Special Functions
Module Development
You can choose to include contain three specially named functions that are automatically recognized and processed by the Core script: the installation, uninstallation and upgrade script. These allow standardized integration with the Form Tools script so that when the user performs one of those tasks, you can execute whatever code you need.
All three functions are optional. For simple modules, you may find you don't need any.
N.B. Your core module code can be procedural or object-oriented; it doesn't matter. However, these three must be functions. If you wrap it in a class or rename it, the code won't be executed.
Where are they located?
You can place these functions anywhere you want, but they must be included in your library.php file.