public function toXML(DOMElement $parent = null) : DOMElement
    {
        $element = parent::toXML($parent);

        if ($this->Format !== null) {
            $element->setAttribute('Format', $this->Format);
        }

        if ($this->SPProvidedID !== null) {
            $element->setAttribute('SPProvidedID', $this->SPProvidedID);
        }

        $value = $element->ownerDocument->createTextNode($this->value);
        $element->appendChild($value);

        return $element;
    }