WordPress at a glance
filter is not described

the_generator filter-hook . WP 2.5.0

Filters the output of the XHTML generator tag for display.

Usage

add_filter( 'the_generator', 'filter_function_name_9988', 10, 2 );
function filter_function_name_9988( $generator_type, $type ){
	// filter...

	return $generator_type;
}
$generator_type(string)
The generator output.
$type(string)
The type of generator to output. Accepts 'html', 'xhtml', 'atom', 'rss2', 'rdf', 'comment', 'export'.

Where the hook is called

the_generator()
the_generator
wp-includes/general-template.php 4118
echo apply_filters( 'the_generator', get_the_generator($type), $type ) . "\n";

Where the hook is used (in WP core)

Does not used.