If I recall correctly, H0 terrain was used in second edition and caused some confusion (as 0 tends to do if you overthink it), so flat terrain was introduced in 3rd edition so that the concept could be handled better.
If I recall correctly, H0 terrain was used in second edition and caused some confusion (as 0 tends to do if you overthink it), so flat terrain was introduced in 3rd edition so that the concept could be handled better.