Generate only keyword names in keyword strings; omit their values. See KEYWORD SUBSTITUTION below. For example, for the Revision keyword, generate the string $Revision$ instead of $Revision: 5.13 $. This option is useful to ignore differences due to keyword substitution when comparing different revisions of a file. Log messages are inserted after $Log$ keywords even if -kk is specified, since this tends to be more useful when merging changes.