When you save whole document:
DOMDocument->saveXML() produces string in encoding defined in property DOMDocument->encoding.
When you save only one node:
DOMDocument->saveXML(DOMNode) produces always string in UTF-8.
When you save whole document:
DOMDocument->saveXML() produces string in encoding defined in property DOMDocument->encoding.
When you save only one node:
DOMDocument->saveXML(DOMNode) produces always string in UTF-8.