ediff-word-4 is a variable defined in `ediff-diff.el'.
Its value is
"^-[:word:]_0-9.,`'?!:;\"{}[]()
\240"
Automatically becomes buffer-local when set.
Documentation:
Characters that constitute words of type 4.
More precisely, [ediff-word-4] is a regexp that matches type 4 words.
See `ediff-forward-word' for more details.