When I had opened msoffice file that I had previously saved on my desktop, I saw another kind of file named ~$doc. What type of file is this ?
I have marked both the files.
It's a temporary file that disappears when you close Word.
This particular file is actually an Owner File.
From that KB article:
Actually, it is a temporary "lock" for the file that you are writting.
If someone else try to edit the same file(if you are editing a file on a network share for example), this lock will disallow simultaneous editions. Here is a quick reference.