Just some thoughts in my uncaffeinated brain as I read this thread for the first time...
Horizontal vs. vertical? Wide vs. narrow? 1-up vs. N-up? Long-edge vs. short-edge? The 1-up vs. N-up is, to me, the most "accurate" as it somewhat describes a screen like paper and indicates fit N pages on a sheet -- or in this case, screen -- before moving on to the next sheet / screen. (Not quite a parallel to paper, as 4-up would not be 1 2 3 4 but rather 1 2 3 4 Long- vs. short- is, I think, well-understood by anyone doing duplex printing as to which way the pages flip. Again, not exactly completely analogous to paper, but easy to grasp the concept IF you print duplex...
