vtkCxxSetObjectMacro(vtkMedFieldStep, ParentField, vtkMedField);
vtkCxxSetObjectMacro(vtkMedFieldStep, PreviousStep, vtkMedFieldStep);
vtkCxxSetObjectMacro(vtkMedFieldStep, ParentField, vtkMedField);
vtkCxxSetObjectMacro(vtkMedFieldStep, PreviousStep, vtkMedFieldStep);