anchor.diff:    FValue := aValue;
   end;
   
  -procedure TNullableBoolean.Assign(aSource: TNullableBoolean);
  +procedure TNullableBoolean.Assign(const aSource: TNullableBoolean);
   begin
     if not aSource.IsNull then
       Self.Value := aSource.Value
  
positive.code:   FTagChanged:= false;
  end;
  
  procedure TNullableInteger.Assign(aSourceField: TField);
  begin
    if aSourceField.IsNull then
      Self.IsNull:= true
  
negative.code:   Self.Value:= aValue;
  end;
  
  procedure TNullableString.Assign(const aSource: TNullableString);
  begin
    if not aSource.IsNull then
      Self.Value:= aSource.Value
  