TITLE: Track changes in LaTeX for reviewer comments
DATE: 2020-03-05
AUTHOR: John L. Godlee
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I have recently submitted a paper and got reviews back with minor
changes before publication, YAY! The journal thankfully supplied a
LaTeX template for writing the paper which made me very happy, so I
wrote the paper in LaTeX and have been using vimdiff to collaborate
with co-authors, for those co-authors who are willing to edit .tex
files, and using .pdf comments for those co-authors who are less
keen on LaTeX.

Now I have to reply to the reviewers’ comments and supply a revised
version of the manuscript. They recommend on the website using
“track changes” to make the changes clear in the manuscript, however
LaTeX doesn’t have this functionality, not being a WYSIWYG editor.
If I was being smarmy I would recommend they use a plain-text diff
utility, but that’s probably not a good way to make friends. So I am
now looking for a way to do “track changes” in LaTeX.

I have found a few notable options while searching the internet:

-   [latexdiff] - A Perl program which automatically diffs and
    highlights changes between 2 .tex files, conveniently includes
    --flatten if document is divided into separate files using
    \input or \include statements. See also [texdiff], a less
    complex option.
-   [changes] - A TeX package which allows manual markup with
    changes as comments in the gutter. Conveniently supplies the
    final option to the package declaration, which clears markup.
-   [changebar] - Adds simple highlighted bars where text has been
    changed.
-   [revdiff] - A LaTeX package which is built specifically with
    the goal of making the work of reviewers of papers easier by
    marking changes in the text, adding tags and comments.
-   Manually declare highlight options with \newcommand,
    e.g. \newcommand{\added}[1]{\color{added}{}#1}

  [latexdiff]: https://ctan.org/pkg/latexdiff
  [texdiff]: https://www.ctan.org/tex-archive/support/texdiff/
  [changes]: https://www.ctan.org/tex-archive/macros/latex/contrib/changes
  [changebar]: https://www.ctan.org/tex-archive/macros/latex/contrib/changebar/
  [revdiff]: https://github.com/pedromateo/revdiff-LaTeX

LaTeXDiff

This tool is handy because it automates most of the diff-ing between
two .tex files, providing simple red strikethrough lines when text
is removed and blue if text is added. I found that this small
utility doesn’t handle complex changes well though, and is best
suited to smaller edits like spelling and word choice. When whole
paragraphs start moving around, a manual commenting system is still
required, understandably.

I had some small issues getting this to run on the Windows machine I
am using while working away from home, but I found [this Stack
Overflow page very helpful in providing a solution]. I imagine
when I try it on a UNIX machine the process will be considerably
more streamlined as perl is already installed.

  [this Stack Overflow page very helpful in providing a solution]: https://tex.stackexchange.com/questions/165543/using-latexdiff-in-miktex

Changes

A manual change highlighter, which is well developed. I ran into a
few conflicts with definition of the \highlight command, which I
think came from the listings package, but this was solved by
redefining my lstlisting style.

This package adds:

-   \added and \deleted
-   \replaced
-   \highlight and \comment

It also provides the \listofchanges command which is similar to the
list of figures output.

It provides options to clear the markup using the final option in
the package declaration. There are a bunch of other package options
which change what markup is shown in the output .pdf.

RevDiff

revdiff is another manual change highlighter. I guess the value of
manual change highlighters is when a single author is preparing a
document to send back to reviewers, so they can see how you have
implemented changes. It comes with a few basic functions:

-   \rnew and \rold
-   \rchange
-   \rcomment, \rtcomment, \renclose and \rtenclose

It provides an option to remove markup and display the new version
with \usepackage[clean]{revdiff}.

The package requires you to download revdiff.sty and keep it
somewhere it can be foundby each project, like ~/.texmf/.

It’s unfortunate that comments appear inline rather than in the
gutter like “track changes”.

Manual:

If your needs are simple, it’s not difficult to create a couple of
custom commands which style the enclosed text to show if something
has been deleted or added. I’ve done this for a long time to add
TODO notes for myself, using:

    \newcommand{\todo}[1]{\textcolor{red}{\textbf{#1}}} 

Summary

The only option I found which didn’t give me any issues, and the one
I ended up using for this project, was revdiff, which contains the
minimum of commands I need and produces smart looking .pdf markup.

For future projects I think I will try and make sure that I will try
to incorporate latexdiff into my workflow from the start. If I
change my editing technique then latexdiff will be able to handle
all of this automatically. Possibly if I have one round of latexdiff
and then also use revdiff or changes to provide comments.