int getSetType() throws Exception {			
      int sum = 0;
      int type = -1;
      if (nominal) { sum ++; type = Attribute.NOMINAL; }
      if (numeric) { sum ++; type = Attribute.NUMERIC; }
      if (string) { sum ++; type = Attribute.STRING; }
      if (date) { sum ++; type = Attribute.DATE; }
      if (relational) { sum ++; type = Attribute.RELATIONAL; }
      if (sum > 1)
	throw new Exception("Expected to have only one type set used wrongly.");
      if (type < 0)
	throw new Exception("No type set.");
      return type;
    }