/**
* Read properties from an XML input stream.
*/
-bool readProperties (istream &input, SGPropertyNode * start_node,
+void readProperties (istream &input, SGPropertyNode * start_node,
const string &base = "");
/**
* Read properties from an XML file.
*/
-bool readProperties (const string &file, SGPropertyNode * start_node);
+void readProperties (const string &file, SGPropertyNode * start_node);
/**
* Write properties to an XML output stream.
*/
-bool writeProperties (ostream &output, const SGPropertyNode * start_node);
+void writeProperties (ostream &output, const SGPropertyNode * start_node);
/**
* Write properties to an XML file.
*/
-bool writeProperties (const string &file, const SGPropertyNode * start_node);
+void writeProperties (const string &file, const SGPropertyNode * start_node);
/**