sorry, i failed to express clearly what i meant. maybe that's because of my lousy english, i'm just a kraut. i'll try my best to correct my mistake:
what i meant was to show places where it's obvious for a normal player who doesn't edit levels or analyse them with tools of any kind that there is such a 5d-space where you can go to the same place using 2 ways. of course this means x, y and z, for example the corridor crossing right through the hall in 'this side towards enemy'.
btw - i found another one: in the eastern maze in 'smells like napalm...' there's one, too. i always thought it's just 2 corridors overlapping, but they actually cross each other (if i'm wrong please correct me).