# [NTG-context] visualising evolution from one version to another

Sun Aug 6 15:41:58 CEST 2006

On Sun, 6 Aug 2006, Peter Münster wrote:

> Hello,
> if you know a bit MS-Word, then you have seen perhaps the feature, that
> permits visualising differences between 2 versions of a document: added
> text in red, and deleted text stroke out.
>
> I would like to make something similar with ConTeXt: making a pdf-file from
> doc-versionX.tex and doc-versionY.tex with added text in some colour and
> deleted text displayed with \overstrikes{}.
>
> Do you have some ideas, how to do that?

There was a latex package with a perl script that did something like
that. But I found it to be too cumbersome to use. If you are just
using plain text, then it is easy to identify and mark what has
changed. But what should happen if you change markup? What if a \bf is
changed to \it or a \framed is added around a bit of text?
Marking differences in math is altogether a different story. For small
documents (~10 pages) I found it easier to copy version2 by another
name, diff the two files in an editor, and add the markup by hand. (I
actualy had a macro to mark the change, so it was just pressing one of
three keystokes). With context, you can have \DIFFdeleted,
\DIFFchanged{before}{after} \DIFFadded with these expanding to the
default MS word look and feel for changed files.

There are various diff programs, but I feel that for something
slightly complicated, it is very hard to do identify the changes in a
sensible way automatically. YMMV.