host_danube/danube/page/default_introduction/default_introduction.php

<?php
class default_introduction extends SYSTEM\PAGE\Page {
    public function html(){
        $vars = \SYSTEM\PAGE\text::tag('danube');
        return SYSTEM\PAGE\replace::replaceFile((new PPAGE('default_introduction/tpl/introduction.tpl'))->SERVERPATH(), $vars);
    }
}