The ARRL reports that its Logbook of the World (LoTW) committee has worked with WSJT developer Joe Taylor, K1JT, "to harmonize the designation of FST4 among WSJT-X, the ADIF standard and LoTW," to make sure contacts using that mode are properly recorded. FST4 and FST4W are WSJT-X modes designed primarily for use on 630 and 2200 meters, to accomodate the unique characteristics of the MF and LF portions of the spectrum.
|FST4 waterfall (from K1JT website)|
The ARRL Letter also reports that Taylor has expressed "puzzlement" over why anyone would use FT8 in a contest rather than FT4, which was designed specifically for contest use. Taylor reportedly told the Mt. Airy VHF Society's Cheese Bits newsletter, "I fail to understand why anyone who uses FT8 in a contest would fail to use FT4 for much of the time," adding, "FT4 is about 3 dB less sensitive than FT8, but it's twice as fast."