FIE stands for the Federation Internationale d'Escrime, which is the international governing body of modern fencing. They decide on all the rules, regulations, and all those other juicy morsels which we fencers generally ignore as much as possible. To further complicate things, the FIE's rules are superceded by the rules laid down by the national governing bodies (the United States Fencing Association, for example) except at an international competition.