| ERROR | The parameter type in an ORDER method must be the containing object type. |
| CAUSE | An order member function was declared without the user- specified parameter. Order member functions have two parameters, one is the default SELF parameter which is added by the compiler. the second parameter is added by the user and must declare an order method which must be the same type as the containing object type. |
| ACTION | Check and correct the way the parameter is specified. |