Adding a helpful use message to your application lets people receive an instant online reminder for command-line arguments and basic usage simply by typing use app_name.
Usage messages are plain text files, typically named app_name.use, which are located in the root of your application's project directory. For example, if you had the nodetime project open, its usage message might be in nodetime.use. This convention lets the recursive Makefile system automatically find your usage message data.
For information about writing usage messages, see usemsg in the Utilities Reference.