On Macintosh, the path. For example: KeyFilename=Notes:JForgo.ID
On UNIX, the path. For example: KeyFilename=/home/server1/notes/kbowker.id
On Windows, a drive letter, path, and file name. For example: KeyFileName=C:\Notes\DMccarrick.ID
Note for the Server ID used there is a ServerKeyFilename, this can ensure the server can run with another ID the the Client installed in the same directory.