anchor.diff:        Self.InternalSetValue(tmpDate);
     end;
     SetTagChanged(SavedIsUnassigned or Result or GetTagChanged);
  +end;
  +
  +function TNullableDateTime.YearOf: variant;
  +begin
  +  if Self.NotNull then
  +    Result := dateutils.YearOf(Self.Value)
  +  else
  +    Result := null;
   end;
   
   class function TNullableDateTime.StringToVariant(const aValue: String): Variant;
  
positive.code: implementation
  
  uses
    SysUtils {$IFDEF FPC}, LazUtf8{$ENDIF};
  
  { TNullableValue }
  
  
negative.code:       procedure Assign (const aSource : TNullableDateTimeRecord); overload;
        function AsVariant: Variant; override;
        function CheckIfDifferentAndAssign(const aValue: Variant): boolean; override;
        function YearOf: variant;
  
        class function StringToVariant(const aValue : String): Variant;
        class function VariantToString(const aValue: Variant; const aShowTime: boolean): String;
  