-- done: C, Q, R
-- not done: 

--- From OpenMath ---
OMSEvaluators#"fieldname1" = new MutableHashTable;
OMSEvaluators#"fieldname1"#"Q" = QQ;
OMSEvaluators#"fieldname1"#"C" = CC;
OMSEvaluators#"fieldname1"#"R" = RR;
