Searches the working file for keyword values to determine its revision number, creation date, state, and author (see co(1)), and assigns these values to the deposited revision, rather than computing them locally. It also generates a default login message noting the login of the caller and the actual checkin date. This option is useful for software distribution. A revision that is sent to several sites should be checked in with the -k option at these sites to preserve the original number, date, author, and state. The extracted keyword values and the default log message can be overridden with the options -d, -m, -s, -w, and any option that carries a revision number.