FT terminology

Pre-2007 NCW on 747s: two configurations, either 38 or 70 seats in Club World, called Lo-J and Hi-J (or 38J and 70J) respectively.

Until today, when the 747s were being converted to NNCW, the 70J would still have 70 J seats, but the 38J would be reconfigured by putting WT+ in front of CW which would enable 52 CW seats to be fitted. 52 is between 38 and 70 hence 52J was termed Mid-J. But now it seems it'll be no more.

I agree with the above poster - IMO they could very likely decide to configure all the 744s as 70J and use 777s on the lower-J routes.