I believe if you join CX on the freighter fleet you join as a senior F/O, 2 and a half stripes. Middle F/O, don't know what that is. You join CX now as an S/O or Snr F/O on freighters. Takes about 1.5 to 2.5 years to be a Relief pilot which I just achieved!
(I'd like the thank the academy for nominating me as relief in the "Cathay Story, one pilot's dream")
I hope that after the merger with Air China and Dragon Air we change our name To Air Dragon Pacific and I get promoted to Senior Relief Political Officer. I'll have 3.5 stripes, a red star on my hat, a small goatee with braids and carry a large stick to flog all of the infidels and capitalist pigs. Hey that's just me though. Good luck.