Automake will ignore these additions. There are some caveats to doing this. Although you can overload a target already used by Automake, it is often inadvisable, particularly in the topmost directory of a non-flat package. Automake will supplement the standard target with these user-supplied targets. It doesn't make sense to uninstall just data or just executables.
Some targets also have a way to run another target, called a hook , after their work is done.