That's just old satellite abbreviations from the past. Still used on 4dtv and old timers.
The sats have been renamed or replaced by now. Mainly for 4dtv, you just know the position (degrees west) position by the abbreviation. Not really the satellite's name.
For instance "W-4" we know as amc-4 C-band "X4" we know as amc-4 KU band.