I. CORRECTIONS:
(1) The notation has square brackets for the old version:
[-old-]{+new+}
—I made several typos in the original post.
(2) The incantation is `git diff --word-diff=plain'.
II. NOTES:
(a) There is also --word-diff-regex="." marking differences at single character granularity.
(b) Sometimes I run `git diff' directly from the command line and sometimes from another environment, such as Emacs.
The defaults may vary.

