-) "FD" refers just to the bayonet in combination with the arrangement of all the actuators

-) "FD-new" is used to distinguish between the older FD breechlock bayonet from the newer "true" bayonet-handling coupling. As indicated this is in first instance a handling/design issue. In same cases the optics are slightly different too.

-) "L" stands for very advanced (and expensive) optical designs within Canon's different lens ranges