Many times I've come across that there is an "X" added to the end of network-related names on equipment, like how copper cables have wires in them called TX and RX, and ports on switches can have names like "100BASE-FX". Why is the X there? Does it mean anything?
Optical link that uses short wavelength (850 nm) lasers over two FDDI grade multimode optical Fibers, with eXternal sourced coding. Supports up to at least 2 km.
So, F=fiber, X=external sourced coding