anchor.diff:  
   procedure TJSONWriter.ValueNullInArray;
   begin
  -  valueInArray('null');
  +  raise Exception.Create('Need to override '+className+'.ValueNullInArray');
   end;
   
   procedure TJSONWriter.ValueNumber(const name, avalue: String);
  
positive.code:     ValueNullInArray
    Else
      FCache := JSONString(value);
  end;
  
  procedure TJsonWriterDirect.FinishObject;
  
negative.code:     Procedure ValueArray(Const name : String); override;
      Procedure FinishArray; override;
      Procedure ValueInArray(Const value : String); overload; override;
      procedure valueNullInArray; override;
    End;
  
    TCanonicalJsonNodeType = (jntProperty, jntObject, jntArray);
  