anchor.diff:  procedure TmCustomVirtualDataset.BeforeDestruction;
   begin
     FModifiedFields.Free;
  -//  FMasterDataLink.Free;
     FSortManager.Free;
     FFilterManager.Free;
     FSummaryManager.Free;
  
positive.code:       AVariant := {$IFDEF FPC}(PInteger(ABuffer)^ = 1){$ELSE}WordBool(ABuffer^){$ENDIF};
      ftFloat, ftCurrency:
        AVariant := Double(ABuffer^);
      ftBlob, ftMemo, ftGraphic, ftWideMemo:
        AVariant := Variant(ABuffer^);
      ftDate, ftTime, ftDateTime:
        if ANativeFormat then
          DataConvert(AField, ABuffer, @TVarData(AVariant).VDate, False)
  
negative.code:     property Active;
      property Filtered;
      property ReadOnly;
  
      property AfterCancel;
      property AfterClose;
  