protected function getTemplateQtiVariables(){

        $variables = parent::getTemplateQtiVariables();

        $tag = static::$qtiTagName;

        //search existing mathML ns declaration:
        $ns = $this->getXIncludeNamespace();
        if(empty($ns)){
            //add one!
            $relatedItem = $this->getRelatedItem();
            if(!is_null($relatedItem)){
                $ns = 'xi';
                $relatedItem->addNamespace($ns, 'http://www.w3.org/2001/XInclude');
            }
        }
        if(!empty($ns)){
            //proceed to ns addition:
            $tag = $ns.':'.$tag;
        }

        $variables['tag'] = $tag;

        return $variables;
    }