The FMS Zeroes are marked with an arrow on shrinkwrap(?) at the termination. I think I saw another thread here recently related to identifying FMS grey cables - it had a response from someone whom I took to be Alex Gibson (FMS owner/designer) or, if not he, someone very knowledge about the cables. You might look for that and send him an e-mail about your cables. Alex was always helpful whenever I communicated with him. Also, a Web address:
http://homepage.mac.com/fmscable/PhotoAlbum1.html
http://homepage.mac.com/fmscable/PhotoAlbum1.html