From the microsoft-doku:
Theprefix will access the Win32 device namespace instead of
the Win32 file namespace. This is how access to physical disks and
volumes is accomplished directly, without going through the file
system, if the API supports this type of access. You can access many
devices other than disks this way (using the CreateFile and
DefineDosDevice functions, for example).
For example, if you want to open the system's serial communications
port 1, you can use "COM1" in the call to the CreateFile function.
This works because COM1–COM9 are part of the reserved names in the NT
namespace, although using theprefix will also work with these
Ok, I will answer my own question. There is a software called WinObj , with which one can see the information .