public function scanChild($lang)
    {
        assert(isset($this->childScanners[$lang]));
        $scanner = $this->childScanners[$lang];
        $scanner->pos($this->pos());
        $substr = $scanner->main();
        $this->record($scanner->tagged(), 'XML', true);
        $this->pos($scanner->pos());
        if ($scanner->interrupt) {
            $this->childState = array($lang, $this->pos());
        } else {
            $this->childState = null;
        }
    }