For example, suppose that another programmer makes a change to the /COPY file that contains the prototypes. When you request a rebuild of your application, any module or program that makes use of the /COPY file will be recompiled automatically. You will find out quickly if the changes to the /COPY file affect the calls or procedure interfaces in your application. If there are compilation errors, you can then decide whether to accept the change to prototypes to avoid these errors, or whether to change the call interface.