Normally, the key is converted to lowercase before being stored in the database makemap. When the key entries are case-sensitive, the -f switch is used by makemap to prevent conversion to lowercase. This -f command-line switch causes editmap to match that behavior when looking up a key. When the -f is absent, the key specified in the command line is converted to lowercase before it is looked up. If the -f is present, the key is looked up as is.

In general, if the configuration file's corresponding K command for a database uses the -f, you should also use -f when running editmap on that database file.