If a modification package is downloaded using the Download a package by url option it is not subsequently listed on the 'Browse Packages' screen.
Also, if the modification is installed as part of the Download a package by url process it is only listed in the 'Installed Packages' screen.
As a result it is not possible to easily tell that a modification has been uploaded and/or installed and it is also not possible to list the contents of the modification package. Also, and even if the installed modification is uninstalled via the 'Installed Packages' screen, the modification package file cannot be deleted using the Package Manager.
Finally, when the modification package file is downloaded it is given a name like 'mod=\NNNN' instead of its actual modification package filename.