Well, I haven't seen that before. The closest thing I can think of it HTML (and DOS, and *nix, when you get down to it) notation for relative directories, which doesn't quite seem to make sense in that context.

(I.E. With two periods meaning the prev directory, and one period meaning th ecurrent directory, so http://blah.com/dir1/dir2/../ is the same as http://blah.com/dir1/ )