anchor.diff:    Result := TNullableInteger.VariantToString(Self.AsVariant);
   end;
   
  +function TNullableInteger.AsFormattedString(aFormat: String): String;
  +begin
  +  if Self.IsNull then
  +    Result := ''
  +  else
  +    Result := FormatFloat(aFormat, Self.Value);
  +end;
  +
   class function TNullableInteger.StringToVariant(const aValue: String): Variant;
   begin
     if IsNumeric(aValue, false) then
  
positive.code:     procedure Assign(const aValue : Variant); override; overload;
  
      function CheckIfDifferentAndAssign(const aValue : Variant) : boolean; override;
      function AsVariant : Variant; override;
      function AsString : String;
  
      class function StringToVariant(const aValue : String) : Variant;
      class function VariantToString(const aValue : Variant) : String;
  
negative.code: 
      function AsString : String;
      function AsFloat : Double;
      function AsFormattedString (aFormat: String): String;
  
      property Value : Double read GetValue write SetValue;
      property Digits : byte read FDigits write SetDigits;
  