JimL, according to puntosaurus, civilian traffic must abide by the minimum height rule and fly quadrantals; is he wrong or can you fly IFR outside CAS as long as you simply stay above safety altitude.
The military fly reversionary night flying at or above 500' msd or on NVG at any height - it is certainly not IFR (other than roads,railways etc
) but it's not called night VFR even though that is what it is.