Ediff has variables to control the way fine differences are highlighted. This feature gives you control over the process of refinement. Note that refinement ignores spaces, tabs, and newlines.
On a slow machine, automatic refinement may be painful. In that case, you can turn auto-refining on or off interactively by typing @. You can also turn off display of refining that has already been done.
When auto-refining is off, fine differences are shown only for regions for which these differences have been computed and saved before. If auto-refining and display of refining are both turned off, fine differences are not shown at all.
Typing * computes and displays fine differences for the current
difference region, regardless of whether auto-refining is turned on.
You can always refine the current region by typing *.
Fine differences are computed by first splitting the current difference
region into words and then passing the result to
ediff-diff-program. For the default forward word function (which is
ediff-forward-word), a word is a string consisting of letters,
‘-’, or ‘_’; a string of punctuation symbols; a string of digits,
or a string consisting of symbols that are neither space, nor a letter.
This default behavior is controlled by four variables:
ediff-word-4. See the on-line documentation for these variables
and for the function
ediff-forward-word for an explanation of how to
modify these variables.
Sometimes, when a region has too many differences between the variants, highlighting of fine differences is inconvenient, especially on color displays. If that is the case, type * with a negative prefix argument. This unhighlights fine differences for the current region.
To unhighlight fine differences in all difference regions, use the command @. Repeated typing of this key cycles through three different states: auto-refining, no-auto-refining, and no-highlighting of fine differences.