Описание
DOMDocumentFragment
bool appendXML
( string $data
)
Appends raw XML data to a DOMDocumentFragment.
This method is not part of the DOM standard. It was created as a simplier
approach for appending an XML DocumentFragment in a DOMDocument.
If you want to stick to the standards, you will have to create a temporary
DOMDocument with a dummy root and then loop through the child nodes of the
root of your XML data to append them.