  print STDERR "Parsing $newfile \n" if $verbose;
+  my @newwords = splitlatex($newwords);
+  my $token;
+
+  print STDERR "(",exetime()," s)\n","Pass 1: Expanding text commands and merging isolated identities with changed blocks  " if $verbose;
+  pass1(\@oldwords, \@newwords);
+
+
+  print STDERR "(",exetime()," s)\n","Pass 2: inserting DIF tokens and mark up.  " if $verbose;
+
+  @retwords=pass2(\@oldwords, \@newwords);
+
+  return(@retwords);
+}
+
+
+
+
+# @words=splitlatex($string)
+# split string according to latex rules
+# Each element of words is either
+# a word (including trailing spaces and punctuation)
+# a latex command
+sub splitlatex {
+  my ($string) = @_ ;
+  my @retval=($string =~ m/$pat/osg);  
+
+  if (length($string) != length(join("",@retval))) {
+    print STDERR "\nWARNING: Inconsistency in length of input string and parsed string:\n     This often indicates faulty or non-standard latex code.\n     In many cases you can ignore this and the following warning messages.\n Note that character numbers in the following are counted beginning after \\begin{document} and are only approximate." unless $ignorewarnings;
+    print STDERR "DEBUG Original length ",length($string),"  Parsed length ",length(join("",@retval)),"\n" if $debug;
+    print STDERR "DEBUG Input string:  |$string|\n" if (length($string)<500) && $debug;
+    print STDERR "DEBUG Token parsing: |",join("+",@retval),"|\n" if (length($string)<500) && $debug ;
+    @retval=();
+    # slow way only do this if other m//sg method fails
+    my $last = 0;
+    while ( $string =~ m/$pat/osg ) {
+      my $match=$&;
+      if ($last + length $& != pos $string  ) {
+	my $pos=pos($string);
+	my $offset=30<$last ? 30 : $last;
+	my $dum=substr($string,$last-$offset,$pos-$last+2*$offset);
+	my $dum1=$dum;
+	my $cnt=$#retval;
+	my $i;
+	$dum1 =~ s/\n/ /g;
+	unless ($ignorewarnings) {
+	  print STDERR "\n$dum1\n";
+	  print STDERR " " x 30,"^" x ($pos-$last)," " x 30,"\n";
+	  print STDERR "Missing characters near word " . (scalar @retval) . " character index: " . $last . "-" .  pos($string) . " Length: " . length($match) . " Match: |$match| (expected match marked above).\n";
+	}
+	  # put in missing characters `by hand'
+	push (@retval, substr($dum,$offset,$pos-$last-length($match)));
+#       Note: there seems to be a bug in substr with utf8 that made the following line output substr which were too long,
+#             using dum instead appears to work
+#	push (@retval, substr($string,$last, pos($string)-$last-length($match)));
+      }
+      push (@retval, $match);
+      $last=pos $string;
+    }
+
+  }
+  return @retval;
+}
+
+
+# pass1( \@seq1,\@seq2)
+# Look for differences between seq1 and seq2.
+# Where an common-subsequence block is flanked by deleted or appended blocks, 
+# and is shorter than $MINWORDSBLOCK words it is appended
+# to the last deleted or appended word.  If the block contains tokens other than words 
+# or punctuation it is not merged.
+# Deleted or appended block consisting of words and safe commands only are
+# also merged, to prevent break-up in pass2 (after previous isolated words have been removed)
+# If there are commands with textual arguments (e.g. \caption) both in corresponding 
+# appended and deleted blocks split them such that the command and opening bracket 
+# are one token, then the rest is split up following standard rules, and the closing 
+# bracket is a separate token, ie. turn
+# "\caption{This is a textual argument}" into 
+# ("\caption{","This ","is ","a ","textual ","argument","}")
+# No return value.  Destructively changes sequences
+sub pass1 {
+  my $seq1 = shift ;
+  my $seq2 = shift ;
+
+  my $len1 = scalar @$seq1;
+  my $len2 = scalar @$seq2;
+  my $wpat=qr/^(?:[a-zA-Z.,'`:;?()!]*)[\s~]*$/;   #'
+
+  my ($last1,$last2)=(-1,-1) ;
+  my $cnt=0;
+  my $block=[];
+  my $addblock=[];
+  my $delblock=[];
+  my $todo=[];
+  my $instruction=[];
+  my $i;
+  my (@delmid,@addmid,@dummy);
+
+  my ($addcmds,$delcmds,$matchindex);
+  my ($addtextblocks,$deltextblocks);
+  my ($addtokcnt,$deltokcnt,$mattokcnt)=(0,0,0);
+  my ($addblkcnt,$delblkcnt,$matblkcnt)=(0,0,0);
+
+  my $adddiscard = sub {
+                      if ($cnt > 0 ) {
+			$matblkcnt++;
+			# just after an unchanged block 
+#			print STDERR "Unchanged block $cnt, $last1,$last2 \n";
+                        if ($cnt < $MINWORDSBLOCK 
+			    && $cnt==scalar (
+				     grep { /^$wpat/ || ( /^\\([\w\d\*]+)((?:\[$brat0\]|\{$pat4\})*)/o 
+							   && iscmd($1,\@SAFECMDLIST,\@SAFECMDEXCL) 
+							   && scalar(@dummy=split(" ",$2))<3 ) }
+					     @$block) )  {
+			  # merge identical blocks shorter than $MINWORDSBLOCK 
+			  # and only containing ordinary words
+			  # with preceding different word
+			  # We cannot carry out this merging immediately as this
+			  # would change the index numbers of seq1 and seq2 and confuse
+			  # the algorithm, instead we store in @$todo where we have to merge
+                          push(@$todo, [ $last1,$last2,$cnt,@$block ]);
+			}
+			$block = []; 
+			$cnt=0; $last1=-1; $last2=-1;
+		      }
+		    };
+  my $discard=sub { $deltokcnt++;
+                    &$adddiscard; #($_[0],$_[1]);
+		    push(@$delblock,[ $seq1->[$_[0]],$_[0] ]);
+		    $last1=$_[0] };		      
+
+  my $add =   sub { $addtokcnt++;
+                    &$adddiscard; #($_[0],$_[1]);
+		    push(@$addblock,[ $seq2->[$_[1]],$_[1] ]);
+		    $last2=$_[1] };		      
+
+  my $match = sub { $mattokcnt++;
+                    if ($cnt==0) {   # first word of matching sequence after changed sequence or at beginning of word sequence
+		      $deltextblocks = extracttextblocks($delblock); 
+		      $delblkcnt++ if scalar @$delblock;
+		      $addtextblocks = extracttextblocks($addblock);
+		      $addblkcnt++ if scalar @$addblock;
+
+		      $delcmds = extractcommands($delblock);
+      		      $addcmds = extractcommands($addblock);
+		      # keygen(third argument of _longestCommonSubsequence) implies to sort on command (0th elements of $addcmd elements)
+		      # the calling format for longestCommonSubsequence has changed between versions of
+		      # Algorithm::Diff so we need to check which one we are using
+		      if ( $algodiffversion  > 1.15 ) {
+			### Algorithm::Diff 1.19
+			$matchindex=Algorithm::Diff::_longestCommonSubsequence($delcmds,$addcmds, 0, sub { $_[0]->[0] } );
+		      } else {
+			### Algorithm::Diff 1.15	
+			$matchindex=Algorithm::Diff::_longestCommonSubsequence($delcmds,$addcmds, sub { $_[0]->[0] } );
+		      }
+
+		      for ($i=0 ; $i<=$#$matchindex ; $i++) {
+			if (defined($matchindex->[$i])){
+			  $j=$matchindex->[$i];
+			  @delmid=splitlatex($delcmds->[$i][3]);
+			  @addmid=splitlatex($addcmds->[$j][3]);
+			  while (scalar(@$deltextblocks)  && $deltextblocks->[0][0]<$delcmds->[$i][1]) {
+			    my ($index,$block,$cnt)=@{ shift(@$deltextblocks) };
+			    push(@$todo, [$index,-1,$cnt,@$block]);
+			  }
+			  push(@$todo, [ $delcmds->[$i][1],-1,-1,$delcmds->[$i][2],@delmid,$delcmds->[$i][4]]);
+
+			  while (scalar(@$addtextblocks) && $addtextblocks->[0][0]<$addcmds->[$j][1]) {
+			    my ($index,$block,$cnt)=@{ shift(@$addtextblocks) };
+			    push(@$todo, [-1,$index,$cnt,@$block]);
+			  }
+			  push(@$todo, [ -1,$addcmds->[$j][1],-1,$addcmds->[$j][2],@addmid,$addcmds->[$j][4]]);
+			}
+		      }
+		      # mop up remaining textblocks
+		      while (scalar(@$deltextblocks)) {
+			my ($index,$block,$cnt)=@{ shift(@$deltextblocks) } ;
+			push(@$todo, [$index,-1,$cnt,@$block]);
+		      }
+		      while (scalar(@$addtextblocks)) {
+			my ($index,$block,$cnt)=@{ shift(@$addtextblocks) };
+			push(@$todo, [-1,$index,$cnt,@$block]);
+		      }
+		      
+		      $addblock=[];
+		      $delblock=[];
+		    }
+		    push(@$block,$seq2->[$_[1]]);  
+		    $cnt++  };
+
+  my $keyfunc = sub { join("  ",split(" ",shift())) };
+
+  traverse_sequences($seq1,$seq2, { MATCH=>$match, DISCARD_A=>$discard, DISCARD_B=>$add }, $keyfunc );
+
+
+  # now carry out the merging/splitting.  Refer to elements relative from 
+  # the end (with negative indices) as these offsets don't change before the instruction is executed
+  # cnt>0: merged small unchanged groups with previous changed blocks
+  # cnt==-1: split textual commands into components
+  foreach $instruction ( @$todo) {
+    ($last1,$last2,$cnt,@$block)=@$instruction ;
+    if ($cnt>=0) {
+      splice(@$seq1,$last1-$len1,1+$cnt,join("",$seq1->[$last1-$len1],@$block)) if $last1>=0;
+      splice(@$seq2,$last2-$len2,1+$cnt,join("",$seq2->[$last2-$len2],@$block)) if $last2>=0;
+    } else {
+      splice(@$seq1,$last1-$len1,1,@$block) if $last1>=0;
+      splice(@$seq2,$last2-$len2,1,@$block) if $last2>=0;
+    }
+  }
+
+  if ($verbose) { 
+    print STDERR "\n";
+    print STDERR "  $mattokcnt matching  tokens in $matblkcnt blocks.\n";
+    print STDERR "  $deltokcnt discarded tokens in $delblkcnt blocks.\n";
+    print STDERR "  $addtokcnt appended  tokens in $addblkcnt blocks.\n";
+  }
+}
+
+
+# extracttextblocks(\@blockindex)
+# $blockindex has the following format 
+# [ [ token1, index1 ], [token2, index2],.. ] 
+# where index refers to the index in the original old or new word sequence 
+# Returns: reference to an array of the form  
+# [[ $index, $textblock, $cnt ], ..
+# where $index index of block to be merged
+#       $textblock contains all the words to be merged with the word at $index (but does not contain this word)
+#       $cnt   is length of block
+#
+# requires: iscmd
+#
+sub extracttextblocks { 
+  my $block=shift;
+  my ($i,$token,$index);
+  my $textblock=[];
+  my $last=-1;
+  my $wpat=qr/^(?:[a-zA-Z.,'`:;?()!]*)[\s~]*$/;  #'
+  my $retval=[];
+
+  for ($i=0;$i< scalar @$block;$i++) {
+    ($token,$index)=@{ $block->[$i] };
+    # store pure text blocks
+    if ($token =~ /$wpat/ ||  ( $token =~/^\\([\w\d\*]+)((?:${extraspace}\[$brat0\]${extraspace}|${extraspace}\{$pat4\})*)/o 
+				&& iscmd($1,\@SAFECMDLIST,\@SAFECMDEXCL) 
+				&& !iscmd($1,\@TEXTCMDLIST,\@TEXTCMDEXCL))) {
+      # we have text or a command which can be treated as text
+      if ($last<0) {
+	# new pure-text block
+	$last=$index;
+      } else {
+	# add to pure-text block
+	push(@$textblock, $token); 
+      }
+    } else {
+      # it is not text
+      if (scalar(@$textblock)) {
+	push(@$retval,[ $last, $textblock, scalar(@$textblock) ]);
+      }
+      $textblock=[];
+      $last=-1;
+    }
+  }
+  # finish processing a possibly unfinished block before returning
+  if (scalar(@$textblock)) {
+    push(@$retval,[ $last, $textblock, scalar(@$textblock) ]);
+  }
+  return($retval)
+}
+
+
+
+# extractcommands( \@blockindex )
+# $blockindex has the following format 
+# [ [ token1, index1 ], [token2, index2],.. ] 
+# where index refers to the index in the original old or new word sequence 
+# Returns: reference to an array of the form  
+# [ [ "\cmd1", index, "\cmd1[optarg]{arg1}{", "arg2" ,"} " ],.. 
+# where index is just taken from input array 
+# command must have a textual argument as last argument 
+# 
+# requires: iscmd 
+# 
+sub extractcommands { 
+  my $block=shift;
+  my ($i,$token,$index,$cmd,$open,$mid,$closing);
+  my $retval=[];
+
+  for ($i=0;$i< scalar @$block;$i++) {
+    ($token,$index)=@{ $block->[$i] };
+    # check if token is an alphanumeric command sequence with at least one non-optional argument
+    # \cmd[...]{...}{last argument}  
+    # Capturing in the following results in these associations
+    # $1: \cmd[...]{...}{
+    # $2: \cmd
+    # $3: last argument
+    # $4: }  + trailing spaces
+    if ( ( $token =~ m/^(\\([\w\d\*]+)(?:${extraspace}\[$brat0\]|${extraspace}\{$pat4\})*${extraspace}\{)($pat4)(\}\s*)$/so )
+	 && iscmd($2,\@TEXTCMDLIST,\@TEXTCMDEXCL) ) {
+      #      push(@$retval,[ $2,$index,$1,$3,$4 ]);
+      ($cmd,$open,$mid,$closing) = ($2,$1,$3,$4) ;
+      $closing =~ s/\}/\\RIGHTBRACE/ ;
+      push(@$retval,[ $cmd,$index,$open,$mid,$closing ]);
+    }
+  }
+  return $retval;
+}
+
+# iscmd($cmd,\@regexarray,\@regexexcl) checks
+# return 1 if $cmd matches any of the patterns in the 
+# array $@regexarray, and none of the patterns in \@regexexcl, otherwise return 0
+sub iscmd {
+  my ($cmd,$regexar,$regexexcl)=@_;
+  my ($ret)=0;
+  foreach $pat ( @$regexar ) {
+    if ( $cmd =~ m/^${pat}$/ ) {
+      $ret=1 ; 
+      last;
+    }
+  }
+  return 0 unless $ret;
+  foreach $pat ( @$regexexcl ) {
+    return 0 if ( $cmd =~ m/^${pat}$/ );
+  }
+  return 1;
+}
+
+
+# pass2( \@seq1,\@seq2)
+# Look for differences between seq1 and seq2.  
+# Mark begin and end of deleted and appended sequences with tags $DELOPEN and $DELCLOSE
+# and $ADDOPEN and $ADDCLOSE, respectively, however exclude { } & and all comands, unless
+# they match an element of the whitelist (SAFECMD)
+# For words in TEXTCMD but not in SAFECMD, enclose interior with $ADDOPEN and $ADDCLOSE brackets
+# Deleted comment lines are marked with %DIF < 
+# Added comment lines are marked with %DIF > 
+sub pass2 {
+  my $seq1 = shift ;
+  my $seq2 = shift ;
+
+  my ($addtokcnt,$deltokcnt,$mattokcnt)=(0,0,0);
+  my ($addblkcnt,$delblkcnt,$matblkcnt)=(0,0,0);
+
+  my $retval = [];
+  my $delhunk   = [];
+  my $addhunk   = [];
+
+  my $discard = sub { $deltokcnt++;
+                      push ( @$delhunk, $seq1->[$_[0]]) };
+
+  my $add = sub { $addtokcnt++;
+                  push ( @$addhunk, $seq2->[$_[1]]) };
+
+  my $match = sub { $mattokcnt++;
+		    if ( scalar @$delhunk ) {
+                      $delblkcnt++;
+		      # mark up changes, but comment out commands
+                      push @$retval,marktags($DELMARKOPEN,$DELMARKCLOSE,$DELOPEN,$DELCLOSE,$DELCMDOPEN,$DELCMDCLOSE,$DELCOMMENT,$delhunk);
+		      $delhunk = [];
+		    }
+                    if ( scalar @$addhunk ) {
+                      $addblkcnt++;
+                      # we mark up changes, but simply quote commands
+                      push @$retval,marktags($ADDMARKOPEN,$ADDMARKCLOSE,$ADDOPEN,$ADDCLOSE,"","",$ADDCOMMENT,$addhunk);
+		      $addhunk = [];
+		    }
+		    push(@$retval,$seq2->[$_[1]]) };
+ 
+  my $keyfunc = sub { join("  ",split(" ",shift())) };
+
+  traverse_sequences($seq1,$seq2, { MATCH=>$match, DISCARD_A=>$discard, DISCARD_B=>$add }, $keyfunc );
+  # clear up unprocessed hunks
+  push @$retval,marktags($DELMARKOPEN,$DELMARKCLOSE,$DELOPEN,$DELCLOSE,$DELCMDOPEN,$DELCMDCLOSE,$DELCOMMENT,$delhunk) if scalar @$delhunk;
+  push @$retval,marktags($ADDMARKOPEN,$ADDMARKCLOSE,$ADDOPEN,$ADDCLOSE,"","",$ADDCOMMENT,$addhunk) if scalar @$addhunk;
+
+
+  if ($verbose) { 
+    print STDERR "\n";
+    print STDERR "  $mattokcnt matching  tokens. \n";
+    print STDERR "  $deltokcnt discarded tokens in $delblkcnt blocks.\n";
+    print STDERR "  $addtokcnt appended  tokens in $addblkcnt blocks.\n";
+  }
+
+  return(@$retval);
+}
+
+# marktags($openmark,$closemark,$open,$close,$opencmd,$closecmd,$comment,\@block)
+# returns ($openmark,$open,$block,$close,$closemark) if @block only contains no commands (except white-listed ones),
+# braces, ampersands, or comments
+# mark comments with $comment
+# exclude all other exceptions from scope of open, close like this
+# ($openmark, $open,...,$close, $opencomd,command, command,$closecmd, $open, ..., $close, $closemark)
+# If $opencmd begins with "%" marktags assumes it is operating on a deleted block, otherwise on an added block
+sub marktags {
+  my ($openmark,$closemark,$open,$close,$opencmd,$closecmd,$comment,$block)=@_;
+  my $word;
+  my (@argtext);
+  my $retval=[];
+  my $noncomment=0;
+  my $cmd=-1;    # -1 at beginning 0: last token written is a ordinary word 
+                 # 1: last token written is a command
+                # for keeping track whether we are just in a command sequence or in a word sequence
+  my $cmdcomment= ($opencmd =~ m/^%/);  # Flag to indicate whether opencmd is a comment (i.e. if we intend to simply comment out changed commands)
+  my ($command,$commandword,$closingbracket) ; # temporary variables needed below to remember sub-pattern matches
+
+# split this block to flatten out sequences joined in pass1
+  @$block=splitlatex(join "",@$block);
+  foreach (@$block) {
+    $word=$_; 
+    if ( $word =~ s/^%/%$comment/ ) {
+      # a comment
+      if ($cmd==1) {
+	push (@$retval,$closecmd) ;
+	$cmd=-1;
+      }
+      push (@$retval,$word); 
+      next;
+    }
+    if (! $noncomment) {
+      push (@$retval,$openmark); 
+      $noncomment=1;
+    }
+    # negative lookahead pattern (?!) in second clause is put in to avoid mathcing \( .. \) patterns
+    if ( $word =~ /^[&{}\[\]]/ || ( $word =~ /^\\(?!\()([\w*@]*)/ && !iscmd($1,\@SAFECMDLIST,\@SAFECMDEXCL)) ) {
+      # word is a command or other significant token (not in SAFECMDLIST)
+	## same conditions as in subroutine extractcommand:
+	# check if token is an alphanumeric command sequence with at least one non-optional argument
+	# \cmd[...]{...}{last argument}  
+	# Capturing in the following results in these associations
+	# $1: \cmd[...]{...}{
+	# $2: \cmd
+	# $3: last argument
+	# $4: }  + trailing spaces
+	### pre-0.3    if ( ( $token =~ m/^(\\([\w\d\*]+)(?:\[$brat0\]|\{$pat4\})*\{)($pat4)(\}\s*)$/so )
+      if ( ( $word =~ m/^(\\([\w\d\*]+)(?:${extraspace}\[$brat0\]|${extraspace}\{$pat4\})*${extraspace}\{)($pat4)(\}\s*)$/so )
+	   && iscmd($2,\@TEXTCMDLIST,\@TEXTCMDEXCL)  && ( !$cmdcomment || !iscmd($2,\@CONTEXT2CMDLIST, \@CONTEXT2CMDEXCL) )  ) {	 
+	# word is a text command - we mark up the interior of the word. But if we are in a deleted block ($cmdcomment=1) and
+        # $2 (the command) is in context2, just treat it as an ordinary command (i.e. comment it open with $opencmd)
+        # Because we do not want to disable this command
+	# here we do not use $opencmd and $closecmd($opencmd is empty) 
+	if ($cmd==1) {
+	  push (@$retval,$closecmd) ;
+	} elsif ($cmd==0) { 
+	  push (@$retval,$close) ;
+	}
+        $command=$1; $commandword=$2; $closingbracket=$4;
+	@argtext=splitlatex($3);   # split textual argument into tokens
+	# and mark it up (but we do not need openmark and closemark)
+        # insert command with initial arguments, marked-up final argument, and closing bracket
+	if ( $cmdcomment && iscmd($commandword,\@CONTEXT1CMDLIST, \@CONTEXT1CMDEXCL) ) {
+	  # context1cmd in a deleted environment; delete command itself but keep last argument, marked up
+	  push (@$retval,$opencmd);
+	  $command =~ s/\n/\n${opencmd}/sg ; # repeat opencmd at the beginning of each line
+	  # argument, note that the additional comment character is included
+          # to suppress linebreak after opening parentheses, which is important
+          # for latexrevise
+          push (@$retval,$command,"%\n{$AUXCMD\n",marktags("","",$open,$close,$opencmd,$closecmd,$comment,\@argtext),$closingbracket);
+	} else {
+	  # normal textcmd or context1cmd in an added block
+	  push (@$retval,$command,marktags("","",$open,$close,$opencmd,$closecmd,$comment,\@argtext),$closingbracket);  
+	}
+	push (@$retval,$AUXCMD,"\n") if $cmdcomment ;
+	$cmd=-1 ;
+      } else {
+	# ordinary command
+	push (@$retval,$opencmd) if $cmd==-1 ;
+	push (@$retval,$close,$opencmd) if $cmd==0 ;
+	$word =~ s/\n/\n${opencmd}/sg if $cmdcomment ;   # if opencmd is a comment, repeat this at the beginning of every line
+	push (@$retval,$word);
+	$cmd=1;
+      }
+    } else {
+      # just an ordinary word or word in SAFECMD
+      push (@$retval,$open) if $cmd==-1 ;
+      push (@$retval,$closecmd,$open) if $cmd==1 ;
+      push (@$retval,$word);
+      $cmd=0;
+    }
+  }
+  push (@$retval,$close) if $cmd==0;
+  push (@$retval,$closecmd) if $cmd==1;
+
+  push (@$retval,$closemark) if ($noncomment);
+  return @$retval;
+}
+
+# preprocess($string, ..)
+# carry out the following pre-processing steps for all arguments:
+# 1. Remove leading white-space
+# 2. mark all first empty line (in block of several) with \PAR tokens
+# 3. Convert all '\%' into '\PERCENTAGE ' to make parsing regular expressions easier
+# 4. Convert all \verb|some verbatim text| commands (where | can be an arbitrary character)
+#    into \verb{hash}
+# 5. Convert \begin{verbatim} some verbatim text \end{verbatim} into \verbatim{hash}
+# 6. Convert _n into \SUBSCRIPTNB{n} and _{nnn} into \SUBSCRIPT{nn}
+# 7. Convert ^n into \SUPERSCRIPTNB{n} and ^{nnn} into \SUPERSCRIPT{nn}
+# 8. a. Convert $$ $$ into \begin{DOLLARDOLLAR} \end{DOLLARDOLLAR}
+#    b. Convert \[ \] into \begin{SQUAREBRACKET} \end{SQUAREBRACKET}
+
+# 9. Add final token STOP to the very end.  This is put in because the algorithm works better if the last token is identical.  This is removed again in postprocessing.
+#
+# NB: step 6 and 7 is likely to  convert some "_" inappropriately, e.g. in file
+#     names or labels but it does not matter because they are converted back in the postprocessing step
+# Returns: leading white space removed in step 1
+sub preprocess {
+  my @leadin=() ;
+  for (@_) { 
+    s/^(\s*)//s;
+    push(@leadin,$1);
+    s/\n(\s*?)\n((?:\s*\n)*)/\n$1\\PAR\n$2/g ;
+    s/(?<!\\)\\%/\\PERCENTAGE /g ;  # (?<! is negative lookbehind assertion to prevent \\% from being converted
+    s/(\\verb\*?)(\S)(.*?)\2/"${1}{". tohash(\%verbhash,"${2}${3}${2}") ."}"/esg;
+    s/\\begin\{(verbatim\*?)\}(.*?)\\end\{\1\}/"\\${1}{". tohash(\%verbhash,"${2}") . "}"/esg;
+    # Convert _n or _\cmd into \SUBSCRIPTNB{n} or \SUBSCRIPTNB{\cmd} and _{nnn} into \SUBSCRIPT{nn}
+    s/_([^{\\]|\\\w+)/\\SUBSCRIPTNB{$1}/g ;
+    s/_{($pat4)}/\\SUBSCRIPT{$1}/g ;
+    # Convert ^n into \SUPERSCRIPTNB{n} and ^{nnn} into \SUPERSCRIPT{nn}
+    s/\^([^{\\]|\\\w+)/\\SUPERSCRIPTNB{$1}/g ;
+    s/\^{($pat4)}/\\SUPERSCRIPT{$1}/g ;
+    # Convert $$ $$ into \begin{DOLLARDOLLAR} \end{DOLLARDOLLAR}
+    s/\$\$(.*?)\$\$/\\begin{DOLLARDOLLAR}$1\\end{DOLLARDOLLAR}/sg;
+    # Convert \[ \] into \begin{SQUAREBRACKET} \end{SQUAREBRACKET}
+    s/(?<!\\)\\\[/\\begin{SQUAREBRACKET}/sg;
+    s/\\\]/\\end{SQUAREBRACKET}/sg;
+    # add final token " STOP"
+    $_ .= " STOP"
+  }
+  return(@leadin);
+}
+
+#hashstring=tohash(\%hash,$string)
+# creates a hash value based on string and stores in %hash
+sub tohash {
+  my ($hash,$string)=@_;
+  my (@arr,$val);
+  my ($sum,$i)=(0,1);
+  my ($hstr);
+
+  @arr=unpack('c*',$string);
+
+  foreach $val (@arr) {
+    $sum += $i*$val;
+    $i++;
+  }
+  $hstr= "$sum";
+  if (defined($hash->{$hstr}) && $string ne $hash->{$hstr}) {
+    warn "Repeated hash value for verbatim mode in spite of different content.";
+    $hstr="-$hstr";
+  }
+  $hash->{$hstr}=$string;
+  return($hstr);
+}
+
+#string=fromhash(\%hash,$fromstring)
+# restores string value stored in hash
+#string=fromhash(\%hash,$fromstring,$prependstring)
+# additionally begins each line with prependstring
+sub fromhash {
+  my ($hash,$hstr)=($_[0],$_[1]);
+  my $retstr=$hash->{$hstr};
+  if ( $#_ >= 2) {
+    $retstr =~ s/^/$_[2]/mg;
+  }
+  return $retstr;
+}
+
+
+# postprocess($string, ..)
+# carry out the following post-processing steps for all arguments:
+# * Remove STOP token from the end
+# * Replace \RIGHTBRACE by }
+# 1. Check all deleted blocks: 
+#    a.where a deleted block contains a matching \begin and
+#      \end environment (these will be disabled by a %DIFDELCMD statements), for selected environment enable enable
+#      these commands again (such that for example displayed math in a deleted equation
+#      is properly within math mode.  For math mode environments replace numbered equation
+#      environments with their display only variety (so that equation numbers in new file and
+#      diff file are identical).  Where the correct type of math environment cannot be determined
+#      use a place holder MATHMODE
+#    b.where one of the commands matching $COUNTERCMD is used as a DIFAUXCMD, add a statement
+#      subtracting one from the respective counter to keep numbering consistent with new file
+#    Replace all MATHMODE environment commands by the correct environment to achieve matching
+#    pairs
+#    c. If in-line math mode contains array environment, enclose the whole environment in \mbox'es
+# 2. Remove DIFadd, DIFdel, DIFFaddbegin , ... from picture environments
+# 3. Convert DIFadd, DIFdel, DIFFaddbegin , ... into FL varieties
+#    within floats (currently recognised float environments: plate,table,figure
+#    plus starred varieties).
+# 4. Remove empty %DIFDELCMD < lines 
+# 4. Convert \begin{SQUAREBRACKET} \end{SQUAREBRACKET} into \[ \]
+#    Convert \begin{DOLLARDOLLAR} \end{DOLLARDOLLAR} into $$ $$
+# 5. Convert  \SUPERSCRIPTNB{n} into ^n  and  \SUPERSCRIPT{nn} into ^{nnn}
+# 6. Convert  \SUBSCRIPTNB{n} into _n  and  \SUBCRIPT{nn} into _{nnn}
+# 7. Expand hashes of verb and verbatim environments
+# 8. Convert '\PERCENTAGE ' back into '\%'
+# 9.. remove all \PAR tokens
+# 10.  package specific processing:  endfloat: make sure \begin{figure} and \end{figure} are always
+#      on a line by themselves, similarly for table environment
+#  4, undo renaming of the \begin and \end in comments
+
+#
+# Note have to manually synchronize substitution commands below and 
+# DIF.. command names in the header
+sub postprocess {
+  my ($begin,$len,$cnt,$float,$delblock,$addblock);
+  # second level blocks
+  my ($begin2,$cnt2,$len2,$eqarrayblock,$mathblock);
+
+  for (@_) { 
+
+    # change $'s in comments to something harmless
+    1 while s/(%.*)\$/$1DOLLARDIF/mg ;
+
+    # Remove final STOP token
+    s/ STOP$//;
+    # Replace \RIGHTBRACE by }    
+    s/\\RIGHTBRACE/}/g;
+    # Check all deleted blocks: where a deleted block contains a matching \begin and
+    #    \end environment (these will be disabled by a %DIFDELCMD statements), enable
+    #    these commands again (such that for example displayed math in a deleted equation
+    #    is properly within math mode.  For math mode environments replace numbered equation
+    #    environments with their display only variety (so that equation numbers in new file and
+    #    diff file are identical
+    while ( m/\\DIFdelbegin.*?\\DIFdelend/sg ) {
+      $cnt=0;
+      $len=length($&);
+      $begin=pos($_) - $len;
+      $delblock=$&;
+
+
+      ### (.*?[^\n]?)\n? construct is necessary to avoid empty lines in math mode, which result in
+      ### an error
+      # displayed math environments
+      $delblock=~ s/(\%DIFDELCMD < \s*\\begin\{((?:$MATHENV)|SQUAREBRACKET)\}\s*?(?:$DELCMDCLOSE|\n))(.*?[^\n]?)\n?(\%DIFDELCMD < \s*\\end\{\2\})/\\begin{$MATHREPL}$AUXCMD\n$1$3\n\\end{$MATHREPL}$AUXCMD\n$4/sg;
+      # also transform the opposite pair \end{displaymath} .. \begin{displaymath} but we have to be careful not to interfere with the results of the transformation in the line directly above
+      $delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\end\{((?:$MATHENV)|SQUAREBRACKET)\}\s*?(?:$DELCMDCLOSE|\n))(.*?[^\n]?)\n?(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\begin\{\2\})/\\end{MATHMODE}$AUXCMD\n$1$3\n\\begin{MATHMODE}$AUXCMD\n$4/sg;
+
+      # now look for unpaired %DIFDELCMD < \begin{MATHENV}; if found add \begin{$MATHREPL} and insert \end{$MATHREPL} 
+      # just before end of block; again we use look-behind assertion to avoid matching constructions which have already been converted
+      if ($delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\begin\{((?:$MATHENV)|SQUAREBRACKET)\}\s*?(?:$DELCMDCLOSE|\n))/$1\\begin{$MATHREPL}$AUXCMD\n/sg ) {
+	$delblock =~ s/(\\DIFdelend$)/\\end{$MATHREPL}$AUXCMD\n$1/s ;
+      }
+      # now look for unpaired %DIFDELCMD < \end{MATHENV}; if found add \end{MATHMODE} and insert \begin{MATHMODE} 
+      # just before end of block; again we use look-behind assertion to avoid matching constructions which have already been converted
+      if ($delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\end\{((?:$MATHENV)|SQUAREBRACKET)\}\s*?(?:$DELCMDCLOSE|\n))/$1\\end{MATHMODE}$AUXCMD\n/sg ) {
+	$delblock =~ s/(\\DIFdelend$)/\\begin{MATHMODE}$AUXCMD\n$1/s ;
+      }
+
+
+      # equation array environment
+      $delblock=~ s/(\%DIFDELCMD < \s*\\begin\{($MATHARRENV)\}\s*?(?:$DELCMDCLOSE|\n))(.*?[^\n]?)\n?(\%DIFDELCMD < \s*\\end\{\2\})/\\begin{$MATHARRREPL}$AUXCMD\n$1$3\n\\end{$MATHARRREPL}$AUXCMD\n$4/sg;
+      $delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\end\{($MATHARRENV)\}\s*?(?:$DELCMDCLOSE|\n))(.*?[^\n]?)\n?(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\begin\{\2\})/\\end{MATHMODE}$AUXCMD\n$1$3\n\\begin{MATHMODE}$AUXCMD\n$4/sg;
+
+      # now look for unpaired %DIFDELCMD < \begin{MATHARRENV}; if found add \begin{$MATHARRREPL} and insert \end{$MATHARRREPL} 
+      # just before end of block; again we use look-behind assertion to avoid matching constructions which have already been converted
+      if ($delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\begin\{($MATHARRENV)\}\s*?(?:$DELCMDCLOSE|\n))/$1\\begin{$MATHARRREPL}$AUXCMD\n/sg ) {
+	$delblock =~ s/(\\DIFdelend$)/\\end{$MATHARRREPL}$AUXCMD\n$1/s ;
+      }
+      # now look for unpaired %DIFDELCMD < \end{MATHENV}; if found add \end{MATHMODE} and insert \begin{MATHMODE} 
+      # just before end of block; again we use look-behind assertion to avoid matching constructions which have already been converted
+      if ($delblock=~ s/(?<!${AUXCMD}\n)(\%DIFDELCMD < \s*\\end\{($MATHARRENV)\}\s*?(?:$DELCMDCLOSE|\n))/$1\\end{MATHMODE}$AUXCMD\n/sg ) {
+	$delblock =~ s/(\\DIFdelend$)/\\begin{MATHMODE}$AUXCMD\n$1/s ;
+      }
+
+      # parse $delblock for deleted and reinstated eqnarray* environments - within those reinstate \\ and & commands
+      while ( $delblock =~ m/\\begin\Q{$MATHARRREPL}$AUXCMD\E\n.*?\n\\end\Q{$MATHARRREPL}$AUXCMD\E\n/sg ) {
+	$cnt2=0;
+	$len2=length($&);
+	$begin2=pos($delblock) - $len2;
+	$eqarrayblock=$&;
+	# reinstate deleted & and \\ commands
+	$eqarrayblock=~ s/(\%DIFDELCMD < \s*(\&|\\\\)\s*?(?:$DELCMDCLOSE|\n))/$1$2$AUXCMD\n/sg ;
+
+	substr($delblock,$begin2,$len2)=$eqarrayblock;
+	pos($delblock) = $begin2 + length($eqarrayblock);
+      }
+
+
+
+#    b.where one of the commands matching $COUNTERCMD is used as a DIFAUXCMD, add a statement
+#      subtracting one from the respective counter to keep numbering consistent with new file
+      $delblock=~ s/\\($COUNTERCMD)((?:${extraspace}\[$brat0\]${extraspace}|${extraspace}\{$pat4\})*\s*${AUXCMD}\n)/\\$1$2\\addtocounter{$1}{-1}${AUXCMD}\n/sg ;
+#     c. If in-line math mode contains array environment, enclose the whole environment in \mbox'es
+      while ( $delblock =~ m/($math)(\s*)/sg ) {
+	$cnt2=0;
+	$len2=length($&);
+	$begin2=pos($delblock) - $len2;
+	$mathblock="%\n\\mbox{$AUXCMD\n$1\n}$AUXCMD\n";
+        next unless $mathblock =~ m/\{$ARRENV\}/ ;
+	substr($delblock,$begin2,$len2)=$mathblock;
+	pos($delblock) = $begin2 + length($mathblock);
+      }
+
+#     splice in modified delblock
+      substr($_,$begin,$len)=$delblock;
+      pos = $begin + length($delblock);
+    }
+    # make the array modification in added blocks
+    while ( m/\\DIFaddbegin.*?\\DIFaddend/sg ) {
+      $cnt=0;
+      $len=length($&);
+      $begin=pos($_) - $len;
+      $addblock=$&;
+      while ( $addblock =~ m/($math)(\s*)/sg ) {
+	$cnt2=0;
+	$len2=length($&);
+	$begin2=pos($addblock) - $len2;
+	$mathblock="%\n\\mbox{$AUXCMD\n$1\n}$AUXCMD\n";
+        next unless $mathblock =~ m/\{$ARRENV\}/ ;
+	substr($addblock,$begin2,$len2)=$mathblock;
+	pos($addblock) = $begin2 + length($mathblock);
+      }
+
+#     splice in modified addblock
+      substr($_,$begin,$len)=$addblock;
+      pos = $begin + length($addblock);
+    }
+
+
+    ### old place for BEGINDIF, ENDDIF replacement
+    # change begin and end commands  within comments such that they
+    # don't disturb the pattern matching (if there are several \begin or \end in one line
+    # this substitution is insufficient but that appears unlikely)
+    s/(%.*)\\begin\{(.*)$/$1\\BEGINDIF\{$2/mg ;
+    s/(%.*)\\end\{(.*)$/$1\\ENDDIF\{$2/mg ;
+
+    # Replace MATHMODE environments from step 1a above by the correct Math environment
+
+    # The next line is complicated.  The negative look-ahead insertion makes sure that no \end{$MATHENV} (or other mathematical
+    # environments) are between the \begin{$MATHENV} and \end{MATHMODE} commands. This is necessary as the minimal matching 
+    # is not globally minimal but only 'locally' (matching is beginning from the left side of the string)
+    1 while s/\\begin{((?:$MATHENV)|(?:$MATHARRENV)|SQUAREBRACKET)}((?:.(?!(?:\\end{(?:(?:$MATHENV)|(?:$MATHARRENV)|SQUAREBRACKET)}|\\begin{MATHMODE})))*?)\\end{MATHMODE}/\\begin{$1}$2\\end{$1}/s;
+    1 while s/\\begin{MATHMODE}((?:.(?!\\end{MATHMODE}))*?)\\end{((?:$MATHENV)|(?:$MATHARRENV)|SQUAREBRACKET)}/\\begin{$2}$1\\end{$2}/s;
+    # convert remaining \begin{MATHMODE} \end{MATHMODE} (and not containing & or \\ )into MATHREPL environments
+    s/\\begin{MATHMODE}((?:(.(?!(?<!\\)\&|\\\\))*)?)\\end{MATHMODE}/\\begin{$MATHREPL}$1\\end{$MATHREPL}/sg;
+    # others into MATHARRREPL
+    s/\\begin{MATHMODE}(.*?)\\end{MATHMODE}/\\begin{$MATHARRREPL}$1\\end{$MATHARRREPL}/sg;
+
+    # now look for AUXCMD math-mode pairs which have only comments (or empty lines between them), and remove the added commands
+    s/\\begin{((?:$MATHENV)|(?:$MATHARRENV)|SQUAREBRACKET)}$AUXCMD\n((?:\s*%.[^\n]*\n)*)\\end{\1}$AUXCMD\n/$2/sg; 
+
+
+    # Remove all mark up within picture environments
+    while ( m/\\begin\{($PICTUREENV)\}.*?\\end\{\1\}/sg ) {
+      $cnt=0;
+      $len=length($&);
+      $begin=pos($_) - $len;
+      $float=$&;
+      $float =~ s/\\DIFaddbegin //g;
+      $float =~ s/\\DIFaddend //g;
+      $float =~ s/\\DIFadd\{($pat4)\}/$1/g;
+      $float =~ s/\\DIFdelbegin //g;
+      $float =~ s/\\DIFdelend //g;
+      $float =~ s/\\DIFdel\{($pat4)\}//g;
+      substr($_,$begin,$len)=$float;
+      pos = $begin + length($float);
+    }
+    # Convert DIFadd, DIFdel, DIFFaddbegin , ... into  varieties
+    #    within floats (currently recognised float environments: plate,table,figure
+    #    plus starred varieties).
+    while ( m/\\begin\{($FLOATENV)\}.*?\\end\{\1\}/sg ) {
+      $cnt=0;
+      $len=length($&);
+      $begin=pos($_) - $len;
+      $float=$&;
+      $float =~ s/\\DIFaddbegin /\\DIFaddbeginFL /g;
+      $float =~ s/\\DIFaddend /\\DIFaddendFL /g;
+      $float =~ s/\\DIFadd\{/\\DIFaddFL{/g;
+      $float =~ s/\\DIFdelbegin /\\DIFdelbeginFL /g;
+      $float =~ s/\\DIFdelend /\\DIFdelendFL /g;
+      $float =~ s/\\DIFdel\{/\\DIFdelFL{/g;
+      substr($_,$begin,$len)=$float;
+      pos = $begin + length($float);
+    }
+    ### former location of undo renaming of \begin and \end in comments
+
+    # remove empty DIFCMD < lines
+    s/^\Q${DELCMDOPEN}\E\n//msg;
+
+    # Expand hashes of verb and verbatim environments (note negative look behind assertion to not leak out of DIFDELCMD comments
+    s/(\\verb\*?)\{([-\d]*?)\}/"${1}". fromhash(\%verbhash,$2)/esg;
+    s/${DELCMDOPEN}\\(verbatim\*?)\{([-\d]*?)\}/"${DELCMDOPEN}\\begin{${1}}".fromhash(\%verbhash,$2,$DELCMDOPEN)."${DELCMDOPEN}\\end{${1}}"/esg;
+    s/\\(verbatim\*?)\{([-\d]*?)\}/"\\begin{${1}}".fromhash(\%verbhash,$2)."\\end{${1}}"/esg;
+    # Convert '\PERCENTAGE ' back into '\%'			       
+    s/\\PERCENTAGE /\\%/g;
+    # remove all \PAR tokens (taking care to properly keep commented out PAR's
+    # from introducing uncommented newlines - next line)
+    s/(%DIF < )([^\n]*?)\\PAR\n/$1$2\n$1\n/sg;
+    # convert PAR commands which are on a line by themselves
+    s/\n(\s*?)\\PAR\n/\n\n/sg;
+    # convert remaining PAR commands (which are preceded by non-white space characters, usually "}" ($ADDCLOSE)
+    s/\\PAR\n/\n\n/sg;
+
+    #  package specific processing: 
+    if ( defined($packages{"endfloat"})) {
+      #endfloat: make sure \begin{figure} and \end{figure} are always
+      #      on a line by themselves, similarly for table environment
+      print STDERR "endfloat package detected.\n" if $verbose ;
+      # eliminate whitespace before and after
+      s/^(\s*)(\\(?:begin|end)\{(?:figure|table)\})(\s*)$/$2/mg;
+      # split lines with remaining characters before float enviroment conmmand
+      s/^(.+)(\\(?:begin|end)\{(?:figure|table)\})/$1\n$2/mg;
+      # split lines with remaining characters after float enviroment conmmand
+      s/(\\(?:begin|end)\{(?:figure|table)\})(.+)$/$1\n$2/mg;
+    }
+    # undo renaming of the \begin and \end  and dollars in comments 
+    s/(%.*)\\BEGINDIF\{(.*)$/$1\\begin\{$2/mg ;
+    s/(%.*)\\ENDDIF\{(.*)$/$1\\end\{$2/mg ;
+    1 while s/(%.*)DOLLARDIF/$1\$/mg ;
+#   Convert \begin{SQUAREBRACKET} \end{SQUAREBRACKET} into \[ \]
+    s/\\end{SQUAREBRACKET}/\\\]/sg;
+    s/\\begin{SQUAREBRACKET}/\\\[/sg;
+# 4. Convert \begin{DOLLARDOLLAR} \end{DOLLARDOLLAR} into $$ $$
+    s/\\begin\{DOLLARDOLLAR\}(.*?)\\end\{DOLLARDOLLAR\}/\$\$$1\$\$/sg;
+# 5. Convert  \SUPERSCRIPTNB{n} into ^n  and  \SUPERSCRIPT{nn} into ^{nnn}
+    s/\\SUPERSCRIPTNB{($pat0)}/^$1/g ;
+    s/\\SUPERSCRIPT{($pat4)}/^{$1}/g ;
+    # Convert  \SUBSCRIPNB{n} into _n  and  \SUBCRIPT{nn} into _{nnn}
+    s/\\SUBSCRIPTNB{($pat0)}/_$1/g ;
+    s/\\SUBSCRIPT{($pat4)}/_{$1}/g ;
+
+  return;
+  }
+}
+
+
+# @diffs=linediff(\@seq1, \@seq2)
+# mark up lines like this
+#%DIF mm-mmdnn
+#%< old deleted line(s)
+#%DIF -------
+#%DIF mmann-nn
+#new appended line %< 
+#%DIF -------
+# Future extension: mark change explicitly
+# Assumes: traverse_sequence traverses deletions before insertions in changed sequences
+#          all line numbers relative to line 0 (first line of real file)
+sub linediff {
+  my $seq1 = shift ;
+  my $seq2 = shift ;
+
+  my $block = [];
+  my $retseq = [];
+  my @begin=('','',''); # dummy initialisation
+  my $instring ; 
+
+  my $discard = sub { @begin=('d',$_[0],$_[1]) unless scalar @$block ; 
+                      push(@$block, "%DIF < " . $seq1->[$_[0]]) };
+  my $add = sub { if (! scalar  @$block) {
+		    @begin=('a',$_[0],$_[1]) ;}
+		  elsif ( $begin[0] eq 'd' ) {
+                    $begin[0]='c'; $begin[2]=$_[1];
+		    push(@$block, "%DIF -------") }
+                  push(@$block,  $seq2->[$_[1]] . " %DIF > " ) };
+  my $match = sub { if ( scalar @$block ) {
+                      if ( $begin[0] eq 'd' && $begin[1]!=$_[0]-1) {
+			$instring = sprintf "%%DIF %d-%dd%d",$begin[1],$_[0]-1,$begin[2]; }
+		      elsif ( $begin[0] eq 'a' && $begin[2]!=$_[1]-1) {
+			$instring = sprintf "%%DIF %da%d-%d",$begin[1],$begin[2],$_[1]-1; }
+		      elsif ( $begin[0] eq 'c' ) {
+			$instring = sprintf "%%DIF %sc%s",
+			                     ($begin[1]==$_[0]-1) ? "$begin[1]" : $begin[1]."-".($_[0]-1)  , 
+			                     ($begin[2]==$_[1]-1) ? "$begin[2]" : $begin[2]."-".($_[1]-1)  ; }
+		      else {
+			$instring = sprintf "%%DIF %d%s%d",$begin[1],$begin[0],$begin[2]; }
+		      push @$retseq, $instring,@$block, "%DIF -------" ; 
+		      $block = []; 
+		    }
+		    push @$retseq, $seq2->[$_[1]]
+		  };
+  # key function: remove multiple spaces (such that insertion or deletion of redundant white space is not reported)
+  my $keyfunc = sub { join("  ",split(" ",shift())) };
+
+  traverse_sequences($seq1,$seq2, { MATCH=>$match, DISCARD_A=>$discard, DISCARD_B=>$add }, $keyfunc );
+  push @$retseq, @$block if scalar @$block; 
+
+  return wantarray ? @$retseq : $retseq ;
+}
+
+
+
+# init_regex_arr_data(\@array,"TOKEN INIT")
+# scans DATA file handel for line "%% TOKEN INIT" line
+# then appends each line not beginning with % into array (as a quoted regex)
+sub init_regex_arr_data {
+  my ($arr,$token)=@_;
+  my ($copy);
+  while (<DATA>) {
+    if ( m/^%%BEGIN $token\s*$/ ) {
+      $copy=1; }
+    elsif ( m/^%%END $token\s*/ )  {
+      last; }
+    chomp;
+    push (@$arr,qr/^$_$/) if ( $copy && !/^%/ ) ;
+  }
+  seek DATA,0,0;    # rewind DATA handle to file begin
+}
+
+
+# init_regex_arr_ext(\@array,$arg)
+# fills array with regular expressions.
+# if arg is a file name, then read in list of regular expressions from that file
+# (one expression per line)
+# Otherwise treat arg as a comma separated list of regular expressions
+sub init_regex_arr_ext {
+  my ($arr,$arg)=@_;
+  my $regex;
+  if ( -f $ arg ) {
+    open(FILE,"$arg") or die ("Couldn't open $arg: $!");
+    while (<FILE>) {
+      chomp;
+      next if /^\s*#/ || /^\s*%/ || /^\s*$/ ;
+      push (@$arr,qr/^$_$/);
+    }
+    close(FILE);
+  }
+  else {
+    # assume it is a comma-separated list of reg-ex
+    foreach $regex (split(qr/(?<!\\),/,$arg)) {
+      $regex =~ s/\\,/,/g;
+      push (@$arr,qr/^$regex$/);
+    }
+  }
+}
+
+#exetime() returns time since last execution of this command
+#exetime(1) resets this time
+my $lasttime=-1;   # global variable for persistence
+sub exetime {
+  my $reset=0;
+  my $retval;
+  if ((scalar @_) >=1) {
+    $reset=shift;
+  }
+  if ($reset) {
+    $lasttime=times();
+  }
+  else {
+    $retval=times()-$lasttime;
+    $lasttime=$lasttime+$retval;
+    return($retval);
+  }
+}
+
+
+sub usage {
+  die <<"EOF"; 
+Usage: $0 [options] old.tex new.tex > diff.tex
+
+Compares two latex files and writes tex code to stdout, which has the same
+format as new.tex but has all changes relative to old.tex marked up or commented.
+
+--type=markupstyle
+-t markupstyle         Add code to preamble for selected markup style
+                       Available styles: UNDERLINE CTRADITIONAL TRADITIONAL CFONT FONTSTRIKE INVISIBLE 
+                                         CHANGEBAR CCHANGEBAR CULINECHBAR CFONTCBHBAR
+                       [ Default: UNDERLINE ]
+
+--subtype=markstyle
+-s markstyle           Add code to preamble for selected style for bracketing
+                       commands (e.g. to mark changes in  margin)
+                       Available styles: SAFE MARGINAL DVIPSCOL
+                       [ Default: SAFE ]
+
+--floattype=markstyle
+-f markstyle           Add code to preamble for selected style which 
+                       replace standard marking and markup commands within floats
+                       (e.g., marginal remarks cause an error within floats
+                       so marginal marking can be disabled thus)
+                       Available styles: FLOATSAFE IDENTICAL
+                       [ Default: FLOATSAFE ]
+
+--encoding=enc
+-e enc                 Specify encoding of old.tex and new.tex. Typical encodings are
+                       ascii, utf8, latin1, latin9.  A list of available encodings can be 
+                       obtained by executing 
+                       perl -MEncode -e 'print join ("\\n",Encode->encodings( ":all" )) ;'
+                       [Default encoding is utf8 unless the first few lines of the preamble contain
+                       an invocation "\\usepackage[..]{inputenc} in which case the 
+                       encoding chosen by this command is asssumed. Note that ASCII (standard
+                       latex) is a subset of utf8]
+
+--preamble=file
+-p file                Insert file at end of preamble instead of auto-generating
+                       preamble.  The preamble must define the following commands
+                       \\DIFaddbegin,\\DIFaddend,\\DIFadd{..},
+                       \\DIFdelbegin,\\DIFdelend,\\DIFdel{..},
+                       and varieties for use within floats
+                       \\DIFaddbeginFL,\\DIFaddendFL,\\DIFaddFL{..},
+                       \\DIFdelbeginFL,\\DIFdelendFL,\\DIFdelFL{..}
+                       (If this option is set -t, -s, and -f options
+                       are ignored.)
+
+--exclude-safecmd=exclude-file
+--exclude-safecmd="cmd1,cmd2,..."
+-A exclude-file 
+--replace-safecmd=replace-file
+--append-safecmd=append-file
+--append-safecmd="cmd1,cmd2,..."
+-a append-file         Exclude from, replace or append to the list of regex
+                       matching commands which are safe to use within the 
+                       scope of a \\DIFadd or \\DIFdel command.  The file must contain
+                       one Perl-RegEx per line (Comment lines beginning with # or % are
+                       ignored). A literal comma within the comma-separated list must be
+                       escaped thus "\\,",   Note that the RegEx needs to match the whole of 
+                       the token, i.e., /^regex\$/ is implied and that the initial
+                       "\\" of the command is not included. The --exclude-safecmd
+                       and --append-safecmd options can be combined with the --replace-safecmd 
+                       option and can be used repeatedly to add cumulatively to the lists.
+
+--exclude-textcmd=exclude-file 
+--exclude-textcmd="cmd1,cmd2,..."
+-X exclude-file
+--replace-textcmd=replace-file
+--append-textcmd=append-file
+--append-textcmd="cmd1,cmd2,..."
+-x append-file         Exclude from, replace or append to the list of regex
+                       matching commands whose last argument is text.  See
+                       entry for --exclude-safecmd directly above for further details.
+
+--replace-context1cmd=replace-file
+--append-context1cmd=append-file
+--append-context1cmd="cmd1,cmd2,..."
+                       Replace or append to the list of regex matching commands
+                       whose last argument is text but which require a particular
+                       context to work, e.g. \\caption will only work within a figure
+                       or table.  These commands behave like text commands, except when 
+                       they occur in a deleted section, when they are disabled, but their
+                       argument is shown as deleted text.
+
+--replace-context2cmd=replace-file
+--append-context2cmd=append-file
+--append-context2cmd="cmd1,cmd2,..."
+                       As corresponding commands for context1.  The only difference is that
+                       context2 commands are completely disabled in deleted sections, including
+                       their arguments.
+
+
+--config var1=val1,var2=val2,...
+-c var1=val1,..        Set configuration variables.
+-c configfile           Available variables: 
+                          MINWORDSBLOCK (integer)
+                          FLOATENV (RegEx)
+                          PICTUREENV (RegEx)
+                          MATHENV (RegEx)
+                          MATHREPL (String)
+                          MATHARRENV (RegEx)
+                          MATHARRREPL (String)
+                          ARRENV (RegEx)
+                          COUNTERCMD (RegEx)
+                       This option can be repeated.
+
+
+--packages=pkg1,pkg2,..
+                       Tell latexdiff that .tex file is processed with the packages in list 
+                       loaded.  This is normally not necessary if the .tex file includes the
+                       preamble, as the preamble is automatically scanned for \\usepackage commands.
+                       Use of the --packages option disables automatic scanning, so if for any
+                       reason package specific parsing needs to be switched off, use --packages=none.
+                       The following packages trigger special behaviour:
+                       endfloat hyperref amsmath
+                       [ Default: scan the preamble for \\usepackage commands to determine
+                         loaded packages.]
+
+--show-preamble        Print generated or included preamble commands to stdout.
+
+--show-safecmd         Print list of regex matching and excluding safe commands.
+
+--show-textcmd         Print list of regex matching and excluding commands with text argument.
+
+--show-config          Show values of configuration variables
+
+--show-all             Show all of the above
+
+   NB For all --show commands, no old.tex or new.tex file needs to be given, and no 
+      differencing takes place.
+
+--allow-spaces         Allow spaces between bracketed or braced arguments to commands
+                       [Default requires arguments to directly follow each other without 
+                                intervening spaces]
+
+--flatten              Replace \\input and \\include commands within body by the content
+                       of the files in their argument.  If \\includeonly is present in the
+                       preamble, only those files are expanded into the document. However, 
+                       no recursion is done, i.e. \\input and \\include commands within 
+                       included sections are not expanded.  The included files are assumed to 
+                       be located in the same directories as the old and new master files,
+                       respectively, making it possible to organise files into old and new directories.
+
+--help
+-h                     Show this help text.
+
+--ignore-warnings      Suppress warnings about inconsistencies in length between input
+                       and parsed strings and missing characters. 
+
+--verbose
+-V                     Output various status information to stderr during processing.
+                       Default is to work silently.
+
+--version              Show version number.
+EOF
+}
+
+=head1 NAME
+
+latexdiff - determine and markup differences between two latex files
+
+=head1 SYNOPSIS
+
+B<latexdiff> [ B<OPTIONS> ] F<old.tex> F<new.tex> > F<diff.tex>
+
+=head1 DESCRIPTION
+
+Briefly, I<latexdiff> is a utility program to aid in the management of
+revisions of latex documents. It compares two valid latex files, here
+called C<old.tex> and C<new.tex>, finds significant differences
+between them (i.e., ignoring the number of white spaces and position
+of line breaks), and adds special commands to highlight the
+differences.  Where visual highlighting is not possible, e.g. for changes
+in the formatting, the differences are
+nevertheless marked up in the source.
+
+The program treats the preamble differently from the main document.
+Differences between the preambles are found using line-based
+differencing (similarly to the Unix diff command, but ignoring white
+spaces).  A comment, "S<C<%DIF E<gt>>>" is appended to each added line, i.e. a 
+line present in C<new.tex> but not in C<old.tex>.  Discarded lines 
+ are deactivated by prepending "S<C<%DIF E<lt>>>". Changed blocks are preceded  by
+comment lines giving information about line numbers in the original files.  Where there are insignificant
+differences, the resulting file C<diff.tex> will be similar to
+C<new.tex>.  At the end of the preamble, the definitions for I<latexdiff> markup commands are inserted.
+In differencing the main body of the text, I<latexdiff> attempts to
+satisfy the following guidelines (in order of priority):
+
+=over 3
+
+=item 1
+
+If both C<old.tex> and C<new.tex> are valid LaTeX, then the resulting
+C<diff.tex> should also be valid LateX. (NB If a few plain TeX commands
+are used within C<old.tex> or C<new.tex> then C<diff.tex> is not
+guaranteed to work but usually will).
+
+=item 2
+
+Significant differences are determined on the level of
+individual words. All significant differences, including differences
+between comments should be clearly marked in the resulting source code
+C<diff.tex>.
+
+=item 3
+
+If a changed passage contains text or text-producing commands, then
+running C<diff.tex> through LateX should produce output where added
+and discarded passages are highlighted.
+
+=item 4
+
+Where there are insignificant differences, e.g. in the positioning of
+line breaks, C<diff.tex> should follow the formatting of C<new.tex>
+
+=back
+
+For differencing the same algorithm as I<diff> is used but words
+instead of lines are compared.  An attempt is made to recognize
+blocks which are completely changed such that they can be marked up as a unit.
+Comments are differenced line by line
+but the number of spaces within comments is ignored. Commands including
+all their arguments are generally compared as one unit, i.e., no mark-up
+is inserted into the arguments of commands.  However, for a selected
+number of commands (for example, C<\caption> and all sectioning
+commands) the last argument is known to be text. This text is
+split into words and differenced just as ordinary text (use options to
+show and change the list of text commands, see below). As the
+algorithm has no detailed knowledge of LaTeX, it assumes all pairs of
+curly braces immediately following a command (i.e. a sequence of
+letters beginning with a backslash) are arguments for that command.
+As a restriction to condition 1 above it is thus necessary to surround
+all arguments with curly braces, and to not insert
+extraneous spaces.  For example, write 
+
+  \section{\textem{This is an emphasized section title}}
+
+and not
+
+  \section {\textem{This is an emphasized section title}}
+
+or
+
+  \section\textem{This is an emphasized section title}
+
+even though all varieties are the same to LaTeX (but see
+B<--allow-spaces> option which allows the second variety).
+
+For environments whose content does not conform to standard LaTeX or
+where graphical markup does not make sense all markup commands can be
+removed by setting the PICTUREENV configuration variable, set by
+default to C<picture> and C<DIFnomarkup> environments; see B<--config>
+option).  The latter environment (C<DIFnomarkup>) can be used to
+protect parts of the latex file where the markup results in illegal
+markup. You have to surround the offending passage in both the old and
+new file by C<\begin{DIFnomarkup}> and C<\end{DIFnomarkup}>. You must
+define the environment in the preambles of both old and new
+documents. I prefer to define it as a null-environment,
+
+C<\newenvironment{DIFnomarkup}{}{}>
+
+but the choice is yours.  Any markup within the environment will be
+removed, and generally everything within the environment will just be
+taken from the new file.
+
+It is also possible to difference files which do not have a preamble. 
+ In this case, the file is processed in the main document
+mode, but the definitions of the markup commands are not inserted.
+
+All markup commands inserted by I<latexdiff> begin with "C<\DIF>".  Added
+blocks containing words, commands or comments which are in C<new.tex>
+but not in C<old.tex> are marked by C<\DIFaddbegin> and C<\DIFaddend>.
+Discarded blocks are marked by C<\DIFdelbegin> and C<\DIFdelend>.
+Within added blocks all text is highlighted with C<\DIFadd> like this:
+C<\DIFadd{Added text block}>
+Selected `safe' commands can be contained in these text blocks as well
+(use options to show and change the list of safe commands, see below).
+All other commands as well as braces "{" and "}" are never put within
+the scope of C<\DIFadd>.  Added comments are marked by prepending
+"S<C<%DIF E<gt> >>".
+
+Within deleted blocks text is highlighted with C<\DIFdel>.  Deleted
+comments are marked by prepending "S<C<%DIF E<lt> >>".  Non-safe command
+and curly braces within deleted blocks are commented out with 
+"S<C<%DIFDELCMD E<lt> >>".
+
+
+
+=head1 OPTIONS
+
+=head2 Preamble
+
+The following options determine the visual markup style by adding the appropriate
+command definitions to the preamble. See the end of this section for a description of 
+available styles.
+
+=over 4
+
+=item B<--type=markupstyle> or
+B<-t markupstyle>
+
+Add code to preamble for selected markup style. This option defines
+C<\DIFadd> and C<\DIFdel> commands.
+Available styles: 
+
+C<UNDERLINE CTRADITIONAL TRADITIONAL CFONT FONTSTRIKE INVISIBLE 
+CHANGEBAR CCHANGEBAR CULINECHBAR CFONTCBHBAR>
+
+[ Default: C<UNDERLINE> ]
+
+=item B<--subtype=markstyle> or
+B<-s markstyle> 
+
+Add code to preamble for selected style for bracketing
+commands (e.g. to mark changes in  margin). This option defines
+C<\DIFaddbegin>, C<\DIFaddend>, C<\DIFdelbegin> and C<\DIFdelend> commands.
+Available styles: C<SAFE MARGINAL DVIPSCOL>
+
+[ Default: C<SAFE> ]
+
+=item B<--floattype=markstyle> or
+B<-f markstyle>
+
+Add code to preamble for selected style which 
+replace standard marking and markup commands within floats
+(e.g., marginal remarks cause an error within floats
+so marginal marking can be disabled thus). This option defines all 
+C<\DIF...FL> commands.
+Available styles: C<FLOATSAFE TRADITIONALSAFE IDENTICAL>
+
+[ Default: C<FLOATSAFE> ]
+
+=item B<--encoding=enc> or 
+B<-e enc>
+
+Specify encoding of old.tex and new.tex. Typical encodings are
+C<ascii>, C<utf8>, C<latin1>, C<latin9>.  A list of available encodings can be 
+obtained by executing 
+
+C<perl -MEncode -e 'print join ("\n",Encode->encodings( ":all" )) ;' >
+
+[Default encoding is utf8 unless the first few lines of the preamble contain
+an invocation C<\usepackage[..]{inputenc}> in which case the 
+encoding chosen by this command is asssumed. Note that ASCII (standard
+latex) is a subset of utf8]
+
+=item B<--preamble=file> or
+B<-p file>
+
+Insert file at end of preamble instead of generating
+preamble.  The preamble must define the following commands
+C<\DIFaddbegin, \DIFaddend, \DIFadd{..},
+\DIFdelbegin,\DIFdelend,\DIFdel{..},>
+and varieties for use within floats
+C<\DIFaddbeginFL, \DIFaddendFL, \DIFaddFL{..},
+\DIFdelbeginFL, \DIFdelendFL, \DIFdelFL{..}>
+(If this option is set B<-t>, B<-s>, and B<-f> options
+are ignored.)
+
+=item B<--packages=pkg1,pkg2,..> 
+
+Tell latexdiff that .tex file is processed with the packages in list
+loaded.  This is normally not necessary if the .tex file includes the
+preamble, as the preamble is automatically scanned for C<\usepackage> commands.
+Use of the B<--packages> option disables automatic scanning, so if for any
+reason package specific parsing needs to be switched off, use B<--packages=none>.
+The following packages trigger special behaviour:
+
+=over 8
+
+=item C<amsmath> 
+
+Configuration variable amsmath is set to C<align*> (Default: C<eqnarray*>)
+
+=item C<endfloat> 
+
+Ensure that C<\begin{figure}> and C<\end{figure}> always appear by themselves on a line.
+
+=item C<hyperref>
+
+Change name of C<\DIFadd> and C<\DIFdel> commands to C<\DIFaddtex> and C<\DIFdeltex> and 
+define new C<\DIFadd> and C<\DIFdel> commands, which provide a wrapper for these commands,
+using them for the text but not for the link defining command (where any markup would cause
+errors).
+
+=back
+
+[ Default: scan the preamble for C<\\usepackage> commands to determine
+  loaded packages.]
+
+
+
+=item B<--show-preamble>
+
+Print generated or included preamble commands to stdout.
+
+=back
+
+=head2 Configuration
+
+=over 4
+
+=item B<--exclude-safecmd=exclude-file> or
+B<-A exclude-file> or  B<--exclude-safecmd="cmd1,cmd2,...">
+
+=item B<--replace-safecmd=replace-file>
+
+=item B<--append-safecmd=append-file> or 
+B<-a append-file> or B<--append-safecmd="cmd1,cmd2,...">
+
+Exclude from, replace or append to the list of regular expressions (RegEx)
+matching commands which are safe to use within the 
+scope of a C<\DIFadd> or C<\DIFdel> command.  The file must contain
+one Perl-RegEx per line (Comment lines beginning with # or % are
+ignored).  Note that the RegEx needs to match the whole of 
+the token, i.e., /^regex$/ is implied and that the initial
+"\" of the command is not included. 
+The B<--exclude-safecmd> and B<--append-safecmd> options can be combined with the -B<--replace-safecmd> 
+option and can be used repeatedly to add cumulatively to the lists.
+ B<--exclude-safecmd>
+and B<--append-safecmd> can also take a comma separated list as input. If a
+comma for one of the regex is required, escape it thus "\,". In most cases it
+will be necessary to protect the comma-separated list from the shell by putting
+it in quotation marks.
+
+=item B<--exclude-textcmd=exclude-file> or
+B<-X exclude-file> or B<--exclude-textcmd="cmd1,cmd2,...">
+
+=item B<--replace-textcmd=replace-file>
+
+=item B<--append-textcmd=append-file> or 
+B<-x append-file> or B<--append-textcmd="cmd1,cmd2,...">
+
+Exclude from, replace or append to the list of regular expressions
+matching commands whose last argument is text.  See
+entry for B<--exclude-safecmd> directly above for further details.
+
+
+=item B<--replace-context1cmd=replace-file> 
+
+=item B<--append-context1cmd=append-file> or
+=item B<--append-context1cmd="cmd1,cmd2,...">
+
+Replace or append to the list of regex matching commands
+whose last argument is text but which require a particular
+context to work, e.g. \caption will only work within a figure
+or table.  These commands behave like text commands, except when 
+they occur in a deleted section, when they are disabled, but their
+argument is shown as deleted text.
+
+=item B<--replace-context1cmd=replace-file> 
+
+=item B<--append-context2cmd=append-file> or
+=item B<--append-context2cmd="cmd1,cmd2,...">
+As corresponding commands for context1.  The only difference is that
+context2 commands are completely disabled in deleted sections, including
+their arguments.
+
+
+
+=item B<--config var1=val1,var2=val2,...> or B<-c var1=val1,..>
+
+=item B<-c configfile>
+
+Set configuration variables.  The option can be repeated to set different
+variables (as an alternative to the comma-separated list).
+Available variables (see below for further explanations): 
+
+C<MINWORDSBLOCK> (integer)
+
+C<FLOATENV> (RegEx)
+
+C<PICTUREENV> (RegEx)
+
+C<MATHENV> (RegEx)
+
+C<MATHREPL> (String)
+
+C<MATHARRENV> (RegEx)
+
+C<MATHARRREPL> (String)
+
+C<ARRENV> (RegEx)
+
+C<COUNTERCMD> (RegEx)
+
+=item B<--show-safecmd>
+
+Print list of RegEx matching and excluding safe commands.
+
+=item B<--show-textcmd>
+
+Print list of RegEx matching and excluding commands with text argument.
+
+=item B<--show-config>
+
+Show values of configuration variables.
+
+=item B<--show-all>
+
+Combine all --show commands.
+
+NB For all --show commands, no C<old.tex> or C<new.tex> file needs to be specified, and no 
+differencing takes place.
+
+
+=back
+
+=head2 Miscellaneous
+
+=over 4
+
+=item B<--verbose> or B<-V>
+
+Output various status information to stderr during processing.
+Default is to work silently.
+
+=item B<--ignore-warnings>
+
+Suppress warnings about inconsistencies in length between input and
+parsed strings and missing characters.  These warning messages are
+often related to non-standard latex or latex constructions with a
+syntax unknown to C<latexdiff> but the resulting difference argument
+is often fully functional anyway, particularly if the non-standard
+latex only occurs in parts of the text which have not changed.
+
+=item B<--allow-spaces>
+
+Allow spaces between bracketed or braced arguments to commands.  Note
+that this option might have undesirable side effects (unrelated scope
+might get lumpeded with preceding commands) so should only be used if the
+default produces erroneous results.  (Default requires arguments to
+directly follow each other without intervening spaces).
+
+=item B<--flatten>
+
+Replace C<\input> and C<\include> commands within body by the content
+of the files in their argument.  If C<\includeonly> is present in the
+preamble, only those files are expanded into the document. However, 
+no recursion is done, i.e. C<\input> and C<\include> commands within 
+included sections are not expanded.  The included files are assumed to 
+ be located in the same directories as the old and new master files,
+respectively, making it possible to organise files into old and new directories. 
+
+Use of this option is not recommended
+primarily the processing time for the large documents is prohibitive, and
+the resulting difference document no longer reflects the structure of the 
+input documents. 
+
+=item B<--help> or
+B<-h>
+
+Show help text
+
+=item B<--version>
+
+Show version number
+
+=back
+
+=head2 Predefined styles 
+
+=head2 Major types
+
+The major type determine the markup of plain text and some selected latex commands outside floats by defining the markup commands C<\DIFadd{...}> and C<\DIFdel{...}> .
+
+=over 10
+
+=item C<UNDERLINE>
+
+Added text is wavy-underlined and blue, discarded text is struck out and red
+(Requires color and ulem packages).  Overstriking does not work in displayed math equations such that deleted parts of equation are underlined, not struck out (this is a shortcoming inherent to the ulem package).
+
+=item C<CTRADITIONAL>
+
+Added text is blue and set in sans-serif, and a red footnote is created for each discarded 
+piece of text. (Requires color package)
+
+=item C<TRADITIONAL>
+
+Like C<CTRADITIONAL> but without the use of color.
+
+=item C<CFONT>
+
+Added text is blue and set in sans-serif, and discarded text is red and very small size.
+
+=item C<FONTSTRIKE>
+
+Added tex is set in sans-serif, discarded text small and struck out
+
+=item C<CCHANGEBAR>
+
+Added text is blue, and discarded text is red.  Additionally, the changed text is marked with a bar in the margin (Requires color and changebar packages).
+
+=item C<CFONTCHBAR>
+
+Like C<CFONT> but with additional changebars (Requires color and changebar packages).
+
+=item C<CULINECHBAR>
+
+Like C<UNDERLINE> but with additional changebars (Requires color, ulem and changebar packages).
+
+=item C<CHANGEBAR>
+
+No mark up of text, but mark margins with changebars (Requires changebar package).
+
+=item C<INVISIBLE>
+
+No visible markup (but generic markup commands will still be inserted.
+
+=back
+
+=head2 Subtypes
+
+The subtype defines the commands that are inserted at the begin and end of added or discarded blocks, irrespectively of whether these blocks contain text or commands (Defined commands: C<\DIFaddbegin, \DIFaddend, \DIFdelbegin, \DIFdelend>) 
+
+=over 10
+
+=item C<SAFE>
+
+No additional markup (Recommended choice)
+
+=item C<MARGIN>
+
+Mark beginning and end of changed blocks with symbols in the margin nearby (using
+the standard C<\marginpar> command - note that this sometimes moves somewhat
+from the intended position.
+
+=item C<DVIPSCOL>
+
+An alternative way of marking added passages in blue, and deleted ones in red. Note
+that C<DVIPSCOL> only works with the dvips converter, e.g. not pdflatex.
+(it is recommeneded to use instead the main types to effect colored markup,
+although in some cases coloring with dvipscol can be more complete).
+
+=back
+
+=head2 Float Types
+
+Some of the markup used in the main text might cause problems when used within 
+floats (e.g. figures or tables).  For this reason alternative versions of all
+markup commands are used within floats. The float type defines these alternative commands.
+
+=over 10
+
+=item C<FLOATSAFE>
+
+Use identical markup for text as in the main body, but set all commands marking the begin and end of changed blocks to null-commands.  You have to choose this float type if your subtype is C<MARGIN> as C<\marginpar> does not work properly within floats.
+
+=item C<TRADITIONALSAFE>
+
+Mark additions the same way as in the main text.  Deleted environments are marked by angular brackets \[ and \] and the deleted text is set in scriptscript size. This float type should always be used with the C<TRADITIONAL> and  C<CTRADITIONAL> markup types as the \footnote command does not work properly in floating environments.
+
+=item C<IDENTICAL>
+
+Make no difference between the main text and floats.
+
+=back
+
+
+=head2 Configuration Variables
+
+=over 10
+
+=item C<MINWORDSBLOCK>
+
+Minimum number of tokens required to form an independent block. This value is
+used in the algorithm to detect changes of complete blocks by merging identical text parts of less than C<MINWORDSBLOCK> to the preceding added and discarded parts.
+
+[ Default: 3 ]
+
+=item C<FLOATENV>
+
+Environments whose name matches the regular expression in C<FLOATENV> are 
+considered floats.  Within these environments, the I<latexdiff> markup commands
+are replaced by their FL variaties.
+
+[ Default: S<C<(?:figure|table|plate)[\w\d*@]*> >]
+
+=item C<PICTUREENV>
+
+Within environments whose name matches the regular expression in C<PICTUREENV>
+all latexdiff markup is removed (in pathologic cases this might lead to
+ inconsistent markup but this situation should be rare).
+
+[ Default: S<C<(?:picture|DIFnomarkup)[\w\d*@]*> >]
+
+=item C<MATHENV>,C<MATHREPL>
+
+If both \begin and \end for a math environment (environment name matching C<MATHENV>
+or \[ and \])
+are within the same deleted block, they are replaced by a \begin and \end commands for C<MATHREPL>
+rather than being commented out.
+
+[ Default: C<MATHENV>=S<C<(?:displaymath|equation)> >, C<MATHREPL>=S<C<displaymath> >]
+
+=item C<MATHARRENV>,C<MATHARRREPL>
+
+as C<MATHENV>,C<MATHREPL> but for equation arrays
+
+[ Default: C<MATHARRENV>=S<C<eqnarray\*?> >, C<MATHREPL>=S<C<eqnarray> >]
+
+=item C<ARRENV>
+
+If a match to C<ARRENV> is found within an inline math environment within a deleted or added block, then the inlined math 
+is surrounded by C<\mbox{>...C<}>.  This is necessary as underlining does not work within inlined array environments.
+
+[ Default: C<ARRENV>=S<C<(?:array|[pbvBV]matrix)> >
+
+=item C<COUNTERCMD>
+
+If a command in a deleted block which is also in the textcmd list matches C<COUNTERCMD> then an
+additional command C<\addtocounter{>F<cntcmd>C<}{-1}>, where F<cntcmd> is the matching command, is appended in the diff file such that the numbering in the diff file remains synchronized with the
+numbering in the new file.
+
+[ Default: C<COUNTERCMD>=C<(?:footnote|part|section|subsection> ...
+
+C<|subsubsection|paragraph|subparagraph)>  ]
+
+=back
+
+=head1 BUGS
+
+UTF-8 support requires a relatively new version of perl (5.8.0 is sufficient 
+but 5.6.2 up would work OK, too).
+
+Option allow-spaces not implemented entirely consistently. It breaks
+the rules that number and type of white space does not matter, as
+different numbers of inter-argument spaces are treated as significant.
+
+Please send bug reports
+to I<tilmann@esc.cam.ac.uk>.  Include the serial number of I<latexdiff>
+(from comments at the top of the source or use B<--version>).  If you come across latex
+files that are error-free and conform to the specifications set out
+above, and whose differencing still does not result in error-free
+latex, please send me those files, ideally edited to only contain the
+offending passage as long as that still reproduces the problem. 
+
+=head1 SEE ALSO
+
+L<latexrevise>
+
+=head1 PORTABILITY
+
+I<latexdiff> does not make use of external commands and thus should run
+on any platform  supporting Perl 5.6 or higher.  If files with encodings 
+other than ASCII or UTF-8 are processed, Perl 5.8 or higher is required.
+
+The standard version of I<latexdiff> requires installation of the Perl package
+C<Algorithm::Diff> (available from I<www.cpan.org> - 
+I<http://search.cpan.org/~nedkonz/Algorithm-Diff-1.15>) but a stand-alone
+version, I<latexdiff-so>, which has this package inlined, is available, too.
+I<latexdiff-fast> requires the I<diff> command to be present.
+
+=head1 AUTHOR
+
+Copyright (C) 2004-2007 Frederik Tilmann
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License Version 2
+
+Contributors of fixes and additions: V. Kuhlmann, J. Paisley, N. Becker, T. Doerges, K. Huebner
+Thanks to everyone who send in bug reports.
+
+=cut
+
+__END__
+%%BEGIN SAFE COMMANDS
+% Regex matching commands which can safely be in the
+% argument of a \DIFadd or \DIFdel command (leave out the \)
+arabic
+dashbox
+emph
+fbox
+framebox
+hspace
+math.*
+makebox
+mbox
+pageref
+ref
+symbol
+raisebox
+rule
+text.*
+shortstack
+usebox
+dag
+ddag
+copyright
+pounds
+S
+P
+oe
+OE
+ae
+AE
+aa
+AA
+o
+O
+l
+L
+frac
+ss
+sqrt
+ldots
+cdots
+vdots
+ddots
+alpha
+beta
+gamma
+delta
+epsilon
+varepsilon
+zeta
+eta
+theta
+vartheta
+iota
+kappa
+lambda
+mu
+nu
+xi
+pi
+varpi
+rho
+varrho
+sigma
+varsigma
+tau
+upsilon
+phi
+varphi
+chi
+psi
+omega
+Gamma
+Delta
+Theta
+Lambda
+Xi
+Pi
+Sigma
+Upsilon
+Phi
+Psi
+Omega
+ps
+mp
+times
+div
+ast
+star
+circ
+bullet
+cdot
+cap
+cup
+uplus
+sqcap
+vee
+wedge
+setminus
+wr
+diamond
+(?:big)?triangle.*
+lhd
+rhd
+unlhd
+unrhd
+oplus
+ominus
+otimes
+oslash
+odot
+bigcirc
+d?dagger
+amalg
+leq
+prec
+preceq
+ll
+(?:sq)?su[bp]set(?:eq)?
+in
+vdash
+geq
+succ(?:eq)?
+gg
+ni
+dashv
+equiv
+sim(?:eq)?
+asymp
+approx
+cong
+neq
+doteq
+propto
+models
+perp
+mid
+parallel
+bowtie
+Join
+smile
+frown
+.*arrow
+(?:long)?mapsto
+.*harpoon.*
+leadsto
+aleph
+hbar
+imath
+jmath
+ell
+wp
+Re
+Im
+mho
+prime
+emptyset
+nabla
+surd
+top
+bot
+angle
+forall
+exists
+neg
+flat
+natural
+sharp
+backslash
+partial
+infty
+Box
+Diamond
+triangle
+clubsuit
+diamondsuit
+heartsuit
+spadesuit
+sum
+prod
+coprod
+int
+oint
+big(?:sq)?c[au]p
+bigvee
+bigwedge
+bigodot
+bigotimes
+bigoplus
+biguplus
+(?:arc)?(?:cos|sin|tan|cot)h?
+csc
+arg
+deg
+det
+dim
+exp
+gcd
+hom
+inf
+ker
+lg
+lim
+liminf
+limsup
+ln
+log
+max
+min
+Pr
+sec
+sup
+(SUPER|SUB)SCRIPTNB
+(SUPER|SUB)SCRIPT
+%%END SAFE COMMANDS
+
+%%BEGIN TEXT COMMANDS
+% Regex matching commands with a text argument (leave out the \)
+addcontents.*
+cc
+closing
+chapter
+dashbox
+emph
+encl
+fbox
+framebox
+footnote
+footnotetext
+framebox
+part
+(sub){0,2}section\*?
+(sub)?paragraph\*?
+makebox
+mbox
+opening
+parbox
+raisebox
+savebox
+sbox
+shortstack
+signature
+text.*
+value
+underline
+sqrt
+(SUPER|SUB)SCRIPT
+%%END TEXT COMMANDS 
+
+%%BEGIN CONTEXT1 COMMANDS
+% Regex matching commands with a text argument (leave out the \), which will fail out of context, but who's arguemtn should be printed as plain text
+caption
+%%END CONTEXT1 COMMANDS 
+
+%%BEGIN CONTEXT2 COMMANDS
+% Regex matching commands with a text argument (leave out the \), which will fail out of context, but who's arguemtn should be printed as plain text
+title
+author
+%%END CONTEXT2 COMMANDS 
+
+
+%% TYPES (Commands for highlighting changed blocks)
+
+%DIF UNDERLINE PREAMBLE
+\RequirePackage[normalem]{ulem}
+\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
+\providecommand{\DIFadd}[1]{{\protect\color{blue}\uwave{#1}}}
+\providecommand{\DIFdel}[1]{{\protect\color{red}\sout{#1}}}                     
+%DIF END UNDERLINE PREAMBLE
+
+%DIF CTRADITIONAL PREAMBLE
+\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
+\RequirePackage[stable]{footmisc}
+\providecommand{\DIFadd}[1]{{\protect\color{blue} \sf #1}}
+\providecommand{\DIFdel}[1]{{\protect\color{red} [..\footnote{removed: #1} ]}}
+%DIF END CTRADITIONAL PREAMBLE
+
+%DIF TRADITIONAL PREAMBLE
+\RequirePackage[stable]{footmisc}
+\providecommand{\DIFadd}[1]{{\sf #1}}
+\providecommand{\DIFdel}[1]{{[..\footnote{removed: #1} ]}}
+%DIF END TRADITIONAL PREAMBLE
+
+%DIF CFONT PREAMBLE
+\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
+\providecommand{\DIFadd}[1]{{\protect\color{blue} \sf #1}}
+\providecommand{\DIFdel}[1]{{\protect\color{red} \scriptsize #1}}
+%DIF END CFONT PREAMBLE
+
+%DIF FONTSTRIKE PREAMBLE
+\RequirePackage[normalem]{ulem}
+\providecommand{\DIFadd}[1]{{\sf #1}}
+\providecommand{\DIFdel}[1]{{\footnotesize \sout{#1}}}
+%DIF END FONTSTRIKE PREAMBLE
+
+%DIF CCHANGEBAR PREAMBLE
+\RequirePackage[dvips]{changebar}
+\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
+\providecommand{\DIFadd}[1]{\protect\cbstart{\protect\color{blue}#1}\protect\cbend}
+\providecommand{\DIFdel}[1]{\protect\cbdelete{\protect\color{red}#1}\protect\cbdelete}
+%DIF END CCHANGEBAR PREAMBLE
+
+%DIF CFONTCHBAR PREAMBLE
+\RequirePackage[dvips]{changebar}
+\RequirePackage{color}\definecolor{RED}{rgb}{1,0,0}\definecolor{BLUE}{rgb}{0,0,1}
+\providecommand{\DIFadd}[1]{\protect\cbstart{\protect\color{blue}\sf #1}\protect\cbend}
+\providecommand{\DIFdel}[1]{\protect\cbdelete{\protect\color{red}\scriptsize #1}\protect\cbdelete}
+%DIF END CFONTCHBAR PREAMBLE
+
+%DIF CULINECHBAR PREAMBLE
+\RequirePackage[normalem]{ulem}
+\RequirePackage[dvips]{changebar}
+\RequirePackage{color}
+\providecommand{\DIFadd}[1]{\protect\cbstart{\protect\color{blue}\uwave{#1}}\protect\cbend}
+\providecommand{\DIFdel}[1]{\protect\cbdelete{\protect\color{red}\sout{#1}}\protect\cbdelete}
+%DIF END CULINECHBAR PREAMBLE
+
+%DIF CHANGEBAR PREAMBLE
+\RequirePackage[dvips]{changebar}
+\providecommand{\DIFadd}[1]{\protect\cbstart{#1}\protect\cbend}
+\providecommand{\DIFdel}[1]{\protect\cbdelete}
+%DIF END CHANGEBAR PREAMBLE
+
+%DIF INVISIBLE PREAMBLE
+\providecommand{\DIFadd}[1]{#1}
+\providecommand{\DIFdel}[1]{}
+%DIF END INVISIBLE PREAMBLE
+
+
+%% SUBTYPES (Markers for beginning and end of changed blocks)
+
+%DIF SAFE PREAMBLE
+\providecommand{\DIFaddbegin}{}
+\providecommand{\DIFaddend}{}
+\providecommand{\DIFdelbegin}{}
+\providecommand{\DIFdelend}{}
+%DIF END SAFE PREAMBLE
+
+%DIF MARGIN PREAMBLE
+\providecommand{\DIFaddbegin}{\protect\marginpar{a[}}
+\providecommand{\DIFaddend}{\protect\marginpar{]}}
+\providecommand{\DIFdelbegin}{\protect\marginpar{d[}}
+\providecommand{\DIFdelend}{\protect\marginpar{]}}
+%DIF END BRACKET PREAMBLE
+
+%DIF DVIPSCOL PREAMBLE
+%Note: only works with dvips converter
+\RequirePackage{color}
+\RequirePackage{dvipscol}
+\providecommand{\DIFaddbegin}{\protect\nogroupcolor{blue}}
+\providecommand{\DIFaddend}{\protect\nogroupcolor{black}}
+\providecommand{\DIFdelbegin}{\protect\nogroupcolor{red}}
+\providecommand{\DIFdelend}{\protect\nogroupcolor{black}}
+%DIF END DVIPSCOL PREAMBLE
+
+
+%% FLOAT TYPES 
+
+%DIF FLOATSAFE PREAMBLE
+\providecommand{\DIFaddFL}[1]{\DIFadd{#1}}
+\providecommand{\DIFdelFL}[1]{\DIFdel{#1}}
+\providecommand{\DIFaddbeginFL}{}
+\providecommand{\DIFaddendFL}{}
+\providecommand{\DIFdelbeginFL}{}
+\providecommand{\DIFdelendFL}{}
+%DIF END FLOATSAFE PREAMBLE
+
+%DIF IDENTICAL PREAMBLE
+\providecommand{\DIFaddFL}[1]{\DIFadd{#1}}
+\providecommand{\DIFdelFL}[1]{\DIFdel{#1}}
+\providecommand{\DIFaddbeginFL}{\DIFaddbegin}
+\providecommand{\DIFaddendFL}{\DIFaddend}
+\providecommand{\DIFdelbeginFL}{\DIFdelbegin}
+\providecommand{\DIFdelendFL}{\DIFdelend}
+%DIF END IDENTICAL PREAMBLE
+
+%DIF TRADITIONALSAFE PREAMBLE
+% procidecommand color to make this work for TRADITIONAL and CTRADITIONAL
+\providecommand{\color}[1]{}
+\providecommand{\DIFaddFL}[1]{\DIFadd{#1}}
+\providecommand{\DIFdel}[1]{{\protect\color{red}[..{\scriptsize {removed: #1}} ]}}
+\providecommand{\DIFaddbeginFL}{}
+\providecommand{\DIFaddendFL}{}
+\providecommand{\DIFdelbeginFL}{}
+\providecommand{\DIFdelendFL}{}
+%DIF END FLOATSAFE PREAMBLE
+
+%% SPECIAL PACKAGE PREAMBLE COMMANDS
+
+% Standard \DIFadd and \DIFdel are redefined as \DIFaddtex and \DIFdeltex
+% when hyperref package is included.
+%DIF HYPERREF PREAMBLE
+\providecommand{\DIFadd}[1]{\texorpdfstring{\DIFaddtex{#1}}{#1}}
+\providecommand{\DIFdel}[1]{\texorpdfstring{\DIFdeltex{#1}}{}}
+%DIF END HYPERREF PACKAGE
diff --git a/Master/texmf-dist/doc/latex/latexdiff/latexdiff-man.pdf b/Master/texmf-dist/doc/latex/latexdiff/latexdiff-man.pdf
new file mode 100644
index 00000000000..09493af5fe7
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+++ b/Master/texmf-dist/doc/latex/latexdiff/latexdiff-man.pdf