A program may track jobs that a developer needs to do. In the beginning your application simply lists the jobs, the order you need to do them in, and if they are completed. After you start using your program, you discover sometimes these jobs come from emails and they contain information required for the job. It can be helpfull to reference back to the email, so a new feature can be added to your job list "EMailRef". From experience you learn somtimes need to delegate a job to someone, so a "DelegateTo" column can be added.