@david_2018
Sorry if I'm making heavy weather of this, but I'm still confused. In post #25 DaveX said "To find the first set of 880, while excluding reflections and rotations, you'd have to do something more interesting than this code's exhaustive search."
By 'this code'? I assumed he meant jremington's serial-only version? Implying that those 880 were not unique. And in post #28 he seemed to reinforce that with "You can't use the first 880 solutions generated by this code as the unique set to reflect and rotate."
So, are the 880 unique or not? By 'unique' I mean not one of the 6,160 others obtained by up to three rotations or vertical or horizontal mirroring.
I had assumed until post #25 that they were unique. Hence my post #26 and the surprise I expressed in #28.