if (node) return node->get(attr_name); else return XS_String();
if (!node) { node = new XMLNode(name); add_child(node); }  return (*node)[attr_name];
	XS_String subvalue(const XS_String& name, const XS_String& attr_name, int n=0) const	{		const XMLNode* node = find(name, n);		if (node)			return node->get(attr_name);		else			return XS_String();	}