Used to call the registered callback for a plugin screen.
This hook uses a dynamic hook name,
$page_hook, which refers to a mixture of plugin
page information including:
- The page type. If the plugin page is registered as a submenu page, such as for Settings, the page type would be 'settings'. Otherwise the type is 'toplevel'.
- A separator of 'page'.
- The plugin basename minus the file extension.
Together, the three parts form the
$page_hook. Citing the example above,
the hook name used would be 'settings_page_pluginbasename'.