anchor.diff:  
   constructor TmFormulaField.Create;
   begin
  -  FDataType:= vftUnknown;
  +  FDataType:= fftFloat;
     FSize := 0;
     FName := '';
     FOnChangeName:= nil;
  
positive.code: interface
  
  uses
    Classes, contnrs,
    mVirtualFieldDefs, StrHashMap;
  
  type
  
    { TmFormulaField }
  
    TmFormulaField = class
    strict private
      FDataType : TVirtualFieldDefType;
      FSize : integer;
      FFormula : String;
      FName : string;
  
negative.code:   public
      constructor Create;
  
      property DataType : TmFormulaFieldType read FDataType write FDataType;
      property Size : integer read FSize write FSize;
      property Formula : string read FFormula write FFormula;
      property Name : string read FName write SetName;
  