Example to understand this function and difference with call_user_func:

<?php
class Beer {
    const NAME = 'Beer!';
    public static function printed(){
        echo 'static Beer:NAME = '. static::NAME . PHP_EOL;
    }
}

class Ale extends Beer {
    const NAME = 'Ale!';
    public static function printed(){
        forward_static_call(array('parent','printed'));
        call_user_func(array('parent','printed'));

        forward_static_call(array('Beer','printed'));
        call_user_func(array('Beer','printed'));
    }
}

Ale::printed();
echo '</pre>';
?>