Around 1992, I checked out a great little program for change tracking (by a crowd based in or called Cambridge). Microsoft Word soon incorporated minimal change tracking functionality (what we have now), and they disappeared, AFAIK.
To give an idea of what they offered, if you moved a chunk of text from one place to another, the software would show deleted source, inserted target, and a CURVED ARROW linking the two locations.
Incidentally, a shout-out to Woody Leonhard, who wrote an absolutely great book called "Hacker's Guide to Word for Windows" (1994), an amazing guide to the absolute mess that was WordBasic.
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