anchor.diff:      procedure Assign(const aValue: variant); overload; virtual; abstract;
   
       function CheckIfDifferentAndAssign(const aValue : Variant) : boolean; virtual; abstract;
  +    function AsString: String; virtual; abstract;
   
       property IsNull: Boolean read FIsNull write FIsNull;
       property NotNull: Boolean read GetNotNull;
  
positive.code: 
      function CheckIfDifferentAndAssign(const aValue : Variant) : boolean; override;
  
      function AsString : String;
      function AsFloat : Double;
      function AsFormattedString (aFormat: String): String;
  
  
negative.code:     procedure Assign(const aValue : String); override; overload;
      function CheckIfDifferentAndAssign(const aValue : Variant) : boolean; override;
      function AsVariant : Variant; override;
      function AsString : String; override;
  
      property Value : TColor read GetValue write SetValue;
    end;
  