protected function getHeaderAdditions($header)
    {
        $insert = '';
        if ($this->injectDate) {
            $insert .= $this
                ->createTag($this->injectDate, (string)$header->datestamp);
        }
        if (isset($header->setSpec)
            && ($this->injectSetSpec || $this->injectSetName)
        ) {
            $insert .= $this->getHeaderSetAdditions($header->setSpec);
        }
        if ($this->injectHeaderElements) {
            foreach ($this->injectHeaderElements as $element) {
                if (isset($header->$element)) {
                    $insert .= $header->$element->asXML();
                }
            }
        }
        return $insert;
    }