Windows 7: ftype in command prompt

I was wondering why the "ftype" command doesn't display all file types associated with file extensions.

For example if I execute "assoc", some of the output is
.txt=txtfile
...
.RDP=RDP.File

When I execute the "ftype" I find an entry for "txtfile" as per below but not for "RDP".file
txtfile=%SystemRoot%\system32\NOTEPAD.EXE %1

How come?

Note: .RDP files are remote desktop files and are opened with %windir%\system32\mstsc.exe

Thanks!

Ftype shows the Open command string, if there is one, for a file type. If you look at .rdp in the root classes hive of the registry, you'll see that there is no 'open' command, as such, for RDP files.

txt files are opened with Notepad, as you know; but RDP files are nont 'opened' in the same way. That's my guess...

More info on ftype: Ftype