Random thoughts: One, I had that Mars map from 1972. On the back of it was a really cool painting of a sandstorm plume rising up into a mostly black Martian sky. I used to stare at that for hours thinking, one day.... Two, the Z axis thing is shared with Star Trek, as well. Remember the scene in Wrath of Khan when Kirk outsmarts Khan by ordering the Enterprise to drop below the flat plane that Reliant was flying in? "Z minus 1000 meters" I think was the command. It was "Z," regardless of the number of meters, though. Welcome to Carrara! - Dex