Well it could indicate that, as in the LSWR Drummond 4-2-2-0's were the two driving axles were powered by their own sets of cylinders but there were no coupling rods between the drivers, or it could just indicate a simple *rigid* [1] load carrying non driving axle.
[1] as in not having side control springs etc. the class that springs to mind is the LNER E4's.
: : There's one odd-ball example which contradicts that. It's the Gresley W1 : which is generally referred to as a 4-6-4, but some learned scholars say : it's really a 4-6-2-2 as the four carrying wheels under the cab are not : connected in a conventional bogie. :
W1 *was* a 4-6-4 and always was, the rear truck did the same job as done on the A3's and 4's etc. but had to carry a lot greater weight due to the larger boiler carried, at varying times in it's history the loco was fitted with a booster on the rear trailing truck, which is were some of the confusion probably occurs.