What does controlfile.RB do?

I was asked by some colleagues of mine what this file is. It is located in
the Temporary internet files and reappears when it is deleted. Now a google
search only shows one answer and that is that it appears when Windows Update
is activated. I'm willing to accept that its some kind of tagging or marker
for BITS (my Wild Ass Guess)
But I'd like to have to have some confirmation from someone in the know.


--
In theory, there's no difference between theory and practice, but in
practice, there is.