anchor.diff:      if Result then
         Self.InternalSetValue(tmpDate);
     end;
  -  SetTagChanged(Result or GetTagChanged);
  +  SetTagChanged(SavedIsUnassigned or Result or GetTagChanged);
   end;
   
   class function TNullableDateTime.StringToVariant(const aValue: String): Variant;
  
positive.code: function TNullableDouble.CheckIfDifferentAndAssign(const aValue: Variant): boolean;
  var
    tmpDouble : double;
  begin
    if VarIsNull(aValue) then
    begin
      Result := Self.NotNull;
  
negative.code:     procedure Subtract(const aValue : double); overload;
      procedure Subtract(const aValue : TNullableDouble); overload;
  
      class function StringToVariant(const aValue: String): Variant;
      class function VariantToString(const aValue: Variant; const aDisplayFormat : string): String;
  
  