DOM/DOMXPathNavigator.php
public function getNamespaceURI()
	{
		if ( is_null( $this->domNode ) ) return null;
		return is_null( $this->domNode->namespaceURI ) ? "" : $this->domNode->namespaceURI;
	}
public function getNamespaceURI()
	{
		if ( is_null( $this->domNode ) ) return null;
		return is_null( $this->domNode->namespaceURI ) ? "" : $this->domNode->namespaceURI;
	}
public function getNamespaceURI ( ) { if ( is_null ( $ this -> domNode ) ) return null ; return is_null ( $ this -> domNode -> namespaceURI ) ? "" : $ this -> domNode -> namespaceURI ; }
When overridden in a derived class, gets the namespace URI of the current node.

@return string  A string that contains the namespace URI of the current node,
or Empty if the current node has no namespace URI.
When overridden in a derived class gets the namespace URI of the current node .