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## NAME

       latexdiff - determine and markup differences between two latex files



## SYNOPSIS

       latexdiff [ OPTIONS ] old.tex new.tex > diff.tex



## DESCRIPTION

       Briefly, latexdiff is a utility program to aid in the management of
revisions of latex documents. It compares two valid latex files, here
called "old.tex" and "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, ""%DIF >"" is appended to each added line, i.e. a
line present in "new.tex" but not in "old.tex".  Discarded lines
are deactivated by prepending ""%DIF <"". Changed blocks are preceded
by comment lines giving information about line numbers in the original
files.  Where there are insignificant differences, the resulting file
"diff.tex" will be similar to "new.tex".  At the end of the preamble,
the definitions for latexdiff markup commands are inserted.  In
differencing the main body of the text, latexdiff attempts to satisfy
the following guidelines (in order of priority):

1. If both "old.tex" and "new.tex" are valid LaTeX, then the resulting
"diff.tex" should also be valid LateX. (NB If a few plain TeX
commands are used within "old.tex" or "new.tex" then "diff.tex" is
not guaranteed to work but usually will).

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
"diff.tex".

3. If a changed passage contains text or text-producing commands, then
running "diff.tex" through LateX should produce output where added

4. Where there are insignificant differences, e.g. in the positioning
of line breaks, "diff.tex" should follow the formatting of "new.tex"

For differencing the same algorithm as 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, "\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 --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 "picture" and "DIFnomarkup" environments; see --config
option).  The latter environment ("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
"\begin{DIFnomarkup}" and "\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,

"\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 latexdiff begin with ""\DIF"".  Added
blocks containing words, commands or comments which are in "new.tex"
Discarded blocks are marked by "\DIFdelbegin" and "\DIFdelend".  Within
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 "{"
are marked by prepending ""%DIF > "".

Within deleted blocks text is highlighted with "\DIFdel".  Deleted
comments are marked by prepending ""%DIF < "".  Non-safe command and
curly braces within deleted blocks are commented out with
""%DIFDELCMD < "".



## OPTIONS

   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.

--type=markupstyle or -t markupstyle
Add code to preamble for selected markup style. This option defines
"\DIFadd" and "\DIFdel" commands.  Available styles:

CHANGEBAR CCHANGEBAR CULINECHBAR CFONTCBHBAR"

[ Default: "UNDERLINE" ]

--subtype=markstyle or -s markstyle
Add code to preamble for selected style for bracketing commands
(e.g. to mark changes in  margin). This option defines
commands.  Available styles: "SAFE MARGINAL DVIPSCOL"

[ Default: "SAFE" ]

--floattype=markstyle or -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 "\DIF...FL" commands.  Available

[ Default: "FLOATSAFE" ]

--encoding=enc or -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 or -p file
Insert file at end of preamble instead of generating preamble.  The
preamble must define the following commands "\DIFaddbegin,
this option is set -t, -s, and -f options are ignored.)

--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:

"amsmath"
Configuration variable amsmath is set to "align*" (Default:
"eqnarray*")

"endfloat"
Ensure that "\begin{figure}" and "\end{figure}" always
appear by themselves on a line.

"hyperref"
Change name of "\DIFadd" and "\DIFdel" commands to
"\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).

[ Default: scan the preamble for "\\usepackage" commands to
determine

--show-preamble
Print generated or included preamble commands to stdout.

Configuration
--exclude-safecmd=exclude-file or -A exclude-file or
--exclude-safecmd="cmd1,cmd2,..."
--replace-safecmd=replace-file
--append-safecmd=append-file or -a append-file or
--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 "\DIFadd" or "\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 --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-safecmd and --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.

--exclude-textcmd=exclude-file or -X exclude-file or
--exclude-textcmd="cmd1,cmd2,..."
--replace-textcmd=replace-file
--append-textcmd=append-file or -x append-file or
--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
--exclude-safecmd directly above for further details.

--replace-context1cmd=replace-file
--append-context1cmd=append-file or =item
--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-context1cmd=replace-file
--append-context2cmd=append-file or =item
--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,... or -c var1=val1,..
-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):

"MINWORDSBLOCK" (integer)

"FLOATENV" (RegEx)

"PICTUREENV" (RegEx)

"MATHENV" (RegEx)

"MATHREPL" (String)

"MATHARRENV" (RegEx)

"MATHARRREPL" (String)

"ARRENV" (RegEx)

"COUNTERCMD" (RegEx)

--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
Combine all --show commands.

NB For all --show commands, no "old.tex" or "new.tex" file needs to
be specified, and no differencing takes place.

Miscellaneous
--verbose or -V
Output various status information to stderr during processing.
Default is to work silently.

--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 "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.

--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).

--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.

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.

--help or -h
Show help text

--version
Show version number

Predefined styles
Major types
The major type determine the markup of plain text and some selected
latex commands outside floats by defining the markup commands

"UNDERLINE"
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).

Added text is blue and set in sans-serif, and a red footnote
is created for each discarded piece of text. (Requires color
package)

Like "CTRADITIONAL" but without the use of color.

"CFONT"   Added text is blue and set in sans-serif, and discarded text
is red and very small size.

"FONTSTRIKE"
struck out

"CCHANGEBAR"
the changed text is marked with a bar in the margin (Requires
color and changebar packages).

"CFONTCHBAR"
Like "CFONT" but with additional changebars (Requires color
and changebar packages).

"CULINECHBAR"
Like "UNDERLINE" but with additional changebars (Requires
color, ulem and changebar packages).

"CHANGEBAR"
No mark up of text, but mark margins with changebars
(Requires changebar package).

"INVISIBLE"
No visible markup (but generic markup commands will still be
inserted.

Subtypes
The subtype defines the commands that are inserted at the begin and end
\DIFdelbegin, \DIFdelend")

"SAFE"    No additional markup (Recommended choice)

"MARGIN"  Mark beginning and end of changed blocks with symbols in the
margin nearby (using the standard "\marginpar" command - note
that this sometimes moves somewhat from the intended
position.

"DVIPSCOL"
An alternative way of marking added passages in blue, and
deleted ones in red. Note that "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).

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.

"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 "MARGIN" as "\marginpar" does not work properly
within floats.

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 "TRADITIONAL" and
"CTRADITIONAL" markup types as the \footnote command does not
work properly in floating environments.

"IDENTICAL"
Make no difference between the main text and floats.

Configuration Variables
"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
parts.

[ Default: 3 ]

"FLOATENV"
Environments whose name matches the regular expression in
"FLOATENV" are considered floats.  Within these environments,
the latexdiff markup commands are replaced by their FL
variaties.

[ Default: "(?:figure|table|plate)[\w\d*@]*" ]

"PICTUREENV"
Within environments whose name matches the regular expression
in "PICTUREENV" all latexdiff markup is removed (in
pathologic cases this might lead to
inconsistent markup but this situation should be rare).

[ Default: "(?:picture|DIFnomarkup)[\w\d*@]*" ]

"MATHENV","MATHREPL"
If both \begin and \end for a math environment (environment
name matching "MATHENV" or $and$) are within the same
deleted block, they are replaced by a \begin and \end
commands for "MATHREPL" rather than being commented out.

[ Default: "MATHENV"="(?:displaymath|equation)" ,
"MATHREPL"="displaymath" ]

"MATHARRENV","MATHARRREPL"
as "MATHENV","MATHREPL" but for equation arrays

[ Default: "MATHARRENV"="eqnarray\*?" ,
"MATHREPL"="eqnarray" ]

"ARRENV"  If a match to "ARRENV" is found within an inline math
environment within a deleted or added block, then the inlined
math is surrounded by "\mbox{"..."}".  This is necessary as
underlining does not work within inlined array environments.

[ Default: "ARRENV"="(?:array|[pbvBV]matrix)".ie n .IP
"""COUNTERCMD""" 10 If a command in a deleted block which is
also in the textcmd list matches "COUNTERCMD" then an
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: "COUNTERCMD"="(?:footnote|part|section|subsection"
...

"|subsubsection|paragraph|subparagraph)"  ]



## 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 tilmann@esc.cam.ac.uk.  Include the serial
number of latexdiff (from comments at the top of the source or use
--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.



       latexrevise



## PORTABILITY

       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 latexdiff requires installation of the Perl
package "Algorithm::Diff" (available from www.cpan.org -
http://search.cpan.org/~nedkonz/Algorithm-Diff-1.15) but a stand-alone
version, latexdiff-so, which has this package inlined, is available,
too.  latexdiff-fast requires the diff command to be present.



## 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.