protected function marshall(QtiComponent $component)
    {
        $element = static::getDOMCradle()->createElement($component->getQtiClassName());
        $this->setDOMElementAttribute($element, 'identifiers', implode("\x20", $component->getIdentifiers()->getArrayCopy()));
        
        $fixedIdentifiers = $component->getFixedIdentifiers();
        if (count($fixedIdentifiers) > 0) {
            $this->setDOMElementAttribute($element, 'fixedIdentifiers', implode("\x20", $component->getFixedIdentifiers()->getArrayCopy()));
        }

        return $element;
    }