anchor.diff:      property FileSystem : TAbGzFileSystem {Default: osFat (Windows); osUnix (Linux)}
         read GetFileSystem write SetFileSystem;
   
  -    property ExtraField : AnsiString
  -      read FExtraField write SetExtraField;
  +    property ExtraField : TAbGzipExtraField
  +      read FExtraField;
   
       property IsEncrypted : Boolean
         read GetIsEncrypted;
  
positive.code: {$ENDIF MSWINDOWS }
  end;
  
  function TAbGzipItem.GetExternalFileAttributes: LongInt;
  begin
    { GZip has no provision for storing attributes }
  
negative.code: 
    FileName := '';
    FFileComment := '';
    FExtraField := TAbGzipExtraField.Create(@FGzHeader);
  
    { source OS ID }
  {$IFDEF LINUX } {assume EXT2 system }
  