No examples of these have been found from after the mid-80s renaming exercise (the Canon and Facit typewriter examples at Deskthority are each from around 1982 and 1983 respectively), so this would make all of them KFF series, unless any of them pre-date the previous renaming exercise! Apple list them as KFF, and the Canon AP400 typewriter keyboard is model KFFBA010, again KFF series.
The full series supports integrated sprung LEDs and double action.